Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

34 files changed, 18893 insertions, 0 deletions

diff --git a/js/src/irregexp/imported/gen-regexp-special-case.cc b/js/src/irregexp/imported/gen-regexp-special-case.cc
new file mode 100644
index 0000000000..8f6557ed30
--- /dev/null
+++ b/js/src/irregexp/imported/gen-regexp-special-case.cc
@@ -0,0 +1,214 @@
+// Copyright 2020 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <fstream>
+#include <iomanip>
+#include <iostream>
+#include <sstream>
+
+#include "irregexp/imported/special-case.h"
+#include "unicode/usetiter.h"
+
+namespace v8 {
+namespace internal {
+
+static const base::uc32 kSurrogateStart = 0xd800;
+static const base::uc32 kSurrogateEnd = 0xdfff;
+static const base::uc32 kNonBmpStart = 0x10000;
+
+// The following code generates "src/regexp/special-case.cc".
+void PrintSet(std::ofstream& out, const char* name,
+              const icu::UnicodeSet& set) {
+  out << "icu::UnicodeSet Build" << name << "() {\n"
+      << "  icu::UnicodeSet set;\n";
+  for (int32_t i = 0; i < set.getRangeCount(); i++) {
+    if (set.getRangeStart(i) == set.getRangeEnd(i)) {
+      out << "  set.add(0x" << set.getRangeStart(i) << ");\n";
+    } else {
+      out << "  set.add(0x" << set.getRangeStart(i) << ", 0x"
+          << set.getRangeEnd(i) << ");\n";
+    }
+  }
+  out << "  set.freeze();\n"
+      << "  return set;\n"
+      << "}\n\n";
+
+  out << "struct " << name << "Data {\n"
+      << "  " << name << "Data() : set(Build" << name << "()) {}\n"
+      << "  const icu::UnicodeSet set;\n"
+      << "};\n\n";
+
+  out << "//static\n"
+      << "const icu::UnicodeSet& RegExpCaseFolding::" << name << "() {\n"
+      << "  static base::LazyInstance<" << name << "Data>::type set =\n"
+      << "      LAZY_INSTANCE_INITIALIZER;\n"
+      << "  return set.Pointer()->set;\n"
+      << "}\n\n";
+}
+
+void PrintSpecial(std::ofstream& out) {
+  icu::UnicodeSet current;
+  icu::UnicodeSet special_add;
+  icu::UnicodeSet ignore;
+  UErrorCode status = U_ZERO_ERROR;
+  icu::UnicodeSet upper("[\\p{Lu}]", status);
+  CHECK(U_SUCCESS(status));
+
+  // Iterate through all chars in BMP except surrogates.
+  for (UChar32 i = 0; i < static_cast<UChar32>(kNonBmpStart); i++) {
+    if (i >= static_cast<UChar32>(kSurrogateStart) &&
+        i <= static_cast<UChar32>(kSurrogateEnd)) {
+      continue;  // Ignore surrogate range
+    }
+    current.set(i, i);
+    current.closeOver(USET_CASE_INSENSITIVE);
+
+    // Check to see if all characters in the case-folding equivalence
+    // class as defined by UnicodeSet::closeOver all map to the same
+    // canonical value.
+    UChar32 canonical = RegExpCaseFolding::Canonicalize(i);
+    bool class_has_matching_canonical_char = false;
+    bool class_has_non_matching_canonical_char = false;
+    for (int32_t j = 0; j < current.getRangeCount(); j++) {
+      for (UChar32 c = current.getRangeStart(j); c <= current.getRangeEnd(j);
+           c++) {
+        if (c == i) {
+          continue;
+        }
+        UChar32 other_canonical = RegExpCaseFolding::Canonicalize(c);
+        if (canonical == other_canonical) {
+          class_has_matching_canonical_char = true;
+        } else {
+          class_has_non_matching_canonical_char = true;
+        }
+      }
+    }
+    // If any other character in i's equivalence class has a
+    // different canonical value, then i needs special handling.  If
+    // no other character shares a canonical value with i, we can
+    // ignore i when adding alternatives for case-independent
+    // comparison.  If at least one other character shares a
+    // canonical value, then i needs special handling.
+    if (class_has_non_matching_canonical_char) {
+      if (class_has_matching_canonical_char) {
+        special_add.add(i);
+      } else {
+        ignore.add(i);
+      }
+    }
+  }
+
+  // Verify that no Unicode equivalence class contains two non-trivial
+  // JS equivalence classes. Every character in SpecialAddSet has the
+  // same canonical value as every other non-IgnoreSet character in
+  // its Unicode equivalence class. Therefore, if we call closeOver on
+  // a set containing no IgnoreSet characters, the only characters
+  // that must be removed from the result are in IgnoreSet. This fact
+  // is used in CharacterRange::AddCaseEquivalents.
+  for (int32_t i = 0; i < special_add.getRangeCount(); i++) {
+    for (UChar32 c = special_add.getRangeStart(i);
+         c <= special_add.getRangeEnd(i); c++) {
+      UChar32 canonical = RegExpCaseFolding::Canonicalize(c);
+      current.set(c, c);
+      current.closeOver(USET_CASE_INSENSITIVE);
+      current.removeAll(ignore);
+      for (int32_t j = 0; j < current.getRangeCount(); j++) {
+        for (UChar32 c2 = current.getRangeStart(j);
+             c2 <= current.getRangeEnd(j); c2++) {
+          CHECK_EQ(canonical, RegExpCaseFolding::Canonicalize(c2));
+        }
+      }
+    }
+  }
+
+  PrintSet(out, "IgnoreSet", ignore);
+  PrintSet(out, "SpecialAddSet", special_add);
+}
+
+void PrintUnicodeSpecial(std::ofstream& out) {
+  icu::UnicodeSet non_simple_folding;
+  icu::UnicodeSet current;
+  UErrorCode status = U_ZERO_ERROR;
+  // Look at all characters except white spaces.
+  icu::UnicodeSet interestingCP(u"[^[:White_Space:]]", status);
+  CHECK_EQ(status, U_ZERO_ERROR);
+  icu::UnicodeSetIterator iter(interestingCP);
+  while (iter.next()) {
+    UChar32 c = iter.getCodepoint();
+    current.set(c, c);
+    current.closeOver(USET_CASE_INSENSITIVE).removeAllStrings();
+    CHECK(!current.isBogus());
+    // Remove characters from the closeover that have a simple case folding.
+    icu::UnicodeSet toRemove;
+    icu::UnicodeSetIterator closeOverIter(current);
+    while (closeOverIter.next()) {
+      UChar32 closeOverChar = closeOverIter.getCodepoint();
+      UChar32 closeOverSCF = u_foldCase(closeOverChar, U_FOLD_CASE_DEFAULT);
+      if (closeOverChar != closeOverSCF) {
+        toRemove.add(closeOverChar);
+      }
+    }
+    CHECK(!toRemove.isBogus());
+    current.removeAll(toRemove);
+
+    // The current character and its simple case folding are also always OK.
+    UChar32 scf = u_foldCase(c, U_FOLD_CASE_DEFAULT);
+    current.remove(c);
+    current.remove(scf);
+
+    // If there are any characters remaining, they were added due to full case
+    // foldings and shouldn't match the current charcter according to the spec.
+    if (!current.isEmpty()) {
+      // Ensure that the character doesn't have a simple case folding.
+      // Otherwise the current approach of simply removing the character from
+      // the set before calling closeOver won't work.
+      CHECK_EQ(c, scf);
+      non_simple_folding.add(c);
+    }
+  }
+  CHECK(!non_simple_folding.isBogus());
+
+  PrintSet(out, "UnicodeNonSimpleCloseOverSet", non_simple_folding);
+}
+
+void WriteHeader(const char* header_filename) {
+  std::ofstream out(header_filename);
+  out << std::hex << std::setfill('0') << std::setw(4);
+  out << "// Copyright 2020 the V8 project authors. All rights reserved.\n"
+      << "// Use of this source code is governed by a BSD-style license that\n"
+      << "// can be found in the LICENSE file.\n\n"
+      << "// Automatically generated by regexp/gen-regexp-special-case.cc\n\n"
+      << "// The following functions are used to build UnicodeSets\n"
+      << "// for special cases where the case-folding algorithm used by\n"
+      << "// UnicodeSet::closeOver(USET_CASE_INSENSITIVE) does not match\n"
+      << "// the algorithm defined in ECMAScript 2020 21.2.2.8.2 (Runtime\n"
+      << "// Semantics: Canonicalize) step 3.\n\n"
+      << "#ifdef V8_INTL_SUPPORT\n"
+      << "#include \"src/base/lazy-instance.h\"\n\n"
+      << "#include \"src/regexp/special-case.h\"\n\n"
+      << "#include \"unicode/uniset.h\"\n"
+      << "namespace v8 {\n"
+      << "namespace internal {\n\n";
+
+  PrintSpecial(out);
+  PrintUnicodeSpecial(out);
+
+  out << "\n"
+      << "}  // namespace internal\n"
+      << "}  // namespace v8\n"
+      << "#endif  // V8_INTL_SUPPORT\n";
+}
+
+}  // namespace internal
+}  // namespace v8
+
+int main(int argc, const char** argv) {
+  if (argc != 2) {
+    std::cerr << "Usage: " << argv[0] << " <output filename>\n";
+    std::exit(1);
+  }
+  v8::internal::WriteHeader(argv[1]);
+
+  return 0;
+}
diff --git a/js/src/irregexp/imported/property-sequences.cc b/js/src/irregexp/imported/property-sequences.cc
new file mode 100644
index 0000000000..b37ec63115
--- /dev/null
+++ b/js/src/irregexp/imported/property-sequences.cc
@@ -0,0 +1,1246 @@
+// Copyright 2018 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifdef V8_INTL_SUPPORT
+
+#include "irregexp/imported/property-sequences.h"
+
+namespace v8 {
+namespace internal {
+
+/*
+Generated from following Node.js source:
+
+package.json
+
+```
+{
+  "private": true,
+  "dependencies": {
+    "unicode-12.0.0": "^0.7.9"
+  }
+}
+```
+
+generate-unicode-sequence-property-data.js
+
+```
+const toHex = (symbol) => {
+  return '0x' + symbol.codePointAt(0).toString(16)
+                      .toUpperCase().padStart(6, '0');
+};
+
+const generateData = (property) => {
+  const sequences =
+      require(`unicode-12.0.0/Sequence_Property/${ property }/index.js`);
+  const id = property.replace(/_/g, '') + 's';
+  const buffer = [];
+  for (const sequence of sequences) {
+    const symbols = [...sequence];
+    const codePoints = symbols.map(symbol => toHex(symbol));
+    buffer.push('    ' + codePoints.join(', ') + ', 0,');
+  }
+  const output =
+      `const base::uc32 UnicodePropertySequences::k${ id }[] = {\n` +
+      `${ buffer.join('\n') }\n    0  // null-terminating the list\n};\n`;
+  return output;
+};
+
+const properties = [
+  'Emoji_Flag_Sequence',
+  'Emoji_Tag_Sequence',
+  'Emoji_ZWJ_Sequence',
+];
+
+for (const property of properties) {
+  console.log(generateData(property));
+}
+```
+*/
+
+// clang-format off
+const base::uc32 UnicodePropertySequences::kEmojiFlagSequences[] = {
+    0x01F1E6, 0x01F1E8, 0,
+    0x01F1FF, 0x01F1FC, 0,
+    0x01F1E6, 0x01F1EA, 0,
+    0x01F1E6, 0x01F1EB, 0,
+    0x01F1E6, 0x01F1EC, 0,
+    0x01F1E6, 0x01F1EE, 0,
+    0x01F1E6, 0x01F1F1, 0,
+    0x01F1E6, 0x01F1F2, 0,
+    0x01F1E6, 0x01F1F4, 0,
+    0x01F1E6, 0x01F1F6, 0,
+    0x01F1E6, 0x01F1F7, 0,
+    0x01F1E6, 0x01F1F8, 0,
+    0x01F1E6, 0x01F1F9, 0,
+    0x01F1E6, 0x01F1FA, 0,
+    0x01F1E6, 0x01F1FC, 0,
+    0x01F1E6, 0x01F1FD, 0,
+    0x01F1E6, 0x01F1FF, 0,
+    0x01F1E7, 0x01F1E6, 0,
+    0x01F1E7, 0x01F1E7, 0,
+    0x01F1E7, 0x01F1E9, 0,
+    0x01F1E7, 0x01F1EA, 0,
+    0x01F1E7, 0x01F1EB, 0,
+    0x01F1E7, 0x01F1EC, 0,
+    0x01F1E7, 0x01F1ED, 0,
+    0x01F1E7, 0x01F1EE, 0,
+    0x01F1E7, 0x01F1EF, 0,
+    0x01F1E7, 0x01F1F1, 0,
+    0x01F1E7, 0x01F1F2, 0,
+    0x01F1E7, 0x01F1F3, 0,
+    0x01F1E7, 0x01F1F4, 0,
+    0x01F1E7, 0x01F1F6, 0,
+    0x01F1E7, 0x01F1F7, 0,
+    0x01F1E7, 0x01F1F8, 0,
+    0x01F1E7, 0x01F1F9, 0,
+    0x01F1E7, 0x01F1FB, 0,
+    0x01F1E7, 0x01F1FC, 0,
+    0x01F1E7, 0x01F1FE, 0,
+    0x01F1E7, 0x01F1FF, 0,
+    0x01F1E8, 0x01F1E6, 0,
+    0x01F1E8, 0x01F1E8, 0,
+    0x01F1E8, 0x01F1E9, 0,
+    0x01F1E8, 0x01F1EB, 0,
+    0x01F1E8, 0x01F1EC, 0,
+    0x01F1E8, 0x01F1ED, 0,
+    0x01F1E8, 0x01F1EE, 0,
+    0x01F1E8, 0x01F1F0, 0,
+    0x01F1E8, 0x01F1F1, 0,
+    0x01F1E8, 0x01F1F2, 0,
+    0x01F1E8, 0x01F1F3, 0,
+    0x01F1E8, 0x01F1F4, 0,
+    0x01F1E8, 0x01F1F5, 0,
+    0x01F1E8, 0x01F1F7, 0,
+    0x01F1E8, 0x01F1FA, 0,
+    0x01F1E8, 0x01F1FB, 0,
+    0x01F1E8, 0x01F1FC, 0,
+    0x01F1E8, 0x01F1FD, 0,
+    0x01F1E8, 0x01F1FE, 0,
+    0x01F1E8, 0x01F1FF, 0,
+    0x01F1E9, 0x01F1EA, 0,
+    0x01F1E9, 0x01F1EC, 0,
+    0x01F1E9, 0x01F1EF, 0,
+    0x01F1E9, 0x01F1F0, 0,
+    0x01F1E9, 0x01F1F2, 0,
+    0x01F1E9, 0x01F1F4, 0,
+    0x01F1E9, 0x01F1FF, 0,
+    0x01F1EA, 0x01F1E6, 0,
+    0x01F1EA, 0x01F1E8, 0,
+    0x01F1EA, 0x01F1EA, 0,
+    0x01F1EA, 0x01F1EC, 0,
+    0x01F1EA, 0x01F1ED, 0,
+    0x01F1EA, 0x01F1F7, 0,
+    0x01F1EA, 0x01F1F8, 0,
+    0x01F1EA, 0x01F1F9, 0,
+    0x01F1EA, 0x01F1FA, 0,
+    0x01F1EB, 0x01F1EE, 0,
+    0x01F1EB, 0x01F1EF, 0,
+    0x01F1EB, 0x01F1F0, 0,
+    0x01F1EB, 0x01F1F2, 0,
+    0x01F1EB, 0x01F1F4, 0,
+    0x01F1EB, 0x01F1F7, 0,
+    0x01F1EC, 0x01F1E6, 0,
+    0x01F1EC, 0x01F1E7, 0,
+    0x01F1EC, 0x01F1E9, 0,
+    0x01F1EC, 0x01F1EA, 0,
+    0x01F1EC, 0x01F1EB, 0,
+    0x01F1EC, 0x01F1EC, 0,
+    0x01F1EC, 0x01F1ED, 0,
+    0x01F1EC, 0x01F1EE, 0,
+    0x01F1EC, 0x01F1F1, 0,
+    0x01F1EC, 0x01F1F2, 0,
+    0x01F1EC, 0x01F1F3, 0,
+    0x01F1EC, 0x01F1F5, 0,
+    0x01F1EC, 0x01F1F6, 0,
+    0x01F1EC, 0x01F1F7, 0,
+    0x01F1EC, 0x01F1F8, 0,
+    0x01F1EC, 0x01F1F9, 0,
+    0x01F1EC, 0x01F1FA, 0,
+    0x01F1EC, 0x01F1FC, 0,
+    0x01F1EC, 0x01F1FE, 0,
+    0x01F1ED, 0x01F1F0, 0,
+    0x01F1ED, 0x01F1F2, 0,
+    0x01F1ED, 0x01F1F3, 0,
+    0x01F1ED, 0x01F1F7, 0,
+    0x01F1ED, 0x01F1F9, 0,
+    0x01F1ED, 0x01F1FA, 0,
+    0x01F1EE, 0x01F1E8, 0,
+    0x01F1EE, 0x01F1E9, 0,
+    0x01F1EE, 0x01F1EA, 0,
+    0x01F1EE, 0x01F1F1, 0,
+    0x01F1EE, 0x01F1F2, 0,
+    0x01F1EE, 0x01F1F3, 0,
+    0x01F1EE, 0x01F1F4, 0,
+    0x01F1EE, 0x01F1F6, 0,
+    0x01F1EE, 0x01F1F7, 0,
+    0x01F1EE, 0x01F1F8, 0,
+    0x01F1EE, 0x01F1F9, 0,
+    0x01F1EF, 0x01F1EA, 0,
+    0x01F1EF, 0x01F1F2, 0,
+    0x01F1EF, 0x01F1F4, 0,
+    0x01F1EF, 0x01F1F5, 0,
+    0x01F1F0, 0x01F1EA, 0,
+    0x01F1F0, 0x01F1EC, 0,
+    0x01F1F0, 0x01F1ED, 0,
+    0x01F1F0, 0x01F1EE, 0,
+    0x01F1F0, 0x01F1F2, 0,
+    0x01F1F0, 0x01F1F3, 0,
+    0x01F1F0, 0x01F1F5, 0,
+    0x01F1F0, 0x01F1F7, 0,
+    0x01F1F0, 0x01F1FC, 0,
+    0x01F1E6, 0x01F1E9, 0,
+    0x01F1F0, 0x01F1FF, 0,
+    0x01F1F1, 0x01F1E6, 0,
+    0x01F1F1, 0x01F1E7, 0,
+    0x01F1F1, 0x01F1E8, 0,
+    0x01F1F1, 0x01F1EE, 0,
+    0x01F1F1, 0x01F1F0, 0,
+    0x01F1F1, 0x01F1F7, 0,
+    0x01F1F1, 0x01F1F8, 0,
+    0x01F1F1, 0x01F1F9, 0,
+    0x01F1F1, 0x01F1FA, 0,
+    0x01F1F1, 0x01F1FB, 0,
+    0x01F1F1, 0x01F1FE, 0,
+    0x01F1F2, 0x01F1E6, 0,
+    0x01F1F2, 0x01F1E8, 0,
+    0x01F1F2, 0x01F1E9, 0,
+    0x01F1F2, 0x01F1EA, 0,
+    0x01F1F2, 0x01F1EB, 0,
+    0x01F1F2, 0x01F1EC, 0,
+    0x01F1F2, 0x01F1ED, 0,
+    0x01F1F2, 0x01F1F0, 0,
+    0x01F1F2, 0x01F1F1, 0,
+    0x01F1F2, 0x01F1F2, 0,
+    0x01F1F2, 0x01F1F3, 0,
+    0x01F1F2, 0x01F1F4, 0,
+    0x01F1F2, 0x01F1F5, 0,
+    0x01F1F2, 0x01F1F6, 0,
+    0x01F1F2, 0x01F1F7, 0,
+    0x01F1F2, 0x01F1F8, 0,
+    0x01F1F2, 0x01F1F9, 0,
+    0x01F1F2, 0x01F1FA, 0,
+    0x01F1F2, 0x01F1FB, 0,
+    0x01F1F2, 0x01F1FC, 0,
+    0x01F1F2, 0x01F1FD, 0,
+    0x01F1F2, 0x01F1FE, 0,
+    0x01F1F2, 0x01F1FF, 0,
+    0x01F1F3, 0x01F1E6, 0,
+    0x01F1F3, 0x01F1E8, 0,
+    0x01F1F3, 0x01F1EA, 0,
+    0x01F1F3, 0x01F1EB, 0,
+    0x01F1F3, 0x01F1EC, 0,
+    0x01F1F3, 0x01F1EE, 0,
+    0x01F1F3, 0x01F1F1, 0,
+    0x01F1F3, 0x01F1F4, 0,
+    0x01F1F3, 0x01F1F5, 0,
+    0x01F1F3, 0x01F1F7, 0,
+    0x01F1F3, 0x01F1FA, 0,
+    0x01F1F3, 0x01F1FF, 0,
+    0x01F1F4, 0x01F1F2, 0,
+    0x01F1F5, 0x01F1E6, 0,
+    0x01F1F5, 0x01F1EA, 0,
+    0x01F1F5, 0x01F1EB, 0,
+    0x01F1F5, 0x01F1EC, 0,
+    0x01F1F5, 0x01F1ED, 0,
+    0x01F1F5, 0x01F1F0, 0,
+    0x01F1F5, 0x01F1F1, 0,
+    0x01F1F5, 0x01F1F2, 0,
+    0x01F1F5, 0x01F1F3, 0,
+    0x01F1F5, 0x01F1F7, 0,
+    0x01F1F5, 0x01F1F8, 0,
+    0x01F1F5, 0x01F1F9, 0,
+    0x01F1F5, 0x01F1FC, 0,
+    0x01F1F5, 0x01F1FE, 0,
+    0x01F1F6, 0x01F1E6, 0,
+    0x01F1F7, 0x01F1EA, 0,
+    0x01F1F7, 0x01F1F4, 0,
+    0x01F1F7, 0x01F1F8, 0,
+    0x01F1F7, 0x01F1FA, 0,
+    0x01F1F7, 0x01F1FC, 0,
+    0x01F1F8, 0x01F1E6, 0,
+    0x01F1F8, 0x01F1E7, 0,
+    0x01F1F8, 0x01F1E8, 0,
+    0x01F1F8, 0x01F1E9, 0,
+    0x01F1F8, 0x01F1EA, 0,
+    0x01F1F8, 0x01F1EC, 0,
+    0x01F1F8, 0x01F1ED, 0,
+    0x01F1F8, 0x01F1EE, 0,
+    0x01F1F8, 0x01F1EF, 0,
+    0x01F1F8, 0x01F1F0, 0,
+    0x01F1F8, 0x01F1F1, 0,
+    0x01F1F8, 0x01F1F2, 0,
+    0x01F1F8, 0x01F1F3, 0,
+    0x01F1F8, 0x01F1F4, 0,
+    0x01F1F8, 0x01F1F7, 0,
+    0x01F1F8, 0x01F1F8, 0,
+    0x01F1F8, 0x01F1F9, 0,
+    0x01F1F8, 0x01F1FB, 0,
+    0x01F1F8, 0x01F1FD, 0,
+    0x01F1F8, 0x01F1FE, 0,
+    0x01F1F8, 0x01F1FF, 0,
+    0x01F1F9, 0x01F1E6, 0,
+    0x01F1F9, 0x01F1E8, 0,
+    0x01F1F9, 0x01F1E9, 0,
+    0x01F1F9, 0x01F1EB, 0,
+    0x01F1F9, 0x01F1EC, 0,
+    0x01F1F9, 0x01F1ED, 0,
+    0x01F1F9, 0x01F1EF, 0,
+    0x01F1F9, 0x01F1F0, 0,
+    0x01F1F9, 0x01F1F1, 0,
+    0x01F1F9, 0x01F1F2, 0,
+    0x01F1F9, 0x01F1F3, 0,
+    0x01F1F9, 0x01F1F4, 0,
+    0x01F1F9, 0x01F1F7, 0,
+    0x01F1F9, 0x01F1F9, 0,
+    0x01F1F9, 0x01F1FB, 0,
+    0x01F1F9, 0x01F1FC, 0,
+    0x01F1F9, 0x01F1FF, 0,
+    0x01F1FA, 0x01F1E6, 0,
+    0x01F1FA, 0x01F1EC, 0,
+    0x01F1FA, 0x01F1F2, 0,
+    0x01F1FA, 0x01F1F3, 0,
+    0x01F1FA, 0x01F1F8, 0,
+    0x01F1FA, 0x01F1FE, 0,
+    0x01F1FA, 0x01F1FF, 0,
+    0x01F1FB, 0x01F1E6, 0,
+    0x01F1FB, 0x01F1E8, 0,
+    0x01F1FB, 0x01F1EA, 0,
+    0x01F1FB, 0x01F1EC, 0,
+    0x01F1FB, 0x01F1EE, 0,
+    0x01F1FB, 0x01F1F3, 0,
+    0x01F1FB, 0x01F1FA, 0,
+    0x01F1FC, 0x01F1EB, 0,
+    0x01F1FC, 0x01F1F8, 0,
+    0x01F1FD, 0x01F1F0, 0,
+    0x01F1FE, 0x01F1EA, 0,
+    0x01F1FE, 0x01F1F9, 0,
+    0x01F1FF, 0x01F1E6, 0,
+    0x01F1FF, 0x01F1F2, 0,
+    0x01F1F0, 0x01F1FE, 0,
+    0  // null-terminating the list
+};
+
+const base::uc32 UnicodePropertySequences::kEmojiTagSequences[] = {
+    0x01F3F4, 0x0E0067, 0x0E0062, 0x0E0065, 0x0E006E, 0x0E0067, 0x0E007F, 0,
+    0x01F3F4, 0x0E0067, 0x0E0062, 0x0E0073, 0x0E0063, 0x0E0074, 0x0E007F, 0,
+    0x01F3F4, 0x0E0067, 0x0E0062, 0x0E0077, 0x0E006C, 0x0E0073, 0x0E007F, 0,
+    0  // null-terminating the list
+};
+
+const base::uc32 UnicodePropertySequences::kEmojiZWJSequences[] = {
+    0x01F468, 0x00200D, 0x002764, 0x00FE0F, 0x00200D, 0x01F468, 0,
+    0x01F441, 0x00FE0F, 0x00200D, 0x01F5E8, 0x00FE0F, 0,
+    0x01F468, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F466, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F467, 0,
+    0x01F468, 0x00200D, 0x01F467, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F467, 0x00200D, 0x01F467, 0,
+    0x01F468, 0x00200D, 0x01F468, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F468, 0x00200D, 0x01F466, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F468, 0x00200D, 0x01F467, 0,
+    0x01F468, 0x00200D, 0x01F468, 0x00200D, 0x01F467, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F468, 0x00200D, 0x01F467, 0x00200D, 0x01F467, 0,
+    0x01F468, 0x00200D, 0x01F469, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F469, 0x00200D, 0x01F466, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F469, 0x00200D, 0x01F467, 0,
+    0x01F468, 0x00200D, 0x01F469, 0x00200D, 0x01F467, 0x00200D, 0x01F466, 0,
+    0x01F468, 0x00200D, 0x01F469, 0x00200D, 0x01F467, 0x00200D, 0x01F467, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FB, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FB, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FC, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FB, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FC, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FD, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FB, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FC, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FD, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FE, 0,
+    0x01F469, 0x00200D, 0x002764, 0x00FE0F, 0x00200D, 0x01F468, 0,
+    0x01F469, 0x00200D, 0x002764, 0x00FE0F, 0x00200D, 0x01F469, 0,
+    0x01F469, 0x00200D, 0x002764, 0x00FE0F, 0x00200D, 0x01F48B, 0x00200D,
+        0x01F468, 0,
+    0x01F469, 0x00200D, 0x002764, 0x00FE0F, 0x00200D, 0x01F48B, 0x00200D,
+        0x01F469, 0,
+    0x01F469, 0x00200D, 0x01F466, 0,
+    0x01F469, 0x00200D, 0x01F466, 0x00200D, 0x01F466, 0,
+    0x01F469, 0x00200D, 0x01F467, 0,
+    0x01F469, 0x00200D, 0x01F467, 0x00200D, 0x01F466, 0,
+    0x01F469, 0x00200D, 0x01F467, 0x00200D, 0x01F467, 0,
+    0x01F469, 0x00200D, 0x01F469, 0x00200D, 0x01F466, 0,
+    0x01F469, 0x00200D, 0x01F469, 0x00200D, 0x01F466, 0x00200D, 0x01F466, 0,
+    0x01F469, 0x00200D, 0x01F469, 0x00200D, 0x01F467, 0,
+    0x01F469, 0x00200D, 0x01F469, 0x00200D, 0x01F467, 0x00200D, 0x01F466, 0,
+    0x01F469, 0x00200D, 0x01F469, 0x00200D, 0x01F467, 0x00200D, 0x01F467, 0,
+    0x01F469, 0x01F3FB, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FC, 0,
+    0x01F469, 0x01F3FB, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FD, 0,
+    0x01F469, 0x01F3FB, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FE, 0,
+    0x01F469, 0x01F3FB, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FF, 0,
+    0x01F469, 0x01F3FC, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FB, 0,
+    0x01F469, 0x01F3FC, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FD, 0,
+    0x01F469, 0x01F3FC, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FE, 0,
+    0x01F469, 0x01F3FC, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FF, 0,
+    0x01F469, 0x01F3FC, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FB, 0,
+    0x01F469, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FB, 0,
+    0x01F469, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FC, 0,
+    0x01F469, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FE, 0,
+    0x01F469, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FF, 0,
+    0x01F469, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FB, 0,
+    0x01F469, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FC, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FB, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FC, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FD, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FF, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FB, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FC, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FD, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FB, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FC, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FD, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F468, 0x01F3FE, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FB, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FC, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FD, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F469, 0x01F3FE, 0,
+    0x01F9D1, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0,
+    0x01F9D1, 0x01F3FB, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FB, 0,
+    0x01F9D1, 0x01F3FC, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FB, 0,
+    0x01F9D1, 0x01F3FC, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FC, 0,
+    0x01F9D1, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FB, 0,
+    0x01F9D1, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FC, 0,
+    0x01F9D1, 0x01F3FD, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FD, 0,
+    0x01F9D1, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FB, 0,
+    0x01F9D1, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FC, 0,
+    0x01F9D1, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FD, 0,
+    0x01F9D1, 0x01F3FE, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FE, 0,
+    0x01F9D1, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FB, 0,
+    0x01F9D1, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FC, 0,
+    0x01F9D1, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FD, 0,
+    0x01F9D1, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FE, 0,
+    0x01F9D1, 0x01F3FF, 0x00200D, 0x01F91D, 0x00200D, 0x01F9D1, 0x01F3FF, 0,
+    0x01F468, 0x00200D, 0x002695, 0x00FE0F, 0,
+    0x01F468, 0x00200D, 0x002696, 0x00FE0F, 0,
+    0x01F468, 0x00200D, 0x002708, 0x00FE0F, 0,
+    0x01F468, 0x00200D, 0x01F33E, 0,
+    0x01F468, 0x00200D, 0x01F373, 0,
+    0x01F468, 0x00200D, 0x01F393, 0,
+    0x01F468, 0x00200D, 0x01F3A4, 0,
+    0x01F468, 0x00200D, 0x01F3A8, 0,
+    0x01F468, 0x00200D, 0x01F3EB, 0,
+    0x01F468, 0x00200D, 0x01F3ED, 0,
+    0x01F468, 0x00200D, 0x01F4BB, 0,
+    0x01F468, 0x00200D, 0x01F4BC, 0,
+    0x01F468, 0x00200D, 0x01F527, 0,
+    0x01F468, 0x00200D, 0x01F52C, 0,
+    0x01F468, 0x00200D, 0x01F680, 0,
+    0x01F468, 0x00200D, 0x01F692, 0,
+    0x01F468, 0x00200D, 0x01F9AF, 0,
+    0x01F468, 0x00200D, 0x01F9BC, 0,
+    0x01F468, 0x00200D, 0x01F9BD, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x002695, 0x00FE0F, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x002696, 0x00FE0F, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x002708, 0x00FE0F, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F33E, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F373, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F393, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F3A4, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F3A8, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F3EB, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F3ED, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F4BB, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F4BC, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F527, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F52C, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F680, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F692, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F9AF, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F9BC, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F9BD, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x002695, 0x00FE0F, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x002696, 0x00FE0F, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x002708, 0x00FE0F, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F33E, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F373, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F393, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F3A4, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F3A8, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F3EB, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F3ED, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F4BB, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F4BC, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F527, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F52C, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F680, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F692, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F9AF, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F9BC, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F9BD, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x002695, 0x00FE0F, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x002696, 0x00FE0F, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x002708, 0x00FE0F, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F33E, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F373, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F393, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F3A4, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F3A8, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F3EB, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F3ED, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F4BB, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F4BC, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F527, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F52C, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F680, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F692, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F9AF, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F9BC, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F9BD, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x002695, 0x00FE0F, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x002696, 0x00FE0F, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x002708, 0x00FE0F, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F33E, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F373, 0,
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+    0x01F9DD, 0x01F3FF, 0x00200D, 0x002642, 0x00FE0F, 0,
+    0x01F9DE, 0x00200D, 0x002640, 0x00FE0F, 0,
+    0x01F9DE, 0x00200D, 0x002642, 0x00FE0F, 0,
+    0x01F9DF, 0x00200D, 0x002640, 0x00FE0F, 0,
+    0x01F9DF, 0x00200D, 0x002642, 0x00FE0F, 0,
+    0x01F468, 0x00200D, 0x01F9B0, 0,
+    0x01F468, 0x00200D, 0x01F9B1, 0,
+    0x01F468, 0x00200D, 0x01F9B2, 0,
+    0x01F468, 0x00200D, 0x01F9B3, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F9B0, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F9B1, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F9B2, 0,
+    0x01F468, 0x01F3FB, 0x00200D, 0x01F9B3, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F9B0, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F9B1, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F9B2, 0,
+    0x01F468, 0x01F3FC, 0x00200D, 0x01F9B3, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F9B0, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F9B1, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F9B2, 0,
+    0x01F468, 0x01F3FD, 0x00200D, 0x01F9B3, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F9B0, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F9B1, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F9B2, 0,
+    0x01F468, 0x01F3FE, 0x00200D, 0x01F9B3, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F9B0, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F9B1, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F9B2, 0,
+    0x01F468, 0x01F3FF, 0x00200D, 0x01F9B3, 0,
+    0x01F469, 0x00200D, 0x01F9B0, 0,
+    0x01F469, 0x00200D, 0x01F9B1, 0,
+    0x01F469, 0x00200D, 0x01F9B2, 0,
+    0x01F469, 0x00200D, 0x01F9B3, 0,
+    0x01F469, 0x01F3FB, 0x00200D, 0x01F9B0, 0,
+    0x01F469, 0x01F3FB, 0x00200D, 0x01F9B1, 0,
+    0x01F469, 0x01F3FB, 0x00200D, 0x01F9B2, 0,
+    0x01F469, 0x01F3FB, 0x00200D, 0x01F9B3, 0,
+    0x01F469, 0x01F3FC, 0x00200D, 0x01F9B0, 0,
+    0x01F469, 0x01F3FC, 0x00200D, 0x01F9B1, 0,
+    0x01F469, 0x01F3FC, 0x00200D, 0x01F9B2, 0,
+    0x01F469, 0x01F3FC, 0x00200D, 0x01F9B3, 0,
+    0x01F469, 0x01F3FD, 0x00200D, 0x01F9B0, 0,
+    0x01F469, 0x01F3FD, 0x00200D, 0x01F9B1, 0,
+    0x01F469, 0x01F3FD, 0x00200D, 0x01F9B2, 0,
+    0x01F469, 0x01F3FD, 0x00200D, 0x01F9B3, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F9B0, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F9B1, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F9B2, 0,
+    0x01F469, 0x01F3FE, 0x00200D, 0x01F9B3, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F9B0, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F9B1, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F9B2, 0,
+    0x01F469, 0x01F3FF, 0x00200D, 0x01F9B3, 0,
+    0x01F3F3, 0x00FE0F, 0x00200D, 0x01F308, 0,
+    0x01F3F4, 0x00200D, 0x002620, 0x00FE0F, 0,
+    0x01F415, 0x00200D, 0x01F9BA, 0,
+    0x01F482, 0x01F3FB, 0x00200D, 0x002640, 0x00FE0F, 0,
+    0  // null-terminating the list
+};
+// clang-format on
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_INTL_SUPPORT
diff --git a/js/src/irregexp/imported/property-sequences.h b/js/src/irregexp/imported/property-sequences.h
new file mode 100644
index 0000000000..9b3a188865
--- /dev/null
+++ b/js/src/irregexp/imported/property-sequences.h
@@ -0,0 +1,27 @@
+// Copyright 2018 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_PROPERTY_SEQUENCES_H_
+#define V8_REGEXP_PROPERTY_SEQUENCES_H_
+
+#ifdef V8_INTL_SUPPORT
+
+#include "irregexp/RegExpShim.h"
+
+namespace v8 {
+namespace internal {
+
+class UnicodePropertySequences : public AllStatic {
+ public:
+  static const base::uc32 kEmojiFlagSequences[];
+  static const base::uc32 kEmojiTagSequences[];
+  static const base::uc32 kEmojiZWJSequences[];
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_INTL_SUPPORT
+
+#endif  // V8_REGEXP_PROPERTY_SEQUENCES_H_
diff --git a/js/src/irregexp/imported/regexp-ast.cc b/js/src/irregexp/imported/regexp-ast.cc
new file mode 100644
index 0000000000..63eeb5c05d
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-ast.cc
@@ -0,0 +1,432 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "irregexp/imported/regexp-ast.h"
+
+
+namespace v8 {
+namespace internal {
+
+#define MAKE_ACCEPT(Name)                                          \
+  void* RegExp##Name::Accept(RegExpVisitor* visitor, void* data) { \
+    return visitor->Visit##Name(this, data);                       \
+  }
+FOR_EACH_REG_EXP_TREE_TYPE(MAKE_ACCEPT)
+#undef MAKE_ACCEPT
+
+#define MAKE_TYPE_CASE(Name)                               \
+  RegExp##Name* RegExpTree::As##Name() { return nullptr; } \
+  bool RegExpTree::Is##Name() { return false; }
+FOR_EACH_REG_EXP_TREE_TYPE(MAKE_TYPE_CASE)
+#undef MAKE_TYPE_CASE
+
+#define MAKE_TYPE_CASE(Name)                              \
+  RegExp##Name* RegExp##Name::As##Name() { return this; } \
+  bool RegExp##Name::Is##Name() { return true; }
+FOR_EACH_REG_EXP_TREE_TYPE(MAKE_TYPE_CASE)
+#undef MAKE_TYPE_CASE
+
+namespace {
+
+Interval ListCaptureRegisters(ZoneList<RegExpTree*>* children) {
+  Interval result = Interval::Empty();
+  for (int i = 0; i < children->length(); i++)
+    result = result.Union(children->at(i)->CaptureRegisters());
+  return result;
+}
+
+}  // namespace
+
+Interval RegExpAlternative::CaptureRegisters() {
+  return ListCaptureRegisters(nodes());
+}
+
+
+Interval RegExpDisjunction::CaptureRegisters() {
+  return ListCaptureRegisters(alternatives());
+}
+
+
+Interval RegExpLookaround::CaptureRegisters() {
+  return body()->CaptureRegisters();
+}
+
+
+Interval RegExpCapture::CaptureRegisters() {
+  Interval self(StartRegister(index()), EndRegister(index()));
+  return self.Union(body()->CaptureRegisters());
+}
+
+
+Interval RegExpQuantifier::CaptureRegisters() {
+  return body()->CaptureRegisters();
+}
+
+
+bool RegExpAssertion::IsAnchoredAtStart() {
+  return assertion_type() == RegExpAssertion::Type::START_OF_INPUT;
+}
+
+
+bool RegExpAssertion::IsAnchoredAtEnd() {
+  return assertion_type() == RegExpAssertion::Type::END_OF_INPUT;
+}
+
+
+bool RegExpAlternative::IsAnchoredAtStart() {
+  ZoneList<RegExpTree*>* nodes = this->nodes();
+  for (int i = 0; i < nodes->length(); i++) {
+    RegExpTree* node = nodes->at(i);
+    if (node->IsAnchoredAtStart()) {
+      return true;
+    }
+    if (node->max_match() > 0) {
+      return false;
+    }
+  }
+  return false;
+}
+
+
+bool RegExpAlternative::IsAnchoredAtEnd() {
+  ZoneList<RegExpTree*>* nodes = this->nodes();
+  for (int i = nodes->length() - 1; i >= 0; i--) {
+    RegExpTree* node = nodes->at(i);
+    if (node->IsAnchoredAtEnd()) {
+      return true;
+    }
+    if (node->max_match() > 0) {
+      return false;
+    }
+  }
+  return false;
+}
+
+
+bool RegExpDisjunction::IsAnchoredAtStart() {
+  ZoneList<RegExpTree*>* alternatives = this->alternatives();
+  for (int i = 0; i < alternatives->length(); i++) {
+    if (!alternatives->at(i)->IsAnchoredAtStart()) return false;
+  }
+  return true;
+}
+
+
+bool RegExpDisjunction::IsAnchoredAtEnd() {
+  ZoneList<RegExpTree*>* alternatives = this->alternatives();
+  for (int i = 0; i < alternatives->length(); i++) {
+    if (!alternatives->at(i)->IsAnchoredAtEnd()) return false;
+  }
+  return true;
+}
+
+
+bool RegExpLookaround::IsAnchoredAtStart() {
+  return is_positive() && type() == LOOKAHEAD && body()->IsAnchoredAtStart();
+}
+
+
+bool RegExpCapture::IsAnchoredAtStart() { return body()->IsAnchoredAtStart(); }
+
+
+bool RegExpCapture::IsAnchoredAtEnd() { return body()->IsAnchoredAtEnd(); }
+
+namespace {
+
+// Convert regular expression trees to a simple sexp representation.
+// This representation should be different from the input grammar
+// in as many cases as possible, to make it more difficult for incorrect
+// parses to look as correct ones which is likely if the input and
+// output formats are alike.
+class RegExpUnparser final : public RegExpVisitor {
+ public:
+  RegExpUnparser(std::ostream& os, Zone* zone) : os_(os), zone_(zone) {}
+  void VisitCharacterRange(CharacterRange that);
+#define MAKE_CASE(Name) void* Visit##Name(RegExp##Name*, void* data) override;
+  FOR_EACH_REG_EXP_TREE_TYPE(MAKE_CASE)
+#undef MAKE_CASE
+ private:
+  std::ostream& os_;
+  Zone* zone_;
+};
+
+}  // namespace
+
+void* RegExpUnparser::VisitDisjunction(RegExpDisjunction* that, void* data) {
+  os_ << "(|";
+  for (int i = 0; i < that->alternatives()->length(); i++) {
+    os_ << " ";
+    that->alternatives()->at(i)->Accept(this, data);
+  }
+  os_ << ")";
+  return nullptr;
+}
+
+
+void* RegExpUnparser::VisitAlternative(RegExpAlternative* that, void* data) {
+  os_ << "(:";
+  for (int i = 0; i < that->nodes()->length(); i++) {
+    os_ << " ";
+    that->nodes()->at(i)->Accept(this, data);
+  }
+  os_ << ")";
+  return nullptr;
+}
+
+
+void RegExpUnparser::VisitCharacterRange(CharacterRange that) {
+  os_ << AsUC32(that.from());
+  if (!that.IsSingleton()) {
+    os_ << "-" << AsUC32(that.to());
+  }
+}
+
+void* RegExpUnparser::VisitClassRanges(RegExpClassRanges* that, void* data) {
+  if (that->is_negated()) os_ << "^";
+  os_ << "[";
+  for (int i = 0; i < that->ranges(zone_)->length(); i++) {
+    if (i > 0) os_ << " ";
+    VisitCharacterRange(that->ranges(zone_)->at(i));
+  }
+  os_ << "]";
+  return nullptr;
+}
+
+void* RegExpUnparser::VisitClassSetOperand(RegExpClassSetOperand* that,
+                                           void* data) {
+  os_ << "![";
+  for (int i = 0; i < that->ranges()->length(); i++) {
+    if (i > 0) os_ << " ";
+    VisitCharacterRange(that->ranges()->at(i));
+  }
+  if (that->has_strings()) {
+    for (auto iter : *that->strings()) {
+      os_ << " '";
+      os_ << std::string(iter.first.begin(), iter.first.end());
+      os_ << "'";
+    }
+  }
+  os_ << "]";
+  return nullptr;
+}
+
+void* RegExpUnparser::VisitClassSetExpression(RegExpClassSetExpression* that,
+                                              void* data) {
+  switch (that->operation()) {
+    case RegExpClassSetExpression::OperationType::kUnion:
+      os_ << "++";
+      break;
+    case RegExpClassSetExpression::OperationType::kIntersection:
+      os_ << "&&";
+      break;
+    case RegExpClassSetExpression::OperationType::kSubtraction:
+      os_ << "--";
+      break;
+  }
+  if (that->is_negated()) os_ << "^";
+  os_ << "[";
+  for (int i = 0; i < that->operands()->length(); i++) {
+    if (i > 0) os_ << " ";
+    that->operands()->at(i)->Accept(this, data);
+  }
+  os_ << "]";
+  return nullptr;
+}
+
+void* RegExpUnparser::VisitAssertion(RegExpAssertion* that, void* data) {
+  switch (that->assertion_type()) {
+    case RegExpAssertion::Type::START_OF_INPUT:
+      os_ << "@^i";
+      break;
+    case RegExpAssertion::Type::END_OF_INPUT:
+      os_ << "@$i";
+      break;
+    case RegExpAssertion::Type::START_OF_LINE:
+      os_ << "@^l";
+      break;
+    case RegExpAssertion::Type::END_OF_LINE:
+      os_ << "@$l";
+      break;
+    case RegExpAssertion::Type::BOUNDARY:
+      os_ << "@b";
+      break;
+    case RegExpAssertion::Type::NON_BOUNDARY:
+      os_ << "@B";
+      break;
+  }
+  return nullptr;
+}
+
+
+void* RegExpUnparser::VisitAtom(RegExpAtom* that, void* data) {
+  os_ << "'";
+  base::Vector<const base::uc16> chardata = that->data();
+  for (int i = 0; i < chardata.length(); i++) {
+    os_ << AsUC16(chardata[i]);
+  }
+  os_ << "'";
+  return nullptr;
+}
+
+
+void* RegExpUnparser::VisitText(RegExpText* that, void* data) {
+  if (that->elements()->length() == 1) {
+    that->elements()->at(0).tree()->Accept(this, data);
+  } else {
+    os_ << "(!";
+    for (int i = 0; i < that->elements()->length(); i++) {
+      os_ << " ";
+      that->elements()->at(i).tree()->Accept(this, data);
+    }
+    os_ << ")";
+  }
+  return nullptr;
+}
+
+
+void* RegExpUnparser::VisitQuantifier(RegExpQuantifier* that, void* data) {
+  os_ << "(# " << that->min() << " ";
+  if (that->max() == RegExpTree::kInfinity) {
+    os_ << "- ";
+  } else {
+    os_ << that->max() << " ";
+  }
+  os_ << (that->is_greedy() ? "g " : that->is_possessive() ? "p " : "n ");
+  that->body()->Accept(this, data);
+  os_ << ")";
+  return nullptr;
+}
+
+
+void* RegExpUnparser::VisitCapture(RegExpCapture* that, void* data) {
+  os_ << "(^ ";
+  that->body()->Accept(this, data);
+  os_ << ")";
+  return nullptr;
+}
+
+void* RegExpUnparser::VisitGroup(RegExpGroup* that, void* data) {
+  os_ << "(?: ";
+  that->body()->Accept(this, data);
+  os_ << ")";
+  return nullptr;
+}
+
+void* RegExpUnparser::VisitLookaround(RegExpLookaround* that, void* data) {
+  os_ << "(";
+  os_ << (that->type() == RegExpLookaround::LOOKAHEAD ? "->" : "<-");
+  os_ << (that->is_positive() ? " + " : " - ");
+  that->body()->Accept(this, data);
+  os_ << ")";
+  return nullptr;
+}
+
+
+void* RegExpUnparser::VisitBackReference(RegExpBackReference* that,
+                                         void* data) {
+  os_ << "(<- " << that->index() << ")";
+  return nullptr;
+}
+
+
+void* RegExpUnparser::VisitEmpty(RegExpEmpty* that, void* data) {
+  os_ << '%';
+  return nullptr;
+}
+
+std::ostream& RegExpTree::Print(std::ostream& os, Zone* zone) {
+  RegExpUnparser unparser(os, zone);
+  Accept(&unparser, nullptr);
+  return os;
+}
+
+RegExpDisjunction::RegExpDisjunction(ZoneList<RegExpTree*>* alternatives)
+    : alternatives_(alternatives) {
+  DCHECK_LT(1, alternatives->length());
+  RegExpTree* first_alternative = alternatives->at(0);
+  min_match_ = first_alternative->min_match();
+  max_match_ = first_alternative->max_match();
+  for (int i = 1; i < alternatives->length(); i++) {
+    RegExpTree* alternative = alternatives->at(i);
+    min_match_ = std::min(min_match_, alternative->min_match());
+    max_match_ = std::max(max_match_, alternative->max_match());
+  }
+}
+
+namespace {
+
+int IncreaseBy(int previous, int increase) {
+  if (RegExpTree::kInfinity - previous < increase) {
+    return RegExpTree::kInfinity;
+  } else {
+    return previous + increase;
+  }
+}
+
+}  // namespace
+
+RegExpAlternative::RegExpAlternative(ZoneList<RegExpTree*>* nodes)
+    : nodes_(nodes) {
+  DCHECK_LT(1, nodes->length());
+  min_match_ = 0;
+  max_match_ = 0;
+  for (int i = 0; i < nodes->length(); i++) {
+    RegExpTree* node = nodes->at(i);
+    int node_min_match = node->min_match();
+    min_match_ = IncreaseBy(min_match_, node_min_match);
+    int node_max_match = node->max_match();
+    max_match_ = IncreaseBy(max_match_, node_max_match);
+  }
+}
+
+RegExpClassSetOperand::RegExpClassSetOperand(ZoneList<CharacterRange>* ranges,
+                                             CharacterClassStrings* strings)
+    : ranges_(ranges), strings_(strings) {
+  DCHECK_NOT_NULL(ranges);
+  min_match_ = 0;
+  max_match_ = 0;
+  if (!ranges->is_empty()) {
+    min_match_ = 1;
+    max_match_ = 2;
+  }
+  if (has_strings()) {
+    for (auto string : *strings) {
+      min_match_ = std::min(min_match_, string.second->min_match());
+      max_match_ = std::max(max_match_, string.second->max_match());
+    }
+  }
+}
+
+RegExpClassSetExpression::RegExpClassSetExpression(
+    OperationType op, bool is_negated, bool may_contain_strings,
+    ZoneList<RegExpTree*>* operands)
+    : operation_(op),
+      is_negated_(is_negated),
+      may_contain_strings_(may_contain_strings),
+      operands_(operands) {
+  DCHECK_NOT_NULL(operands);
+  DCHECK_IMPLIES(is_negated_, !may_contain_strings_);
+  max_match_ = 0;
+  for (auto op : *operands) {
+    max_match_ = std::max(max_match_, op->max_match());
+  }
+}
+
+// static
+RegExpClassSetExpression* RegExpClassSetExpression::Empty(Zone* zone,
+                                                          bool is_negated) {
+  ZoneList<CharacterRange>* ranges =
+      zone->template New<ZoneList<CharacterRange>>(0, zone);
+  RegExpClassSetOperand* op =
+      zone->template New<RegExpClassSetOperand>(ranges, nullptr);
+  ZoneList<RegExpTree*>* operands =
+      zone->template New<ZoneList<RegExpTree*>>(1, zone);
+  operands->Add(op, zone);
+  return zone->template New<RegExpClassSetExpression>(
+      RegExpClassSetExpression::OperationType::kUnion, is_negated, false,
+      operands);
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/irregexp/imported/regexp-ast.h b/js/src/irregexp/imported/regexp-ast.h
new file mode 100644
index 0000000000..997282e519
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-ast.h
@@ -0,0 +1,735 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_AST_H_
+#define V8_REGEXP_REGEXP_AST_H_
+
+#ifdef V8_INTL_SUPPORT
+#include "unicode/uniset.h"
+#endif  // V8_INTL_SUPPORT
+#include "irregexp/RegExpShim.h"
+
+namespace v8 {
+namespace internal {
+
+#define FOR_EACH_REG_EXP_TREE_TYPE(VISIT) \
+  VISIT(Disjunction)                      \
+  VISIT(Alternative)                      \
+  VISIT(Assertion)                        \
+  VISIT(ClassRanges)                      \
+  VISIT(ClassSetOperand)                  \
+  VISIT(ClassSetExpression)               \
+  VISIT(Atom)                             \
+  VISIT(Quantifier)                       \
+  VISIT(Capture)                          \
+  VISIT(Group)                            \
+  VISIT(Lookaround)                       \
+  VISIT(BackReference)                    \
+  VISIT(Empty)                            \
+  VISIT(Text)
+
+#define FORWARD_DECLARE(Name) class RegExp##Name;
+FOR_EACH_REG_EXP_TREE_TYPE(FORWARD_DECLARE)
+#undef FORWARD_DECLARE
+
+class RegExpCompiler;
+class RegExpNode;
+class RegExpTree;
+
+class RegExpVisitor {
+ public:
+  virtual ~RegExpVisitor() = default;
+#define MAKE_CASE(Name) \
+  virtual void* Visit##Name(RegExp##Name*, void* data) = 0;
+  FOR_EACH_REG_EXP_TREE_TYPE(MAKE_CASE)
+#undef MAKE_CASE
+};
+
+// A simple closed interval.
+class Interval {
+ public:
+  Interval() : from_(kNone), to_(kNone - 1) {}  // '- 1' for branchless size().
+  Interval(int from, int to) : from_(from), to_(to) {}
+  Interval Union(Interval that) {
+    if (that.from_ == kNone) return *this;
+    if (from_ == kNone) return that;
+    return Interval(std::min(from_, that.from_), std::max(to_, that.to_));
+  }
+
+  static Interval Empty() { return Interval(); }
+
+  bool Contains(int value) const { return (from_ <= value) && (value <= to_); }
+  bool is_empty() const { return from_ == kNone; }
+  int from() const { return from_; }
+  int to() const { return to_; }
+  int size() const { return to_ - from_ + 1; }
+
+  static constexpr int kNone = -1;
+
+ private:
+  int from_;
+  int to_;
+};
+
+// Named standard character sets.
+enum class StandardCharacterSet : char {
+  kWhitespace = 's',         // Like /\s/.
+  kNotWhitespace = 'S',      // Like /\S/.
+  kWord = 'w',               // Like /\w/.
+  kNotWord = 'W',            // Like /\W/.
+  kDigit = 'd',              // Like /\d/.
+  kNotDigit = 'D',           // Like /\D/.
+  kLineTerminator = 'n',     // The inverse of /./.
+  kNotLineTerminator = '.',  // Like /./.
+  kEverything = '*',         // Matches every character, like /./s.
+};
+
+// Represents code points (with values up to 0x10FFFF) in the range from from_
+// to to_, both ends are inclusive.
+class CharacterRange {
+ public:
+  CharacterRange() = default;
+  // For compatibility with the CHECK_OK macro.
+  CharacterRange(void* null) { DCHECK_NULL(null); }  // NOLINT
+
+  static inline CharacterRange Singleton(base::uc32 value) {
+    return CharacterRange(value, value);
+  }
+  static inline CharacterRange Range(base::uc32 from, base::uc32 to) {
+    DCHECK(0 <= from && to <= kMaxCodePoint);
+    DCHECK(static_cast<uint32_t>(from) <= static_cast<uint32_t>(to));
+    return CharacterRange(from, to);
+  }
+  static inline CharacterRange Everything() {
+    return CharacterRange(0, kMaxCodePoint);
+  }
+
+  static inline ZoneList<CharacterRange>* List(Zone* zone,
+                                               CharacterRange range) {
+    ZoneList<CharacterRange>* list =
+        zone->New<ZoneList<CharacterRange>>(1, zone);
+    list->Add(range, zone);
+    return list;
+  }
+
+  // Add class escapes. Add case equivalent closure for \w and \W if necessary.
+  V8_EXPORT_PRIVATE static void AddClassEscape(
+      StandardCharacterSet standard_character_set,
+      ZoneList<CharacterRange>* ranges, bool add_unicode_case_equivalents,
+      Zone* zone);
+  // Add case equivalents to ranges. Only used for /i, not for /ui or /vi, as
+  // the semantics for unicode mode are slightly different.
+  // See https://tc39.es/ecma262/#sec-runtime-semantics-canonicalize-ch Note 4.
+  V8_EXPORT_PRIVATE static void AddCaseEquivalents(
+      Isolate* isolate, Zone* zone, ZoneList<CharacterRange>* ranges,
+      bool is_one_byte);
+  // Add case equivalent code points to ranges. Only used for /ui and /vi, not
+  // for /i, as the semantics for non-unicode mode are slightly different.
+  // See https://tc39.es/ecma262/#sec-runtime-semantics-canonicalize-ch Note 4.
+  static void AddUnicodeCaseEquivalents(ZoneList<CharacterRange>* ranges,
+                                        Zone* zone);
+
+#ifdef V8_INTL_SUPPORT
+  // Creates the closeOver of the given UnicodeSet, removing all
+  // characters/strings that can't be derived via simple case folding.
+  static void UnicodeSimpleCloseOver(icu::UnicodeSet& set);
+#endif  // V8_INTL_SUPPORT
+
+  bool Contains(base::uc32 i) const { return from_ <= i && i <= to_; }
+  base::uc32 from() const { return from_; }
+  base::uc32 to() const { return to_; }
+  bool IsEverything(base::uc32 max) const { return from_ == 0 && to_ >= max; }
+  bool IsSingleton() const { return from_ == to_; }
+
+  // Whether a range list is in canonical form: Ranges ordered by from value,
+  // and ranges non-overlapping and non-adjacent.
+  V8_EXPORT_PRIVATE static bool IsCanonical(
+      const ZoneList<CharacterRange>* ranges);
+  // Convert range list to canonical form. The characters covered by the ranges
+  // will still be the same, but no character is in more than one range, and
+  // adjacent ranges are merged. The resulting list may be shorter than the
+  // original, but cannot be longer.
+  static void Canonicalize(ZoneList<CharacterRange>* ranges);
+  // Negate the contents of a character range in canonical form.
+  static void Negate(const ZoneList<CharacterRange>* src,
+                     ZoneList<CharacterRange>* dst, Zone* zone);
+  // Intersect the contents of two character ranges in canonical form.
+  static void Intersect(const ZoneList<CharacterRange>* lhs,
+                        const ZoneList<CharacterRange>* rhs,
+                        ZoneList<CharacterRange>* dst, Zone* zone);
+  // Subtract the contents of |to_remove| from the contents of |src|.
+  static void Subtract(const ZoneList<CharacterRange>* src,
+                       const ZoneList<CharacterRange>* to_remove,
+                       ZoneList<CharacterRange>* dst, Zone* zone);
+  // Remove all ranges outside the one-byte range.
+  static void ClampToOneByte(ZoneList<CharacterRange>* ranges);
+  // Checks if two ranges (both need to be canonical) are equal.
+  static bool Equals(const ZoneList<CharacterRange>* lhs,
+                     const ZoneList<CharacterRange>* rhs);
+
+ private:
+  CharacterRange(base::uc32 from, base::uc32 to) : from_(from), to_(to) {}
+
+  static constexpr int kMaxCodePoint = 0x10ffff;
+
+  base::uc32 from_ = 0;
+  base::uc32 to_ = 0;
+};
+
+inline bool operator==(const CharacterRange& lhs, const CharacterRange& rhs) {
+  return lhs.from() == rhs.from() && lhs.to() == rhs.to();
+}
+inline bool operator!=(const CharacterRange& lhs, const CharacterRange& rhs) {
+  return !operator==(lhs, rhs);
+}
+
+#define DECL_BOILERPLATE(Name)                                         \
+  void* Accept(RegExpVisitor* visitor, void* data) override;           \
+  RegExpNode* ToNode(RegExpCompiler* compiler, RegExpNode* on_success) \
+      override;                                                        \
+  RegExp##Name* As##Name() override;                                   \
+  bool Is##Name() override
+
+class RegExpTree : public ZoneObject {
+ public:
+  static const int kInfinity = kMaxInt;
+  virtual ~RegExpTree() = default;
+  virtual void* Accept(RegExpVisitor* visitor, void* data) = 0;
+  virtual RegExpNode* ToNode(RegExpCompiler* compiler,
+                             RegExpNode* on_success) = 0;
+  virtual bool IsTextElement() { return false; }
+  virtual bool IsAnchoredAtStart() { return false; }
+  virtual bool IsAnchoredAtEnd() { return false; }
+  virtual int min_match() = 0;
+  virtual int max_match() = 0;
+  // Returns the interval of registers used for captures within this
+  // expression.
+  virtual Interval CaptureRegisters() { return Interval::Empty(); }
+  virtual void AppendToText(RegExpText* text, Zone* zone);
+  V8_EXPORT_PRIVATE std::ostream& Print(std::ostream& os, Zone* zone);
+#define MAKE_ASTYPE(Name)           \
+  virtual RegExp##Name* As##Name(); \
+  virtual bool Is##Name();
+  FOR_EACH_REG_EXP_TREE_TYPE(MAKE_ASTYPE)
+#undef MAKE_ASTYPE
+};
+
+
+class RegExpDisjunction final : public RegExpTree {
+ public:
+  explicit RegExpDisjunction(ZoneList<RegExpTree*>* alternatives);
+
+  DECL_BOILERPLATE(Disjunction);
+
+  Interval CaptureRegisters() override;
+  bool IsAnchoredAtStart() override;
+  bool IsAnchoredAtEnd() override;
+  int min_match() override { return min_match_; }
+  int max_match() override { return max_match_; }
+  ZoneList<RegExpTree*>* alternatives() const { return alternatives_; }
+
+ private:
+  bool SortConsecutiveAtoms(RegExpCompiler* compiler);
+  void RationalizeConsecutiveAtoms(RegExpCompiler* compiler);
+  void FixSingleCharacterDisjunctions(RegExpCompiler* compiler);
+  ZoneList<RegExpTree*>* alternatives_;
+  int min_match_;
+  int max_match_;
+};
+
+
+class RegExpAlternative final : public RegExpTree {
+ public:
+  explicit RegExpAlternative(ZoneList<RegExpTree*>* nodes);
+
+  DECL_BOILERPLATE(Alternative);
+
+  Interval CaptureRegisters() override;
+  bool IsAnchoredAtStart() override;
+  bool IsAnchoredAtEnd() override;
+  int min_match() override { return min_match_; }
+  int max_match() override { return max_match_; }
+  ZoneList<RegExpTree*>* nodes() const { return nodes_; }
+
+ private:
+  ZoneList<RegExpTree*>* nodes_;
+  int min_match_;
+  int max_match_;
+};
+
+
+class RegExpAssertion final : public RegExpTree {
+ public:
+  enum class Type {
+    START_OF_LINE = 0,
+    START_OF_INPUT = 1,
+    END_OF_LINE = 2,
+    END_OF_INPUT = 3,
+    BOUNDARY = 4,
+    NON_BOUNDARY = 5,
+    LAST_ASSERTION_TYPE = NON_BOUNDARY,
+  };
+  explicit RegExpAssertion(Type type) : assertion_type_(type) {}
+
+  DECL_BOILERPLATE(Assertion);
+
+  bool IsAnchoredAtStart() override;
+  bool IsAnchoredAtEnd() override;
+  int min_match() override { return 0; }
+  int max_match() override { return 0; }
+  Type assertion_type() const { return assertion_type_; }
+
+ private:
+  const Type assertion_type_;
+};
+
+class CharacterSet final {
+ public:
+  explicit CharacterSet(StandardCharacterSet standard_set_type)
+      : standard_set_type_(standard_set_type) {}
+  explicit CharacterSet(ZoneList<CharacterRange>* ranges) : ranges_(ranges) {}
+
+  ZoneList<CharacterRange>* ranges(Zone* zone);
+  StandardCharacterSet standard_set_type() const {
+    return standard_set_type_.value();
+  }
+  void set_standard_set_type(StandardCharacterSet standard_set_type) {
+    standard_set_type_ = standard_set_type;
+  }
+  bool is_standard() const { return standard_set_type_.has_value(); }
+  V8_EXPORT_PRIVATE void Canonicalize();
+
+ private:
+  ZoneList<CharacterRange>* ranges_ = nullptr;
+  base::Optional<StandardCharacterSet> standard_set_type_;
+};
+
+class RegExpClassRanges final : public RegExpTree {
+ public:
+  // NEGATED: The character class is negated and should match everything but
+  //     the specified ranges.
+  // CONTAINS_SPLIT_SURROGATE: The character class contains part of a split
+  //     surrogate and should not be unicode-desugared (crbug.com/641091).
+  enum Flag {
+    NEGATED = 1 << 0,
+    CONTAINS_SPLIT_SURROGATE = 1 << 1,
+  };
+  using ClassRangesFlags = base::Flags<Flag>;
+
+  RegExpClassRanges(Zone* zone, ZoneList<CharacterRange>* ranges,
+                    ClassRangesFlags class_ranges_flags = ClassRangesFlags())
+      : set_(ranges), class_ranges_flags_(class_ranges_flags) {
+    // Convert the empty set of ranges to the negated Everything() range.
+    if (ranges->is_empty()) {
+      ranges->Add(CharacterRange::Everything(), zone);
+      class_ranges_flags_ ^= NEGATED;
+    }
+  }
+  explicit RegExpClassRanges(StandardCharacterSet standard_set_type)
+      : set_(standard_set_type), class_ranges_flags_() {}
+
+  DECL_BOILERPLATE(ClassRanges);
+
+  bool IsTextElement() override { return true; }
+  int min_match() override { return 1; }
+  // The character class may match two code units for unicode regexps.
+  // TODO(yangguo): we should split this class for usage in TextElement, and
+  //                make max_match() dependent on the character class content.
+  int max_match() override { return 2; }
+
+  void AppendToText(RegExpText* text, Zone* zone) override;
+
+  // TODO(lrn): Remove need for complex version if is_standard that
+  // recognizes a mangled standard set and just do { return set_.is_special(); }
+  bool is_standard(Zone* zone);
+  // Returns a value representing the standard character set if is_standard()
+  // returns true.
+  StandardCharacterSet standard_type() const {
+    return set_.standard_set_type();
+  }
+
+  CharacterSet character_set() const { return set_; }
+  ZoneList<CharacterRange>* ranges(Zone* zone) { return set_.ranges(zone); }
+
+  bool is_negated() const { return (class_ranges_flags_ & NEGATED) != 0; }
+  bool contains_split_surrogate() const {
+    return (class_ranges_flags_ & CONTAINS_SPLIT_SURROGATE) != 0;
+  }
+
+ private:
+  CharacterSet set_;
+  ClassRangesFlags class_ranges_flags_;
+};
+
+struct CharacterClassStringLess {
+  bool operator()(const base::Vector<const base::uc32>& lhs,
+                  const base::Vector<const base::uc32>& rhs) const {
+    // Longer strings first so we generate matches for the largest string
+    // possible.
+    if (lhs.length() != rhs.length()) {
+      return lhs.length() > rhs.length();
+    }
+    for (int i = 0; i < lhs.length(); i++) {
+      if (lhs[i] != rhs[i]) {
+        return lhs[i] < rhs[i];
+      }
+    }
+    return false;
+  }
+};
+
+// A type used for strings as part of character classes (only possible in
+// unicode sets mode).
+// We use a ZoneMap instead of an UnorderedZoneMap because we need to match
+// the longest alternatives first. By using a ZoneMap with the custom comparator
+// we can avoid sorting before assembling the code.
+// Strings are likely short (the largest string in current unicode properties
+// consists of 10 code points).
+using CharacterClassStrings = ZoneMap<base::Vector<const base::uc32>,
+                                      RegExpTree*, CharacterClassStringLess>;
+
+// TODO(pthier): If we are sure we don't want to use icu::UnicodeSets
+// (performance evaluation pending), this class can be merged with
+// RegExpClassRanges.
+class RegExpClassSetOperand final : public RegExpTree {
+ public:
+  RegExpClassSetOperand(ZoneList<CharacterRange>* ranges,
+                        CharacterClassStrings* strings);
+
+  DECL_BOILERPLATE(ClassSetOperand);
+
+  bool IsTextElement() override { return true; }
+  int min_match() override { return min_match_; }
+  int max_match() override { return max_match_; }
+
+  void Union(RegExpClassSetOperand* other, Zone* zone);
+  void Intersect(RegExpClassSetOperand* other,
+                 ZoneList<CharacterRange>* temp_ranges, Zone* zone);
+  void Subtract(RegExpClassSetOperand* other,
+                ZoneList<CharacterRange>* temp_ranges, Zone* zone);
+
+  bool has_strings() const { return strings_ != nullptr && !strings_->empty(); }
+  ZoneList<CharacterRange>* ranges() { return ranges_; }
+  CharacterClassStrings* strings() {
+    DCHECK_NOT_NULL(strings_);
+    return strings_;
+  }
+
+ private:
+  ZoneList<CharacterRange>* ranges_;
+  CharacterClassStrings* strings_;
+  int min_match_;
+  int max_match_;
+};
+
+class RegExpClassSetExpression final : public RegExpTree {
+ public:
+  enum class OperationType { kUnion, kIntersection, kSubtraction };
+
+  RegExpClassSetExpression(OperationType op, bool is_negated,
+                           bool may_contain_strings,
+                           ZoneList<RegExpTree*>* operands);
+
+  DECL_BOILERPLATE(ClassSetExpression);
+
+  // Create an empty class set expression (matches everything if |is_negated|,
+  // nothing otherwise).
+  static RegExpClassSetExpression* Empty(Zone* zone, bool is_negated);
+
+  bool IsTextElement() override { return true; }
+  int min_match() override { return 0; }
+  int max_match() override { return max_match_; }
+
+  OperationType operation() const { return operation_; }
+  bool is_negated() const { return is_negated_; }
+  bool may_contain_strings() const { return may_contain_strings_; }
+  const ZoneList<RegExpTree*>* operands() const { return operands_; }
+  ZoneList<RegExpTree*>* operands() { return operands_; }
+
+ private:
+  // Recursively evaluates the tree rooted at |root|, computing the valid
+  // CharacterRanges and strings after applying all set operations.
+  // The original tree will be modified by this method, so don't store pointers
+  // to inner nodes of the tree somewhere else!
+  // Modifying the tree in-place saves memory and speeds up multiple calls of
+  // the method (e.g. when unrolling quantifiers).
+  // |temp_ranges| is used for intermediate results, passed as parameter to
+  // avoid allocating new lists all the time.
+  static RegExpClassSetOperand* ComputeExpression(
+      RegExpTree* root, ZoneList<CharacterRange>* temp_ranges, Zone* zone);
+
+  const OperationType operation_;
+  const bool is_negated_;
+  const bool may_contain_strings_;
+  ZoneList<RegExpTree*>* operands_ = nullptr;
+  int max_match_;
+};
+
+class RegExpAtom final : public RegExpTree {
+ public:
+  explicit RegExpAtom(base::Vector<const base::uc16> data) : data_(data) {}
+
+  DECL_BOILERPLATE(Atom);
+
+  bool IsTextElement() override { return true; }
+  int min_match() override { return data_.length(); }
+  int max_match() override { return data_.length(); }
+  void AppendToText(RegExpText* text, Zone* zone) override;
+
+  base::Vector<const base::uc16> data() const { return data_; }
+  int length() const { return data_.length(); }
+
+ private:
+  base::Vector<const base::uc16> data_;
+};
+
+class TextElement final {
+ public:
+  enum TextType { ATOM, CLASS_RANGES };
+
+  static TextElement Atom(RegExpAtom* atom);
+  static TextElement ClassRanges(RegExpClassRanges* class_ranges);
+
+  int cp_offset() const { return cp_offset_; }
+  void set_cp_offset(int cp_offset) { cp_offset_ = cp_offset; }
+  int length() const;
+
+  TextType text_type() const { return text_type_; }
+
+  RegExpTree* tree() const { return tree_; }
+
+  RegExpAtom* atom() const {
+    DCHECK(text_type() == ATOM);
+    return reinterpret_cast<RegExpAtom*>(tree());
+  }
+
+  RegExpClassRanges* class_ranges() const {
+    DCHECK(text_type() == CLASS_RANGES);
+    return reinterpret_cast<RegExpClassRanges*>(tree());
+  }
+
+ private:
+  TextElement(TextType text_type, RegExpTree* tree)
+      : cp_offset_(-1), text_type_(text_type), tree_(tree) {}
+
+  int cp_offset_;
+  TextType text_type_;
+  RegExpTree* tree_;
+};
+
+class RegExpText final : public RegExpTree {
+ public:
+  explicit RegExpText(Zone* zone) : elements_(2, zone) {}
+
+  DECL_BOILERPLATE(Text);
+
+  bool IsTextElement() override { return true; }
+  int min_match() override { return length_; }
+  int max_match() override { return length_; }
+  void AppendToText(RegExpText* text, Zone* zone) override;
+  void AddElement(TextElement elm, Zone* zone) {
+    elements_.Add(elm, zone);
+    length_ += elm.length();
+  }
+  ZoneList<TextElement>* elements() { return &elements_; }
+
+ private:
+  ZoneList<TextElement> elements_;
+  int length_ = 0;
+};
+
+
+class RegExpQuantifier final : public RegExpTree {
+ public:
+  enum QuantifierType { GREEDY, NON_GREEDY, POSSESSIVE };
+  RegExpQuantifier(int min, int max, QuantifierType type, RegExpTree* body)
+      : body_(body),
+        min_(min),
+        max_(max),
+        quantifier_type_(type) {
+    if (min > 0 && body->min_match() > kInfinity / min) {
+      min_match_ = kInfinity;
+    } else {
+      min_match_ = min * body->min_match();
+    }
+    if (max > 0 && body->max_match() > kInfinity / max) {
+      max_match_ = kInfinity;
+    } else {
+      max_match_ = max * body->max_match();
+    }
+  }
+
+  DECL_BOILERPLATE(Quantifier);
+
+  static RegExpNode* ToNode(int min, int max, bool is_greedy, RegExpTree* body,
+                            RegExpCompiler* compiler, RegExpNode* on_success,
+                            bool not_at_start = false);
+  Interval CaptureRegisters() override;
+  int min_match() override { return min_match_; }
+  int max_match() override { return max_match_; }
+  int min() const { return min_; }
+  int max() const { return max_; }
+  QuantifierType quantifier_type() const { return quantifier_type_; }
+  bool is_possessive() const { return quantifier_type_ == POSSESSIVE; }
+  bool is_non_greedy() const { return quantifier_type_ == NON_GREEDY; }
+  bool is_greedy() const { return quantifier_type_ == GREEDY; }
+  RegExpTree* body() const { return body_; }
+
+ private:
+  RegExpTree* body_;
+  int min_;
+  int max_;
+  int min_match_;
+  int max_match_;
+  QuantifierType quantifier_type_;
+};
+
+
+class RegExpCapture final : public RegExpTree {
+ public:
+  explicit RegExpCapture(int index)
+      : body_(nullptr),
+        index_(index),
+        min_match_(0),
+        max_match_(0),
+        name_(nullptr) {}
+
+  DECL_BOILERPLATE(Capture);
+
+  static RegExpNode* ToNode(RegExpTree* body, int index,
+                            RegExpCompiler* compiler, RegExpNode* on_success);
+  bool IsAnchoredAtStart() override;
+  bool IsAnchoredAtEnd() override;
+  Interval CaptureRegisters() override;
+  int min_match() override { return min_match_; }
+  int max_match() override { return max_match_; }
+  RegExpTree* body() { return body_; }
+  void set_body(RegExpTree* body) {
+    body_ = body;
+    min_match_ = body->min_match();
+    max_match_ = body->max_match();
+  }
+  int index() const { return index_; }
+  const ZoneVector<base::uc16>* name() const { return name_; }
+  void set_name(const ZoneVector<base::uc16>* name) { name_ = name; }
+  static int StartRegister(int index) { return index * 2; }
+  static int EndRegister(int index) { return index * 2 + 1; }
+
+ private:
+  RegExpTree* body_ = nullptr;
+  int index_;
+  int min_match_ = 0;
+  int max_match_ = 0;
+  const ZoneVector<base::uc16>* name_ = nullptr;
+};
+
+class RegExpGroup final : public RegExpTree {
+ public:
+  explicit RegExpGroup(RegExpTree* body)
+      : body_(body),
+        min_match_(body->min_match()),
+        max_match_(body->max_match()) {}
+
+  DECL_BOILERPLATE(Group);
+
+  bool IsAnchoredAtStart() override { return body_->IsAnchoredAtStart(); }
+  bool IsAnchoredAtEnd() override { return body_->IsAnchoredAtEnd(); }
+  int min_match() override { return min_match_; }
+  int max_match() override { return max_match_; }
+  Interval CaptureRegisters() override { return body_->CaptureRegisters(); }
+  RegExpTree* body() const { return body_; }
+
+ private:
+  RegExpTree* body_;
+  int min_match_;
+  int max_match_;
+};
+
+class RegExpLookaround final : public RegExpTree {
+ public:
+  enum Type { LOOKAHEAD, LOOKBEHIND };
+
+  RegExpLookaround(RegExpTree* body, bool is_positive, int capture_count,
+                   int capture_from, Type type)
+      : body_(body),
+        is_positive_(is_positive),
+        capture_count_(capture_count),
+        capture_from_(capture_from),
+        type_(type) {}
+
+  DECL_BOILERPLATE(Lookaround);
+
+  Interval CaptureRegisters() override;
+  bool IsAnchoredAtStart() override;
+  int min_match() override { return 0; }
+  int max_match() override { return 0; }
+  RegExpTree* body() const { return body_; }
+  bool is_positive() const { return is_positive_; }
+  int capture_count() const { return capture_count_; }
+  int capture_from() const { return capture_from_; }
+  Type type() const { return type_; }
+
+  class Builder {
+   public:
+    Builder(bool is_positive, RegExpNode* on_success,
+            int stack_pointer_register, int position_register,
+            int capture_register_count = 0, int capture_register_start = 0);
+    RegExpNode* on_match_success() const { return on_match_success_; }
+    RegExpNode* ForMatch(RegExpNode* match);
+
+   private:
+    bool is_positive_;
+    RegExpNode* on_match_success_;
+    RegExpNode* on_success_;
+    int stack_pointer_register_;
+    int position_register_;
+  };
+
+ private:
+  RegExpTree* body_;
+  bool is_positive_;
+  int capture_count_;
+  int capture_from_;
+  Type type_;
+};
+
+
+class RegExpBackReference final : public RegExpTree {
+ public:
+  explicit RegExpBackReference(RegExpFlags flags) : flags_(flags) {}
+  RegExpBackReference(RegExpCapture* capture, RegExpFlags flags)
+      : capture_(capture), flags_(flags) {}
+
+  DECL_BOILERPLATE(BackReference);
+
+  int min_match() override { return 0; }
+  // The back reference may be recursive, e.g. /(\2)(\1)/. To avoid infinite
+  // recursion, we give up. Ignorance is bliss.
+  int max_match() override { return kInfinity; }
+  int index() const { return capture_->index(); }
+  RegExpCapture* capture() const { return capture_; }
+  void set_capture(RegExpCapture* capture) { capture_ = capture; }
+  const ZoneVector<base::uc16>* name() const { return name_; }
+  void set_name(const ZoneVector<base::uc16>* name) { name_ = name; }
+
+ private:
+  RegExpCapture* capture_ = nullptr;
+  const ZoneVector<base::uc16>* name_ = nullptr;
+  const RegExpFlags flags_;
+};
+
+
+class RegExpEmpty final : public RegExpTree {
+ public:
+  DECL_BOILERPLATE(Empty);
+  int min_match() override { return 0; }
+  int max_match() override { return 0; }
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#undef DECL_BOILERPLATE
+
+#endif  // V8_REGEXP_REGEXP_AST_H_
diff --git a/js/src/irregexp/imported/regexp-bytecode-generator-inl.h b/js/src/irregexp/imported/regexp-bytecode-generator-inl.h
new file mode 100644
index 0000000000..807ca66f47
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-bytecode-generator-inl.h
@@ -0,0 +1,55 @@
+// Copyright 2008-2009 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_BYTECODE_GENERATOR_INL_H_
+#define V8_REGEXP_REGEXP_BYTECODE_GENERATOR_INL_H_
+
+#include "irregexp/imported/regexp-bytecode-generator.h"
+
+#include "irregexp/imported/regexp-bytecodes.h"
+
+namespace v8 {
+namespace internal {
+
+void RegExpBytecodeGenerator::Emit(uint32_t byte, uint32_t twenty_four_bits) {
+  DCHECK(is_uint24(twenty_four_bits));
+  Emit32((twenty_four_bits << BYTECODE_SHIFT) | byte);
+}
+
+void RegExpBytecodeGenerator::Emit(uint32_t byte, int32_t twenty_four_bits) {
+  DCHECK(is_int24(twenty_four_bits));
+  Emit32((static_cast<uint32_t>(twenty_four_bits) << BYTECODE_SHIFT) | byte);
+}
+
+void RegExpBytecodeGenerator::Emit16(uint32_t word) {
+  DCHECK(pc_ <= static_cast<int>(buffer_.size()));
+  if (pc_ + 1 >= static_cast<int>(buffer_.size())) {
+    ExpandBuffer();
+  }
+  *reinterpret_cast<uint16_t*>(buffer_.data() + pc_) = word;
+  pc_ += 2;
+}
+
+void RegExpBytecodeGenerator::Emit8(uint32_t word) {
+  DCHECK(pc_ <= static_cast<int>(buffer_.size()));
+  if (pc_ == static_cast<int>(buffer_.size())) {
+    ExpandBuffer();
+  }
+  *reinterpret_cast<unsigned char*>(buffer_.data() + pc_) = word;
+  pc_ += 1;
+}
+
+void RegExpBytecodeGenerator::Emit32(uint32_t word) {
+  DCHECK(pc_ <= static_cast<int>(buffer_.size()));
+  if (pc_ + 3 >= static_cast<int>(buffer_.size())) {
+    ExpandBuffer();
+  }
+  *reinterpret_cast<uint32_t*>(buffer_.data() + pc_) = word;
+  pc_ += 4;
+}
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_BYTECODE_GENERATOR_INL_H_
diff --git a/js/src/irregexp/imported/regexp-bytecode-generator.cc b/js/src/irregexp/imported/regexp-bytecode-generator.cc
new file mode 100644
index 0000000000..934a39130d
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-bytecode-generator.cc
@@ -0,0 +1,405 @@
+// Copyright 2008-2009 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "irregexp/imported/regexp-bytecode-generator.h"
+
+#include "irregexp/imported/regexp-bytecode-generator-inl.h"
+#include "irregexp/imported/regexp-bytecode-peephole.h"
+#include "irregexp/imported/regexp-bytecodes.h"
+#include "irregexp/imported/regexp-macro-assembler.h"
+
+namespace v8 {
+namespace internal {
+
+RegExpBytecodeGenerator::RegExpBytecodeGenerator(Isolate* isolate, Zone* zone)
+    : RegExpMacroAssembler(isolate, zone),
+      buffer_(kInitialBufferSize, zone),
+      pc_(0),
+      advance_current_end_(kInvalidPC),
+      jump_edges_(zone),
+      isolate_(isolate) {}
+
+RegExpBytecodeGenerator::~RegExpBytecodeGenerator() {
+  if (backtrack_.is_linked()) backtrack_.Unuse();
+}
+
+RegExpBytecodeGenerator::IrregexpImplementation
+RegExpBytecodeGenerator::Implementation() {
+  return kBytecodeImplementation;
+}
+
+void RegExpBytecodeGenerator::Bind(Label* l) {
+  advance_current_end_ = kInvalidPC;
+  DCHECK(!l->is_bound());
+  if (l->is_linked()) {
+    int pos = l->pos();
+    while (pos != 0) {
+      int fixup = pos;
+      pos = *reinterpret_cast<int32_t*>(buffer_.data() + fixup);
+      *reinterpret_cast<uint32_t*>(buffer_.data() + fixup) = pc_;
+      jump_edges_.emplace(fixup, pc_);
+    }
+  }
+  l->bind_to(pc_);
+}
+
+void RegExpBytecodeGenerator::EmitOrLink(Label* l) {
+  if (l == nullptr) l = &backtrack_;
+  int pos = 0;
+  if (l->is_bound()) {
+    pos = l->pos();
+    jump_edges_.emplace(pc_, pos);
+  } else {
+    if (l->is_linked()) {
+      pos = l->pos();
+    }
+    l->link_to(pc_);
+  }
+  Emit32(pos);
+}
+
+void RegExpBytecodeGenerator::PopRegister(int register_index) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_POP_REGISTER, register_index);
+}
+
+void RegExpBytecodeGenerator::PushRegister(int register_index,
+                                           StackCheckFlag check_stack_limit) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_PUSH_REGISTER, register_index);
+}
+
+void RegExpBytecodeGenerator::WriteCurrentPositionToRegister(int register_index,
+                                                             int cp_offset) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_SET_REGISTER_TO_CP, register_index);
+  Emit32(cp_offset);  // Current position offset.
+}
+
+void RegExpBytecodeGenerator::ClearRegisters(int reg_from, int reg_to) {
+  DCHECK(reg_from <= reg_to);
+  for (int reg = reg_from; reg <= reg_to; reg++) {
+    SetRegister(reg, -1);
+  }
+}
+
+void RegExpBytecodeGenerator::ReadCurrentPositionFromRegister(
+    int register_index) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_SET_CP_TO_REGISTER, register_index);
+}
+
+void RegExpBytecodeGenerator::WriteStackPointerToRegister(int register_index) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_SET_REGISTER_TO_SP, register_index);
+}
+
+void RegExpBytecodeGenerator::ReadStackPointerFromRegister(int register_index) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_SET_SP_TO_REGISTER, register_index);
+}
+
+void RegExpBytecodeGenerator::SetCurrentPositionFromEnd(int by) {
+  DCHECK(is_uint24(by));
+  Emit(BC_SET_CURRENT_POSITION_FROM_END, by);
+}
+
+void RegExpBytecodeGenerator::SetRegister(int register_index, int to) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_SET_REGISTER, register_index);
+  Emit32(to);
+}
+
+void RegExpBytecodeGenerator::AdvanceRegister(int register_index, int by) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_ADVANCE_REGISTER, register_index);
+  Emit32(by);
+}
+
+void RegExpBytecodeGenerator::PopCurrentPosition() { Emit(BC_POP_CP, 0); }
+
+void RegExpBytecodeGenerator::PushCurrentPosition() { Emit(BC_PUSH_CP, 0); }
+
+void RegExpBytecodeGenerator::Backtrack() {
+  int error_code =
+      can_fallback() ? RegExp::RE_FALLBACK_TO_EXPERIMENTAL : RegExp::RE_FAILURE;
+  Emit(BC_POP_BT, error_code);
+}
+
+void RegExpBytecodeGenerator::GoTo(Label* l) {
+  if (advance_current_end_ == pc_) {
+    // Combine advance current and goto.
+    pc_ = advance_current_start_;
+    Emit(BC_ADVANCE_CP_AND_GOTO, advance_current_offset_);
+    EmitOrLink(l);
+    advance_current_end_ = kInvalidPC;
+  } else {
+    // Regular goto.
+    Emit(BC_GOTO, 0);
+    EmitOrLink(l);
+  }
+}
+
+void RegExpBytecodeGenerator::PushBacktrack(Label* l) {
+  Emit(BC_PUSH_BT, 0);
+  EmitOrLink(l);
+}
+
+bool RegExpBytecodeGenerator::Succeed() {
+  Emit(BC_SUCCEED, 0);
+  return false;  // Restart matching for global regexp not supported.
+}
+
+void RegExpBytecodeGenerator::Fail() { Emit(BC_FAIL, 0); }
+
+void RegExpBytecodeGenerator::AdvanceCurrentPosition(int by) {
+  // TODO(chromium:1166138): Turn back into DCHECKs once the underlying issue
+  // is fixed.
+  CHECK_LE(kMinCPOffset, by);
+  CHECK_GE(kMaxCPOffset, by);
+  advance_current_start_ = pc_;
+  advance_current_offset_ = by;
+  Emit(BC_ADVANCE_CP, by);
+  advance_current_end_ = pc_;
+}
+
+void RegExpBytecodeGenerator::CheckGreedyLoop(
+    Label* on_tos_equals_current_position) {
+  Emit(BC_CHECK_GREEDY, 0);
+  EmitOrLink(on_tos_equals_current_position);
+}
+
+void RegExpBytecodeGenerator::LoadCurrentCharacterImpl(int cp_offset,
+                                                       Label* on_failure,
+                                                       bool check_bounds,
+                                                       int characters,
+                                                       int eats_at_least) {
+  DCHECK_GE(eats_at_least, characters);
+  if (eats_at_least > characters && check_bounds) {
+    DCHECK(is_int24(cp_offset + eats_at_least));
+    Emit(BC_CHECK_CURRENT_POSITION, cp_offset + eats_at_least);
+    EmitOrLink(on_failure);
+    check_bounds = false;  // Load below doesn't need to check.
+  }
+
+  DCHECK_LE(kMinCPOffset, cp_offset);
+  DCHECK_GE(kMaxCPOffset, cp_offset);
+  int bytecode;
+  if (check_bounds) {
+    if (characters == 4) {
+      bytecode = BC_LOAD_4_CURRENT_CHARS;
+    } else if (characters == 2) {
+      bytecode = BC_LOAD_2_CURRENT_CHARS;
+    } else {
+      DCHECK_EQ(1, characters);
+      bytecode = BC_LOAD_CURRENT_CHAR;
+    }
+  } else {
+    if (characters == 4) {
+      bytecode = BC_LOAD_4_CURRENT_CHARS_UNCHECKED;
+    } else if (characters == 2) {
+      bytecode = BC_LOAD_2_CURRENT_CHARS_UNCHECKED;
+    } else {
+      DCHECK_EQ(1, characters);
+      bytecode = BC_LOAD_CURRENT_CHAR_UNCHECKED;
+    }
+  }
+  Emit(bytecode, cp_offset);
+  if (check_bounds) EmitOrLink(on_failure);
+}
+
+void RegExpBytecodeGenerator::CheckCharacterLT(base::uc16 limit,
+                                               Label* on_less) {
+  Emit(BC_CHECK_LT, limit);
+  EmitOrLink(on_less);
+}
+
+void RegExpBytecodeGenerator::CheckCharacterGT(base::uc16 limit,
+                                               Label* on_greater) {
+  Emit(BC_CHECK_GT, limit);
+  EmitOrLink(on_greater);
+}
+
+void RegExpBytecodeGenerator::CheckCharacter(uint32_t c, Label* on_equal) {
+  if (c > MAX_FIRST_ARG) {
+    Emit(BC_CHECK_4_CHARS, 0);
+    Emit32(c);
+  } else {
+    Emit(BC_CHECK_CHAR, c);
+  }
+  EmitOrLink(on_equal);
+}
+
+void RegExpBytecodeGenerator::CheckAtStart(int cp_offset, Label* on_at_start) {
+  Emit(BC_CHECK_AT_START, cp_offset);
+  EmitOrLink(on_at_start);
+}
+
+void RegExpBytecodeGenerator::CheckNotAtStart(int cp_offset,
+                                              Label* on_not_at_start) {
+  Emit(BC_CHECK_NOT_AT_START, cp_offset);
+  EmitOrLink(on_not_at_start);
+}
+
+void RegExpBytecodeGenerator::CheckNotCharacter(uint32_t c,
+                                                Label* on_not_equal) {
+  if (c > MAX_FIRST_ARG) {
+    Emit(BC_CHECK_NOT_4_CHARS, 0);
+    Emit32(c);
+  } else {
+    Emit(BC_CHECK_NOT_CHAR, c);
+  }
+  EmitOrLink(on_not_equal);
+}
+
+void RegExpBytecodeGenerator::CheckCharacterAfterAnd(uint32_t c, uint32_t mask,
+                                                     Label* on_equal) {
+  if (c > MAX_FIRST_ARG) {
+    Emit(BC_AND_CHECK_4_CHARS, 0);
+    Emit32(c);
+  } else {
+    Emit(BC_AND_CHECK_CHAR, c);
+  }
+  Emit32(mask);
+  EmitOrLink(on_equal);
+}
+
+void RegExpBytecodeGenerator::CheckNotCharacterAfterAnd(uint32_t c,
+                                                        uint32_t mask,
+                                                        Label* on_not_equal) {
+  if (c > MAX_FIRST_ARG) {
+    Emit(BC_AND_CHECK_NOT_4_CHARS, 0);
+    Emit32(c);
+  } else {
+    Emit(BC_AND_CHECK_NOT_CHAR, c);
+  }
+  Emit32(mask);
+  EmitOrLink(on_not_equal);
+}
+
+void RegExpBytecodeGenerator::CheckNotCharacterAfterMinusAnd(
+    base::uc16 c, base::uc16 minus, base::uc16 mask, Label* on_not_equal) {
+  Emit(BC_MINUS_AND_CHECK_NOT_CHAR, c);
+  Emit16(minus);
+  Emit16(mask);
+  EmitOrLink(on_not_equal);
+}
+
+void RegExpBytecodeGenerator::CheckCharacterInRange(base::uc16 from,
+                                                    base::uc16 to,
+                                                    Label* on_in_range) {
+  Emit(BC_CHECK_CHAR_IN_RANGE, 0);
+  Emit16(from);
+  Emit16(to);
+  EmitOrLink(on_in_range);
+}
+
+void RegExpBytecodeGenerator::CheckCharacterNotInRange(base::uc16 from,
+                                                       base::uc16 to,
+                                                       Label* on_not_in_range) {
+  Emit(BC_CHECK_CHAR_NOT_IN_RANGE, 0);
+  Emit16(from);
+  Emit16(to);
+  EmitOrLink(on_not_in_range);
+}
+
+void RegExpBytecodeGenerator::CheckBitInTable(Handle<ByteArray> table,
+                                              Label* on_bit_set) {
+  Emit(BC_CHECK_BIT_IN_TABLE, 0);
+  EmitOrLink(on_bit_set);
+  for (int i = 0; i < kTableSize; i += kBitsPerByte) {
+    int byte = 0;
+    for (int j = 0; j < kBitsPerByte; j++) {
+      if (table->get(i + j) != 0) byte |= 1 << j;
+    }
+    Emit8(byte);
+  }
+}
+
+void RegExpBytecodeGenerator::CheckNotBackReference(int start_reg,
+                                                    bool read_backward,
+                                                    Label* on_not_equal) {
+  DCHECK_LE(0, start_reg);
+  DCHECK_GE(kMaxRegister, start_reg);
+  Emit(read_backward ? BC_CHECK_NOT_BACK_REF_BACKWARD : BC_CHECK_NOT_BACK_REF,
+       start_reg);
+  EmitOrLink(on_not_equal);
+}
+
+void RegExpBytecodeGenerator::CheckNotBackReferenceIgnoreCase(
+    int start_reg, bool read_backward, bool unicode, Label* on_not_equal) {
+  DCHECK_LE(0, start_reg);
+  DCHECK_GE(kMaxRegister, start_reg);
+  Emit(read_backward ? (unicode ? BC_CHECK_NOT_BACK_REF_NO_CASE_UNICODE_BACKWARD
+                                : BC_CHECK_NOT_BACK_REF_NO_CASE_BACKWARD)
+                     : (unicode ? BC_CHECK_NOT_BACK_REF_NO_CASE_UNICODE
+                                : BC_CHECK_NOT_BACK_REF_NO_CASE),
+       start_reg);
+  EmitOrLink(on_not_equal);
+}
+
+void RegExpBytecodeGenerator::IfRegisterLT(int register_index, int comparand,
+                                           Label* on_less_than) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_CHECK_REGISTER_LT, register_index);
+  Emit32(comparand);
+  EmitOrLink(on_less_than);
+}
+
+void RegExpBytecodeGenerator::IfRegisterGE(int register_index, int comparand,
+                                           Label* on_greater_or_equal) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_CHECK_REGISTER_GE, register_index);
+  Emit32(comparand);
+  EmitOrLink(on_greater_or_equal);
+}
+
+void RegExpBytecodeGenerator::IfRegisterEqPos(int register_index,
+                                              Label* on_eq) {
+  DCHECK_LE(0, register_index);
+  DCHECK_GE(kMaxRegister, register_index);
+  Emit(BC_CHECK_REGISTER_EQ_POS, register_index);
+  EmitOrLink(on_eq);
+}
+
+Handle<HeapObject> RegExpBytecodeGenerator::GetCode(Handle<String> source) {
+  Bind(&backtrack_);
+  Backtrack();
+
+  Handle<ByteArray> array;
+  if (v8_flags.regexp_peephole_optimization) {
+    array = RegExpBytecodePeepholeOptimization::OptimizeBytecode(
+        isolate_, zone(), source, buffer_.data(), length(), jump_edges_);
+  } else {
+    array = isolate_->factory()->NewByteArray(length());
+    Copy(array->GetDataStartAddress());
+  }
+
+  return array;
+}
+
+int RegExpBytecodeGenerator::length() { return pc_; }
+
+void RegExpBytecodeGenerator::Copy(byte* a) {
+  MemCopy(a, buffer_.data(), length());
+}
+
+void RegExpBytecodeGenerator::ExpandBuffer() {
+  // TODO(jgruber): The growth strategy could be smarter for large sizes.
+  // TODO(jgruber): It's not necessary to default-initialize new elements.
+  buffer_.resize(buffer_.size() * 2);
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/irregexp/imported/regexp-bytecode-generator.h b/js/src/irregexp/imported/regexp-bytecode-generator.h
new file mode 100644
index 0000000000..351f6e0cc6
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-bytecode-generator.h
@@ -0,0 +1,140 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_BYTECODE_GENERATOR_H_
+#define V8_REGEXP_REGEXP_BYTECODE_GENERATOR_H_
+
+#include "irregexp/imported/regexp-macro-assembler.h"
+
+namespace v8 {
+namespace internal {
+
+// An assembler/generator for the Irregexp byte code.
+class V8_EXPORT_PRIVATE RegExpBytecodeGenerator : public RegExpMacroAssembler {
+ public:
+  // Create an assembler. Instructions and relocation information are emitted
+  // into a buffer, with the instructions starting from the beginning and the
+  // relocation information starting from the end of the buffer. See CodeDesc
+  // for a detailed comment on the layout (globals.h).
+  //
+  // The assembler allocates and grows its own buffer, and buffer_size
+  // determines the initial buffer size. The buffer is owned by the assembler
+  // and deallocated upon destruction of the assembler.
+  RegExpBytecodeGenerator(Isolate* isolate, Zone* zone);
+  ~RegExpBytecodeGenerator() override;
+  // The byte-code interpreter checks on each push anyway.
+  int stack_limit_slack() override { return 1; }
+  bool CanReadUnaligned() const override { return false; }
+  void Bind(Label* label) override;
+  void AdvanceCurrentPosition(int by) override;  // Signed cp change.
+  void PopCurrentPosition() override;
+  void PushCurrentPosition() override;
+  void Backtrack() override;
+  void GoTo(Label* label) override;
+  void PushBacktrack(Label* label) override;
+  bool Succeed() override;
+  void Fail() override;
+  void PopRegister(int register_index) override;
+  void PushRegister(int register_index,
+                    StackCheckFlag check_stack_limit) override;
+  void AdvanceRegister(int reg, int by) override;  // r[reg] += by.
+  void SetCurrentPositionFromEnd(int by) override;
+  void SetRegister(int register_index, int to) override;
+  void WriteCurrentPositionToRegister(int reg, int cp_offset) override;
+  void ClearRegisters(int reg_from, int reg_to) override;
+  void ReadCurrentPositionFromRegister(int reg) override;
+  void WriteStackPointerToRegister(int reg) override;
+  void ReadStackPointerFromRegister(int reg) override;
+  void LoadCurrentCharacterImpl(int cp_offset, Label* on_end_of_input,
+                                bool check_bounds, int characters,
+                                int eats_at_least) override;
+  void CheckCharacter(unsigned c, Label* on_equal) override;
+  void CheckCharacterAfterAnd(unsigned c, unsigned mask,
+                              Label* on_equal) override;
+  void CheckCharacterGT(base::uc16 limit, Label* on_greater) override;
+  void CheckCharacterLT(base::uc16 limit, Label* on_less) override;
+  void CheckGreedyLoop(Label* on_tos_equals_current_position) override;
+  void CheckAtStart(int cp_offset, Label* on_at_start) override;
+  void CheckNotAtStart(int cp_offset, Label* on_not_at_start) override;
+  void CheckNotCharacter(unsigned c, Label* on_not_equal) override;
+  void CheckNotCharacterAfterAnd(unsigned c, unsigned mask,
+                                 Label* on_not_equal) override;
+  void CheckNotCharacterAfterMinusAnd(base::uc16 c, base::uc16 minus,
+                                      base::uc16 mask,
+                                      Label* on_not_equal) override;
+  void CheckCharacterInRange(base::uc16 from, base::uc16 to,
+                             Label* on_in_range) override;
+  void CheckCharacterNotInRange(base::uc16 from, base::uc16 to,
+                                Label* on_not_in_range) override;
+  bool CheckCharacterInRangeArray(const ZoneList<CharacterRange>* ranges,
+                                  Label* on_in_range) override {
+    // Disabled in the interpreter, because 1) there is no constant pool that
+    // could store the ByteArray pointer, 2) bytecode size limits are not as
+    // restrictive as code (e.g. branch distances on arm), 3) bytecode for
+    // large character classes is already quite compact.
+    // TODO(jgruber): Consider using BytecodeArrays (with a constant pool)
+    // instead of plain ByteArrays; then we could implement
+    // CheckCharacterInRangeArray in the interpreter.
+    return false;
+  }
+  bool CheckCharacterNotInRangeArray(const ZoneList<CharacterRange>* ranges,
+                                     Label* on_not_in_range) override {
+    return false;
+  }
+  void CheckBitInTable(Handle<ByteArray> table, Label* on_bit_set) override;
+  void CheckNotBackReference(int start_reg, bool read_backward,
+                             Label* on_no_match) override;
+  void CheckNotBackReferenceIgnoreCase(int start_reg, bool read_backward,
+                                       bool unicode,
+                                       Label* on_no_match) override;
+  void IfRegisterLT(int register_index, int comparand, Label* if_lt) override;
+  void IfRegisterGE(int register_index, int comparand, Label* if_ge) override;
+  void IfRegisterEqPos(int register_index, Label* if_eq) override;
+
+  IrregexpImplementation Implementation() override;
+  Handle<HeapObject> GetCode(Handle<String> source) override;
+
+ private:
+  void ExpandBuffer();
+
+  // Code and bitmap emission.
+  inline void EmitOrLink(Label* label);
+  inline void Emit32(uint32_t x);
+  inline void Emit16(uint32_t x);
+  inline void Emit8(uint32_t x);
+  inline void Emit(uint32_t bc, uint32_t arg);
+  inline void Emit(uint32_t bc, int32_t arg);
+  // Bytecode buffer.
+  int length();
+  void Copy(byte* a);
+
+  // The buffer into which code and relocation info are generated.
+  static constexpr int kInitialBufferSize = 1024;
+  ZoneVector<byte> buffer_;
+
+  // The program counter.
+  int pc_;
+  Label backtrack_;
+
+  int advance_current_start_;
+  int advance_current_offset_;
+  int advance_current_end_;
+
+  // Stores jump edges emitted for the bytecode (used by
+  // RegExpBytecodePeepholeOptimization).
+  // Key: jump source (offset in buffer_ where jump destination is stored).
+  // Value: jump destination (offset in buffer_ to jump to).
+  ZoneUnorderedMap<int, int> jump_edges_;
+
+  Isolate* isolate_;
+
+  static const int kInvalidPC = -1;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(RegExpBytecodeGenerator);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_BYTECODE_GENERATOR_H_
diff --git a/js/src/irregexp/imported/regexp-bytecode-peephole.cc b/js/src/irregexp/imported/regexp-bytecode-peephole.cc
new file mode 100644
index 0000000000..9e49bfbeca
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-bytecode-peephole.cc
@@ -0,0 +1,1027 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "irregexp/imported/regexp-bytecode-peephole.h"
+
+#include "irregexp/imported/regexp-bytecodes.h"
+
+namespace v8 {
+namespace internal {
+
+namespace {
+
+struct BytecodeArgument {
+  int offset;
+  int length;
+
+  BytecodeArgument(int offset, int length) : offset(offset), length(length) {}
+};
+
+struct BytecodeArgumentMapping : BytecodeArgument {
+  int new_length;
+
+  BytecodeArgumentMapping(int offset, int length, int new_length)
+      : BytecodeArgument(offset, length), new_length(new_length) {}
+};
+
+struct BytecodeArgumentCheck : BytecodeArgument {
+  enum CheckType { kCheckAddress = 0, kCheckValue };
+  CheckType type;
+  int check_offset;
+  int check_length;
+
+  BytecodeArgumentCheck(int offset, int length, int check_offset)
+      : BytecodeArgument(offset, length),
+        type(kCheckAddress),
+        check_offset(check_offset) {}
+  BytecodeArgumentCheck(int offset, int length, int check_offset,
+                        int check_length)
+      : BytecodeArgument(offset, length),
+        type(kCheckValue),
+        check_offset(check_offset),
+        check_length(check_length) {}
+};
+
+// Trie-Node for storing bytecode sequences we want to optimize.
+class BytecodeSequenceNode {
+ public:
+  // Dummy bytecode used when we need to store/return a bytecode but it's not a
+  // valid bytecode in the current context.
+  static constexpr int kDummyBytecode = -1;
+
+  BytecodeSequenceNode(int bytecode, Zone* zone);
+  // Adds a new node as child of the current node if it isn't a child already.
+  BytecodeSequenceNode& FollowedBy(int bytecode);
+  // Marks the end of a sequence and sets optimized bytecode to replace all
+  // bytecodes of the sequence with.
+  BytecodeSequenceNode& ReplaceWith(int bytecode);
+  // Maps arguments of bytecodes in the sequence to the optimized bytecode.
+  // Order of invocation determines order of arguments in the optimized
+  // bytecode.
+  // Invoking this method is only allowed on nodes that mark the end of a valid
+  // sequence (i.e. after ReplaceWith()).
+  // bytecode_index_in_sequence: Zero-based index of the referred bytecode
+  // within the sequence (e.g. the bytecode passed to CreateSequence() has
+  // index 0).
+  // argument_offset: Zero-based offset to the argument within the bytecode
+  // (e.g. the first argument that's not packed with the bytecode has offset 4).
+  // argument_byte_length: Length of the argument.
+  // new_argument_byte_length: Length of the argument in the new bytecode
+  // (= argument_byte_length if omitted).
+  BytecodeSequenceNode& MapArgument(int bytecode_index_in_sequence,
+                                    int argument_offset,
+                                    int argument_byte_length,
+                                    int new_argument_byte_length = 0);
+  // Adds a check to the sequence node making it only a valid sequence when the
+  // argument of the current bytecode at the specified offset matches the offset
+  // to check against.
+  // argument_offset: Zero-based offset to the argument within the bytecode
+  // (e.g. the first argument that's not packed with the bytecode has offset 4).
+  // argument_byte_length: Length of the argument.
+  // check_byte_offset: Zero-based offset relative to the beginning of the
+  // sequence that needs to match the value given by argument_offset. (e.g.
+  // check_byte_offset 0 matches the address of the first bytecode in the
+  // sequence).
+  BytecodeSequenceNode& IfArgumentEqualsOffset(int argument_offset,
+                                               int argument_byte_length,
+                                               int check_byte_offset);
+  // Adds a check to the sequence node making it only a valid sequence when the
+  // argument of the current bytecode at the specified offset matches the
+  // argument of another bytecode in the sequence.
+  // This is similar to IfArgumentEqualsOffset, except that this method matches
+  // the values of both arguments.
+  BytecodeSequenceNode& IfArgumentEqualsValueAtOffset(
+      int argument_offset, int argument_byte_length,
+      int other_bytecode_index_in_sequence, int other_argument_offset,
+      int other_argument_byte_length);
+  // Marks an argument as unused.
+  // All arguments that are not mapped explicitly have to be marked as unused.
+  // bytecode_index_in_sequence: Zero-based index of the referred bytecode
+  // within the sequence (e.g. the bytecode passed to CreateSequence() has
+  // index 0).
+  // argument_offset: Zero-based offset to the argument within the bytecode
+  // (e.g. the first argument that's not packed with the bytecode has offset 4).
+  // argument_byte_length: Length of the argument.
+  BytecodeSequenceNode& IgnoreArgument(int bytecode_index_in_sequence,
+                                       int argument_offset,
+                                       int argument_byte_length);
+  // Checks if the current node is valid for the sequence. I.e. all conditions
+  // set by IfArgumentEqualsOffset and IfArgumentEquals are fulfilled by this
+  // node for the actual bytecode sequence.
+  bool CheckArguments(const byte* bytecode, int pc);
+  // Returns whether this node marks the end of a valid sequence (i.e. can be
+  // replaced with an optimized bytecode).
+  bool IsSequence() const;
+  // Returns the length of the sequence in bytes.
+  int SequenceLength() const;
+  // Returns the optimized bytecode for the node or kDummyBytecode if it is not
+  // the end of a valid sequence.
+  int OptimizedBytecode() const;
+  // Returns the child of the current node matching the given bytecode or
+  // nullptr if no such child is found.
+  BytecodeSequenceNode* Find(int bytecode) const;
+  // Returns number of arguments mapped to the current node.
+  // Invoking this method is only allowed on nodes that mark the end of a valid
+  // sequence (i.e. if IsSequence())
+  size_t ArgumentSize() const;
+  // Returns the argument-mapping of the argument at index.
+  // Invoking this method is only allowed on nodes that mark the end of a valid
+  // sequence (i.e. if IsSequence())
+  BytecodeArgumentMapping ArgumentMapping(size_t index) const;
+  // Returns an iterator to begin of ignored arguments.
+  // Invoking this method is only allowed on nodes that mark the end of a valid
+  // sequence (i.e. if IsSequence())
+  ZoneLinkedList<BytecodeArgument>::iterator ArgumentIgnoredBegin() const;
+  // Returns an iterator to end of ignored arguments.
+  // Invoking this method is only allowed on nodes that mark the end of a valid
+  // sequence (i.e. if IsSequence())
+  ZoneLinkedList<BytecodeArgument>::iterator ArgumentIgnoredEnd() const;
+  // Returns whether the current node has ignored argument or not.
+  bool HasIgnoredArguments() const;
+
+ private:
+  // Returns a node in the sequence specified by its index within the sequence.
+  BytecodeSequenceNode& GetNodeByIndexInSequence(int index_in_sequence);
+  Zone* zone() const;
+
+  int bytecode_;
+  int bytecode_replacement_;
+  int index_in_sequence_;
+  int start_offset_;
+  BytecodeSequenceNode* parent_;
+  ZoneUnorderedMap<int, BytecodeSequenceNode*> children_;
+  ZoneVector<BytecodeArgumentMapping>* argument_mapping_;
+  ZoneLinkedList<BytecodeArgumentCheck>* argument_check_;
+  ZoneLinkedList<BytecodeArgument>* argument_ignored_;
+
+  Zone* zone_;
+};
+
+// These definitions are here in order to please the linker, which in debug mode
+// sometimes requires static constants to be defined in .cc files.
+constexpr int BytecodeSequenceNode::kDummyBytecode;
+
+class RegExpBytecodePeephole {
+ public:
+  RegExpBytecodePeephole(Zone* zone, size_t buffer_size,
+                         const ZoneUnorderedMap<int, int>& jump_edges);
+
+  // Parses bytecode and fills the internal buffer with the potentially
+  // optimized bytecode. Returns true when optimizations were performed, false
+  // otherwise.
+  bool OptimizeBytecode(const byte* bytecode, int length);
+  // Copies the internal bytecode buffer to another buffer. The caller is
+  // responsible for allocating/freeing the memory.
+  void CopyOptimizedBytecode(byte* to_address) const;
+  int Length() const;
+
+ private:
+  // Sets up all sequences that are going to be used.
+  void DefineStandardSequences();
+  // Starts a new bytecode sequence.
+  BytecodeSequenceNode& CreateSequence(int bytecode);
+  // Checks for optimization candidates at pc and emits optimized bytecode to
+  // the internal buffer. Returns the length of replaced bytecodes in bytes.
+  int TryOptimizeSequence(const byte* bytecode, int bytecode_length,
+                          int start_pc);
+  // Emits optimized bytecode to the internal buffer. start_pc points to the
+  // start of the sequence in bytecode and last_node is the last
+  // BytecodeSequenceNode of the matching sequence found.
+  void EmitOptimization(int start_pc, const byte* bytecode,
+                        const BytecodeSequenceNode& last_node);
+  // Adds a relative jump source fixup at pos.
+  // Jump source fixups are used to find offsets in the new bytecode that
+  // contain jump sources.
+  void AddJumpSourceFixup(int fixup, int pos);
+  // Adds a relative jump destination fixup at pos.
+  // Jump destination fixups are used to find offsets in the new bytecode that
+  // can be jumped to.
+  void AddJumpDestinationFixup(int fixup, int pos);
+  // Sets an absolute jump destination fixup at pos.
+  void SetJumpDestinationFixup(int fixup, int pos);
+  // Prepare internal structures used to fixup jumps.
+  void PrepareJumpStructures(const ZoneUnorderedMap<int, int>& jump_edges);
+  // Updates all jump targets in the new bytecode.
+  void FixJumps();
+  // Update a single jump.
+  void FixJump(int jump_source, int jump_destination);
+  void AddSentinelFixups(int pos);
+  template <typename T>
+  void EmitValue(T value);
+  template <typename T>
+  void OverwriteValue(int offset, T value);
+  void CopyRangeToOutput(const byte* orig_bytecode, int start, int length);
+  void SetRange(byte value, int count);
+  void EmitArgument(int start_pc, const byte* bytecode,
+                    BytecodeArgumentMapping arg);
+  int pc() const;
+  Zone* zone() const;
+
+  ZoneVector<byte> optimized_bytecode_buffer_;
+  BytecodeSequenceNode* sequences_;
+  // Jumps used in old bytecode.
+  // Key: Jump source (offset where destination is stored in old bytecode)
+  // Value: Destination
+  ZoneMap<int, int> jump_edges_;
+  // Jumps used in new bytecode.
+  // Key: Jump source (offset where destination is stored in new bytecode)
+  // Value: Destination
+  ZoneMap<int, int> jump_edges_mapped_;
+  // Number of times a jump destination is used within the bytecode.
+  // Key: Jump destination (offset in old bytecode).
+  // Value: Number of times jump destination is used.
+  ZoneMap<int, int> jump_usage_counts_;
+  // Maps offsets in old bytecode to fixups of sources (delta to new bytecode).
+  // Key: Offset in old bytecode from where the fixup is valid.
+  // Value: Delta to map jump source from old bytecode to new bytecode in bytes.
+  ZoneMap<int, int> jump_source_fixups_;
+  // Maps offsets in old bytecode to fixups of destinations (delta to new
+  // bytecode).
+  // Key: Offset in old bytecode from where the fixup is valid.
+  // Value: Delta to map jump destinations from old bytecode to new bytecode in
+  // bytes.
+  ZoneMap<int, int> jump_destination_fixups_;
+
+  Zone* zone_;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(RegExpBytecodePeephole);
+};
+
+template <typename T>
+T GetValue(const byte* buffer, int pos) {
+  DCHECK(IsAligned(reinterpret_cast<Address>(buffer + pos), alignof(T)));
+  return *reinterpret_cast<const T*>(buffer + pos);
+}
+
+int32_t GetArgumentValue(const byte* bytecode, int offset, int length) {
+  switch (length) {
+    case 1:
+      return GetValue<byte>(bytecode, offset);
+    case 2:
+      return GetValue<int16_t>(bytecode, offset);
+    case 4:
+      return GetValue<int32_t>(bytecode, offset);
+    default:
+      UNREACHABLE();
+  }
+}
+
+BytecodeSequenceNode::BytecodeSequenceNode(int bytecode, Zone* zone)
+    : bytecode_(bytecode),
+      bytecode_replacement_(kDummyBytecode),
+      index_in_sequence_(0),
+      start_offset_(0),
+      parent_(nullptr),
+      children_(ZoneUnorderedMap<int, BytecodeSequenceNode*>(zone)),
+      argument_mapping_(zone->New<ZoneVector<BytecodeArgumentMapping>>(zone)),
+      argument_check_(zone->New<ZoneLinkedList<BytecodeArgumentCheck>>(zone)),
+      argument_ignored_(zone->New<ZoneLinkedList<BytecodeArgument>>(zone)),
+      zone_(zone) {}
+
+BytecodeSequenceNode& BytecodeSequenceNode::FollowedBy(int bytecode) {
+  DCHECK(0 <= bytecode && bytecode < kRegExpBytecodeCount);
+
+  if (children_.find(bytecode) == children_.end()) {
+    BytecodeSequenceNode* new_node =
+        zone()->New<BytecodeSequenceNode>(bytecode, zone());
+    // If node is not the first in the sequence, set offsets and parent.
+    if (bytecode_ != kDummyBytecode) {
+      new_node->start_offset_ = start_offset_ + RegExpBytecodeLength(bytecode_);
+      new_node->index_in_sequence_ = index_in_sequence_ + 1;
+      new_node->parent_ = this;
+    }
+    children_[bytecode] = new_node;
+  }
+
+  return *children_[bytecode];
+}
+
+BytecodeSequenceNode& BytecodeSequenceNode::ReplaceWith(int bytecode) {
+  DCHECK(0 <= bytecode && bytecode < kRegExpBytecodeCount);
+
+  bytecode_replacement_ = bytecode;
+
+  return *this;
+}
+
+BytecodeSequenceNode& BytecodeSequenceNode::MapArgument(
+    int bytecode_index_in_sequence, int argument_offset,
+    int argument_byte_length, int new_argument_byte_length) {
+  DCHECK(IsSequence());
+  DCHECK_LE(bytecode_index_in_sequence, index_in_sequence_);
+
+  BytecodeSequenceNode& ref_node =
+      GetNodeByIndexInSequence(bytecode_index_in_sequence);
+  DCHECK_LT(argument_offset, RegExpBytecodeLength(ref_node.bytecode_));
+
+  int absolute_offset = ref_node.start_offset_ + argument_offset;
+  if (new_argument_byte_length == 0) {
+    new_argument_byte_length = argument_byte_length;
+  }
+
+  argument_mapping_->push_back(BytecodeArgumentMapping{
+      absolute_offset, argument_byte_length, new_argument_byte_length});
+
+  return *this;
+}
+
+BytecodeSequenceNode& BytecodeSequenceNode::IfArgumentEqualsOffset(
+    int argument_offset, int argument_byte_length, int check_byte_offset) {
+  DCHECK_LT(argument_offset, RegExpBytecodeLength(bytecode_));
+  DCHECK(argument_byte_length == 1 || argument_byte_length == 2 ||
+         argument_byte_length == 4);
+
+  int absolute_offset = start_offset_ + argument_offset;
+
+  argument_check_->push_back(BytecodeArgumentCheck{
+      absolute_offset, argument_byte_length, check_byte_offset});
+
+  return *this;
+}
+
+BytecodeSequenceNode& BytecodeSequenceNode::IfArgumentEqualsValueAtOffset(
+    int argument_offset, int argument_byte_length,
+    int other_bytecode_index_in_sequence, int other_argument_offset,
+    int other_argument_byte_length) {
+  DCHECK_LT(argument_offset, RegExpBytecodeLength(bytecode_));
+  DCHECK_LE(other_bytecode_index_in_sequence, index_in_sequence_);
+  DCHECK_EQ(argument_byte_length, other_argument_byte_length);
+
+  BytecodeSequenceNode& ref_node =
+      GetNodeByIndexInSequence(other_bytecode_index_in_sequence);
+  DCHECK_LT(other_argument_offset, RegExpBytecodeLength(ref_node.bytecode_));
+
+  int absolute_offset = start_offset_ + argument_offset;
+  int other_absolute_offset = ref_node.start_offset_ + other_argument_offset;
+
+  argument_check_->push_back(
+      BytecodeArgumentCheck{absolute_offset, argument_byte_length,
+                            other_absolute_offset, other_argument_byte_length});
+
+  return *this;
+}
+
+BytecodeSequenceNode& BytecodeSequenceNode::IgnoreArgument(
+    int bytecode_index_in_sequence, int argument_offset,
+    int argument_byte_length) {
+  DCHECK(IsSequence());
+  DCHECK_LE(bytecode_index_in_sequence, index_in_sequence_);
+
+  BytecodeSequenceNode& ref_node =
+      GetNodeByIndexInSequence(bytecode_index_in_sequence);
+  DCHECK_LT(argument_offset, RegExpBytecodeLength(ref_node.bytecode_));
+
+  int absolute_offset = ref_node.start_offset_ + argument_offset;
+
+  argument_ignored_->push_back(
+      BytecodeArgument{absolute_offset, argument_byte_length});
+
+  return *this;
+}
+
+bool BytecodeSequenceNode::CheckArguments(const byte* bytecode, int pc) {
+  bool is_valid = true;
+  for (auto check_iter = argument_check_->begin();
+       check_iter != argument_check_->end() && is_valid; check_iter++) {
+    auto value =
+        GetArgumentValue(bytecode, pc + check_iter->offset, check_iter->length);
+    if (check_iter->type == BytecodeArgumentCheck::kCheckAddress) {
+      is_valid &= value == pc + check_iter->check_offset;
+    } else if (check_iter->type == BytecodeArgumentCheck::kCheckValue) {
+      auto other_value = GetArgumentValue(
+          bytecode, pc + check_iter->check_offset, check_iter->check_length);
+      is_valid &= value == other_value;
+    } else {
+      UNREACHABLE();
+    }
+  }
+  return is_valid;
+}
+
+bool BytecodeSequenceNode::IsSequence() const {
+  return bytecode_replacement_ != kDummyBytecode;
+}
+
+int BytecodeSequenceNode::SequenceLength() const {
+  return start_offset_ + RegExpBytecodeLength(bytecode_);
+}
+
+int BytecodeSequenceNode::OptimizedBytecode() const {
+  return bytecode_replacement_;
+}
+
+BytecodeSequenceNode* BytecodeSequenceNode::Find(int bytecode) const {
+  auto found = children_.find(bytecode);
+  if (found == children_.end()) return nullptr;
+  return found->second;
+}
+
+size_t BytecodeSequenceNode::ArgumentSize() const {
+  DCHECK(IsSequence());
+  return argument_mapping_->size();
+}
+
+BytecodeArgumentMapping BytecodeSequenceNode::ArgumentMapping(
+    size_t index) const {
+  DCHECK(IsSequence());
+  DCHECK(argument_mapping_ != nullptr);
+  DCHECK_LT(index, argument_mapping_->size());
+
+  return argument_mapping_->at(index);
+}
+
+ZoneLinkedList<BytecodeArgument>::iterator
+BytecodeSequenceNode::ArgumentIgnoredBegin() const {
+  DCHECK(IsSequence());
+  DCHECK(argument_ignored_ != nullptr);
+  return argument_ignored_->begin();
+}
+
+ZoneLinkedList<BytecodeArgument>::iterator
+BytecodeSequenceNode::ArgumentIgnoredEnd() const {
+  DCHECK(IsSequence());
+  DCHECK(argument_ignored_ != nullptr);
+  return argument_ignored_->end();
+}
+
+bool BytecodeSequenceNode::HasIgnoredArguments() const {
+  return argument_ignored_ != nullptr;
+}
+
+BytecodeSequenceNode& BytecodeSequenceNode::GetNodeByIndexInSequence(
+    int index_in_sequence) {
+  DCHECK_LE(index_in_sequence, index_in_sequence_);
+
+  if (index_in_sequence < index_in_sequence_) {
+    DCHECK(parent_ != nullptr);
+    return parent_->GetNodeByIndexInSequence(index_in_sequence);
+  } else {
+    return *this;
+  }
+}
+
+Zone* BytecodeSequenceNode::zone() const { return zone_; }
+
+RegExpBytecodePeephole::RegExpBytecodePeephole(
+    Zone* zone, size_t buffer_size,
+    const ZoneUnorderedMap<int, int>& jump_edges)
+    : optimized_bytecode_buffer_(zone),
+      sequences_(zone->New<BytecodeSequenceNode>(
+          BytecodeSequenceNode::kDummyBytecode, zone)),
+      jump_edges_(zone),
+      jump_edges_mapped_(zone),
+      jump_usage_counts_(zone),
+      jump_source_fixups_(zone),
+      jump_destination_fixups_(zone),
+      zone_(zone) {
+  optimized_bytecode_buffer_.reserve(buffer_size);
+  PrepareJumpStructures(jump_edges);
+  DefineStandardSequences();
+  // Sentinel fixups at beginning of bytecode (position -1) so we don't have to
+  // check for end of iterator inside the fixup loop.
+  // In general fixups are deltas of original offsets of jump
+  // sources/destinations (in the old bytecode) to find them in the new
+  // bytecode. All jump targets are fixed after the new bytecode is fully
+  // emitted in the internal buffer.
+  AddSentinelFixups(-1);
+  // Sentinel fixups at end of (old) bytecode so we don't have to check for
+  // end of iterator inside the fixup loop.
+  DCHECK_LE(buffer_size, std::numeric_limits<int>::max());
+  AddSentinelFixups(static_cast<int>(buffer_size));
+}
+
+void RegExpBytecodePeephole::DefineStandardSequences() {
+  // Commonly used sequences can be found by creating regexp bytecode traces
+  // (--trace-regexp-bytecodes) and using v8/tools/regexp-sequences.py.
+  CreateSequence(BC_LOAD_CURRENT_CHAR)
+      .FollowedBy(BC_CHECK_BIT_IN_TABLE)
+      .FollowedBy(BC_ADVANCE_CP_AND_GOTO)
+      // Sequence is only valid if the jump target of ADVANCE_CP_AND_GOTO is the
+      // first bytecode in this sequence.
+      .IfArgumentEqualsOffset(4, 4, 0)
+      .ReplaceWith(BC_SKIP_UNTIL_BIT_IN_TABLE)
+      .MapArgument(0, 1, 3)      // load offset
+      .MapArgument(2, 1, 3, 4)   // advance by
+      .MapArgument(1, 8, 16)     // bit table
+      .MapArgument(1, 4, 4)      // goto when match
+      .MapArgument(0, 4, 4)      // goto on failure
+      .IgnoreArgument(2, 4, 4);  // loop jump
+
+  CreateSequence(BC_CHECK_CURRENT_POSITION)
+      .FollowedBy(BC_LOAD_CURRENT_CHAR_UNCHECKED)
+      .FollowedBy(BC_CHECK_CHAR)
+      .FollowedBy(BC_ADVANCE_CP_AND_GOTO)
+      // Sequence is only valid if the jump target of ADVANCE_CP_AND_GOTO is the
+      // first bytecode in this sequence.
+      .IfArgumentEqualsOffset(4, 4, 0)
+      .ReplaceWith(BC_SKIP_UNTIL_CHAR_POS_CHECKED)
+      .MapArgument(1, 1, 3)      // load offset
+      .MapArgument(3, 1, 3, 2)   // advance_by
+      .MapArgument(2, 1, 3, 2)   // c
+      .MapArgument(0, 1, 3, 4)   // eats at least
+      .MapArgument(2, 4, 4)      // goto when match
+      .MapArgument(0, 4, 4)      // goto on failure
+      .IgnoreArgument(3, 4, 4);  // loop jump
+
+  CreateSequence(BC_CHECK_CURRENT_POSITION)
+      .FollowedBy(BC_LOAD_CURRENT_CHAR_UNCHECKED)
+      .FollowedBy(BC_AND_CHECK_CHAR)
+      .FollowedBy(BC_ADVANCE_CP_AND_GOTO)
+      // Sequence is only valid if the jump target of ADVANCE_CP_AND_GOTO is the
+      // first bytecode in this sequence.
+      .IfArgumentEqualsOffset(4, 4, 0)
+      .ReplaceWith(BC_SKIP_UNTIL_CHAR_AND)
+      .MapArgument(1, 1, 3)      // load offset
+      .MapArgument(3, 1, 3, 2)   // advance_by
+      .MapArgument(2, 1, 3, 2)   // c
+      .MapArgument(2, 4, 4)      // mask
+      .MapArgument(0, 1, 3, 4)   // eats at least
+      .MapArgument(2, 8, 4)      // goto when match
+      .MapArgument(0, 4, 4)      // goto on failure
+      .IgnoreArgument(3, 4, 4);  // loop jump
+
+  // TODO(pthier): It might make sense for short sequences like this one to only
+  // optimize them if the resulting optimization is not longer than the current
+  // one. This could be the case if there are jumps inside the sequence and we
+  // have to replicate parts of the sequence. A method to mark such sequences
+  // might be useful.
+  CreateSequence(BC_LOAD_CURRENT_CHAR)
+      .FollowedBy(BC_CHECK_CHAR)
+      .FollowedBy(BC_ADVANCE_CP_AND_GOTO)
+      // Sequence is only valid if the jump target of ADVANCE_CP_AND_GOTO is the
+      // first bytecode in this sequence.
+      .IfArgumentEqualsOffset(4, 4, 0)
+      .ReplaceWith(BC_SKIP_UNTIL_CHAR)
+      .MapArgument(0, 1, 3)      // load offset
+      .MapArgument(2, 1, 3, 2)   // advance by
+      .MapArgument(1, 1, 3, 2)   // character
+      .MapArgument(1, 4, 4)      // goto when match
+      .MapArgument(0, 4, 4)      // goto on failure
+      .IgnoreArgument(2, 4, 4);  // loop jump
+
+  CreateSequence(BC_LOAD_CURRENT_CHAR)
+      .FollowedBy(BC_CHECK_CHAR)
+      .FollowedBy(BC_CHECK_CHAR)
+      // Sequence is only valid if the jump targets of both CHECK_CHAR bytecodes
+      // are equal.
+      .IfArgumentEqualsValueAtOffset(4, 4, 1, 4, 4)
+      .FollowedBy(BC_ADVANCE_CP_AND_GOTO)
+      // Sequence is only valid if the jump target of ADVANCE_CP_AND_GOTO is the
+      // first bytecode in this sequence.
+      .IfArgumentEqualsOffset(4, 4, 0)
+      .ReplaceWith(BC_SKIP_UNTIL_CHAR_OR_CHAR)
+      .MapArgument(0, 1, 3)      // load offset
+      .MapArgument(3, 1, 3, 4)   // advance by
+      .MapArgument(1, 1, 3, 2)   // character 1
+      .MapArgument(2, 1, 3, 2)   // character 2
+      .MapArgument(1, 4, 4)      // goto when match
+      .MapArgument(0, 4, 4)      // goto on failure
+      .IgnoreArgument(2, 4, 4)   // goto when match 2
+      .IgnoreArgument(3, 4, 4);  // loop jump
+
+  CreateSequence(BC_LOAD_CURRENT_CHAR)
+      .FollowedBy(BC_CHECK_GT)
+      // Sequence is only valid if the jump target of CHECK_GT is the first
+      // bytecode AFTER the whole sequence.
+      .IfArgumentEqualsOffset(4, 4, 56)
+      .FollowedBy(BC_CHECK_BIT_IN_TABLE)
+      // Sequence is only valid if the jump target of CHECK_BIT_IN_TABLE is
+      // the ADVANCE_CP_AND_GOTO bytecode at the end of the sequence.
+      .IfArgumentEqualsOffset(4, 4, 48)
+      .FollowedBy(BC_GOTO)
+      // Sequence is only valid if the jump target of GOTO is the same as the
+      // jump target of CHECK_GT (i.e. both jump to the first bytecode AFTER the
+      // whole sequence.
+      .IfArgumentEqualsValueAtOffset(4, 4, 1, 4, 4)
+      .FollowedBy(BC_ADVANCE_CP_AND_GOTO)
+      // Sequence is only valid if the jump target of ADVANCE_CP_AND_GOTO is the
+      // first bytecode in this sequence.
+      .IfArgumentEqualsOffset(4, 4, 0)
+      .ReplaceWith(BC_SKIP_UNTIL_GT_OR_NOT_BIT_IN_TABLE)
+      .MapArgument(0, 1, 3)      // load offset
+      .MapArgument(4, 1, 3, 2)   // advance by
+      .MapArgument(1, 1, 3, 2)   // character
+      .MapArgument(2, 8, 16)     // bit table
+      .MapArgument(1, 4, 4)      // goto when match
+      .MapArgument(0, 4, 4)      // goto on failure
+      .IgnoreArgument(2, 4, 4)   // indirect loop jump
+      .IgnoreArgument(3, 4, 4)   // jump out of loop
+      .IgnoreArgument(4, 4, 4);  // loop jump
+}
+
+bool RegExpBytecodePeephole::OptimizeBytecode(const byte* bytecode,
+                                              int length) {
+  int old_pc = 0;
+  bool did_optimize = false;
+
+  while (old_pc < length) {
+    int replaced_len = TryOptimizeSequence(bytecode, length, old_pc);
+    if (replaced_len > 0) {
+      old_pc += replaced_len;
+      did_optimize = true;
+    } else {
+      int bc = bytecode[old_pc];
+      int bc_len = RegExpBytecodeLength(bc);
+      CopyRangeToOutput(bytecode, old_pc, bc_len);
+      old_pc += bc_len;
+    }
+  }
+
+  if (did_optimize) {
+    FixJumps();
+  }
+
+  return did_optimize;
+}
+
+void RegExpBytecodePeephole::CopyOptimizedBytecode(byte* to_address) const {
+  MemCopy(to_address, &(*optimized_bytecode_buffer_.begin()), Length());
+}
+
+int RegExpBytecodePeephole::Length() const { return pc(); }
+
+BytecodeSequenceNode& RegExpBytecodePeephole::CreateSequence(int bytecode) {
+  DCHECK(sequences_ != nullptr);
+  DCHECK(0 <= bytecode && bytecode < kRegExpBytecodeCount);
+
+  return sequences_->FollowedBy(bytecode);
+}
+
+int RegExpBytecodePeephole::TryOptimizeSequence(const byte* bytecode,
+                                                int bytecode_length,
+                                                int start_pc) {
+  BytecodeSequenceNode* seq_node = sequences_;
+  BytecodeSequenceNode* valid_seq_end = nullptr;
+
+  int current_pc = start_pc;
+
+  // Check for the longest valid sequence matching any of the pre-defined
+  // sequences in the Trie data structure.
+  while (current_pc < bytecode_length) {
+    seq_node = seq_node->Find(bytecode[current_pc]);
+    if (seq_node == nullptr) break;
+    if (!seq_node->CheckArguments(bytecode, start_pc)) break;
+
+    if (seq_node->IsSequence()) valid_seq_end = seq_node;
+    current_pc += RegExpBytecodeLength(bytecode[current_pc]);
+  }
+
+  if (valid_seq_end) {
+    EmitOptimization(start_pc, bytecode, *valid_seq_end);
+    return valid_seq_end->SequenceLength();
+  }
+
+  return 0;
+}
+
+void RegExpBytecodePeephole::EmitOptimization(
+    int start_pc, const byte* bytecode, const BytecodeSequenceNode& last_node) {
+#ifdef DEBUG
+  int optimized_start_pc = pc();
+#endif
+  // Jump sources that are mapped or marked as unused will be deleted at the end
+  // of this method. We don't delete them immediately as we might need the
+  // information when we have to preserve bytecodes at the end.
+  // TODO(pthier): Replace with a stack-allocated data structure.
+  ZoneLinkedList<int> delete_jumps = ZoneLinkedList<int>(zone());
+
+  uint32_t bc = last_node.OptimizedBytecode();
+  EmitValue(bc);
+
+  for (size_t arg = 0; arg < last_node.ArgumentSize(); arg++) {
+    BytecodeArgumentMapping arg_map = last_node.ArgumentMapping(arg);
+    int arg_pos = start_pc + arg_map.offset;
+    // If we map any jump source we mark the old source for deletion and insert
+    // a new jump.
+    auto jump_edge_iter = jump_edges_.find(arg_pos);
+    if (jump_edge_iter != jump_edges_.end()) {
+      int jump_source = jump_edge_iter->first;
+      int jump_destination = jump_edge_iter->second;
+      // Add new jump edge add current position.
+      jump_edges_mapped_.emplace(Length(), jump_destination);
+      // Mark old jump edge for deletion.
+      delete_jumps.push_back(jump_source);
+      // Decrement usage count of jump destination.
+      auto jump_count_iter = jump_usage_counts_.find(jump_destination);
+      DCHECK(jump_count_iter != jump_usage_counts_.end());
+      int& usage_count = jump_count_iter->second;
+      --usage_count;
+    }
+    // TODO(pthier): DCHECK that mapped arguments are never sources of jumps
+    // to destinations inside the sequence.
+    EmitArgument(start_pc, bytecode, arg_map);
+  }
+  DCHECK_EQ(pc(), optimized_start_pc +
+                      RegExpBytecodeLength(last_node.OptimizedBytecode()));
+
+  // Remove jumps from arguments we ignore.
+  if (last_node.HasIgnoredArguments()) {
+    for (auto ignored_arg = last_node.ArgumentIgnoredBegin();
+         ignored_arg != last_node.ArgumentIgnoredEnd(); ignored_arg++) {
+      auto jump_edge_iter = jump_edges_.find(start_pc + ignored_arg->offset);
+      if (jump_edge_iter != jump_edges_.end()) {
+        int jump_source = jump_edge_iter->first;
+        int jump_destination = jump_edge_iter->second;
+        // Mark old jump edge for deletion.
+        delete_jumps.push_back(jump_source);
+        // Decrement usage count of jump destination.
+        auto jump_count_iter = jump_usage_counts_.find(jump_destination);
+        DCHECK(jump_count_iter != jump_usage_counts_.end());
+        int& usage_count = jump_count_iter->second;
+        --usage_count;
+      }
+    }
+  }
+
+  int fixup_length = RegExpBytecodeLength(bc) - last_node.SequenceLength();
+
+  // Check if there are any jumps inside the old sequence.
+  // If so we have to keep the bytecodes that are jumped to around.
+  auto jump_destination_candidate = jump_usage_counts_.upper_bound(start_pc);
+  int jump_candidate_destination = jump_destination_candidate->first;
+  int jump_candidate_count = jump_destination_candidate->second;
+  // Jump destinations only jumped to from inside the sequence will be ignored.
+  while (jump_destination_candidate != jump_usage_counts_.end() &&
+         jump_candidate_count == 0) {
+    ++jump_destination_candidate;
+    jump_candidate_destination = jump_destination_candidate->first;
+    jump_candidate_count = jump_destination_candidate->second;
+  }
+
+  int preserve_from = start_pc + last_node.SequenceLength();
+  if (jump_destination_candidate != jump_usage_counts_.end() &&
+      jump_candidate_destination < start_pc + last_node.SequenceLength()) {
+    preserve_from = jump_candidate_destination;
+    // Check if any jump in the sequence we are preserving has a jump
+    // destination inside the optimized sequence before the current position we
+    // want to preserve. If so we have to preserve all bytecodes starting at
+    // this jump destination.
+    for (auto jump_iter = jump_edges_.lower_bound(preserve_from);
+         jump_iter != jump_edges_.end() &&
+         jump_iter->first /* jump source */ <
+             start_pc + last_node.SequenceLength();
+         ++jump_iter) {
+      int jump_destination = jump_iter->second;
+      if (jump_destination > start_pc && jump_destination < preserve_from) {
+        preserve_from = jump_destination;
+      }
+    }
+
+    // We preserve everything to the end of the sequence. This is conservative
+    // since it would be enough to preserve all bytecudes up to an unconditional
+    // jump.
+    int preserve_length = start_pc + last_node.SequenceLength() - preserve_from;
+    fixup_length += preserve_length;
+    // Jumps after the start of the preserved sequence need fixup.
+    AddJumpSourceFixup(fixup_length,
+                       start_pc + last_node.SequenceLength() - preserve_length);
+    // All jump targets after the start of the optimized sequence need to be
+    // fixed relative to the length of the optimized sequence including
+    // bytecodes we preserved.
+    AddJumpDestinationFixup(fixup_length, start_pc + 1);
+    // Jumps to the sequence we preserved need absolute fixup as they could
+    // occur before or after the sequence.
+    SetJumpDestinationFixup(pc() - preserve_from, preserve_from);
+    CopyRangeToOutput(bytecode, preserve_from, preserve_length);
+  } else {
+    AddJumpDestinationFixup(fixup_length, start_pc + 1);
+    // Jumps after the end of the old sequence need fixup.
+    AddJumpSourceFixup(fixup_length, start_pc + last_node.SequenceLength());
+  }
+
+  // Delete jumps we definitely don't need anymore
+  for (int del : delete_jumps) {
+    if (del < preserve_from) {
+      jump_edges_.erase(del);
+    }
+  }
+}
+
+void RegExpBytecodePeephole::AddJumpSourceFixup(int fixup, int pos) {
+  auto previous_fixup = jump_source_fixups_.lower_bound(pos);
+  DCHECK(previous_fixup != jump_source_fixups_.end());
+  DCHECK(previous_fixup != jump_source_fixups_.begin());
+
+  int previous_fixup_value = (--previous_fixup)->second;
+  jump_source_fixups_[pos] = previous_fixup_value + fixup;
+}
+
+void RegExpBytecodePeephole::AddJumpDestinationFixup(int fixup, int pos) {
+  auto previous_fixup = jump_destination_fixups_.lower_bound(pos);
+  DCHECK(previous_fixup != jump_destination_fixups_.end());
+  DCHECK(previous_fixup != jump_destination_fixups_.begin());
+
+  int previous_fixup_value = (--previous_fixup)->second;
+  jump_destination_fixups_[pos] = previous_fixup_value + fixup;
+}
+
+void RegExpBytecodePeephole::SetJumpDestinationFixup(int fixup, int pos) {
+  auto previous_fixup = jump_destination_fixups_.lower_bound(pos);
+  DCHECK(previous_fixup != jump_destination_fixups_.end());
+  DCHECK(previous_fixup != jump_destination_fixups_.begin());
+
+  int previous_fixup_value = (--previous_fixup)->second;
+  jump_destination_fixups_.emplace(pos, fixup);
+  jump_destination_fixups_.emplace(pos + 1, previous_fixup_value);
+}
+
+void RegExpBytecodePeephole::PrepareJumpStructures(
+    const ZoneUnorderedMap<int, int>& jump_edges) {
+  for (auto jump_edge : jump_edges) {
+    int jump_source = jump_edge.first;
+    int jump_destination = jump_edge.second;
+
+    jump_edges_.emplace(jump_source, jump_destination);
+    jump_usage_counts_[jump_destination]++;
+  }
+}
+
+void RegExpBytecodePeephole::FixJumps() {
+  int position_fixup = 0;
+  // Next position where fixup changes.
+  auto next_source_fixup = jump_source_fixups_.lower_bound(0);
+  int next_source_fixup_offset = next_source_fixup->first;
+  int next_source_fixup_value = next_source_fixup->second;
+
+  for (auto jump_edge : jump_edges_) {
+    int jump_source = jump_edge.first;
+    int jump_destination = jump_edge.second;
+    while (jump_source >= next_source_fixup_offset) {
+      position_fixup = next_source_fixup_value;
+      ++next_source_fixup;
+      next_source_fixup_offset = next_source_fixup->first;
+      next_source_fixup_value = next_source_fixup->second;
+    }
+    jump_source += position_fixup;
+
+    FixJump(jump_source, jump_destination);
+  }
+
+  // Mapped jump edges don't need source fixups, as the position already is an
+  // offset in the new bytecode.
+  for (auto jump_edge : jump_edges_mapped_) {
+    int jump_source = jump_edge.first;
+    int jump_destination = jump_edge.second;
+
+    FixJump(jump_source, jump_destination);
+  }
+}
+
+void RegExpBytecodePeephole::FixJump(int jump_source, int jump_destination) {
+  int fixed_jump_destination =
+      jump_destination +
+      (--jump_destination_fixups_.upper_bound(jump_destination))->second;
+  DCHECK_LT(fixed_jump_destination, Length());
+#ifdef DEBUG
+  // TODO(pthier): This check could be better if we track the bytecodes
+  // actually used and check if we jump to one of them.
+  byte jump_bc = optimized_bytecode_buffer_[fixed_jump_destination];
+  DCHECK_GT(jump_bc, 0);
+  DCHECK_LT(jump_bc, kRegExpBytecodeCount);
+#endif
+
+  if (jump_destination != fixed_jump_destination) {
+    OverwriteValue<uint32_t>(jump_source, fixed_jump_destination);
+  }
+}
+
+void RegExpBytecodePeephole::AddSentinelFixups(int pos) {
+  jump_source_fixups_.emplace(pos, 0);
+  jump_destination_fixups_.emplace(pos, 0);
+}
+
+template <typename T>
+void RegExpBytecodePeephole::EmitValue(T value) {
+  DCHECK(optimized_bytecode_buffer_.begin() + pc() ==
+         optimized_bytecode_buffer_.end());
+  byte* value_byte_iter = reinterpret_cast<byte*>(&value);
+  optimized_bytecode_buffer_.insert(optimized_bytecode_buffer_.end(),
+                                    value_byte_iter,
+                                    value_byte_iter + sizeof(T));
+}
+
+template <typename T>
+void RegExpBytecodePeephole::OverwriteValue(int offset, T value) {
+  byte* value_byte_iter = reinterpret_cast<byte*>(&value);
+  byte* value_byte_iter_end = value_byte_iter + sizeof(T);
+  while (value_byte_iter < value_byte_iter_end) {
+    optimized_bytecode_buffer_[offset++] = *value_byte_iter++;
+  }
+}
+
+void RegExpBytecodePeephole::CopyRangeToOutput(const byte* orig_bytecode,
+                                               int start, int length) {
+  DCHECK(optimized_bytecode_buffer_.begin() + pc() ==
+         optimized_bytecode_buffer_.end());
+  optimized_bytecode_buffer_.insert(optimized_bytecode_buffer_.end(),
+                                    orig_bytecode + start,
+                                    orig_bytecode + start + length);
+}
+
+void RegExpBytecodePeephole::SetRange(byte value, int count) {
+  DCHECK(optimized_bytecode_buffer_.begin() + pc() ==
+         optimized_bytecode_buffer_.end());
+  optimized_bytecode_buffer_.insert(optimized_bytecode_buffer_.end(), count,
+                                    value);
+}
+
+void RegExpBytecodePeephole::EmitArgument(int start_pc, const byte* bytecode,
+                                          BytecodeArgumentMapping arg) {
+  int arg_pos = start_pc + arg.offset;
+  switch (arg.length) {
+    case 1:
+      DCHECK_EQ(arg.new_length, arg.length);
+      EmitValue(GetValue<byte>(bytecode, arg_pos));
+      break;
+    case 2:
+      DCHECK_EQ(arg.new_length, arg.length);
+      EmitValue(GetValue<uint16_t>(bytecode, arg_pos));
+      break;
+    case 3: {
+      // Length 3 only occurs in 'packed' arguments where the lowermost byte is
+      // the current bytecode, and the remaining 3 bytes are the packed value.
+      //
+      // We load 4 bytes from position - 1 and shift out the bytecode.
+#ifdef V8_TARGET_BIG_ENDIAN
+      UNIMPLEMENTED();
+      int32_t val = 0;
+#else
+      int32_t val = GetValue<int32_t>(bytecode, arg_pos - 1) >> kBitsPerByte;
+#endif  // V8_TARGET_BIG_ENDIAN
+
+      switch (arg.new_length) {
+        case 2:
+          EmitValue<uint16_t>(val);
+          break;
+        case 3: {
+          // Pack with previously emitted value.
+          auto prev_val =
+              GetValue<int32_t>(&(*optimized_bytecode_buffer_.begin()),
+                                Length() - sizeof(uint32_t));
+#ifdef V8_TARGET_BIG_ENDIAN
+      UNIMPLEMENTED();
+      USE(prev_val);
+#else
+          DCHECK_EQ(prev_val & 0xFFFFFF00, 0);
+          OverwriteValue<uint32_t>(
+              pc() - sizeof(uint32_t),
+              (static_cast<uint32_t>(val) << 8) | (prev_val & 0xFF));
+#endif  // V8_TARGET_BIG_ENDIAN
+          break;
+        }
+        case 4:
+          EmitValue<uint32_t>(val);
+          break;
+      }
+      break;
+    }
+    case 4:
+      DCHECK_EQ(arg.new_length, arg.length);
+      EmitValue(GetValue<uint32_t>(bytecode, arg_pos));
+      break;
+    case 8:
+      DCHECK_EQ(arg.new_length, arg.length);
+      EmitValue(GetValue<uint64_t>(bytecode, arg_pos));
+      break;
+    default:
+      CopyRangeToOutput(bytecode, arg_pos,
+                        std::min(arg.length, arg.new_length));
+      if (arg.length < arg.new_length) {
+        SetRange(0x00, arg.new_length - arg.length);
+      }
+      break;
+  }
+}
+
+int RegExpBytecodePeephole::pc() const {
+  DCHECK_LE(optimized_bytecode_buffer_.size(), std::numeric_limits<int>::max());
+  return static_cast<int>(optimized_bytecode_buffer_.size());
+}
+
+Zone* RegExpBytecodePeephole::zone() const { return zone_; }
+
+}  // namespace
+
+// static
+Handle<ByteArray> RegExpBytecodePeepholeOptimization::OptimizeBytecode(
+    Isolate* isolate, Zone* zone, Handle<String> source, const byte* bytecode,
+    int length, const ZoneUnorderedMap<int, int>& jump_edges) {
+  RegExpBytecodePeephole peephole(zone, length, jump_edges);
+  bool did_optimize = peephole.OptimizeBytecode(bytecode, length);
+  Handle<ByteArray> array = isolate->factory()->NewByteArray(peephole.Length());
+  peephole.CopyOptimizedBytecode(array->GetDataStartAddress());
+
+  if (did_optimize && v8_flags.trace_regexp_peephole_optimization) {
+    PrintF("Original Bytecode:\n");
+    RegExpBytecodeDisassemble(bytecode, length, source->ToCString().get());
+    PrintF("Optimized Bytecode:\n");
+    RegExpBytecodeDisassemble(array->GetDataStartAddress(), peephole.Length(),
+                              source->ToCString().get());
+  }
+
+  return array;
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/irregexp/imported/regexp-bytecode-peephole.h b/js/src/irregexp/imported/regexp-bytecode-peephole.h
new file mode 100644
index 0000000000..5b8a0c7b4b
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-bytecode-peephole.h
@@ -0,0 +1,30 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_BYTECODE_PEEPHOLE_H_
+#define V8_REGEXP_REGEXP_BYTECODE_PEEPHOLE_H_
+
+#include "irregexp/RegExpShim.h"
+
+namespace v8 {
+namespace internal {
+
+class ByteArray;
+
+// Peephole optimization for regexp interpreter bytecode.
+// Pre-defined bytecode sequences occuring in the bytecode generated by the
+// RegExpBytecodeGenerator can be optimized into a single bytecode.
+class RegExpBytecodePeepholeOptimization : public AllStatic {
+ public:
+  // Performs peephole optimization on the given bytecode and returns the
+  // optimized bytecode.
+  static Handle<ByteArray> OptimizeBytecode(
+      Isolate* isolate, Zone* zone, Handle<String> source, const byte* bytecode,
+      int length, const ZoneUnorderedMap<int, int>& jump_edges);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_BYTECODE_PEEPHOLE_H_
diff --git a/js/src/irregexp/imported/regexp-bytecodes.cc b/js/src/irregexp/imported/regexp-bytecodes.cc
new file mode 100644
index 0000000000..829bea9180
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-bytecodes.cc
@@ -0,0 +1,46 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "irregexp/imported/regexp-bytecodes.h"
+
+#include <cctype>
+
+
+namespace v8 {
+namespace internal {
+
+void RegExpBytecodeDisassembleSingle(const byte* code_base, const byte* pc) {
+  int bytecode = *reinterpret_cast<const int32_t*>(pc) & BYTECODE_MASK;
+  PrintF("%s", RegExpBytecodeName(bytecode));
+
+  // Args and the bytecode as hex.
+  for (int i = 0; i < RegExpBytecodeLength(bytecode); i++) {
+    PrintF(", %02x", pc[i]);
+  }
+  PrintF(" ");
+
+  // Args as ascii.
+  for (int i = 1; i < RegExpBytecodeLength(bytecode); i++) {
+    unsigned char b = pc[i];
+    PrintF("%c", std::isprint(b) ? b : '.');
+  }
+  PrintF("\n");
+}
+
+void RegExpBytecodeDisassemble(const byte* code_base, int length,
+                               const char* pattern) {
+  PrintF("[generated bytecode for regexp pattern: '%s']\n", pattern);
+
+  ptrdiff_t offset = 0;
+
+  while (offset < length) {
+    const byte* const pc = code_base + offset;
+    PrintF("%p  %4" V8PRIxPTRDIFF "  ", pc, offset);
+    RegExpBytecodeDisassembleSingle(code_base, pc);
+    offset += RegExpBytecodeLength(*pc);
+  }
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/irregexp/imported/regexp-bytecodes.h b/js/src/irregexp/imported/regexp-bytecodes.h
new file mode 100644
index 0000000000..5602d8d7bc
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-bytecodes.h
@@ -0,0 +1,257 @@
+// Copyright 2011 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_BYTECODES_H_
+#define V8_REGEXP_REGEXP_BYTECODES_H_
+
+#include "irregexp/RegExpShim.h"
+
+namespace v8 {
+namespace internal {
+
+// Maximum number of bytecodes that will be used (next power of 2 of actually
+// defined bytecodes).
+// All slots between the last actually defined bytecode and maximum id will be
+// filled with BREAKs, indicating an invalid operation. This way using
+// BYTECODE_MASK guarantees no OOB access to the dispatch table.
+constexpr int kRegExpPaddedBytecodeCount = 1 << 6;
+constexpr int BYTECODE_MASK = kRegExpPaddedBytecodeCount - 1;
+// The first argument is packed in with the byte code in one word, but so it
+// has 24 bits, but it can be positive and negative so only use 23 bits for
+// positive values.
+const unsigned int MAX_FIRST_ARG = 0x7fffffu;
+const int BYTECODE_SHIFT = 8;
+static_assert(1 << BYTECODE_SHIFT > BYTECODE_MASK);
+
+// The list of bytecodes, in format: V(Name, Code, ByteLength).
+// TODO(pthier): Argument offsets of bytecodes should be easily accessible by
+// name or at least by position.
+// TODO(jgruber): More precise types (e.g. int32/uint32 instead of value32).
+#define BYTECODE_ITERATOR(V)                                                   \
+  V(BREAK, 0, 4)              /* bc8                                        */ \
+  V(PUSH_CP, 1, 4)            /* bc8 pad24                                  */ \
+  V(PUSH_BT, 2, 8)            /* bc8 pad24 offset32                         */ \
+  V(PUSH_REGISTER, 3, 4)      /* bc8 reg_idx24                              */ \
+  V(SET_REGISTER_TO_CP, 4, 8) /* bc8 reg_idx24 offset32                     */ \
+  V(SET_CP_TO_REGISTER, 5, 4) /* bc8 reg_idx24                              */ \
+  V(SET_REGISTER_TO_SP, 6, 4) /* bc8 reg_idx24                              */ \
+  V(SET_SP_TO_REGISTER, 7, 4) /* bc8 reg_idx24                              */ \
+  V(SET_REGISTER, 8, 8)       /* bc8 reg_idx24 value32                      */ \
+  V(ADVANCE_REGISTER, 9, 8)   /* bc8 reg_idx24 value32                      */ \
+  V(POP_CP, 10, 4)            /* bc8 pad24                                  */ \
+  V(POP_BT, 11, 4)            /* bc8 pad24                                  */ \
+  V(POP_REGISTER, 12, 4)      /* bc8 reg_idx24                              */ \
+  V(FAIL, 13, 4)              /* bc8 pad24                                  */ \
+  V(SUCCEED, 14, 4)           /* bc8 pad24                                  */ \
+  V(ADVANCE_CP, 15, 4)        /* bc8 offset24                               */ \
+  /* Jump to another bytecode given its offset.                             */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x10 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F:   0x00 (unused) Padding                                   */ \
+  /* 0x20 - 0x3F:   Address of bytecode to jump to                          */ \
+  V(GOTO, 16, 8) /* bc8 pad24 addr32                           */              \
+  /* Check if offset is in range and load character at given offset.        */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x11 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F:   Offset from current position                            */ \
+  /* 0x20 - 0x3F:   Address of bytecode when load is out of range           */ \
+  V(LOAD_CURRENT_CHAR, 17, 8) /* bc8 offset24 addr32                        */ \
+  /* Load character at given offset without range checks.                   */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x12 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F:   Offset from current position                            */ \
+  V(LOAD_CURRENT_CHAR_UNCHECKED, 18, 4)    /* bc8 offset24 */                  \
+  V(LOAD_2_CURRENT_CHARS, 19, 8)           /* bc8 offset24 addr32 */           \
+  V(LOAD_2_CURRENT_CHARS_UNCHECKED, 20, 4) /* bc8 offset24 */                  \
+  V(LOAD_4_CURRENT_CHARS, 21, 8)           /* bc8 offset24 addr32 */           \
+  V(LOAD_4_CURRENT_CHARS_UNCHECKED, 22, 4) /* bc8 offset24 */                  \
+  V(CHECK_4_CHARS, 23, 12) /* bc8 pad24 uint32 addr32                    */    \
+  /* Check if current character is equal to a given character               */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x19 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x0F:   0x00 (unused) Padding                                   */ \
+  /* 0x10 - 0x1F:   Character to check                                      */ \
+  /* 0x20 - 0x3F:   Address of bytecode when matched                        */ \
+  V(CHECK_CHAR, 24, 8) /* bc8 pad8 uint16 addr32                     */        \
+  V(CHECK_NOT_4_CHARS, 25, 12) /* bc8 pad24 uint32 addr32 */                   \
+  V(CHECK_NOT_CHAR, 26, 8) /* bc8 pad8 uint16 addr32                     */    \
+  V(AND_CHECK_4_CHARS, 27, 16) /* bc8 pad24 uint32 uint32 addr32 */            \
+  /* Checks if the current character combined with mask (bitwise and)       */ \
+  /* matches a character (e.g. used when two characters in a disjunction    */ \
+  /* differ by only a single bit                                            */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x1c (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x0F:   0x00 (unused) Padding                                   */ \
+  /* 0x10 - 0x1F:   Character to match against (after mask aplied)          */ \
+  /* 0x20 - 0x3F:   Bitmask bitwise and combined with current character     */ \
+  /* 0x40 - 0x5F:   Address of bytecode when matched                        */ \
+  V(AND_CHECK_CHAR, 28, 12)        /* bc8 pad8 uint16 uint32 addr32      */    \
+  V(AND_CHECK_NOT_4_CHARS, 29, 16) /* bc8 pad24 uint32 uint32 addr32 */        \
+  V(AND_CHECK_NOT_CHAR, 30, 12)    /* bc8 pad8 uint16 uint32 addr32 */         \
+  V(MINUS_AND_CHECK_NOT_CHAR, 31,                                              \
+    12) /* bc8 pad8 base::uc16 base::uc16 base::uc16 addr32 */                 \
+  V(CHECK_CHAR_IN_RANGE, 32, 12) /* bc8 pad24 base::uc16 base::uc16 addr32 */  \
+  V(CHECK_CHAR_NOT_IN_RANGE, 33,                                               \
+    12) /* bc8 pad24 base::uc16 base::uc16 addr32 */                           \
+  /* Checks if the current character matches any of the characters encoded  */ \
+  /* in a bit table. Similar to/inspired by boyer moore string search       */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x22 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F:   0x00 (unused) Padding                                   */ \
+  /* 0x20 - 0x3F:   Address of bytecode when bit is set                     */ \
+  /* 0x40 - 0xBF:   Bit table                                               */ \
+  V(CHECK_BIT_IN_TABLE, 34, 24) /* bc8 pad24 addr32 bits128           */       \
+  V(CHECK_LT, 35, 8) /* bc8 pad8 base::uc16 addr32                       */    \
+  V(CHECK_GT, 36, 8) /* bc8 pad8 base::uc16 addr32                       */    \
+  V(CHECK_NOT_BACK_REF, 37, 8)         /* bc8 reg_idx24 addr32 */              \
+  V(CHECK_NOT_BACK_REF_NO_CASE, 38, 8) /* bc8 reg_idx24 addr32 */              \
+  V(CHECK_NOT_BACK_REF_NO_CASE_UNICODE, 39, 8)                                 \
+  V(CHECK_NOT_BACK_REF_BACKWARD, 40, 8)         /* bc8 reg_idx24 addr32 */     \
+  V(CHECK_NOT_BACK_REF_NO_CASE_BACKWARD, 41, 8) /* bc8 reg_idx24 addr32 */     \
+  V(CHECK_NOT_BACK_REF_NO_CASE_UNICODE_BACKWARD, 42, 8)                        \
+  V(CHECK_NOT_REGS_EQUAL, 43, 12) /* bc8 regidx24 reg_idx32 addr32 */          \
+  V(CHECK_REGISTER_LT, 44, 12)    /* bc8 reg_idx24 value32 addr32 */           \
+  V(CHECK_REGISTER_GE, 45, 12)    /* bc8 reg_idx24 value32 addr32 */           \
+  V(CHECK_REGISTER_EQ_POS, 46, 8) /* bc8 reg_idx24 addr32 */                   \
+  V(CHECK_AT_START, 47, 8) /* bc8 pad24 addr32                           */    \
+  V(CHECK_NOT_AT_START, 48, 8) /* bc8 offset24 addr32 */                       \
+  /* Checks if the current position matches top of backtrack stack          */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x31 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F:   0x00 (unused) Padding                                   */ \
+  /* 0x20 - 0x3F:   Address of bytecode when current matches tos            */ \
+  V(CHECK_GREEDY, 49, 8) /* bc8 pad24 addr32                           */      \
+  /* Advance character pointer by given offset and jump to another bytecode.*/ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x32 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F:   Number of characters to advance                         */ \
+  /* 0x20 - 0x3F:   Address of bytecode to jump to                          */ \
+  V(ADVANCE_CP_AND_GOTO, 50, 8) /* bc8 offset24 addr32                    */   \
+  V(SET_CURRENT_POSITION_FROM_END, 51, 4) /* bc8 idx24 */                      \
+  /* Checks if current position + given offset is in range.                 */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07:   0x34 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F:   Offset from current position                            */ \
+  /* 0x20 - 0x3F:   Address of bytecode when position is out of range       */ \
+  V(CHECK_CURRENT_POSITION, 52, 8) /* bc8 idx24 addr32                     */  \
+  /* Combination of:                                                        */ \
+  /* LOAD_CURRENT_CHAR, CHECK_BIT_IN_TABLE and ADVANCE_CP_AND_GOTO          */ \
+  /* Emitted by RegExpBytecodePeepholeOptimization.                         */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07    0x35 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F    Load character offset from current position             */ \
+  /* 0x20 - 0x3F    Number of characters to advance                         */ \
+  /* 0x40 - 0xBF    Bit Table                                               */ \
+  /* 0xC0 - 0xDF    Address of bytecode when character is matched           */ \
+  /* 0xE0 - 0xFF    Address of bytecode when no match                       */ \
+  V(SKIP_UNTIL_BIT_IN_TABLE, 53, 32)                                           \
+  /* Combination of:                                                        */ \
+  /* CHECK_CURRENT_POSITION, LOAD_CURRENT_CHAR_UNCHECKED, AND_CHECK_CHAR    */ \
+  /* and ADVANCE_CP_AND_GOTO                                                */ \
+  /* Emitted by RegExpBytecodePeepholeOptimization.                         */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07    0x36 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F    Load character offset from current position             */ \
+  /* 0x20 - 0x2F    Number of characters to advance                         */ \
+  /* 0x30 - 0x3F    Character to match against (after mask applied)         */ \
+  /* 0x40 - 0x5F:   Bitmask bitwise and combined with current character     */ \
+  /* 0x60 - 0x7F    Minimum number of characters this pattern consumes      */ \
+  /* 0x80 - 0x9F    Address of bytecode when character is matched           */ \
+  /* 0xA0 - 0xBF    Address of bytecode when no match                       */ \
+  V(SKIP_UNTIL_CHAR_AND, 54, 24)                                               \
+  /* Combination of:                                                        */ \
+  /* LOAD_CURRENT_CHAR, CHECK_CHAR and ADVANCE_CP_AND_GOTO                  */ \
+  /* Emitted by RegExpBytecodePeepholeOptimization.                         */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07    0x37 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F    Load character offset from current position             */ \
+  /* 0x20 - 0x2F    Number of characters to advance                         */ \
+  /* 0x30 - 0x3F    Character to match                                      */ \
+  /* 0x40 - 0x5F    Address of bytecode when character is matched           */ \
+  /* 0x60 - 0x7F    Address of bytecode when no match                       */ \
+  V(SKIP_UNTIL_CHAR, 55, 16)                                                   \
+  /* Combination of:                                                        */ \
+  /* CHECK_CURRENT_POSITION, LOAD_CURRENT_CHAR_UNCHECKED, CHECK_CHAR        */ \
+  /* and ADVANCE_CP_AND_GOTO                                                */ \
+  /* Emitted by RegExpBytecodePeepholeOptimization.                         */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07    0x38 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F    Load character offset from current position             */ \
+  /* 0x20 - 0x2F    Number of characters to advance                         */ \
+  /* 0x30 - 0x3F    Character to match                                      */ \
+  /* 0x40 - 0x5F    Minimum number of characters this pattern consumes      */ \
+  /* 0x60 - 0x7F    Address of bytecode when character is matched           */ \
+  /* 0x80 - 0x9F    Address of bytecode when no match                       */ \
+  V(SKIP_UNTIL_CHAR_POS_CHECKED, 56, 20)                                       \
+  /* Combination of:                                                        */ \
+  /* LOAD_CURRENT_CHAR, CHECK_CHAR, CHECK_CHAR and ADVANCE_CP_AND_GOTO      */ \
+  /* Emitted by RegExpBytecodePeepholeOptimization.                         */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07    0x39 (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F    Load character offset from current position             */ \
+  /* 0x20 - 0x3F    Number of characters to advance                         */ \
+  /* 0x40 - 0x4F    Character to match                                      */ \
+  /* 0x50 - 0x5F    Other Character to match                                */ \
+  /* 0x60 - 0x7F    Address of bytecode when either character is matched    */ \
+  /* 0x80 - 0x9F    Address of bytecode when no match                       */ \
+  V(SKIP_UNTIL_CHAR_OR_CHAR, 57, 20)                                           \
+  /* Combination of:                                                        */ \
+  /* LOAD_CURRENT_CHAR, CHECK_GT, CHECK_BIT_IN_TABLE, GOTO and              */ \
+  /* and ADVANCE_CP_AND_GOTO                                                */ \
+  /* Emitted by RegExpBytecodePeepholeOptimization.                         */ \
+  /* Bit Layout:                                                            */ \
+  /* 0x00 - 0x07    0x3A (fixed) Bytecode                                   */ \
+  /* 0x08 - 0x1F    Load character offset from current position             */ \
+  /* 0x20 - 0x2F    Number of characters to advance                         */ \
+  /* 0x30 - 0x3F    Character to check if it is less than current char      */ \
+  /* 0x40 - 0xBF    Bit Table                                               */ \
+  /* 0xC0 - 0xDF    Address of bytecode when character is matched           */ \
+  /* 0xE0 - 0xFF    Address of bytecode when no match                       */ \
+  V(SKIP_UNTIL_GT_OR_NOT_BIT_IN_TABLE, 58, 32)
+
+#define COUNT(...) +1
+static constexpr int kRegExpBytecodeCount = BYTECODE_ITERATOR(COUNT);
+#undef COUNT
+
+// Just making sure we assigned values above properly. They should be
+// contiguous, strictly increasing, and start at 0.
+// TODO(jgruber): Do not explicitly assign values, instead generate them
+// implicitly from the list order.
+static_assert(kRegExpBytecodeCount == 59);
+
+#define DECLARE_BYTECODES(name, code, length) \
+  static constexpr int BC_##name = code;
+BYTECODE_ITERATOR(DECLARE_BYTECODES)
+#undef DECLARE_BYTECODES
+
+static constexpr int kRegExpBytecodeLengths[] = {
+#define DECLARE_BYTECODE_LENGTH(name, code, length) length,
+    BYTECODE_ITERATOR(DECLARE_BYTECODE_LENGTH)
+#undef DECLARE_BYTECODE_LENGTH
+};
+
+inline constexpr int RegExpBytecodeLength(int bytecode) {
+  DCHECK(base::IsInRange(bytecode, 0, kRegExpBytecodeCount - 1));
+  return kRegExpBytecodeLengths[bytecode];
+}
+
+static constexpr const char* const kRegExpBytecodeNames[] = {
+#define DECLARE_BYTECODE_NAME(name, ...) #name,
+    BYTECODE_ITERATOR(DECLARE_BYTECODE_NAME)
+#undef DECLARE_BYTECODE_NAME
+};
+
+inline constexpr const char* RegExpBytecodeName(int bytecode) {
+  DCHECK(base::IsInRange(bytecode, 0, kRegExpBytecodeCount - 1));
+  return kRegExpBytecodeNames[bytecode];
+}
+
+void RegExpBytecodeDisassembleSingle(const byte* code_base, const byte* pc);
+void RegExpBytecodeDisassemble(const byte* code_base, int length,
+                               const char* pattern);
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_BYTECODES_H_
diff --git a/js/src/irregexp/imported/regexp-compiler-tonode.cc b/js/src/irregexp/imported/regexp-compiler-tonode.cc
new file mode 100644
index 0000000000..8dc7ed629a
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-compiler-tonode.cc
@@ -0,0 +1,2042 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "irregexp/imported/regexp-compiler.h"
+
+#include "irregexp/imported/regexp.h"
+
+#ifdef V8_INTL_SUPPORT
+#include "irregexp/imported/special-case.h"
+#include "unicode/locid.h"
+#include "unicode/uniset.h"
+#include "unicode/utypes.h"
+#endif  // V8_INTL_SUPPORT
+
+namespace v8 {
+namespace internal {
+
+using namespace regexp_compiler_constants;  // NOLINT(build/namespaces)
+
+constexpr base::uc32 kMaxCodePoint = 0x10ffff;
+constexpr int kMaxUtf16CodeUnit = 0xffff;
+constexpr uint32_t kMaxUtf16CodeUnitU = 0xffff;
+constexpr int32_t kMaxOneByteCharCode = unibrow::Latin1::kMaxChar;
+
+// -------------------------------------------------------------------
+// Tree to graph conversion
+
+RegExpNode* RegExpAtom::ToNode(RegExpCompiler* compiler,
+                               RegExpNode* on_success) {
+  ZoneList<TextElement>* elms =
+      compiler->zone()->New<ZoneList<TextElement>>(1, compiler->zone());
+  elms->Add(TextElement::Atom(this), compiler->zone());
+  return compiler->zone()->New<TextNode>(elms, compiler->read_backward(),
+                                         on_success);
+}
+
+RegExpNode* RegExpText::ToNode(RegExpCompiler* compiler,
+                               RegExpNode* on_success) {
+  return compiler->zone()->New<TextNode>(elements(), compiler->read_backward(),
+                                         on_success);
+}
+
+namespace {
+
+bool CompareInverseRanges(ZoneList<CharacterRange>* ranges,
+                          const int* special_class, int length) {
+  length--;  // Remove final marker.
+
+  DCHECK_EQ(kRangeEndMarker, special_class[length]);
+  DCHECK_NE(0, ranges->length());
+  DCHECK_NE(0, length);
+  DCHECK_NE(0, special_class[0]);
+
+  if (ranges->length() != (length >> 1) + 1) return false;
+
+  CharacterRange range = ranges->at(0);
+  if (range.from() != 0) return false;
+
+  for (int i = 0; i < length; i += 2) {
+    if (static_cast<base::uc32>(special_class[i]) != (range.to() + 1)) {
+      return false;
+    }
+    range = ranges->at((i >> 1) + 1);
+    if (static_cast<base::uc32>(special_class[i + 1]) != range.from()) {
+      return false;
+    }
+  }
+
+  return range.to() == kMaxCodePoint;
+}
+
+bool CompareRanges(ZoneList<CharacterRange>* ranges, const int* special_class,
+                   int length) {
+  length--;  // Remove final marker.
+
+  DCHECK_EQ(kRangeEndMarker, special_class[length]);
+  if (ranges->length() * 2 != length) return false;
+
+  for (int i = 0; i < length; i += 2) {
+    CharacterRange range = ranges->at(i >> 1);
+    if (range.from() != static_cast<base::uc32>(special_class[i]) ||
+        range.to() != static_cast<base::uc32>(special_class[i + 1] - 1)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+}  // namespace
+
+bool RegExpClassRanges::is_standard(Zone* zone) {
+  // TODO(lrn): Remove need for this function, by not throwing away information
+  // along the way.
+  if (is_negated()) {
+    return false;
+  }
+  if (set_.is_standard()) {
+    return true;
+  }
+  if (CompareRanges(set_.ranges(zone), kSpaceRanges, kSpaceRangeCount)) {
+    set_.set_standard_set_type(StandardCharacterSet::kWhitespace);
+    return true;
+  }
+  if (CompareInverseRanges(set_.ranges(zone), kSpaceRanges, kSpaceRangeCount)) {
+    set_.set_standard_set_type(StandardCharacterSet::kNotWhitespace);
+    return true;
+  }
+  if (CompareInverseRanges(set_.ranges(zone), kLineTerminatorRanges,
+                           kLineTerminatorRangeCount)) {
+    set_.set_standard_set_type(StandardCharacterSet::kNotLineTerminator);
+    return true;
+  }
+  if (CompareRanges(set_.ranges(zone), kLineTerminatorRanges,
+                    kLineTerminatorRangeCount)) {
+    set_.set_standard_set_type(StandardCharacterSet::kLineTerminator);
+    return true;
+  }
+  if (CompareRanges(set_.ranges(zone), kWordRanges, kWordRangeCount)) {
+    set_.set_standard_set_type(StandardCharacterSet::kWord);
+    return true;
+  }
+  if (CompareInverseRanges(set_.ranges(zone), kWordRanges, kWordRangeCount)) {
+    set_.set_standard_set_type(StandardCharacterSet::kNotWord);
+    return true;
+  }
+  return false;
+}
+
+UnicodeRangeSplitter::UnicodeRangeSplitter(ZoneList<CharacterRange>* base) {
+  // The unicode range splitter categorizes given character ranges into:
+  // - Code points from the BMP representable by one code unit.
+  // - Code points outside the BMP that need to be split into
+  // surrogate pairs.
+  // - Lone lead surrogates.
+  // - Lone trail surrogates.
+  // Lone surrogates are valid code points, even though no actual characters.
+  // They require special matching to make sure we do not split surrogate pairs.
+
+  for (int i = 0; i < base->length(); i++) AddRange(base->at(i));
+}
+
+void UnicodeRangeSplitter::AddRange(CharacterRange range) {
+  static constexpr base::uc32 kBmp1Start = 0;
+  static constexpr base::uc32 kBmp1End = kLeadSurrogateStart - 1;
+  static constexpr base::uc32 kBmp2Start = kTrailSurrogateEnd + 1;
+  static constexpr base::uc32 kBmp2End = kNonBmpStart - 1;
+
+  // Ends are all inclusive.
+  static_assert(kBmp1Start == 0);
+  static_assert(kBmp1Start < kBmp1End);
+  static_assert(kBmp1End + 1 == kLeadSurrogateStart);
+  static_assert(kLeadSurrogateStart < kLeadSurrogateEnd);
+  static_assert(kLeadSurrogateEnd + 1 == kTrailSurrogateStart);
+  static_assert(kTrailSurrogateStart < kTrailSurrogateEnd);
+  static_assert(kTrailSurrogateEnd + 1 == kBmp2Start);
+  static_assert(kBmp2Start < kBmp2End);
+  static_assert(kBmp2End + 1 == kNonBmpStart);
+  static_assert(kNonBmpStart < kNonBmpEnd);
+
+  static constexpr base::uc32 kStarts[] = {
+      kBmp1Start, kLeadSurrogateStart, kTrailSurrogateStart,
+      kBmp2Start, kNonBmpStart,
+  };
+
+  static constexpr base::uc32 kEnds[] = {
+      kBmp1End, kLeadSurrogateEnd, kTrailSurrogateEnd, kBmp2End, kNonBmpEnd,
+  };
+
+  CharacterRangeVector* const kTargets[] = {
+      &bmp_, &lead_surrogates_, &trail_surrogates_, &bmp_, &non_bmp_,
+  };
+
+  static constexpr int kCount = arraysize(kStarts);
+  static_assert(kCount == arraysize(kEnds));
+  static_assert(kCount == arraysize(kTargets));
+
+  for (int i = 0; i < kCount; i++) {
+    if (kStarts[i] > range.to()) break;
+    const base::uc32 from = std::max(kStarts[i], range.from());
+    const base::uc32 to = std::min(kEnds[i], range.to());
+    if (from > to) continue;
+    kTargets[i]->emplace_back(CharacterRange::Range(from, to));
+  }
+}
+
+namespace {
+
+// Translates between new and old V8-isms (SmallVector, ZoneList).
+ZoneList<CharacterRange>* ToCanonicalZoneList(
+    const UnicodeRangeSplitter::CharacterRangeVector* v, Zone* zone) {
+  if (v->empty()) return nullptr;
+
+  ZoneList<CharacterRange>* result =
+      zone->New<ZoneList<CharacterRange>>(static_cast<int>(v->size()), zone);
+  for (size_t i = 0; i < v->size(); i++) {
+    result->Add(v->at(i), zone);
+  }
+
+  CharacterRange::Canonicalize(result);
+  return result;
+}
+
+void AddBmpCharacters(RegExpCompiler* compiler, ChoiceNode* result,
+                      RegExpNode* on_success, UnicodeRangeSplitter* splitter) {
+  ZoneList<CharacterRange>* bmp =
+      ToCanonicalZoneList(splitter->bmp(), compiler->zone());
+  if (bmp == nullptr) return;
+  result->AddAlternative(GuardedAlternative(TextNode::CreateForCharacterRanges(
+      compiler->zone(), bmp, compiler->read_backward(), on_success)));
+}
+
+using UC16Range = uint32_t;  // {from, to} packed into one uint32_t.
+constexpr UC16Range ToUC16Range(base::uc16 from, base::uc16 to) {
+  return (static_cast<uint32_t>(from) << 16) | to;
+}
+constexpr base::uc16 ExtractFrom(UC16Range r) {
+  return static_cast<base::uc16>(r >> 16);
+}
+constexpr base::uc16 ExtractTo(UC16Range r) {
+  return static_cast<base::uc16>(r);
+}
+
+void AddNonBmpSurrogatePairs(RegExpCompiler* compiler, ChoiceNode* result,
+                             RegExpNode* on_success,
+                             UnicodeRangeSplitter* splitter) {
+  DCHECK(!compiler->one_byte());
+  Zone* const zone = compiler->zone();
+  ZoneList<CharacterRange>* non_bmp =
+      ToCanonicalZoneList(splitter->non_bmp(), zone);
+  if (non_bmp == nullptr) return;
+
+  // Translate each 32-bit code point range into the corresponding 16-bit code
+  // unit representation consisting of the lead- and trail surrogate.
+  //
+  // The generated alternatives are grouped by the leading surrogate to avoid
+  // emitting excessive code. For example, for
+  //
+  //  { \ud800[\udc00-\udc01]
+  //  , \ud800[\udc05-\udc06]
+  //  }
+  //
+  // there's no need to emit matching code for the leading surrogate \ud800
+  // twice. We also create a dedicated grouping for full trailing ranges, i.e.
+  // [dc00-dfff].
+  ZoneUnorderedMap<UC16Range, ZoneList<CharacterRange>*> grouped_by_leading(
+      zone);
+  ZoneList<CharacterRange>* leading_with_full_trailing_range =
+      zone->New<ZoneList<CharacterRange>>(1, zone);
+  const auto AddRange = [&](base::uc16 from_l, base::uc16 to_l,
+                            base::uc16 from_t, base::uc16 to_t) {
+    const UC16Range leading_range = ToUC16Range(from_l, to_l);
+    if (grouped_by_leading.count(leading_range) == 0) {
+      if (from_t == kTrailSurrogateStart && to_t == kTrailSurrogateEnd) {
+        leading_with_full_trailing_range->Add(
+            CharacterRange::Range(from_l, to_l), zone);
+        return;
+      }
+      grouped_by_leading[leading_range] =
+          zone->New<ZoneList<CharacterRange>>(2, zone);
+    }
+    grouped_by_leading[leading_range]->Add(CharacterRange::Range(from_t, to_t),
+                                           zone);
+  };
+
+  // First, create the grouped ranges.
+  CharacterRange::Canonicalize(non_bmp);
+  for (int i = 0; i < non_bmp->length(); i++) {
+    // Match surrogate pair.
+    // E.g. [\u10005-\u11005] becomes
+    //      \ud800[\udc05-\udfff]|
+    //      [\ud801-\ud803][\udc00-\udfff]|
+    //      \ud804[\udc00-\udc05]
+    base::uc32 from = non_bmp->at(i).from();
+    base::uc32 to = non_bmp->at(i).to();
+    base::uc16 from_l = unibrow::Utf16::LeadSurrogate(from);
+    base::uc16 from_t = unibrow::Utf16::TrailSurrogate(from);
+    base::uc16 to_l = unibrow::Utf16::LeadSurrogate(to);
+    base::uc16 to_t = unibrow::Utf16::TrailSurrogate(to);
+
+    if (from_l == to_l) {
+      // The lead surrogate is the same.
+      AddRange(from_l, to_l, from_t, to_t);
+      continue;
+    }
+
+    if (from_t != kTrailSurrogateStart) {
+      // Add [from_l][from_t-\udfff].
+      AddRange(from_l, from_l, from_t, kTrailSurrogateEnd);
+      from_l++;
+    }
+    if (to_t != kTrailSurrogateEnd) {
+      // Add [to_l][\udc00-to_t].
+      AddRange(to_l, to_l, kTrailSurrogateStart, to_t);
+      to_l--;
+    }
+    if (from_l <= to_l) {
+      // Add [from_l-to_l][\udc00-\udfff].
+      AddRange(from_l, to_l, kTrailSurrogateStart, kTrailSurrogateEnd);
+    }
+  }
+
+  // Create the actual TextNode now that ranges are fully grouped.
+  if (!leading_with_full_trailing_range->is_empty()) {
+    CharacterRange::Canonicalize(leading_with_full_trailing_range);
+    result->AddAlternative(GuardedAlternative(TextNode::CreateForSurrogatePair(
+        zone, leading_with_full_trailing_range,
+        CharacterRange::Range(kTrailSurrogateStart, kTrailSurrogateEnd),
+        compiler->read_backward(), on_success)));
+  }
+  for (const auto& it : grouped_by_leading) {
+    CharacterRange leading_range =
+        CharacterRange::Range(ExtractFrom(it.first), ExtractTo(it.first));
+    ZoneList<CharacterRange>* trailing_ranges = it.second;
+    CharacterRange::Canonicalize(trailing_ranges);
+    result->AddAlternative(GuardedAlternative(TextNode::CreateForSurrogatePair(
+        zone, leading_range, trailing_ranges, compiler->read_backward(),
+        on_success)));
+  }
+}
+
+RegExpNode* NegativeLookaroundAgainstReadDirectionAndMatch(
+    RegExpCompiler* compiler, ZoneList<CharacterRange>* lookbehind,
+    ZoneList<CharacterRange>* match, RegExpNode* on_success,
+    bool read_backward) {
+  Zone* zone = compiler->zone();
+  RegExpNode* match_node = TextNode::CreateForCharacterRanges(
+      zone, match, read_backward, on_success);
+  int stack_register = compiler->UnicodeLookaroundStackRegister();
+  int position_register = compiler->UnicodeLookaroundPositionRegister();
+  RegExpLookaround::Builder lookaround(false, match_node, stack_register,
+                                       position_register);
+  RegExpNode* negative_match = TextNode::CreateForCharacterRanges(
+      zone, lookbehind, !read_backward, lookaround.on_match_success());
+  return lookaround.ForMatch(negative_match);
+}
+
+RegExpNode* MatchAndNegativeLookaroundInReadDirection(
+    RegExpCompiler* compiler, ZoneList<CharacterRange>* match,
+    ZoneList<CharacterRange>* lookahead, RegExpNode* on_success,
+    bool read_backward) {
+  Zone* zone = compiler->zone();
+  int stack_register = compiler->UnicodeLookaroundStackRegister();
+  int position_register = compiler->UnicodeLookaroundPositionRegister();
+  RegExpLookaround::Builder lookaround(false, on_success, stack_register,
+                                       position_register);
+  RegExpNode* negative_match = TextNode::CreateForCharacterRanges(
+      zone, lookahead, read_backward, lookaround.on_match_success());
+  return TextNode::CreateForCharacterRanges(
+      zone, match, read_backward, lookaround.ForMatch(negative_match));
+}
+
+void AddLoneLeadSurrogates(RegExpCompiler* compiler, ChoiceNode* result,
+                           RegExpNode* on_success,
+                           UnicodeRangeSplitter* splitter) {
+  ZoneList<CharacterRange>* lead_surrogates =
+      ToCanonicalZoneList(splitter->lead_surrogates(), compiler->zone());
+  if (lead_surrogates == nullptr) return;
+  Zone* zone = compiler->zone();
+  // E.g. \ud801 becomes \ud801(?![\udc00-\udfff]).
+  ZoneList<CharacterRange>* trail_surrogates = CharacterRange::List(
+      zone, CharacterRange::Range(kTrailSurrogateStart, kTrailSurrogateEnd));
+
+  RegExpNode* match;
+  if (compiler->read_backward()) {
+    // Reading backward. Assert that reading forward, there is no trail
+    // surrogate, and then backward match the lead surrogate.
+    match = NegativeLookaroundAgainstReadDirectionAndMatch(
+        compiler, trail_surrogates, lead_surrogates, on_success, true);
+  } else {
+    // Reading forward. Forward match the lead surrogate and assert that
+    // no trail surrogate follows.
+    match = MatchAndNegativeLookaroundInReadDirection(
+        compiler, lead_surrogates, trail_surrogates, on_success, false);
+  }
+  result->AddAlternative(GuardedAlternative(match));
+}
+
+void AddLoneTrailSurrogates(RegExpCompiler* compiler, ChoiceNode* result,
+                            RegExpNode* on_success,
+                            UnicodeRangeSplitter* splitter) {
+  ZoneList<CharacterRange>* trail_surrogates =
+      ToCanonicalZoneList(splitter->trail_surrogates(), compiler->zone());
+  if (trail_surrogates == nullptr) return;
+  Zone* zone = compiler->zone();
+  // E.g. \udc01 becomes (?<![\ud800-\udbff])\udc01
+  ZoneList<CharacterRange>* lead_surrogates = CharacterRange::List(
+      zone, CharacterRange::Range(kLeadSurrogateStart, kLeadSurrogateEnd));
+
+  RegExpNode* match;
+  if (compiler->read_backward()) {
+    // Reading backward. Backward match the trail surrogate and assert that no
+    // lead surrogate precedes it.
+    match = MatchAndNegativeLookaroundInReadDirection(
+        compiler, trail_surrogates, lead_surrogates, on_success, true);
+  } else {
+    // Reading forward. Assert that reading backward, there is no lead
+    // surrogate, and then forward match the trail surrogate.
+    match = NegativeLookaroundAgainstReadDirectionAndMatch(
+        compiler, lead_surrogates, trail_surrogates, on_success, false);
+  }
+  result->AddAlternative(GuardedAlternative(match));
+}
+
+RegExpNode* UnanchoredAdvance(RegExpCompiler* compiler,
+                              RegExpNode* on_success) {
+  // This implements ES2015 21.2.5.2.3, AdvanceStringIndex.
+  DCHECK(!compiler->read_backward());
+  Zone* zone = compiler->zone();
+  // Advance any character. If the character happens to be a lead surrogate and
+  // we advanced into the middle of a surrogate pair, it will work out, as
+  // nothing will match from there. We will have to advance again, consuming
+  // the associated trail surrogate.
+  ZoneList<CharacterRange>* range =
+      CharacterRange::List(zone, CharacterRange::Range(0, kMaxUtf16CodeUnit));
+  return TextNode::CreateForCharacterRanges(zone, range, false, on_success);
+}
+
+}  // namespace
+
+#ifdef V8_INTL_SUPPORT
+// static
+void CharacterRange::UnicodeSimpleCloseOver(icu::UnicodeSet& set) {
+  // Remove characters for which closeOver() adds full-case-folding equivalents
+  // because we should work only with simple case folding mappings.
+  icu::UnicodeSet non_simple = icu::UnicodeSet(set);
+  non_simple.retainAll(RegExpCaseFolding::UnicodeNonSimpleCloseOverSet());
+  set.removeAll(non_simple);
+
+  set.closeOver(USET_CASE_INSENSITIVE);
+  // Full case folding maps single characters to multiple characters.
+  // Those are represented as strings in the set. Remove them so that
+  // we end up with only simple and common case mappings.
+  set.removeAllStrings();
+
+  // Add characters that have non-simple case foldings again (they match
+  // themselves).
+  set.addAll(non_simple);
+}
+#endif  // V8_INTL_SUPPORT
+
+// static
+void CharacterRange::AddUnicodeCaseEquivalents(ZoneList<CharacterRange>* ranges,
+                                               Zone* zone) {
+#ifdef V8_INTL_SUPPORT
+  DCHECK(IsCanonical(ranges));
+
+  // Micro-optimization to avoid passing large ranges to UnicodeSet::closeOver.
+  // See also https://crbug.com/v8/6727.
+  // TODO(jgruber): This only covers the special case of the {0,0x10FFFF} range,
+  // which we use frequently internally. But large ranges can also easily be
+  // created by the user. We might want to have a more general caching mechanism
+  // for such ranges.
+  if (ranges->length() == 1 && ranges->at(0).IsEverything(kNonBmpEnd)) return;
+
+  // Use ICU to compute the case fold closure over the ranges.
+  icu::UnicodeSet set;
+  for (int i = 0; i < ranges->length(); i++) {
+    set.add(ranges->at(i).from(), ranges->at(i).to());
+  }
+  // Clear the ranges list without freeing the backing store.
+  ranges->Rewind(0);
+
+  UnicodeSimpleCloseOver(set);
+  for (int i = 0; i < set.getRangeCount(); i++) {
+    ranges->Add(Range(set.getRangeStart(i), set.getRangeEnd(i)), zone);
+  }
+  // No errors and everything we collected have been ranges.
+  Canonicalize(ranges);
+#endif  // V8_INTL_SUPPORT
+}
+
+RegExpNode* RegExpClassRanges::ToNode(RegExpCompiler* compiler,
+                                      RegExpNode* on_success) {
+  set_.Canonicalize();
+  Zone* const zone = compiler->zone();
+  ZoneList<CharacterRange>* ranges = this->ranges(zone);
+
+  if (NeedsUnicodeCaseEquivalents(compiler->flags())) {
+    CharacterRange::AddUnicodeCaseEquivalents(ranges, zone);
+  }
+
+  if (!IsEitherUnicode(compiler->flags()) || compiler->one_byte() ||
+      contains_split_surrogate()) {
+    return zone->New<TextNode>(this, compiler->read_backward(), on_success);
+  }
+
+  if (is_negated()) {
+    // With /v, character classes are never negated.
+    // TODO(v8:11935): Change permalink once proposal is in stage 4.
+    // https://arai-a.github.io/ecma262-compare/snapshot.html?pr=2418#sec-compileatom
+    // Atom :: CharacterClass
+    //   4. Assert: cc.[[Invert]] is false.
+    // Instead the complement is created when evaluating the class set.
+    // The only exception is the "nothing range" (negated everything), which is
+    // internally created for an empty set.
+    DCHECK_IMPLIES(
+        IsUnicodeSets(compiler->flags()),
+        ranges->length() == 1 && ranges->first().IsEverything(kMaxCodePoint));
+    ZoneList<CharacterRange>* negated =
+        zone->New<ZoneList<CharacterRange>>(2, zone);
+    CharacterRange::Negate(ranges, negated, zone);
+    ranges = negated;
+  }
+
+  if (ranges->length() == 0) {
+    // The empty character class is used as a 'fail' node.
+    RegExpClassRanges* fail = zone->New<RegExpClassRanges>(zone, ranges);
+    return zone->New<TextNode>(fail, compiler->read_backward(), on_success);
+  }
+
+  if (set_.is_standard() &&
+      standard_type() == StandardCharacterSet::kEverything) {
+    return UnanchoredAdvance(compiler, on_success);
+  }
+
+  // Split ranges in order to handle surrogates correctly:
+  // - Surrogate pairs: translate the 32-bit code point into two uc16 code
+  //   units (irregexp operates only on code units).
+  // - Lone surrogates: these require lookarounds to ensure we don't match in
+  //   the middle of a surrogate pair.
+  ChoiceNode* result = zone->New<ChoiceNode>(2, zone);
+  UnicodeRangeSplitter splitter(ranges);
+  AddBmpCharacters(compiler, result, on_success, &splitter);
+  AddNonBmpSurrogatePairs(compiler, result, on_success, &splitter);
+  AddLoneLeadSurrogates(compiler, result, on_success, &splitter);
+  AddLoneTrailSurrogates(compiler, result, on_success, &splitter);
+
+  static constexpr int kMaxRangesToInline = 32;  // Arbitrary.
+  if (ranges->length() > kMaxRangesToInline) result->SetDoNotInline();
+
+  return result;
+}
+
+RegExpNode* RegExpClassSetOperand::ToNode(RegExpCompiler* compiler,
+                                          RegExpNode* on_success) {
+  Zone* zone = compiler->zone();
+  const int size = (has_strings() ? static_cast<int>(strings()->size()) : 0) +
+                   (ranges()->is_empty() ? 0 : 1);
+  if (size == 0) {
+    // If neither ranges nor strings are present, the operand is equal to an
+    // empty range (matching nothing).
+    ZoneList<CharacterRange>* empty =
+        zone->template New<ZoneList<CharacterRange>>(0, zone);
+    return zone->template New<RegExpClassRanges>(zone, empty)
+        ->ToNode(compiler, on_success);
+  }
+  ZoneList<RegExpTree*>* alternatives =
+      zone->template New<ZoneList<RegExpTree*>>(size, zone);
+  // Strings are sorted by length first (larger strings before shorter ones).
+  // See the comment on CharacterClassStrings.
+  // Empty strings (if present) are added after character ranges.
+  RegExpTree* empty_string = nullptr;
+  if (has_strings()) {
+    for (auto string : *strings()) {
+      if (string.second->IsEmpty()) {
+        empty_string = string.second;
+      } else {
+        alternatives->Add(string.second, zone);
+      }
+    }
+  }
+  if (!ranges()->is_empty()) {
+    alternatives->Add(zone->template New<RegExpClassRanges>(zone, ranges()),
+                      zone);
+  }
+  if (empty_string != nullptr) {
+    alternatives->Add(empty_string, zone);
+  }
+
+  RegExpTree* node = nullptr;
+  if (size == 1) {
+    DCHECK_EQ(alternatives->length(), 1);
+    node = alternatives->first();
+  } else {
+    node = zone->template New<RegExpDisjunction>(alternatives);
+  }
+  return node->ToNode(compiler, on_success);
+}
+
+RegExpNode* RegExpClassSetExpression::ToNode(RegExpCompiler* compiler,
+                                             RegExpNode* on_success) {
+  Zone* zone = compiler->zone();
+  ZoneList<CharacterRange>* temp_ranges =
+      zone->template New<ZoneList<CharacterRange>>(4, zone);
+  RegExpClassSetOperand* root = ComputeExpression(this, temp_ranges, zone);
+  return root->ToNode(compiler, on_success);
+}
+
+void RegExpClassSetOperand::Union(RegExpClassSetOperand* other, Zone* zone) {
+  ranges()->AddAll(*other->ranges(), zone);
+  if (other->has_strings()) {
+    if (strings_ == nullptr) {
+      strings_ = zone->template New<CharacterClassStrings>(zone);
+    }
+    strings()->insert(other->strings()->begin(), other->strings()->end());
+  }
+}
+
+void RegExpClassSetOperand::Intersect(RegExpClassSetOperand* other,
+                                      ZoneList<CharacterRange>* temp_ranges,
+                                      Zone* zone) {
+  CharacterRange::Intersect(ranges(), other->ranges(), temp_ranges, zone);
+  std::swap(*ranges(), *temp_ranges);
+  temp_ranges->Rewind(0);
+  if (has_strings()) {
+    if (!other->has_strings()) {
+      strings()->clear();
+    } else {
+      for (auto iter = strings()->begin(); iter != strings()->end();) {
+        if (other->strings()->find(iter->first) == other->strings()->end()) {
+          iter = strings()->erase(iter);
+        } else {
+          iter++;
+        }
+      }
+    }
+  }
+}
+
+void RegExpClassSetOperand::Subtract(RegExpClassSetOperand* other,
+                                     ZoneList<CharacterRange>* temp_ranges,
+                                     Zone* zone) {
+  CharacterRange::Subtract(ranges(), other->ranges(), temp_ranges, zone);
+  std::swap(*ranges(), *temp_ranges);
+  temp_ranges->Rewind(0);
+  if (has_strings() && other->has_strings()) {
+    for (auto iter = strings()->begin(); iter != strings()->end();) {
+      if (other->strings()->find(iter->first) != other->strings()->end()) {
+        iter = strings()->erase(iter);
+      } else {
+        iter++;
+      }
+    }
+  }
+}
+
+// static
+RegExpClassSetOperand* RegExpClassSetExpression::ComputeExpression(
+    RegExpTree* root, ZoneList<CharacterRange>* temp_ranges, Zone* zone) {
+  DCHECK(temp_ranges->is_empty());
+  if (root->IsClassSetOperand()) {
+    return root->AsClassSetOperand();
+  }
+  DCHECK(root->IsClassSetExpression());
+  RegExpClassSetExpression* node = root->AsClassSetExpression();
+  RegExpClassSetOperand* result =
+      ComputeExpression(node->operands()->at(0), temp_ranges, zone);
+  switch (node->operation()) {
+    case OperationType::kUnion: {
+      for (int i = 1; i < node->operands()->length(); i++) {
+        RegExpClassSetOperand* op =
+            ComputeExpression(node->operands()->at(i), temp_ranges, zone);
+        result->Union(op, zone);
+      }
+      CharacterRange::Canonicalize(result->ranges());
+      break;
+    }
+    case OperationType::kIntersection: {
+      for (int i = 1; i < node->operands()->length(); i++) {
+        RegExpClassSetOperand* op =
+            ComputeExpression(node->operands()->at(i), temp_ranges, zone);
+        result->Intersect(op, temp_ranges, zone);
+      }
+      break;
+    }
+    case OperationType::kSubtraction: {
+      for (int i = 1; i < node->operands()->length(); i++) {
+        RegExpClassSetOperand* op =
+            ComputeExpression(node->operands()->at(i), temp_ranges, zone);
+        result->Subtract(op, temp_ranges, zone);
+      }
+      break;
+    }
+  }
+  if (node->is_negated()) {
+    DCHECK(!result->has_strings());
+    CharacterRange::Negate(result->ranges(), temp_ranges, zone);
+    std::swap(*result->ranges(), *temp_ranges);
+    temp_ranges->Rewind(0);
+  }
+  // Store the result as single operand of the current node.
+  node->operands()->Set(0, result);
+  node->operands()->Rewind(1);
+
+  return result;
+}
+
+namespace {
+
+int CompareFirstChar(RegExpTree* const* a, RegExpTree* const* b) {
+  RegExpAtom* atom1 = (*a)->AsAtom();
+  RegExpAtom* atom2 = (*b)->AsAtom();
+  base::uc16 character1 = atom1->data().at(0);
+  base::uc16 character2 = atom2->data().at(0);
+  if (character1 < character2) return -1;
+  if (character1 > character2) return 1;
+  return 0;
+}
+
+#ifdef V8_INTL_SUPPORT
+
+int CompareCaseInsensitive(const icu::UnicodeString& a,
+                           const icu::UnicodeString& b) {
+  return a.caseCompare(b, U_FOLD_CASE_DEFAULT);
+}
+
+int CompareFirstCharCaseInsensitive(RegExpTree* const* a,
+                                    RegExpTree* const* b) {
+  RegExpAtom* atom1 = (*a)->AsAtom();
+  RegExpAtom* atom2 = (*b)->AsAtom();
+  return CompareCaseInsensitive(icu::UnicodeString{atom1->data().at(0)},
+                                icu::UnicodeString{atom2->data().at(0)});
+}
+
+bool Equals(bool ignore_case, const icu::UnicodeString& a,
+            const icu::UnicodeString& b) {
+  if (a == b) return true;
+  if (ignore_case) return CompareCaseInsensitive(a, b) == 0;
+  return false;  // Case-sensitive equality already checked above.
+}
+
+bool CharAtEquals(bool ignore_case, int index, const RegExpAtom* a,
+                  const RegExpAtom* b) {
+  return Equals(ignore_case, a->data().at(index), b->data().at(index));
+}
+
+#else
+
+unibrow::uchar Canonical(
+    unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize,
+    unibrow::uchar c) {
+  unibrow::uchar chars[unibrow::Ecma262Canonicalize::kMaxWidth];
+  int length = canonicalize->get(c, '\0', chars);
+  DCHECK_LE(length, 1);
+  unibrow::uchar canonical = c;
+  if (length == 1) canonical = chars[0];
+  return canonical;
+}
+
+int CompareCaseInsensitive(
+    unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize,
+    unibrow::uchar a, unibrow::uchar b) {
+  if (a == b) return 0;
+  if (a >= 'a' || b >= 'a') {
+    a = Canonical(canonicalize, a);
+    b = Canonical(canonicalize, b);
+  }
+  return static_cast<int>(a) - static_cast<int>(b);
+}
+
+int CompareFirstCharCaseInsensitive(
+    unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize,
+    RegExpTree* const* a, RegExpTree* const* b) {
+  RegExpAtom* atom1 = (*a)->AsAtom();
+  RegExpAtom* atom2 = (*b)->AsAtom();
+  return CompareCaseInsensitive(canonicalize, atom1->data().at(0),
+                                atom2->data().at(0));
+}
+
+bool Equals(bool ignore_case,
+            unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize,
+            unibrow::uchar a, unibrow::uchar b) {
+  if (a == b) return true;
+  if (ignore_case) {
+    return CompareCaseInsensitive(canonicalize, a, b) == 0;
+  }
+  return false;  // Case-sensitive equality already checked above.
+}
+
+bool CharAtEquals(bool ignore_case,
+                  unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize,
+                  int index, const RegExpAtom* a, const RegExpAtom* b) {
+  return Equals(ignore_case, canonicalize, a->data().at(index),
+                b->data().at(index));
+}
+
+#endif  // V8_INTL_SUPPORT
+
+}  // namespace
+
+// We can stable sort runs of atoms, since the order does not matter if they
+// start with different characters.
+// Returns true if any consecutive atoms were found.
+bool RegExpDisjunction::SortConsecutiveAtoms(RegExpCompiler* compiler) {
+  ZoneList<RegExpTree*>* alternatives = this->alternatives();
+  int length = alternatives->length();
+  bool found_consecutive_atoms = false;
+  for (int i = 0; i < length; i++) {
+    while (i < length) {
+      RegExpTree* alternative = alternatives->at(i);
+      if (alternative->IsAtom()) break;
+      i++;
+    }
+    // i is length or it is the index of an atom.
+    if (i == length) break;
+    int first_atom = i;
+    i++;
+    while (i < length) {
+      RegExpTree* alternative = alternatives->at(i);
+      if (!alternative->IsAtom()) break;
+      i++;
+    }
+    // Sort atoms to get ones with common prefixes together.
+    // This step is more tricky if we are in a case-independent regexp,
+    // because it would change /is|I/ to /I|is/, and order matters when
+    // the regexp parts don't match only disjoint starting points. To fix
+    // this we have a version of CompareFirstChar that uses case-
+    // independent character classes for comparison.
+    DCHECK_LT(first_atom, alternatives->length());
+    DCHECK_LE(i, alternatives->length());
+    DCHECK_LE(first_atom, i);
+    if (IsIgnoreCase(compiler->flags())) {
+#ifdef V8_INTL_SUPPORT
+      alternatives->StableSort(CompareFirstCharCaseInsensitive, first_atom,
+                               i - first_atom);
+#else
+      unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize =
+          compiler->isolate()->regexp_macro_assembler_canonicalize();
+      auto compare_closure = [canonicalize](RegExpTree* const* a,
+                                            RegExpTree* const* b) {
+        return CompareFirstCharCaseInsensitive(canonicalize, a, b);
+      };
+      alternatives->StableSort(compare_closure, first_atom, i - first_atom);
+#endif  // V8_INTL_SUPPORT
+    } else {
+      alternatives->StableSort(CompareFirstChar, first_atom, i - first_atom);
+    }
+    if (i - first_atom > 1) found_consecutive_atoms = true;
+  }
+  return found_consecutive_atoms;
+}
+
+// Optimizes ab|ac|az to a(?:b|c|d).
+void RegExpDisjunction::RationalizeConsecutiveAtoms(RegExpCompiler* compiler) {
+  Zone* zone = compiler->zone();
+  ZoneList<RegExpTree*>* alternatives = this->alternatives();
+  int length = alternatives->length();
+  const bool ignore_case = IsIgnoreCase(compiler->flags());
+
+  int write_posn = 0;
+  int i = 0;
+  while (i < length) {
+    RegExpTree* alternative = alternatives->at(i);
+    if (!alternative->IsAtom()) {
+      alternatives->at(write_posn++) = alternatives->at(i);
+      i++;
+      continue;
+    }
+    RegExpAtom* const atom = alternative->AsAtom();
+#ifdef V8_INTL_SUPPORT
+    icu::UnicodeString common_prefix(atom->data().at(0));
+#else
+    unibrow::Mapping<unibrow::Ecma262Canonicalize>* const canonicalize =
+        compiler->isolate()->regexp_macro_assembler_canonicalize();
+    unibrow::uchar common_prefix = atom->data().at(0);
+    if (ignore_case) {
+      common_prefix = Canonical(canonicalize, common_prefix);
+    }
+#endif  // V8_INTL_SUPPORT
+    int first_with_prefix = i;
+    int prefix_length = atom->length();
+    i++;
+    while (i < length) {
+      alternative = alternatives->at(i);
+      if (!alternative->IsAtom()) break;
+      RegExpAtom* const alt_atom = alternative->AsAtom();
+#ifdef V8_INTL_SUPPORT
+      icu::UnicodeString new_prefix(alt_atom->data().at(0));
+      if (!Equals(ignore_case, new_prefix, common_prefix)) break;
+#else
+      unibrow::uchar new_prefix = alt_atom->data().at(0);
+      if (!Equals(ignore_case, canonicalize, new_prefix, common_prefix)) break;
+#endif  // V8_INTL_SUPPORT
+      prefix_length = std::min(prefix_length, alt_atom->length());
+      i++;
+    }
+    if (i > first_with_prefix + 2) {
+      // Found worthwhile run of alternatives with common prefix of at least one
+      // character.  The sorting function above did not sort on more than one
+      // character for reasons of correctness, but there may still be a longer
+      // common prefix if the terms were similar or presorted in the input.
+      // Find out how long the common prefix is.
+      int run_length = i - first_with_prefix;
+      RegExpAtom* const alt_atom =
+          alternatives->at(first_with_prefix)->AsAtom();
+      for (int j = 1; j < run_length && prefix_length > 1; j++) {
+        RegExpAtom* old_atom =
+            alternatives->at(j + first_with_prefix)->AsAtom();
+        for (int k = 1; k < prefix_length; k++) {
+#ifdef V8_INTL_SUPPORT
+          if (!CharAtEquals(ignore_case, k, alt_atom, old_atom)) {
+#else
+          if (!CharAtEquals(ignore_case, canonicalize, k, alt_atom, old_atom)) {
+#endif  // V8_INTL_SUPPORT
+            prefix_length = k;
+            break;
+          }
+        }
+      }
+      RegExpAtom* prefix =
+          zone->New<RegExpAtom>(alt_atom->data().SubVector(0, prefix_length));
+      ZoneList<RegExpTree*>* pair = zone->New<ZoneList<RegExpTree*>>(2, zone);
+      pair->Add(prefix, zone);
+      ZoneList<RegExpTree*>* suffixes =
+          zone->New<ZoneList<RegExpTree*>>(run_length, zone);
+      for (int j = 0; j < run_length; j++) {
+        RegExpAtom* old_atom =
+            alternatives->at(j + first_with_prefix)->AsAtom();
+        int len = old_atom->length();
+        if (len == prefix_length) {
+          suffixes->Add(zone->New<RegExpEmpty>(), zone);
+        } else {
+          RegExpTree* suffix = zone->New<RegExpAtom>(
+              old_atom->data().SubVector(prefix_length, old_atom->length()));
+          suffixes->Add(suffix, zone);
+        }
+      }
+      pair->Add(zone->New<RegExpDisjunction>(suffixes), zone);
+      alternatives->at(write_posn++) = zone->New<RegExpAlternative>(pair);
+    } else {
+      // Just copy any non-worthwhile alternatives.
+      for (int j = first_with_prefix; j < i; j++) {
+        alternatives->at(write_posn++) = alternatives->at(j);
+      }
+    }
+  }
+  alternatives->Rewind(write_posn);  // Trim end of array.
+}
+
+// Optimizes b|c|z to [bcz].
+void RegExpDisjunction::FixSingleCharacterDisjunctions(
+    RegExpCompiler* compiler) {
+  Zone* zone = compiler->zone();
+  ZoneList<RegExpTree*>* alternatives = this->alternatives();
+  int length = alternatives->length();
+
+  int write_posn = 0;
+  int i = 0;
+  while (i < length) {
+    RegExpTree* alternative = alternatives->at(i);
+    if (!alternative->IsAtom()) {
+      alternatives->at(write_posn++) = alternatives->at(i);
+      i++;
+      continue;
+    }
+    RegExpAtom* const atom = alternative->AsAtom();
+    if (atom->length() != 1) {
+      alternatives->at(write_posn++) = alternatives->at(i);
+      i++;
+      continue;
+    }
+    const RegExpFlags flags = compiler->flags();
+    DCHECK_IMPLIES(IsEitherUnicode(flags),
+                   !unibrow::Utf16::IsLeadSurrogate(atom->data().at(0)));
+    bool contains_trail_surrogate =
+        unibrow::Utf16::IsTrailSurrogate(atom->data().at(0));
+    int first_in_run = i;
+    i++;
+    // Find a run of single-character atom alternatives that have identical
+    // flags (case independence and unicode-ness).
+    while (i < length) {
+      alternative = alternatives->at(i);
+      if (!alternative->IsAtom()) break;
+      RegExpAtom* const alt_atom = alternative->AsAtom();
+      if (alt_atom->length() != 1) break;
+      DCHECK_IMPLIES(IsEitherUnicode(flags),
+                     !unibrow::Utf16::IsLeadSurrogate(alt_atom->data().at(0)));
+      contains_trail_surrogate |=
+          unibrow::Utf16::IsTrailSurrogate(alt_atom->data().at(0));
+      i++;
+    }
+    if (i > first_in_run + 1) {
+      // Found non-trivial run of single-character alternatives.
+      int run_length = i - first_in_run;
+      ZoneList<CharacterRange>* ranges =
+          zone->New<ZoneList<CharacterRange>>(2, zone);
+      for (int j = 0; j < run_length; j++) {
+        RegExpAtom* old_atom = alternatives->at(j + first_in_run)->AsAtom();
+        DCHECK_EQ(old_atom->length(), 1);
+        ranges->Add(CharacterRange::Singleton(old_atom->data().at(0)), zone);
+      }
+      RegExpClassRanges::ClassRangesFlags class_ranges_flags;
+      if (IsEitherUnicode(flags) && contains_trail_surrogate) {
+        class_ranges_flags = RegExpClassRanges::CONTAINS_SPLIT_SURROGATE;
+      }
+      alternatives->at(write_posn++) =
+          zone->New<RegExpClassRanges>(zone, ranges, class_ranges_flags);
+    } else {
+      // Just copy any trivial alternatives.
+      for (int j = first_in_run; j < i; j++) {
+        alternatives->at(write_posn++) = alternatives->at(j);
+      }
+    }
+  }
+  alternatives->Rewind(write_posn);  // Trim end of array.
+}
+
+RegExpNode* RegExpDisjunction::ToNode(RegExpCompiler* compiler,
+                                      RegExpNode* on_success) {
+  compiler->ToNodeMaybeCheckForStackOverflow();
+
+  ZoneList<RegExpTree*>* alternatives = this->alternatives();
+
+  if (alternatives->length() > 2) {
+    bool found_consecutive_atoms = SortConsecutiveAtoms(compiler);
+    if (found_consecutive_atoms) RationalizeConsecutiveAtoms(compiler);
+    FixSingleCharacterDisjunctions(compiler);
+    if (alternatives->length() == 1) {
+      return alternatives->at(0)->ToNode(compiler, on_success);
+    }
+  }
+
+  int length = alternatives->length();
+
+  ChoiceNode* result =
+      compiler->zone()->New<ChoiceNode>(length, compiler->zone());
+  for (int i = 0; i < length; i++) {
+    GuardedAlternative alternative(
+        alternatives->at(i)->ToNode(compiler, on_success));
+    result->AddAlternative(alternative);
+  }
+  return result;
+}
+
+RegExpNode* RegExpQuantifier::ToNode(RegExpCompiler* compiler,
+                                     RegExpNode* on_success) {
+  return ToNode(min(), max(), is_greedy(), body(), compiler, on_success);
+}
+
+namespace {
+// Desugar \b to (?<=\w)(?=\W)|(?<=\W)(?=\w) and
+//         \B to (?<=\w)(?=\w)|(?<=\W)(?=\W)
+RegExpNode* BoundaryAssertionAsLookaround(RegExpCompiler* compiler,
+                                          RegExpNode* on_success,
+                                          RegExpAssertion::Type type,
+                                          RegExpFlags flags) {
+  CHECK(NeedsUnicodeCaseEquivalents(flags));
+  Zone* zone = compiler->zone();
+  ZoneList<CharacterRange>* word_range =
+      zone->New<ZoneList<CharacterRange>>(2, zone);
+  CharacterRange::AddClassEscape(StandardCharacterSet::kWord, word_range, true,
+                                 zone);
+  int stack_register = compiler->UnicodeLookaroundStackRegister();
+  int position_register = compiler->UnicodeLookaroundPositionRegister();
+  ChoiceNode* result = zone->New<ChoiceNode>(2, zone);
+  // Add two choices. The (non-)boundary could start with a word or
+  // a non-word-character.
+  for (int i = 0; i < 2; i++) {
+    bool lookbehind_for_word = i == 0;
+    bool lookahead_for_word =
+        (type == RegExpAssertion::Type::BOUNDARY) ^ lookbehind_for_word;
+    // Look to the left.
+    RegExpLookaround::Builder lookbehind(lookbehind_for_word, on_success,
+                                         stack_register, position_register);
+    RegExpNode* backward = TextNode::CreateForCharacterRanges(
+        zone, word_range, true, lookbehind.on_match_success());
+    // Look to the right.
+    RegExpLookaround::Builder lookahead(lookahead_for_word,
+                                        lookbehind.ForMatch(backward),
+                                        stack_register, position_register);
+    RegExpNode* forward = TextNode::CreateForCharacterRanges(
+        zone, word_range, false, lookahead.on_match_success());
+    result->AddAlternative(GuardedAlternative(lookahead.ForMatch(forward)));
+  }
+  return result;
+}
+}  // anonymous namespace
+
+RegExpNode* RegExpAssertion::ToNode(RegExpCompiler* compiler,
+                                    RegExpNode* on_success) {
+  NodeInfo info;
+  Zone* zone = compiler->zone();
+
+  switch (assertion_type()) {
+    case Type::START_OF_LINE:
+      return AssertionNode::AfterNewline(on_success);
+    case Type::START_OF_INPUT:
+      return AssertionNode::AtStart(on_success);
+    case Type::BOUNDARY:
+      return NeedsUnicodeCaseEquivalents(compiler->flags())
+                 ? BoundaryAssertionAsLookaround(
+                       compiler, on_success, Type::BOUNDARY, compiler->flags())
+                 : AssertionNode::AtBoundary(on_success);
+    case Type::NON_BOUNDARY:
+      return NeedsUnicodeCaseEquivalents(compiler->flags())
+                 ? BoundaryAssertionAsLookaround(compiler, on_success,
+                                                 Type::NON_BOUNDARY,
+                                                 compiler->flags())
+                 : AssertionNode::AtNonBoundary(on_success);
+    case Type::END_OF_INPUT:
+      return AssertionNode::AtEnd(on_success);
+    case Type::END_OF_LINE: {
+      // Compile $ in multiline regexps as an alternation with a positive
+      // lookahead in one side and an end-of-input on the other side.
+      // We need two registers for the lookahead.
+      int stack_pointer_register = compiler->AllocateRegister();
+      int position_register = compiler->AllocateRegister();
+      // The ChoiceNode to distinguish between a newline and end-of-input.
+      ChoiceNode* result = zone->New<ChoiceNode>(2, zone);
+      // Create a newline atom.
+      ZoneList<CharacterRange>* newline_ranges =
+          zone->New<ZoneList<CharacterRange>>(3, zone);
+      CharacterRange::AddClassEscape(StandardCharacterSet::kLineTerminator,
+                                     newline_ranges, false, zone);
+      RegExpClassRanges* newline_atom =
+          zone->New<RegExpClassRanges>(StandardCharacterSet::kLineTerminator);
+      TextNode* newline_matcher =
+          zone->New<TextNode>(newline_atom, false,
+                              ActionNode::PositiveSubmatchSuccess(
+                                  stack_pointer_register, position_register,
+                                  0,   // No captures inside.
+                                  -1,  // Ignored if no captures.
+                                  on_success));
+      // Create an end-of-input matcher.
+      RegExpNode* end_of_line = ActionNode::BeginPositiveSubmatch(
+          stack_pointer_register, position_register, newline_matcher);
+      // Add the two alternatives to the ChoiceNode.
+      GuardedAlternative eol_alternative(end_of_line);
+      result->AddAlternative(eol_alternative);
+      GuardedAlternative end_alternative(AssertionNode::AtEnd(on_success));
+      result->AddAlternative(end_alternative);
+      return result;
+    }
+    default:
+      UNREACHABLE();
+  }
+}
+
+RegExpNode* RegExpBackReference::ToNode(RegExpCompiler* compiler,
+                                        RegExpNode* on_success) {
+  return compiler->zone()->New<BackReferenceNode>(
+      RegExpCapture::StartRegister(index()),
+      RegExpCapture::EndRegister(index()), flags_, compiler->read_backward(),
+      on_success);
+}
+
+RegExpNode* RegExpEmpty::ToNode(RegExpCompiler* compiler,
+                                RegExpNode* on_success) {
+  return on_success;
+}
+
+RegExpNode* RegExpGroup::ToNode(RegExpCompiler* compiler,
+                                RegExpNode* on_success) {
+  return body_->ToNode(compiler, on_success);
+}
+
+RegExpLookaround::Builder::Builder(bool is_positive, RegExpNode* on_success,
+                                   int stack_pointer_register,
+                                   int position_register,
+                                   int capture_register_count,
+                                   int capture_register_start)
+    : is_positive_(is_positive),
+      on_success_(on_success),
+      stack_pointer_register_(stack_pointer_register),
+      position_register_(position_register) {
+  if (is_positive_) {
+    on_match_success_ = ActionNode::PositiveSubmatchSuccess(
+        stack_pointer_register, position_register, capture_register_count,
+        capture_register_start, on_success_);
+  } else {
+    Zone* zone = on_success_->zone();
+    on_match_success_ = zone->New<NegativeSubmatchSuccess>(
+        stack_pointer_register, position_register, capture_register_count,
+        capture_register_start, zone);
+  }
+}
+
+RegExpNode* RegExpLookaround::Builder::ForMatch(RegExpNode* match) {
+  if (is_positive_) {
+    return ActionNode::BeginPositiveSubmatch(stack_pointer_register_,
+                                             position_register_, match);
+  } else {
+    Zone* zone = on_success_->zone();
+    // We use a ChoiceNode to represent the negative lookaround. The first
+    // alternative is the negative match. On success, the end node backtracks.
+    // On failure, the second alternative is tried and leads to success.
+    // NegativeLookaheadChoiceNode is a special ChoiceNode that ignores the
+    // first exit when calculating quick checks.
+    ChoiceNode* choice_node = zone->New<NegativeLookaroundChoiceNode>(
+        GuardedAlternative(match), GuardedAlternative(on_success_), zone);
+    return ActionNode::BeginNegativeSubmatch(stack_pointer_register_,
+                                             position_register_, choice_node);
+  }
+}
+
+RegExpNode* RegExpLookaround::ToNode(RegExpCompiler* compiler,
+                                     RegExpNode* on_success) {
+  int stack_pointer_register = compiler->AllocateRegister();
+  int position_register = compiler->AllocateRegister();
+
+  const int registers_per_capture = 2;
+  const int register_of_first_capture = 2;
+  int register_count = capture_count_ * registers_per_capture;
+  int register_start =
+      register_of_first_capture + capture_from_ * registers_per_capture;
+
+  RegExpNode* result;
+  bool was_reading_backward = compiler->read_backward();
+  compiler->set_read_backward(type() == LOOKBEHIND);
+  Builder builder(is_positive(), on_success, stack_pointer_register,
+                  position_register, register_count, register_start);
+  RegExpNode* match = body_->ToNode(compiler, builder.on_match_success());
+  result = builder.ForMatch(match);
+  compiler->set_read_backward(was_reading_backward);
+  return result;
+}
+
+RegExpNode* RegExpCapture::ToNode(RegExpCompiler* compiler,
+                                  RegExpNode* on_success) {
+  return ToNode(body(), index(), compiler, on_success);
+}
+
+RegExpNode* RegExpCapture::ToNode(RegExpTree* body, int index,
+                                  RegExpCompiler* compiler,
+                                  RegExpNode* on_success) {
+  DCHECK_NOT_NULL(body);
+  int start_reg = RegExpCapture::StartRegister(index);
+  int end_reg = RegExpCapture::EndRegister(index);
+  if (compiler->read_backward()) std::swap(start_reg, end_reg);
+  RegExpNode* store_end = ActionNode::StorePosition(end_reg, true, on_success);
+  RegExpNode* body_node = body->ToNode(compiler, store_end);
+  return ActionNode::StorePosition(start_reg, true, body_node);
+}
+
+namespace {
+
+class AssertionSequenceRewriter final {
+ public:
+  // TODO(jgruber): Consider moving this to a separate AST tree rewriter pass
+  // instead of sprinkling rewrites into the AST->Node conversion process.
+  static void MaybeRewrite(ZoneList<RegExpTree*>* terms, Zone* zone) {
+    AssertionSequenceRewriter rewriter(terms, zone);
+
+    static constexpr int kNoIndex = -1;
+    int from = kNoIndex;
+
+    for (int i = 0; i < terms->length(); i++) {
+      RegExpTree* t = terms->at(i);
+      if (from == kNoIndex && t->IsAssertion()) {
+        from = i;  // Start a sequence.
+      } else if (from != kNoIndex && !t->IsAssertion()) {
+        // Terminate and process the sequence.
+        if (i - from > 1) rewriter.Rewrite(from, i);
+        from = kNoIndex;
+      }
+    }
+
+    if (from != kNoIndex && terms->length() - from > 1) {
+      rewriter.Rewrite(from, terms->length());
+    }
+  }
+
+  // All assertions are zero width. A consecutive sequence of assertions is
+  // order-independent. There's two ways we can optimize here:
+  // 1. fold all identical assertions.
+  // 2. if any assertion combinations are known to fail (e.g. \b\B), the entire
+  //    sequence fails.
+  void Rewrite(int from, int to) {
+    DCHECK_GT(to, from + 1);
+
+    // Bitfield of all seen assertions.
+    uint32_t seen_assertions = 0;
+    static_assert(static_cast<int>(RegExpAssertion::Type::LAST_ASSERTION_TYPE) <
+                  kUInt32Size * kBitsPerByte);
+
+    for (int i = from; i < to; i++) {
+      RegExpAssertion* t = terms_->at(i)->AsAssertion();
+      const uint32_t bit = 1 << static_cast<int>(t->assertion_type());
+
+      if (seen_assertions & bit) {
+        // Fold duplicates.
+        terms_->Set(i, zone_->New<RegExpEmpty>());
+      }
+
+      seen_assertions |= bit;
+    }
+
+    // Collapse failures.
+    const uint32_t always_fails_mask =
+        1 << static_cast<int>(RegExpAssertion::Type::BOUNDARY) |
+        1 << static_cast<int>(RegExpAssertion::Type::NON_BOUNDARY);
+    if ((seen_assertions & always_fails_mask) == always_fails_mask) {
+      ReplaceSequenceWithFailure(from, to);
+    }
+  }
+
+  void ReplaceSequenceWithFailure(int from, int to) {
+    // Replace the entire sequence with a single node that always fails.
+    // TODO(jgruber): Consider adding an explicit Fail kind. Until then, the
+    // negated '*' (everything) range serves the purpose.
+    ZoneList<CharacterRange>* ranges =
+        zone_->New<ZoneList<CharacterRange>>(0, zone_);
+    RegExpClassRanges* cc = zone_->New<RegExpClassRanges>(zone_, ranges);
+    terms_->Set(from, cc);
+
+    // Zero out the rest.
+    RegExpEmpty* empty = zone_->New<RegExpEmpty>();
+    for (int i = from + 1; i < to; i++) terms_->Set(i, empty);
+  }
+
+ private:
+  AssertionSequenceRewriter(ZoneList<RegExpTree*>* terms, Zone* zone)
+      : zone_(zone), terms_(terms) {}
+
+  Zone* zone_;
+  ZoneList<RegExpTree*>* terms_;
+};
+
+}  // namespace
+
+RegExpNode* RegExpAlternative::ToNode(RegExpCompiler* compiler,
+                                      RegExpNode* on_success) {
+  compiler->ToNodeMaybeCheckForStackOverflow();
+
+  ZoneList<RegExpTree*>* children = nodes();
+
+  AssertionSequenceRewriter::MaybeRewrite(children, compiler->zone());
+
+  RegExpNode* current = on_success;
+  if (compiler->read_backward()) {
+    for (int i = 0; i < children->length(); i++) {
+      current = children->at(i)->ToNode(compiler, current);
+    }
+  } else {
+    for (int i = children->length() - 1; i >= 0; i--) {
+      current = children->at(i)->ToNode(compiler, current);
+    }
+  }
+  return current;
+}
+
+namespace {
+
+void AddClass(const int* elmv, int elmc, ZoneList<CharacterRange>* ranges,
+              Zone* zone) {
+  elmc--;
+  DCHECK_EQ(kRangeEndMarker, elmv[elmc]);
+  for (int i = 0; i < elmc; i += 2) {
+    DCHECK(elmv[i] < elmv[i + 1]);
+    ranges->Add(CharacterRange::Range(elmv[i], elmv[i + 1] - 1), zone);
+  }
+}
+
+void AddClassNegated(const int* elmv, int elmc,
+                     ZoneList<CharacterRange>* ranges, Zone* zone) {
+  elmc--;
+  DCHECK_EQ(kRangeEndMarker, elmv[elmc]);
+  DCHECK_NE(0x0000, elmv[0]);
+  DCHECK_NE(kMaxCodePoint, elmv[elmc - 1]);
+  base::uc16 last = 0x0000;
+  for (int i = 0; i < elmc; i += 2) {
+    DCHECK(last <= elmv[i] - 1);
+    DCHECK(elmv[i] < elmv[i + 1]);
+    ranges->Add(CharacterRange::Range(last, elmv[i] - 1), zone);
+    last = elmv[i + 1];
+  }
+  ranges->Add(CharacterRange::Range(last, kMaxCodePoint), zone);
+}
+
+}  // namespace
+
+void CharacterRange::AddClassEscape(StandardCharacterSet standard_character_set,
+                                    ZoneList<CharacterRange>* ranges,
+                                    bool add_unicode_case_equivalents,
+                                    Zone* zone) {
+  if (add_unicode_case_equivalents &&
+      (standard_character_set == StandardCharacterSet::kWord ||
+       standard_character_set == StandardCharacterSet::kNotWord)) {
+    // See #sec-runtime-semantics-wordcharacters-abstract-operation
+    // In case of unicode and ignore_case, we need to create the closure over
+    // case equivalent characters before negating.
+    ZoneList<CharacterRange>* new_ranges =
+        zone->New<ZoneList<CharacterRange>>(2, zone);
+    AddClass(kWordRanges, kWordRangeCount, new_ranges, zone);
+    AddUnicodeCaseEquivalents(new_ranges, zone);
+    if (standard_character_set == StandardCharacterSet::kNotWord) {
+      ZoneList<CharacterRange>* negated =
+          zone->New<ZoneList<CharacterRange>>(2, zone);
+      CharacterRange::Negate(new_ranges, negated, zone);
+      new_ranges = negated;
+    }
+    ranges->AddAll(*new_ranges, zone);
+    return;
+  }
+
+  switch (standard_character_set) {
+    case StandardCharacterSet::kWhitespace:
+      AddClass(kSpaceRanges, kSpaceRangeCount, ranges, zone);
+      break;
+    case StandardCharacterSet::kNotWhitespace:
+      AddClassNegated(kSpaceRanges, kSpaceRangeCount, ranges, zone);
+      break;
+    case StandardCharacterSet::kWord:
+      AddClass(kWordRanges, kWordRangeCount, ranges, zone);
+      break;
+    case StandardCharacterSet::kNotWord:
+      AddClassNegated(kWordRanges, kWordRangeCount, ranges, zone);
+      break;
+    case StandardCharacterSet::kDigit:
+      AddClass(kDigitRanges, kDigitRangeCount, ranges, zone);
+      break;
+    case StandardCharacterSet::kNotDigit:
+      AddClassNegated(kDigitRanges, kDigitRangeCount, ranges, zone);
+      break;
+    // This is the set of characters matched by the $ and ^ symbols
+    // in multiline mode.
+    case StandardCharacterSet::kLineTerminator:
+      AddClass(kLineTerminatorRanges, kLineTerminatorRangeCount, ranges, zone);
+      break;
+    case StandardCharacterSet::kNotLineTerminator:
+      AddClassNegated(kLineTerminatorRanges, kLineTerminatorRangeCount, ranges,
+                      zone);
+      break;
+    // This is not a character range as defined by the spec but a
+    // convenient shorthand for a character class that matches any
+    // character.
+    case StandardCharacterSet::kEverything:
+      ranges->Add(CharacterRange::Everything(), zone);
+      break;
+  }
+}
+
+// static
+void CharacterRange::AddCaseEquivalents(Isolate* isolate, Zone* zone,
+                                        ZoneList<CharacterRange>* ranges,
+                                        bool is_one_byte) {
+  CharacterRange::Canonicalize(ranges);
+  int range_count = ranges->length();
+#ifdef V8_INTL_SUPPORT
+  icu::UnicodeSet others;
+  for (int i = 0; i < range_count; i++) {
+    CharacterRange range = ranges->at(i);
+    base::uc32 from = range.from();
+    if (from > kMaxUtf16CodeUnit) continue;
+    base::uc32 to = std::min({range.to(), kMaxUtf16CodeUnitU});
+    // Nothing to be done for surrogates.
+    if (from >= kLeadSurrogateStart && to <= kTrailSurrogateEnd) continue;
+    if (is_one_byte && !RangeContainsLatin1Equivalents(range)) {
+      if (from > kMaxOneByteCharCode) continue;
+      if (to > kMaxOneByteCharCode) to = kMaxOneByteCharCode;
+    }
+    others.add(from, to);
+  }
+
+  // Compute the set of additional characters that should be added,
+  // using UnicodeSet::closeOver. ECMA 262 defines slightly different
+  // case-folding rules than Unicode, so some characters that are
+  // added by closeOver do not match anything other than themselves in
+  // JS. For example, 'ſ' (U+017F LATIN SMALL LETTER LONG S) is the
+  // same case-insensitive character as 's' or 'S' according to
+  // Unicode, but does not match any other character in JS. To handle
+  // this case, we add such characters to the IgnoreSet and filter
+  // them out. We filter twice: once before calling closeOver (to
+  // prevent 'ſ' from adding 's'), and once after calling closeOver
+  // (to prevent 's' from adding 'ſ'). See regexp/special-case.h for
+  // more information.
+  icu::UnicodeSet already_added(others);
+  others.removeAll(RegExpCaseFolding::IgnoreSet());
+  others.closeOver(USET_CASE_INSENSITIVE);
+  others.removeAll(RegExpCaseFolding::IgnoreSet());
+  others.removeAll(already_added);
+
+  // Add others to the ranges
+  for (int32_t i = 0; i < others.getRangeCount(); i++) {
+    UChar32 from = others.getRangeStart(i);
+    UChar32 to = others.getRangeEnd(i);
+    if (from == to) {
+      ranges->Add(CharacterRange::Singleton(from), zone);
+    } else {
+      ranges->Add(CharacterRange::Range(from, to), zone);
+    }
+  }
+#else
+  for (int i = 0; i < range_count; i++) {
+    CharacterRange range = ranges->at(i);
+    base::uc32 bottom = range.from();
+    if (bottom > kMaxUtf16CodeUnit) continue;
+    base::uc32 top = std::min({range.to(), kMaxUtf16CodeUnitU});
+    // Nothing to be done for surrogates.
+    if (bottom >= kLeadSurrogateStart && top <= kTrailSurrogateEnd) continue;
+    if (is_one_byte && !RangeContainsLatin1Equivalents(range)) {
+      if (bottom > kMaxOneByteCharCode) continue;
+      if (top > kMaxOneByteCharCode) top = kMaxOneByteCharCode;
+    }
+    unibrow::uchar chars[unibrow::Ecma262UnCanonicalize::kMaxWidth];
+    if (top == bottom) {
+      // If this is a singleton we just expand the one character.
+      int length = isolate->jsregexp_uncanonicalize()->get(bottom, '\0', chars);
+      for (int i = 0; i < length; i++) {
+        base::uc32 chr = chars[i];
+        if (chr != bottom) {
+          ranges->Add(CharacterRange::Singleton(chars[i]), zone);
+        }
+      }
+    } else {
+      // If this is a range we expand the characters block by block, expanding
+      // contiguous subranges (blocks) one at a time.  The approach is as
+      // follows.  For a given start character we look up the remainder of the
+      // block that contains it (represented by the end point), for instance we
+      // find 'z' if the character is 'c'.  A block is characterized by the
+      // property that all characters uncanonicalize in the same way, except
+      // that each entry in the result is incremented by the distance from the
+      // first element.  So a-z is a block because 'a' uncanonicalizes to ['a',
+      // 'A'] and the k'th letter uncanonicalizes to ['a' + k, 'A' + k].  Once
+      // we've found the end point we look up its uncanonicalization and
+      // produce a range for each element.  For instance for [c-f] we look up
+      // ['z', 'Z'] and produce [c-f] and [C-F].  We then only add a range if
+      // it is not already contained in the input, so [c-f] will be skipped but
+      // [C-F] will be added.  If this range is not completely contained in a
+      // block we do this for all the blocks covered by the range (handling
+      // characters that is not in a block as a "singleton block").
+      unibrow::uchar equivalents[unibrow::Ecma262UnCanonicalize::kMaxWidth];
+      base::uc32 pos = bottom;
+      while (pos <= top) {
+        int length =
+            isolate->jsregexp_canonrange()->get(pos, '\0', equivalents);
+        base::uc32 block_end;
+        if (length == 0) {
+          block_end = pos;
+        } else {
+          DCHECK_EQ(1, length);
+          block_end = equivalents[0];
+        }
+        int end = (block_end > top) ? top : block_end;
+        length = isolate->jsregexp_uncanonicalize()->get(block_end, '\0',
+                                                         equivalents);
+        for (int i = 0; i < length; i++) {
+          base::uc32 c = equivalents[i];
+          base::uc32 range_from = c - (block_end - pos);
+          base::uc32 range_to = c - (block_end - end);
+          if (!(bottom <= range_from && range_to <= top)) {
+            ranges->Add(CharacterRange::Range(range_from, range_to), zone);
+          }
+        }
+        pos = end + 1;
+      }
+    }
+  }
+#endif  // V8_INTL_SUPPORT
+}
+
+bool CharacterRange::IsCanonical(const ZoneList<CharacterRange>* ranges) {
+  DCHECK_NOT_NULL(ranges);
+  int n = ranges->length();
+  if (n <= 1) return true;
+  base::uc32 max = ranges->at(0).to();
+  for (int i = 1; i < n; i++) {
+    CharacterRange next_range = ranges->at(i);
+    if (next_range.from() <= max + 1) return false;
+    max = next_range.to();
+  }
+  return true;
+}
+
+ZoneList<CharacterRange>* CharacterSet::ranges(Zone* zone) {
+  if (ranges_ == nullptr) {
+    ranges_ = zone->New<ZoneList<CharacterRange>>(2, zone);
+    CharacterRange::AddClassEscape(standard_set_type_.value(), ranges_, false,
+                                   zone);
+  }
+  return ranges_;
+}
+
+namespace {
+
+// Move a number of elements in a zonelist to another position
+// in the same list. Handles overlapping source and target areas.
+void MoveRanges(ZoneList<CharacterRange>* list, int from, int to, int count) {
+  // Ranges are potentially overlapping.
+  if (from < to) {
+    for (int i = count - 1; i >= 0; i--) {
+      list->at(to + i) = list->at(from + i);
+    }
+  } else {
+    for (int i = 0; i < count; i++) {
+      list->at(to + i) = list->at(from + i);
+    }
+  }
+}
+
+int InsertRangeInCanonicalList(ZoneList<CharacterRange>* list, int count,
+                               CharacterRange insert) {
+  // Inserts a range into list[0..count[, which must be sorted
+  // by from value and non-overlapping and non-adjacent, using at most
+  // list[0..count] for the result. Returns the number of resulting
+  // canonicalized ranges. Inserting a range may collapse existing ranges into
+  // fewer ranges, so the return value can be anything in the range 1..count+1.
+  base::uc32 from = insert.from();
+  base::uc32 to = insert.to();
+  int start_pos = 0;
+  int end_pos = count;
+  for (int i = count - 1; i >= 0; i--) {
+    CharacterRange current = list->at(i);
+    if (current.from() > to + 1) {
+      end_pos = i;
+    } else if (current.to() + 1 < from) {
+      start_pos = i + 1;
+      break;
+    }
+  }
+
+  // Inserted range overlaps, or is adjacent to, ranges at positions
+  // [start_pos..end_pos[. Ranges before start_pos or at or after end_pos are
+  // not affected by the insertion.
+  // If start_pos == end_pos, the range must be inserted before start_pos.
+  // if start_pos < end_pos, the entire range from start_pos to end_pos
+  // must be merged with the insert range.
+
+  if (start_pos == end_pos) {
+    // Insert between existing ranges at position start_pos.
+    if (start_pos < count) {
+      MoveRanges(list, start_pos, start_pos + 1, count - start_pos);
+    }
+    list->at(start_pos) = insert;
+    return count + 1;
+  }
+  if (start_pos + 1 == end_pos) {
+    // Replace single existing range at position start_pos.
+    CharacterRange to_replace = list->at(start_pos);
+    int new_from = std::min(to_replace.from(), from);
+    int new_to = std::max(to_replace.to(), to);
+    list->at(start_pos) = CharacterRange::Range(new_from, new_to);
+    return count;
+  }
+  // Replace a number of existing ranges from start_pos to end_pos - 1.
+  // Move the remaining ranges down.
+
+  int new_from = std::min(list->at(start_pos).from(), from);
+  int new_to = std::max(list->at(end_pos - 1).to(), to);
+  if (end_pos < count) {
+    MoveRanges(list, end_pos, start_pos + 1, count - end_pos);
+  }
+  list->at(start_pos) = CharacterRange::Range(new_from, new_to);
+  return count - (end_pos - start_pos) + 1;
+}
+
+}  // namespace
+
+void CharacterSet::Canonicalize() {
+  // Special/default classes are always considered canonical. The result
+  // of calling ranges() will be sorted.
+  if (ranges_ == nullptr) return;
+  CharacterRange::Canonicalize(ranges_);
+}
+
+// static
+void CharacterRange::Canonicalize(ZoneList<CharacterRange>* character_ranges) {
+  if (character_ranges->length() <= 1) return;
+  // Check whether ranges are already canonical (increasing, non-overlapping,
+  // non-adjacent).
+  int n = character_ranges->length();
+  base::uc32 max = character_ranges->at(0).to();
+  int i = 1;
+  while (i < n) {
+    CharacterRange current = character_ranges->at(i);
+    if (current.from() <= max + 1) {
+      break;
+    }
+    max = current.to();
+    i++;
+  }
+  // Canonical until the i'th range. If that's all of them, we are done.
+  if (i == n) return;
+
+  // The ranges at index i and forward are not canonicalized. Make them so by
+  // doing the equivalent of insertion sort (inserting each into the previous
+  // list, in order).
+  // Notice that inserting a range can reduce the number of ranges in the
+  // result due to combining of adjacent and overlapping ranges.
+  int read = i;           // Range to insert.
+  int num_canonical = i;  // Length of canonicalized part of list.
+  do {
+    num_canonical = InsertRangeInCanonicalList(character_ranges, num_canonical,
+                                               character_ranges->at(read));
+    read++;
+  } while (read < n);
+  character_ranges->Rewind(num_canonical);
+
+  DCHECK(CharacterRange::IsCanonical(character_ranges));
+}
+
+// static
+void CharacterRange::Negate(const ZoneList<CharacterRange>* ranges,
+                            ZoneList<CharacterRange>* negated_ranges,
+                            Zone* zone) {
+  DCHECK(CharacterRange::IsCanonical(ranges));
+  DCHECK_EQ(0, negated_ranges->length());
+  int range_count = ranges->length();
+  base::uc32 from = 0;
+  int i = 0;
+  if (range_count > 0 && ranges->at(0).from() == 0) {
+    from = ranges->at(0).to() + 1;
+    i = 1;
+  }
+  while (i < range_count) {
+    CharacterRange range = ranges->at(i);
+    negated_ranges->Add(CharacterRange::Range(from, range.from() - 1), zone);
+    from = range.to() + 1;
+    i++;
+  }
+  if (from < kMaxCodePoint) {
+    negated_ranges->Add(CharacterRange::Range(from, kMaxCodePoint), zone);
+  }
+}
+
+// static
+void CharacterRange::Intersect(const ZoneList<CharacterRange>* lhs,
+                               const ZoneList<CharacterRange>* rhs,
+                               ZoneList<CharacterRange>* intersection,
+                               Zone* zone) {
+  DCHECK(CharacterRange::IsCanonical(lhs));
+  DCHECK(CharacterRange::IsCanonical(rhs));
+  DCHECK_EQ(0, intersection->length());
+  int lhs_index = 0;
+  int rhs_index = 0;
+  while (lhs_index < lhs->length() && rhs_index < rhs->length()) {
+    // Skip non-overlapping ranges.
+    if (lhs->at(lhs_index).to() < rhs->at(rhs_index).from()) {
+      lhs_index++;
+      continue;
+    }
+    if (rhs->at(rhs_index).to() < lhs->at(lhs_index).from()) {
+      rhs_index++;
+      continue;
+    }
+
+    base::uc32 from =
+        std::max(lhs->at(lhs_index).from(), rhs->at(rhs_index).from());
+    base::uc32 to = std::min(lhs->at(lhs_index).to(), rhs->at(rhs_index).to());
+    intersection->Add(CharacterRange::Range(from, to), zone);
+    if (to == lhs->at(lhs_index).to()) {
+      lhs_index++;
+    } else {
+      rhs_index++;
+    }
+  }
+
+  DCHECK(IsCanonical(intersection));
+}
+
+namespace {
+
+// Advance |index| and set |from| and |to| to the new range, if not out of
+// bounds of |range|, otherwise |from| is set to a code point beyond the legal
+// unicode character range.
+void SafeAdvanceRange(const ZoneList<CharacterRange>* range, int* index,
+                      base::uc32* from, base::uc32* to) {
+  ++(*index);
+  if (*index < range->length()) {
+    *from = range->at(*index).from();
+    *to = range->at(*index).to();
+  } else {
+    *from = kMaxCodePoint + 1;
+  }
+}
+
+}  // namespace
+
+// static
+void CharacterRange::Subtract(const ZoneList<CharacterRange>* src,
+                              const ZoneList<CharacterRange>* to_remove,
+                              ZoneList<CharacterRange>* result, Zone* zone) {
+  DCHECK(CharacterRange::IsCanonical(src));
+  DCHECK(CharacterRange::IsCanonical(to_remove));
+  DCHECK_EQ(0, result->length());
+
+  if (src->is_empty()) return;
+
+  int src_index = 0;
+  int to_remove_index = 0;
+  base::uc32 from = src->at(src_index).from();
+  base::uc32 to = src->at(src_index).to();
+  while (src_index < src->length() && to_remove_index < to_remove->length()) {
+    CharacterRange remove_range = to_remove->at(to_remove_index);
+    if (remove_range.to() < from) {
+      // (a) Non-overlapping case, ignore current to_remove range.
+      //            |-------|
+      // |-------|
+      to_remove_index++;
+    } else if (to < remove_range.from()) {
+      // (b) Non-overlapping case, add full current range to result.
+      // |-------|
+      //            |-------|
+      result->Add(CharacterRange::Range(from, to), zone);
+      SafeAdvanceRange(src, &src_index, &from, &to);
+    } else if (from >= remove_range.from() && to <= remove_range.to()) {
+      // (c) Current to_remove range fully covers current range.
+      //   |---|
+      // |-------|
+      SafeAdvanceRange(src, &src_index, &from, &to);
+    } else if (from < remove_range.from() && to > remove_range.to()) {
+      // (d) Split current range.
+      // |-------|
+      //   |---|
+      result->Add(CharacterRange::Range(from, remove_range.from() - 1), zone);
+      from = remove_range.to() + 1;
+      to_remove_index++;
+    } else if (from < remove_range.from()) {
+      // (e) End current range.
+      // |-------|
+      //    |-------|
+      to = remove_range.from() - 1;
+      result->Add(CharacterRange::Range(from, to), zone);
+      SafeAdvanceRange(src, &src_index, &from, &to);
+    } else if (to > remove_range.to()) {
+      // (f) Modify start of current range.
+      //    |-------|
+      // |-------|
+      from = remove_range.to() + 1;
+      to_remove_index++;
+    } else {
+      UNREACHABLE();
+    }
+  }
+  // The last range needs special treatment after |to_remove| is exhausted, as
+  // |from| might have been modified by the last |to_remove| range and |to| was
+  // not yet known (i.e. cases d and f).
+  if (from <= to) {
+    result->Add(CharacterRange::Range(from, to), zone);
+  }
+  src_index++;
+
+  // Add remaining ranges after |to_remove| is exhausted.
+  for (; src_index < src->length(); src_index++) {
+    result->Add(src->at(src_index), zone);
+  }
+
+  DCHECK(IsCanonical(result));
+}
+
+// static
+void CharacterRange::ClampToOneByte(ZoneList<CharacterRange>* ranges) {
+  DCHECK(IsCanonical(ranges));
+
+  // Drop all ranges that don't contain one-byte code units, and clamp the last
+  // range s.t. it likewise only contains one-byte code units. Note this relies
+  // on `ranges` being canonicalized, i.e. sorted and non-overlapping.
+
+  static constexpr base::uc32 max_char = String::kMaxOneByteCharCodeU;
+  int n = ranges->length();
+  for (; n > 0; n--) {
+    CharacterRange& r = ranges->at(n - 1);
+    if (r.from() <= max_char) {
+      r.to_ = std::min(r.to_, max_char);
+      break;
+    }
+  }
+
+  ranges->Rewind(n);
+}
+
+// static
+bool CharacterRange::Equals(const ZoneList<CharacterRange>* lhs,
+                            const ZoneList<CharacterRange>* rhs) {
+  DCHECK(IsCanonical(lhs));
+  DCHECK(IsCanonical(rhs));
+  if (lhs->length() != rhs->length()) return false;
+
+  for (int i = 0; i < lhs->length(); i++) {
+    if (lhs->at(i) != rhs->at(i)) return false;
+  }
+
+  return true;
+}
+
+namespace {
+
+// Scoped object to keep track of how much we unroll quantifier loops in the
+// regexp graph generator.
+class RegExpExpansionLimiter {
+ public:
+  static const int kMaxExpansionFactor = 6;
+  RegExpExpansionLimiter(RegExpCompiler* compiler, int factor)
+      : compiler_(compiler),
+        saved_expansion_factor_(compiler->current_expansion_factor()),
+        ok_to_expand_(saved_expansion_factor_ <= kMaxExpansionFactor) {
+    DCHECK_LT(0, factor);
+    if (ok_to_expand_) {
+      if (factor > kMaxExpansionFactor) {
+        // Avoid integer overflow of the current expansion factor.
+        ok_to_expand_ = false;
+        compiler->set_current_expansion_factor(kMaxExpansionFactor + 1);
+      } else {
+        int new_factor = saved_expansion_factor_ * factor;
+        ok_to_expand_ = (new_factor <= kMaxExpansionFactor);
+        compiler->set_current_expansion_factor(new_factor);
+      }
+    }
+  }
+
+  ~RegExpExpansionLimiter() {
+    compiler_->set_current_expansion_factor(saved_expansion_factor_);
+  }
+
+  bool ok_to_expand() { return ok_to_expand_; }
+
+ private:
+  RegExpCompiler* compiler_;
+  int saved_expansion_factor_;
+  bool ok_to_expand_;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(RegExpExpansionLimiter);
+};
+
+}  // namespace
+
+RegExpNode* RegExpQuantifier::ToNode(int min, int max, bool is_greedy,
+                                     RegExpTree* body, RegExpCompiler* compiler,
+                                     RegExpNode* on_success,
+                                     bool not_at_start) {
+  // x{f, t} becomes this:
+  //
+  //             (r++)<-.
+  //               |     `
+  //               |     (x)
+  //               v     ^
+  //      (r=0)-->(?)---/ [if r < t]
+  //               |
+  //   [if r >= f] \----> ...
+  //
+
+  // 15.10.2.5 RepeatMatcher algorithm.
+  // The parser has already eliminated the case where max is 0.  In the case
+  // where max_match is zero the parser has removed the quantifier if min was
+  // > 0 and removed the atom if min was 0.  See AddQuantifierToAtom.
+
+  // If we know that we cannot match zero length then things are a little
+  // simpler since we don't need to make the special zero length match check
+  // from step 2.1.  If the min and max are small we can unroll a little in
+  // this case.
+  static const int kMaxUnrolledMinMatches = 3;  // Unroll (foo)+ and (foo){3,}
+  static const int kMaxUnrolledMaxMatches = 3;  // Unroll (foo)? and (foo){x,3}
+  if (max == 0) return on_success;  // This can happen due to recursion.
+  bool body_can_be_empty = (body->min_match() == 0);
+  int body_start_reg = RegExpCompiler::kNoRegister;
+  Interval capture_registers = body->CaptureRegisters();
+  bool needs_capture_clearing = !capture_registers.is_empty();
+  Zone* zone = compiler->zone();
+
+  if (body_can_be_empty) {
+    body_start_reg = compiler->AllocateRegister();
+  } else if (compiler->optimize() && !needs_capture_clearing) {
+    // Only unroll if there are no captures and the body can't be
+    // empty.
+    {
+      RegExpExpansionLimiter limiter(compiler, min + ((max != min) ? 1 : 0));
+      if (min > 0 && min <= kMaxUnrolledMinMatches && limiter.ok_to_expand()) {
+        int new_max = (max == kInfinity) ? max : max - min;
+        // Recurse once to get the loop or optional matches after the fixed
+        // ones.
+        RegExpNode* answer =
+            ToNode(0, new_max, is_greedy, body, compiler, on_success, true);
+        // Unroll the forced matches from 0 to min.  This can cause chains of
+        // TextNodes (which the parser does not generate).  These should be
+        // combined if it turns out they hinder good code generation.
+        for (int i = 0; i < min; i++) {
+          answer = body->ToNode(compiler, answer);
+        }
+        return answer;
+      }
+    }
+    if (max <= kMaxUnrolledMaxMatches && min == 0) {
+      DCHECK_LT(0, max);  // Due to the 'if' above.
+      RegExpExpansionLimiter limiter(compiler, max);
+      if (limiter.ok_to_expand()) {
+        // Unroll the optional matches up to max.
+        RegExpNode* answer = on_success;
+        for (int i = 0; i < max; i++) {
+          ChoiceNode* alternation = zone->New<ChoiceNode>(2, zone);
+          if (is_greedy) {
+            alternation->AddAlternative(
+                GuardedAlternative(body->ToNode(compiler, answer)));
+            alternation->AddAlternative(GuardedAlternative(on_success));
+          } else {
+            alternation->AddAlternative(GuardedAlternative(on_success));
+            alternation->AddAlternative(
+                GuardedAlternative(body->ToNode(compiler, answer)));
+          }
+          answer = alternation;
+          if (not_at_start && !compiler->read_backward()) {
+            alternation->set_not_at_start();
+          }
+        }
+        return answer;
+      }
+    }
+  }
+  bool has_min = min > 0;
+  bool has_max = max < RegExpTree::kInfinity;
+  bool needs_counter = has_min || has_max;
+  int reg_ctr = needs_counter ? compiler->AllocateRegister()
+                              : RegExpCompiler::kNoRegister;
+  LoopChoiceNode* center = zone->New<LoopChoiceNode>(
+      body->min_match() == 0, compiler->read_backward(), min, zone);
+  if (not_at_start && !compiler->read_backward()) center->set_not_at_start();
+  RegExpNode* loop_return =
+      needs_counter ? static_cast<RegExpNode*>(
+                          ActionNode::IncrementRegister(reg_ctr, center))
+                    : static_cast<RegExpNode*>(center);
+  if (body_can_be_empty) {
+    // If the body can be empty we need to check if it was and then
+    // backtrack.
+    loop_return =
+        ActionNode::EmptyMatchCheck(body_start_reg, reg_ctr, min, loop_return);
+  }
+  RegExpNode* body_node = body->ToNode(compiler, loop_return);
+  if (body_can_be_empty) {
+    // If the body can be empty we need to store the start position
+    // so we can bail out if it was empty.
+    body_node = ActionNode::StorePosition(body_start_reg, false, body_node);
+  }
+  if (needs_capture_clearing) {
+    // Before entering the body of this loop we need to clear captures.
+    body_node = ActionNode::ClearCaptures(capture_registers, body_node);
+  }
+  GuardedAlternative body_alt(body_node);
+  if (has_max) {
+    Guard* body_guard = zone->New<Guard>(reg_ctr, Guard::LT, max);
+    body_alt.AddGuard(body_guard, zone);
+  }
+  GuardedAlternative rest_alt(on_success);
+  if (has_min) {
+    Guard* rest_guard = compiler->zone()->New<Guard>(reg_ctr, Guard::GEQ, min);
+    rest_alt.AddGuard(rest_guard, zone);
+  }
+  if (is_greedy) {
+    center->AddLoopAlternative(body_alt);
+    center->AddContinueAlternative(rest_alt);
+  } else {
+    center->AddContinueAlternative(rest_alt);
+    center->AddLoopAlternative(body_alt);
+  }
+  if (needs_counter) {
+    return ActionNode::SetRegisterForLoop(reg_ctr, 0, center);
+  } else {
+    return center;
+  }
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/irregexp/imported/regexp-compiler.cc b/js/src/irregexp/imported/regexp-compiler.cc
new file mode 100644
index 0000000000..514975d8ed
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-compiler.cc
@@ -0,0 +1,3955 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "irregexp/imported/regexp-compiler.h"
+
+#include "irregexp/imported/regexp-macro-assembler-arch.h"
+
+#ifdef V8_INTL_SUPPORT
+#include "irregexp/imported/special-case.h"
+#include "unicode/locid.h"
+#include "unicode/uniset.h"
+#include "unicode/utypes.h"
+#endif  // V8_INTL_SUPPORT
+
+namespace v8 {
+namespace internal {
+
+using namespace regexp_compiler_constants;  // NOLINT(build/namespaces)
+
+// -------------------------------------------------------------------
+// Implementation of the Irregexp regular expression engine.
+//
+// The Irregexp regular expression engine is intended to be a complete
+// implementation of ECMAScript regular expressions.  It generates either
+// bytecodes or native code.
+
+//   The Irregexp regexp engine is structured in three steps.
+//   1) The parser generates an abstract syntax tree.  See ast.cc.
+//   2) From the AST a node network is created.  The nodes are all
+//      subclasses of RegExpNode.  The nodes represent states when
+//      executing a regular expression.  Several optimizations are
+//      performed on the node network.
+//   3) From the nodes we generate either byte codes or native code
+//      that can actually execute the regular expression (perform
+//      the search).  The code generation step is described in more
+//      detail below.
+
+// Code generation.
+//
+//   The nodes are divided into four main categories.
+//   * Choice nodes
+//        These represent places where the regular expression can
+//        match in more than one way.  For example on entry to an
+//        alternation (foo|bar) or a repetition (*, +, ? or {}).
+//   * Action nodes
+//        These represent places where some action should be
+//        performed.  Examples include recording the current position
+//        in the input string to a register (in order to implement
+//        captures) or other actions on register for example in order
+//        to implement the counters needed for {} repetitions.
+//   * Matching nodes
+//        These attempt to match some element part of the input string.
+//        Examples of elements include character classes, plain strings
+//        or back references.
+//   * End nodes
+//        These are used to implement the actions required on finding
+//        a successful match or failing to find a match.
+//
+//   The code generated (whether as byte codes or native code) maintains
+//   some state as it runs.  This consists of the following elements:
+//
+//   * The capture registers.  Used for string captures.
+//   * Other registers.  Used for counters etc.
+//   * The current position.
+//   * The stack of backtracking information.  Used when a matching node
+//     fails to find a match and needs to try an alternative.
+//
+// Conceptual regular expression execution model:
+//
+//   There is a simple conceptual model of regular expression execution
+//   which will be presented first.  The actual code generated is a more
+//   efficient simulation of the simple conceptual model:
+//
+//   * Choice nodes are implemented as follows:
+//     For each choice except the last {
+//       push current position
+//       push backtrack code location
+//       <generate code to test for choice>
+//       backtrack code location:
+//       pop current position
+//     }
+//     <generate code to test for last choice>
+//
+//   * Actions nodes are generated as follows
+//     <push affected registers on backtrack stack>
+//     <generate code to perform action>
+//     push backtrack code location
+//     <generate code to test for following nodes>
+//     backtrack code location:
+//     <pop affected registers to restore their state>
+//     <pop backtrack location from stack and go to it>
+//
+//   * Matching nodes are generated as follows:
+//     if input string matches at current position
+//       update current position
+//       <generate code to test for following nodes>
+//     else
+//       <pop backtrack location from stack and go to it>
+//
+//   Thus it can be seen that the current position is saved and restored
+//   by the choice nodes, whereas the registers are saved and restored by
+//   by the action nodes that manipulate them.
+//
+//   The other interesting aspect of this model is that nodes are generated
+//   at the point where they are needed by a recursive call to Emit().  If
+//   the node has already been code generated then the Emit() call will
+//   generate a jump to the previously generated code instead.  In order to
+//   limit recursion it is possible for the Emit() function to put the node
+//   on a work list for later generation and instead generate a jump.  The
+//   destination of the jump is resolved later when the code is generated.
+//
+// Actual regular expression code generation.
+//
+//   Code generation is actually more complicated than the above.  In order to
+//   improve the efficiency of the generated code some optimizations are
+//   performed
+//
+//   * Choice nodes have 1-character lookahead.
+//     A choice node looks at the following character and eliminates some of
+//     the choices immediately based on that character.  This is not yet
+//     implemented.
+//   * Simple greedy loops store reduced backtracking information.
+//     A quantifier like /.*foo/m will greedily match the whole input.  It will
+//     then need to backtrack to a point where it can match "foo".  The naive
+//     implementation of this would push each character position onto the
+//     backtracking stack, then pop them off one by one.  This would use space
+//     proportional to the length of the input string.  However since the "."
+//     can only match in one way and always has a constant length (in this case
+//     of 1) it suffices to store the current position on the top of the stack
+//     once.  Matching now becomes merely incrementing the current position and
+//     backtracking becomes decrementing the current position and checking the
+//     result against the stored current position.  This is faster and saves
+//     space.
+//   * The current state is virtualized.
+//     This is used to defer expensive operations until it is clear that they
+//     are needed and to generate code for a node more than once, allowing
+//     specialized an efficient versions of the code to be created. This is
+//     explained in the section below.
+//
+// Execution state virtualization.
+//
+//   Instead of emitting code, nodes that manipulate the state can record their
+//   manipulation in an object called the Trace.  The Trace object can record a
+//   current position offset, an optional backtrack code location on the top of
+//   the virtualized backtrack stack and some register changes.  When a node is
+//   to be emitted it can flush the Trace or update it.  Flushing the Trace
+//   will emit code to bring the actual state into line with the virtual state.
+//   Avoiding flushing the state can postpone some work (e.g. updates of capture
+//   registers).  Postponing work can save time when executing the regular
+//   expression since it may be found that the work never has to be done as a
+//   failure to match can occur.  In addition it is much faster to jump to a
+//   known backtrack code location than it is to pop an unknown backtrack
+//   location from the stack and jump there.
+//
+//   The virtual state found in the Trace affects code generation.  For example
+//   the virtual state contains the difference between the actual current
+//   position and the virtual current position, and matching code needs to use
+//   this offset to attempt a match in the correct location of the input
+//   string.  Therefore code generated for a non-trivial trace is specialized
+//   to that trace.  The code generator therefore has the ability to generate
+//   code for each node several times.  In order to limit the size of the
+//   generated code there is an arbitrary limit on how many specialized sets of
+//   code may be generated for a given node.  If the limit is reached, the
+//   trace is flushed and a generic version of the code for a node is emitted.
+//   This is subsequently used for that node.  The code emitted for non-generic
+//   trace is not recorded in the node and so it cannot currently be reused in
+//   the event that code generation is requested for an identical trace.
+
+namespace {
+
+constexpr base::uc32 MaxCodeUnit(const bool one_byte) {
+  static_assert(String::kMaxOneByteCharCodeU <=
+                std::numeric_limits<uint16_t>::max());
+  static_assert(String::kMaxUtf16CodeUnitU <=
+                std::numeric_limits<uint16_t>::max());
+  return one_byte ? String::kMaxOneByteCharCodeU : String::kMaxUtf16CodeUnitU;
+}
+
+constexpr uint32_t CharMask(const bool one_byte) {
+  static_assert(base::bits::IsPowerOfTwo(String::kMaxOneByteCharCodeU + 1));
+  static_assert(base::bits::IsPowerOfTwo(String::kMaxUtf16CodeUnitU + 1));
+  return MaxCodeUnit(one_byte);
+}
+
+}  // namespace
+
+void RegExpTree::AppendToText(RegExpText* text, Zone* zone) { UNREACHABLE(); }
+
+void RegExpAtom::AppendToText(RegExpText* text, Zone* zone) {
+  text->AddElement(TextElement::Atom(this), zone);
+}
+
+void RegExpClassRanges::AppendToText(RegExpText* text, Zone* zone) {
+  text->AddElement(TextElement::ClassRanges(this), zone);
+}
+
+void RegExpText::AppendToText(RegExpText* text, Zone* zone) {
+  for (int i = 0; i < elements()->length(); i++)
+    text->AddElement(elements()->at(i), zone);
+}
+
+TextElement TextElement::Atom(RegExpAtom* atom) {
+  return TextElement(ATOM, atom);
+}
+
+TextElement TextElement::ClassRanges(RegExpClassRanges* class_ranges) {
+  return TextElement(CLASS_RANGES, class_ranges);
+}
+
+int TextElement::length() const {
+  switch (text_type()) {
+    case ATOM:
+      return atom()->length();
+
+    case CLASS_RANGES:
+      return 1;
+  }
+  UNREACHABLE();
+}
+
+class RecursionCheck {
+ public:
+  explicit RecursionCheck(RegExpCompiler* compiler) : compiler_(compiler) {
+    compiler->IncrementRecursionDepth();
+  }
+  ~RecursionCheck() { compiler_->DecrementRecursionDepth(); }
+
+ private:
+  RegExpCompiler* compiler_;
+};
+
+// Attempts to compile the regexp using an Irregexp code generator.  Returns
+// a fixed array or a null handle depending on whether it succeeded.
+RegExpCompiler::RegExpCompiler(Isolate* isolate, Zone* zone, int capture_count,
+                               RegExpFlags flags, bool one_byte)
+    : next_register_(JSRegExp::RegistersForCaptureCount(capture_count)),
+      unicode_lookaround_stack_register_(kNoRegister),
+      unicode_lookaround_position_register_(kNoRegister),
+      work_list_(nullptr),
+      recursion_depth_(0),
+      flags_(flags),
+      one_byte_(one_byte),
+      reg_exp_too_big_(false),
+      limiting_recursion_(false),
+      optimize_(v8_flags.regexp_optimization),
+      read_backward_(false),
+      current_expansion_factor_(1),
+      frequency_collator_(),
+      isolate_(isolate),
+      zone_(zone) {
+  accept_ = zone->New<EndNode>(EndNode::ACCEPT, zone);
+  DCHECK_GE(RegExpMacroAssembler::kMaxRegister, next_register_ - 1);
+}
+
+RegExpCompiler::CompilationResult RegExpCompiler::Assemble(
+    Isolate* isolate, RegExpMacroAssembler* macro_assembler, RegExpNode* start,
+    int capture_count, Handle<String> pattern) {
+  macro_assembler_ = macro_assembler;
+
+  ZoneVector<RegExpNode*> work_list(zone());
+  work_list_ = &work_list;
+  Label fail;
+  macro_assembler_->PushBacktrack(&fail);
+  Trace new_trace;
+  start->Emit(this, &new_trace);
+  macro_assembler_->BindJumpTarget(&fail);
+  macro_assembler_->Fail();
+  while (!work_list.empty()) {
+    RegExpNode* node = work_list.back();
+    work_list.pop_back();
+    node->set_on_work_list(false);
+    if (!node->label()->is_bound()) node->Emit(this, &new_trace);
+  }
+  if (reg_exp_too_big_) {
+    if (v8_flags.correctness_fuzzer_suppressions) {
+      FATAL("Aborting on excess zone allocation");
+    }
+    macro_assembler_->AbortedCodeGeneration();
+    return CompilationResult::RegExpTooBig();
+  }
+
+  Handle<HeapObject> code = macro_assembler_->GetCode(pattern);
+  isolate->IncreaseTotalRegexpCodeGenerated(code);
+  work_list_ = nullptr;
+
+  return {code, next_register_};
+}
+
+bool Trace::DeferredAction::Mentions(int that) {
+  if (action_type() == ActionNode::CLEAR_CAPTURES) {
+    Interval range = static_cast<DeferredClearCaptures*>(this)->range();
+    return range.Contains(that);
+  } else {
+    return reg() == that;
+  }
+}
+
+bool Trace::mentions_reg(int reg) {
+  for (DeferredAction* action = actions_; action != nullptr;
+       action = action->next()) {
+    if (action->Mentions(reg)) return true;
+  }
+  return false;
+}
+
+bool Trace::GetStoredPosition(int reg, int* cp_offset) {
+  DCHECK_EQ(0, *cp_offset);
+  for (DeferredAction* action = actions_; action != nullptr;
+       action = action->next()) {
+    if (action->Mentions(reg)) {
+      if (action->action_type() == ActionNode::STORE_POSITION) {
+        *cp_offset = static_cast<DeferredCapture*>(action)->cp_offset();
+        return true;
+      } else {
+        return false;
+      }
+    }
+  }
+  return false;
+}
+
+// A (dynamically-sized) set of unsigned integers that behaves especially well
+// on small integers (< kFirstLimit). May do zone-allocation.
+class DynamicBitSet : public ZoneObject {
+ public:
+  V8_EXPORT_PRIVATE bool Get(unsigned value) const {
+    if (value < kFirstLimit) {
+      return (first_ & (1 << value)) != 0;
+    } else if (remaining_ == nullptr) {
+      return false;
+    } else {
+      return remaining_->Contains(value);
+    }
+  }
+
+  // Destructively set a value in this set.
+  void Set(unsigned value, Zone* zone) {
+    if (value < kFirstLimit) {
+      first_ |= (1 << value);
+    } else {
+      if (remaining_ == nullptr)
+        remaining_ = zone->New<ZoneList<unsigned>>(1, zone);
+      if (remaining_->is_empty() || !remaining_->Contains(value))
+        remaining_->Add(value, zone);
+    }
+  }
+
+ private:
+  static constexpr unsigned kFirstLimit = 32;
+
+  uint32_t first_ = 0;
+  ZoneList<unsigned>* remaining_ = nullptr;
+};
+
+int Trace::FindAffectedRegisters(DynamicBitSet* affected_registers,
+                                 Zone* zone) {
+  int max_register = RegExpCompiler::kNoRegister;
+  for (DeferredAction* action = actions_; action != nullptr;
+       action = action->next()) {
+    if (action->action_type() == ActionNode::CLEAR_CAPTURES) {
+      Interval range = static_cast<DeferredClearCaptures*>(action)->range();
+      for (int i = range.from(); i <= range.to(); i++)
+        affected_registers->Set(i, zone);
+      if (range.to() > max_register) max_register = range.to();
+    } else {
+      affected_registers->Set(action->reg(), zone);
+      if (action->reg() > max_register) max_register = action->reg();
+    }
+  }
+  return max_register;
+}
+
+void Trace::RestoreAffectedRegisters(RegExpMacroAssembler* assembler,
+                                     int max_register,
+                                     const DynamicBitSet& registers_to_pop,
+                                     const DynamicBitSet& registers_to_clear) {
+  for (int reg = max_register; reg >= 0; reg--) {
+    if (registers_to_pop.Get(reg)) {
+      assembler->PopRegister(reg);
+    } else if (registers_to_clear.Get(reg)) {
+      int clear_to = reg;
+      while (reg > 0 && registers_to_clear.Get(reg - 1)) {
+        reg--;
+      }
+      assembler->ClearRegisters(reg, clear_to);
+    }
+  }
+}
+
+void Trace::PerformDeferredActions(RegExpMacroAssembler* assembler,
+                                   int max_register,
+                                   const DynamicBitSet& affected_registers,
+                                   DynamicBitSet* registers_to_pop,
+                                   DynamicBitSet* registers_to_clear,
+                                   Zone* zone) {
+  // The "+1" is to avoid a push_limit of zero if stack_limit_slack() is 1.
+  const int push_limit = (assembler->stack_limit_slack() + 1) / 2;
+
+  // Count pushes performed to force a stack limit check occasionally.
+  int pushes = 0;
+
+  for (int reg = 0; reg <= max_register; reg++) {
+    if (!affected_registers.Get(reg)) continue;
+
+    // The chronologically first deferred action in the trace
+    // is used to infer the action needed to restore a register
+    // to its previous state (or not, if it's safe to ignore it).
+    enum DeferredActionUndoType { IGNORE, RESTORE, CLEAR };
+    DeferredActionUndoType undo_action = IGNORE;
+
+    int value = 0;
+    bool absolute = false;
+    bool clear = false;
+    static const int kNoStore = kMinInt;
+    int store_position = kNoStore;
+    // This is a little tricky because we are scanning the actions in reverse
+    // historical order (newest first).
+    for (DeferredAction* action = actions_; action != nullptr;
+         action = action->next()) {
+      if (action->Mentions(reg)) {
+        switch (action->action_type()) {
+          case ActionNode::SET_REGISTER_FOR_LOOP: {
+            Trace::DeferredSetRegisterForLoop* psr =
+                static_cast<Trace::DeferredSetRegisterForLoop*>(action);
+            if (!absolute) {
+              value += psr->value();
+              absolute = true;
+            }
+            // SET_REGISTER_FOR_LOOP is only used for newly introduced loop
+            // counters. They can have a significant previous value if they
+            // occur in a loop. TODO(lrn): Propagate this information, so
+            // we can set undo_action to IGNORE if we know there is no value to
+            // restore.
+            undo_action = RESTORE;
+            DCHECK_EQ(store_position, kNoStore);
+            DCHECK(!clear);
+            break;
+          }
+          case ActionNode::INCREMENT_REGISTER:
+            if (!absolute) {
+              value++;
+            }
+            DCHECK_EQ(store_position, kNoStore);
+            DCHECK(!clear);
+            undo_action = RESTORE;
+            break;
+          case ActionNode::STORE_POSITION: {
+            Trace::DeferredCapture* pc =
+                static_cast<Trace::DeferredCapture*>(action);
+            if (!clear && store_position == kNoStore) {
+              store_position = pc->cp_offset();
+            }
+
+            // For captures we know that stores and clears alternate.
+            // Other register, are never cleared, and if the occur
+            // inside a loop, they might be assigned more than once.
+            if (reg <= 1) {
+              // Registers zero and one, aka "capture zero", is
+              // always set correctly if we succeed. There is no
+              // need to undo a setting on backtrack, because we
+              // will set it again or fail.
+              undo_action = IGNORE;
+            } else {
+              undo_action = pc->is_capture() ? CLEAR : RESTORE;
+            }
+            DCHECK(!absolute);
+            DCHECK_EQ(value, 0);
+            break;
+          }
+          case ActionNode::CLEAR_CAPTURES: {
+            // Since we're scanning in reverse order, if we've already
+            // set the position we have to ignore historically earlier
+            // clearing operations.
+            if (store_position == kNoStore) {
+              clear = true;
+            }
+            undo_action = RESTORE;
+            DCHECK(!absolute);
+            DCHECK_EQ(value, 0);
+            break;
+          }
+          default:
+            UNREACHABLE();
+        }
+      }
+    }
+    // Prepare for the undo-action (e.g., push if it's going to be popped).
+    if (undo_action == RESTORE) {
+      pushes++;
+      RegExpMacroAssembler::StackCheckFlag stack_check =
+          RegExpMacroAssembler::kNoStackLimitCheck;
+      if (pushes == push_limit) {
+        stack_check = RegExpMacroAssembler::kCheckStackLimit;
+        pushes = 0;
+      }
+
+      assembler->PushRegister(reg, stack_check);
+      registers_to_pop->Set(reg, zone);
+    } else if (undo_action == CLEAR) {
+      registers_to_clear->Set(reg, zone);
+    }
+    // Perform the chronologically last action (or accumulated increment)
+    // for the register.
+    if (store_position != kNoStore) {
+      assembler->WriteCurrentPositionToRegister(reg, store_position);
+    } else if (clear) {
+      assembler->ClearRegisters(reg, reg);
+    } else if (absolute) {
+      assembler->SetRegister(reg, value);
+    } else if (value != 0) {
+      assembler->AdvanceRegister(reg, value);
+    }
+  }
+}
+
+// This is called as we come into a loop choice node and some other tricky
+// nodes.  It normalizes the state of the code generator to ensure we can
+// generate generic code.
+void Trace::Flush(RegExpCompiler* compiler, RegExpNode* successor) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+
+  DCHECK(!is_trivial());
+
+  if (actions_ == nullptr && backtrack() == nullptr) {
+    // Here we just have some deferred cp advances to fix and we are back to
+    // a normal situation.  We may also have to forget some information gained
+    // through a quick check that was already performed.
+    if (cp_offset_ != 0) assembler->AdvanceCurrentPosition(cp_offset_);
+    // Create a new trivial state and generate the node with that.
+    Trace new_state;
+    successor->Emit(compiler, &new_state);
+    return;
+  }
+
+  // Generate deferred actions here along with code to undo them again.
+  DynamicBitSet affected_registers;
+
+  if (backtrack() != nullptr) {
+    // Here we have a concrete backtrack location.  These are set up by choice
+    // nodes and so they indicate that we have a deferred save of the current
+    // position which we may need to emit here.
+    assembler->PushCurrentPosition();
+  }
+
+  int max_register =
+      FindAffectedRegisters(&affected_registers, compiler->zone());
+  DynamicBitSet registers_to_pop;
+  DynamicBitSet registers_to_clear;
+  PerformDeferredActions(assembler, max_register, affected_registers,
+                         &registers_to_pop, &registers_to_clear,
+                         compiler->zone());
+  if (cp_offset_ != 0) {
+    assembler->AdvanceCurrentPosition(cp_offset_);
+  }
+
+  // Create a new trivial state and generate the node with that.
+  Label undo;
+  assembler->PushBacktrack(&undo);
+  if (successor->KeepRecursing(compiler)) {
+    Trace new_state;
+    successor->Emit(compiler, &new_state);
+  } else {
+    compiler->AddWork(successor);
+    assembler->GoTo(successor->label());
+  }
+
+  // On backtrack we need to restore state.
+  assembler->BindJumpTarget(&undo);
+  RestoreAffectedRegisters(assembler, max_register, registers_to_pop,
+                           registers_to_clear);
+  if (backtrack() == nullptr) {
+    assembler->Backtrack();
+  } else {
+    assembler->PopCurrentPosition();
+    assembler->GoTo(backtrack());
+  }
+}
+
+void NegativeSubmatchSuccess::Emit(RegExpCompiler* compiler, Trace* trace) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+
+  // Omit flushing the trace. We discard the entire stack frame anyway.
+
+  if (!label()->is_bound()) {
+    // We are completely independent of the trace, since we ignore it,
+    // so this code can be used as the generic version.
+    assembler->Bind(label());
+  }
+
+  // Throw away everything on the backtrack stack since the start
+  // of the negative submatch and restore the character position.
+  assembler->ReadCurrentPositionFromRegister(current_position_register_);
+  assembler->ReadStackPointerFromRegister(stack_pointer_register_);
+  if (clear_capture_count_ > 0) {
+    // Clear any captures that might have been performed during the success
+    // of the body of the negative look-ahead.
+    int clear_capture_end = clear_capture_start_ + clear_capture_count_ - 1;
+    assembler->ClearRegisters(clear_capture_start_, clear_capture_end);
+  }
+  // Now that we have unwound the stack we find at the top of the stack the
+  // backtrack that the BeginNegativeSubmatch node got.
+  assembler->Backtrack();
+}
+
+void EndNode::Emit(RegExpCompiler* compiler, Trace* trace) {
+  if (!trace->is_trivial()) {
+    trace->Flush(compiler, this);
+    return;
+  }
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+  if (!label()->is_bound()) {
+    assembler->Bind(label());
+  }
+  switch (action_) {
+    case ACCEPT:
+      assembler->Succeed();
+      return;
+    case BACKTRACK:
+      assembler->GoTo(trace->backtrack());
+      return;
+    case NEGATIVE_SUBMATCH_SUCCESS:
+      // This case is handled in a different virtual method.
+      UNREACHABLE();
+  }
+  UNIMPLEMENTED();
+}
+
+void GuardedAlternative::AddGuard(Guard* guard, Zone* zone) {
+  if (guards_ == nullptr) guards_ = zone->New<ZoneList<Guard*>>(1, zone);
+  guards_->Add(guard, zone);
+}
+
+ActionNode* ActionNode::SetRegisterForLoop(int reg, int val,
+                                           RegExpNode* on_success) {
+  ActionNode* result =
+      on_success->zone()->New<ActionNode>(SET_REGISTER_FOR_LOOP, on_success);
+  result->data_.u_store_register.reg = reg;
+  result->data_.u_store_register.value = val;
+  return result;
+}
+
+ActionNode* ActionNode::IncrementRegister(int reg, RegExpNode* on_success) {
+  ActionNode* result =
+      on_success->zone()->New<ActionNode>(INCREMENT_REGISTER, on_success);
+  result->data_.u_increment_register.reg = reg;
+  return result;
+}
+
+ActionNode* ActionNode::StorePosition(int reg, bool is_capture,
+                                      RegExpNode* on_success) {
+  ActionNode* result =
+      on_success->zone()->New<ActionNode>(STORE_POSITION, on_success);
+  result->data_.u_position_register.reg = reg;
+  result->data_.u_position_register.is_capture = is_capture;
+  return result;
+}
+
+ActionNode* ActionNode::ClearCaptures(Interval range, RegExpNode* on_success) {
+  ActionNode* result =
+      on_success->zone()->New<ActionNode>(CLEAR_CAPTURES, on_success);
+  result->data_.u_clear_captures.range_from = range.from();
+  result->data_.u_clear_captures.range_to = range.to();
+  return result;
+}
+
+ActionNode* ActionNode::BeginPositiveSubmatch(int stack_reg, int position_reg,
+                                              RegExpNode* on_success) {
+  ActionNode* result =
+      on_success->zone()->New<ActionNode>(BEGIN_POSITIVE_SUBMATCH, on_success);
+  result->data_.u_submatch.stack_pointer_register = stack_reg;
+  result->data_.u_submatch.current_position_register = position_reg;
+  return result;
+}
+
+ActionNode* ActionNode::BeginNegativeSubmatch(int stack_reg, int position_reg,
+                                              RegExpNode* on_success) {
+  ActionNode* result =
+      on_success->zone()->New<ActionNode>(BEGIN_NEGATIVE_SUBMATCH, on_success);
+  result->data_.u_submatch.stack_pointer_register = stack_reg;
+  result->data_.u_submatch.current_position_register = position_reg;
+  return result;
+}
+
+ActionNode* ActionNode::PositiveSubmatchSuccess(int stack_reg, int position_reg,
+                                                int clear_register_count,
+                                                int clear_register_from,
+                                                RegExpNode* on_success) {
+  ActionNode* result = on_success->zone()->New<ActionNode>(
+      POSITIVE_SUBMATCH_SUCCESS, on_success);
+  result->data_.u_submatch.stack_pointer_register = stack_reg;
+  result->data_.u_submatch.current_position_register = position_reg;
+  result->data_.u_submatch.clear_register_count = clear_register_count;
+  result->data_.u_submatch.clear_register_from = clear_register_from;
+  return result;
+}
+
+ActionNode* ActionNode::EmptyMatchCheck(int start_register,
+                                        int repetition_register,
+                                        int repetition_limit,
+                                        RegExpNode* on_success) {
+  ActionNode* result =
+      on_success->zone()->New<ActionNode>(EMPTY_MATCH_CHECK, on_success);
+  result->data_.u_empty_match_check.start_register = start_register;
+  result->data_.u_empty_match_check.repetition_register = repetition_register;
+  result->data_.u_empty_match_check.repetition_limit = repetition_limit;
+  return result;
+}
+
+#define DEFINE_ACCEPT(Type) \
+  void Type##Node::Accept(NodeVisitor* visitor) { visitor->Visit##Type(this); }
+FOR_EACH_NODE_TYPE(DEFINE_ACCEPT)
+#undef DEFINE_ACCEPT
+
+// -------------------------------------------------------------------
+// Emit code.
+
+void ChoiceNode::GenerateGuard(RegExpMacroAssembler* macro_assembler,
+                               Guard* guard, Trace* trace) {
+  switch (guard->op()) {
+    case Guard::LT:
+      DCHECK(!trace->mentions_reg(guard->reg()));
+      macro_assembler->IfRegisterGE(guard->reg(), guard->value(),
+                                    trace->backtrack());
+      break;
+    case Guard::GEQ:
+      DCHECK(!trace->mentions_reg(guard->reg()));
+      macro_assembler->IfRegisterLT(guard->reg(), guard->value(),
+                                    trace->backtrack());
+      break;
+  }
+}
+
+namespace {
+
+#ifdef DEBUG
+bool ContainsOnlyUtf16CodeUnits(unibrow::uchar* chars, int length) {
+  static_assert(sizeof(unibrow::uchar) == 4);
+  for (int i = 0; i < length; i++) {
+    if (chars[i] > String::kMaxUtf16CodeUnit) return false;
+  }
+  return true;
+}
+#endif  // DEBUG
+
+// Returns the number of characters in the equivalence class, omitting those
+// that cannot occur in the source string because it is Latin1.
+int GetCaseIndependentLetters(Isolate* isolate, base::uc16 character,
+                              bool one_byte_subject, unibrow::uchar* letters,
+                              int letter_length) {
+#ifdef V8_INTL_SUPPORT
+  if (RegExpCaseFolding::IgnoreSet().contains(character)) {
+    letters[0] = character;
+    DCHECK(ContainsOnlyUtf16CodeUnits(letters, 1));
+    return 1;
+  }
+  bool in_special_add_set =
+      RegExpCaseFolding::SpecialAddSet().contains(character);
+
+  icu::UnicodeSet set;
+  set.add(character);
+  set = set.closeOver(USET_CASE_INSENSITIVE);
+
+  UChar32 canon = 0;
+  if (in_special_add_set) {
+    canon = RegExpCaseFolding::Canonicalize(character);
+  }
+
+  int32_t range_count = set.getRangeCount();
+  int items = 0;
+  for (int32_t i = 0; i < range_count; i++) {
+    UChar32 start = set.getRangeStart(i);
+    UChar32 end = set.getRangeEnd(i);
+    CHECK(end - start + items <= letter_length);
+    for (UChar32 cu = start; cu <= end; cu++) {
+      if (one_byte_subject && cu > String::kMaxOneByteCharCode) break;
+      if (in_special_add_set && RegExpCaseFolding::Canonicalize(cu) != canon) {
+        continue;
+      }
+      letters[items++] = static_cast<unibrow::uchar>(cu);
+    }
+  }
+  DCHECK(ContainsOnlyUtf16CodeUnits(letters, items));
+  return items;
+#else
+  int length =
+      isolate->jsregexp_uncanonicalize()->get(character, '\0', letters);
+  // Unibrow returns 0 or 1 for characters where case independence is
+  // trivial.
+  if (length == 0) {
+    letters[0] = character;
+    length = 1;
+  }
+
+  if (one_byte_subject) {
+    int new_length = 0;
+    for (int i = 0; i < length; i++) {
+      if (letters[i] <= String::kMaxOneByteCharCode) {
+        letters[new_length++] = letters[i];
+      }
+    }
+    length = new_length;
+  }
+
+  DCHECK(ContainsOnlyUtf16CodeUnits(letters, length));
+  return length;
+#endif  // V8_INTL_SUPPORT
+}
+
+inline bool EmitSimpleCharacter(Isolate* isolate, RegExpCompiler* compiler,
+                                base::uc16 c, Label* on_failure, int cp_offset,
+                                bool check, bool preloaded) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+  bool bound_checked = false;
+  if (!preloaded) {
+    assembler->LoadCurrentCharacter(cp_offset, on_failure, check);
+    bound_checked = true;
+  }
+  assembler->CheckNotCharacter(c, on_failure);
+  return bound_checked;
+}
+
+// Only emits non-letters (things that don't have case).  Only used for case
+// independent matches.
+inline bool EmitAtomNonLetter(Isolate* isolate, RegExpCompiler* compiler,
+                              base::uc16 c, Label* on_failure, int cp_offset,
+                              bool check, bool preloaded) {
+  RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
+  bool one_byte = compiler->one_byte();
+  unibrow::uchar chars[4];
+  int length = GetCaseIndependentLetters(isolate, c, one_byte, chars, 4);
+  if (length < 1) {
+    // This can't match.  Must be an one-byte subject and a non-one-byte
+    // character.  We do not need to do anything since the one-byte pass
+    // already handled this.
+    return false;  // Bounds not checked.
+  }
+  bool checked = false;
+  // We handle the length > 1 case in a later pass.
+  if (length == 1) {
+    if (one_byte && c > String::kMaxOneByteCharCodeU) {
+      // Can't match - see above.
+      return false;  // Bounds not checked.
+    }
+    if (!preloaded) {
+      macro_assembler->LoadCurrentCharacter(cp_offset, on_failure, check);
+      checked = check;
+    }
+    macro_assembler->CheckNotCharacter(c, on_failure);
+  }
+  return checked;
+}
+
+bool ShortCutEmitCharacterPair(RegExpMacroAssembler* macro_assembler,
+                               bool one_byte, base::uc16 c1, base::uc16 c2,
+                               Label* on_failure) {
+  const uint32_t char_mask = CharMask(one_byte);
+  base::uc16 exor = c1 ^ c2;
+  // Check whether exor has only one bit set.
+  if (((exor - 1) & exor) == 0) {
+    // If c1 and c2 differ only by one bit.
+    // Ecma262UnCanonicalize always gives the highest number last.
+    DCHECK(c2 > c1);
+    base::uc16 mask = char_mask ^ exor;
+    macro_assembler->CheckNotCharacterAfterAnd(c1, mask, on_failure);
+    return true;
+  }
+  DCHECK(c2 > c1);
+  base::uc16 diff = c2 - c1;
+  if (((diff - 1) & diff) == 0 && c1 >= diff) {
+    // If the characters differ by 2^n but don't differ by one bit then
+    // subtract the difference from the found character, then do the or
+    // trick.  We avoid the theoretical case where negative numbers are
+    // involved in order to simplify code generation.
+    base::uc16 mask = char_mask ^ diff;
+    macro_assembler->CheckNotCharacterAfterMinusAnd(c1 - diff, diff, mask,
+                                                    on_failure);
+    return true;
+  }
+  return false;
+}
+
+// Only emits letters (things that have case).  Only used for case independent
+// matches.
+inline bool EmitAtomLetter(Isolate* isolate, RegExpCompiler* compiler,
+                           base::uc16 c, Label* on_failure, int cp_offset,
+                           bool check, bool preloaded) {
+  RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
+  bool one_byte = compiler->one_byte();
+  unibrow::uchar chars[4];
+  int length = GetCaseIndependentLetters(isolate, c, one_byte, chars, 4);
+  if (length <= 1) return false;
+  // We may not need to check against the end of the input string
+  // if this character lies before a character that matched.
+  if (!preloaded) {
+    macro_assembler->LoadCurrentCharacter(cp_offset, on_failure, check);
+  }
+  Label ok;
+  switch (length) {
+    case 2: {
+      if (ShortCutEmitCharacterPair(macro_assembler, one_byte, chars[0],
+                                    chars[1], on_failure)) {
+      } else {
+        macro_assembler->CheckCharacter(chars[0], &ok);
+        macro_assembler->CheckNotCharacter(chars[1], on_failure);
+        macro_assembler->Bind(&ok);
+      }
+      break;
+    }
+    case 4:
+      macro_assembler->CheckCharacter(chars[3], &ok);
+      V8_FALLTHROUGH;
+    case 3:
+      macro_assembler->CheckCharacter(chars[0], &ok);
+      macro_assembler->CheckCharacter(chars[1], &ok);
+      macro_assembler->CheckNotCharacter(chars[2], on_failure);
+      macro_assembler->Bind(&ok);
+      break;
+    default:
+      UNREACHABLE();
+  }
+  return true;
+}
+
+void EmitBoundaryTest(RegExpMacroAssembler* masm, int border,
+                      Label* fall_through, Label* above_or_equal,
+                      Label* below) {
+  if (below != fall_through) {
+    masm->CheckCharacterLT(border, below);
+    if (above_or_equal != fall_through) masm->GoTo(above_or_equal);
+  } else {
+    masm->CheckCharacterGT(border - 1, above_or_equal);
+  }
+}
+
+void EmitDoubleBoundaryTest(RegExpMacroAssembler* masm, int first, int last,
+                            Label* fall_through, Label* in_range,
+                            Label* out_of_range) {
+  if (in_range == fall_through) {
+    if (first == last) {
+      masm->CheckNotCharacter(first, out_of_range);
+    } else {
+      masm->CheckCharacterNotInRange(first, last, out_of_range);
+    }
+  } else {
+    if (first == last) {
+      masm->CheckCharacter(first, in_range);
+    } else {
+      masm->CheckCharacterInRange(first, last, in_range);
+    }
+    if (out_of_range != fall_through) masm->GoTo(out_of_range);
+  }
+}
+
+// even_label is for ranges[i] to ranges[i + 1] where i - start_index is even.
+// odd_label is for ranges[i] to ranges[i + 1] where i - start_index is odd.
+void EmitUseLookupTable(RegExpMacroAssembler* masm,
+                        ZoneList<base::uc32>* ranges, uint32_t start_index,
+                        uint32_t end_index, base::uc32 min_char,
+                        Label* fall_through, Label* even_label,
+                        Label* odd_label) {
+  static const uint32_t kSize = RegExpMacroAssembler::kTableSize;
+  static const uint32_t kMask = RegExpMacroAssembler::kTableMask;
+
+  base::uc32 base = (min_char & ~kMask);
+  USE(base);
+
+  // Assert that everything is on one kTableSize page.
+  for (uint32_t i = start_index; i <= end_index; i++) {
+    DCHECK_EQ(ranges->at(i) & ~kMask, base);
+  }
+  DCHECK(start_index == 0 || (ranges->at(start_index - 1) & ~kMask) <= base);
+
+  char templ[kSize];
+  Label* on_bit_set;
+  Label* on_bit_clear;
+  int bit;
+  if (even_label == fall_through) {
+    on_bit_set = odd_label;
+    on_bit_clear = even_label;
+    bit = 1;
+  } else {
+    on_bit_set = even_label;
+    on_bit_clear = odd_label;
+    bit = 0;
+  }
+  for (uint32_t i = 0; i < (ranges->at(start_index) & kMask) && i < kSize;
+       i++) {
+    templ[i] = bit;
+  }
+  uint32_t j = 0;
+  bit ^= 1;
+  for (uint32_t i = start_index; i < end_index; i++) {
+    for (j = (ranges->at(i) & kMask); j < (ranges->at(i + 1) & kMask); j++) {
+      templ[j] = bit;
+    }
+    bit ^= 1;
+  }
+  for (uint32_t i = j; i < kSize; i++) {
+    templ[i] = bit;
+  }
+  Factory* factory = masm->isolate()->factory();
+  // TODO(erikcorry): Cache these.
+  Handle<ByteArray> ba = factory->NewByteArray(kSize, AllocationType::kOld);
+  for (uint32_t i = 0; i < kSize; i++) {
+    ba->set(i, templ[i]);
+  }
+  masm->CheckBitInTable(ba, on_bit_set);
+  if (on_bit_clear != fall_through) masm->GoTo(on_bit_clear);
+}
+
+void CutOutRange(RegExpMacroAssembler* masm, ZoneList<base::uc32>* ranges,
+                 uint32_t start_index, uint32_t end_index, uint32_t cut_index,
+                 Label* even_label, Label* odd_label) {
+  bool odd = (((cut_index - start_index) & 1) == 1);
+  Label* in_range_label = odd ? odd_label : even_label;
+  Label dummy;
+  EmitDoubleBoundaryTest(masm, ranges->at(cut_index),
+                         ranges->at(cut_index + 1) - 1, &dummy, in_range_label,
+                         &dummy);
+  DCHECK(!dummy.is_linked());
+  // Cut out the single range by rewriting the array.  This creates a new
+  // range that is a merger of the two ranges on either side of the one we
+  // are cutting out.  The oddity of the labels is preserved.
+  for (uint32_t j = cut_index; j > start_index; j--) {
+    ranges->at(j) = ranges->at(j - 1);
+  }
+  for (uint32_t j = cut_index + 1; j < end_index; j++) {
+    ranges->at(j) = ranges->at(j + 1);
+  }
+}
+
+// Unicode case.  Split the search space into kSize spaces that are handled
+// with recursion.
+void SplitSearchSpace(ZoneList<base::uc32>* ranges, uint32_t start_index,
+                      uint32_t end_index, uint32_t* new_start_index,
+                      uint32_t* new_end_index, base::uc32* border) {
+  static const uint32_t kSize = RegExpMacroAssembler::kTableSize;
+  static const uint32_t kMask = RegExpMacroAssembler::kTableMask;
+
+  base::uc32 first = ranges->at(start_index);
+  base::uc32 last = ranges->at(end_index) - 1;
+
+  *new_start_index = start_index;
+  *border = (ranges->at(start_index) & ~kMask) + kSize;
+  while (*new_start_index < end_index) {
+    if (ranges->at(*new_start_index) > *border) break;
+    (*new_start_index)++;
+  }
+  // new_start_index is the index of the first edge that is beyond the
+  // current kSize space.
+
+  // For very large search spaces we do a binary chop search of the non-Latin1
+  // space instead of just going to the end of the current kSize space.  The
+  // heuristics are complicated a little by the fact that any 128-character
+  // encoding space can be quickly tested with a table lookup, so we don't
+  // wish to do binary chop search at a smaller granularity than that.  A
+  // 128-character space can take up a lot of space in the ranges array if,
+  // for example, we only want to match every second character (eg. the lower
+  // case characters on some Unicode pages).
+  uint32_t binary_chop_index = (end_index + start_index) / 2;
+  // The first test ensures that we get to the code that handles the Latin1
+  // range with a single not-taken branch, speeding up this important
+  // character range (even non-Latin1 charset-based text has spaces and
+  // punctuation).
+  if (*border - 1 > String::kMaxOneByteCharCode &&  // Latin1 case.
+      end_index - start_index > (*new_start_index - start_index) * 2 &&
+      last - first > kSize * 2 && binary_chop_index > *new_start_index &&
+      ranges->at(binary_chop_index) >= first + 2 * kSize) {
+    uint32_t scan_forward_for_section_border = binary_chop_index;
+    uint32_t new_border = (ranges->at(binary_chop_index) | kMask) + 1;
+
+    while (scan_forward_for_section_border < end_index) {
+      if (ranges->at(scan_forward_for_section_border) > new_border) {
+        *new_start_index = scan_forward_for_section_border;
+        *border = new_border;
+        break;
+      }
+      scan_forward_for_section_border++;
+    }
+  }
+
+  DCHECK(*new_start_index > start_index);
+  *new_end_index = *new_start_index - 1;
+  if (ranges->at(*new_end_index) == *border) {
+    (*new_end_index)--;
+  }
+  if (*border >= ranges->at(end_index)) {
+    *border = ranges->at(end_index);
+    *new_start_index = end_index;  // Won't be used.
+    *new_end_index = end_index - 1;
+  }
+}
+
+// Gets a series of segment boundaries representing a character class.  If the
+// character is in the range between an even and an odd boundary (counting from
+// start_index) then go to even_label, otherwise go to odd_label.  We already
+// know that the character is in the range of min_char to max_char inclusive.
+// Either label can be nullptr indicating backtracking.  Either label can also
+// be equal to the fall_through label.
+void GenerateBranches(RegExpMacroAssembler* masm, ZoneList<base::uc32>* ranges,
+                      uint32_t start_index, uint32_t end_index,
+                      base::uc32 min_char, base::uc32 max_char,
+                      Label* fall_through, Label* even_label,
+                      Label* odd_label) {
+  DCHECK_LE(min_char, String::kMaxUtf16CodeUnit);
+  DCHECK_LE(max_char, String::kMaxUtf16CodeUnit);
+
+  base::uc32 first = ranges->at(start_index);
+  base::uc32 last = ranges->at(end_index) - 1;
+
+  DCHECK_LT(min_char, first);
+
+  // Just need to test if the character is before or on-or-after
+  // a particular character.
+  if (start_index == end_index) {
+    EmitBoundaryTest(masm, first, fall_through, even_label, odd_label);
+    return;
+  }
+
+  // Another almost trivial case:  There is one interval in the middle that is
+  // different from the end intervals.
+  if (start_index + 1 == end_index) {
+    EmitDoubleBoundaryTest(masm, first, last, fall_through, even_label,
+                           odd_label);
+    return;
+  }
+
+  // It's not worth using table lookup if there are very few intervals in the
+  // character class.
+  if (end_index - start_index <= 6) {
+    // It is faster to test for individual characters, so we look for those
+    // first, then try arbitrary ranges in the second round.
+    static uint32_t kNoCutIndex = -1;
+    uint32_t cut = kNoCutIndex;
+    for (uint32_t i = start_index; i < end_index; i++) {
+      if (ranges->at(i) == ranges->at(i + 1) - 1) {
+        cut = i;
+        break;
+      }
+    }
+    if (cut == kNoCutIndex) cut = start_index;
+    CutOutRange(masm, ranges, start_index, end_index, cut, even_label,
+                odd_label);
+    DCHECK_GE(end_index - start_index, 2);
+    GenerateBranches(masm, ranges, start_index + 1, end_index - 1, min_char,
+                     max_char, fall_through, even_label, odd_label);
+    return;
+  }
+
+  // If there are a lot of intervals in the regexp, then we will use tables to
+  // determine whether the character is inside or outside the character class.
+  static const int kBits = RegExpMacroAssembler::kTableSizeBits;
+
+  if ((max_char >> kBits) == (min_char >> kBits)) {
+    EmitUseLookupTable(masm, ranges, start_index, end_index, min_char,
+                       fall_through, even_label, odd_label);
+    return;
+  }
+
+  if ((min_char >> kBits) != first >> kBits) {
+    masm->CheckCharacterLT(first, odd_label);
+    GenerateBranches(masm, ranges, start_index + 1, end_index, first, max_char,
+                     fall_through, odd_label, even_label);
+    return;
+  }
+
+  uint32_t new_start_index = 0;
+  uint32_t new_end_index = 0;
+  base::uc32 border = 0;
+
+  SplitSearchSpace(ranges, start_index, end_index, &new_start_index,
+                   &new_end_index, &border);
+
+  Label handle_rest;
+  Label* above = &handle_rest;
+  if (border == last + 1) {
+    // We didn't find any section that started after the limit, so everything
+    // above the border is one of the terminal labels.
+    above = (end_index & 1) != (start_index & 1) ? odd_label : even_label;
+    DCHECK(new_end_index == end_index - 1);
+  }
+
+  DCHECK_LE(start_index, new_end_index);
+  DCHECK_LE(new_start_index, end_index);
+  DCHECK_LT(start_index, new_start_index);
+  DCHECK_LT(new_end_index, end_index);
+  DCHECK(new_end_index + 1 == new_start_index ||
+         (new_end_index + 2 == new_start_index &&
+          border == ranges->at(new_end_index + 1)));
+  DCHECK_LT(min_char, border - 1);
+  DCHECK_LT(border, max_char);
+  DCHECK_LT(ranges->at(new_end_index), border);
+  DCHECK(border < ranges->at(new_start_index) ||
+         (border == ranges->at(new_start_index) &&
+          new_start_index == end_index && new_end_index == end_index - 1 &&
+          border == last + 1));
+  DCHECK(new_start_index == 0 || border >= ranges->at(new_start_index - 1));
+
+  masm->CheckCharacterGT(border - 1, above);
+  Label dummy;
+  GenerateBranches(masm, ranges, start_index, new_end_index, min_char,
+                   border - 1, &dummy, even_label, odd_label);
+  if (handle_rest.is_linked()) {
+    masm->Bind(&handle_rest);
+    bool flip = (new_start_index & 1) != (start_index & 1);
+    GenerateBranches(masm, ranges, new_start_index, end_index, border, max_char,
+                     &dummy, flip ? odd_label : even_label,
+                     flip ? even_label : odd_label);
+  }
+}
+
+void EmitClassRanges(RegExpMacroAssembler* macro_assembler,
+                     RegExpClassRanges* cr, bool one_byte, Label* on_failure,
+                     int cp_offset, bool check_offset, bool preloaded,
+                     Zone* zone) {
+  ZoneList<CharacterRange>* ranges = cr->ranges(zone);
+  CharacterRange::Canonicalize(ranges);
+
+  // Now that all processing (like case-insensitivity) is done, clamp the
+  // ranges to the set of ranges that may actually occur in the subject string.
+  if (one_byte) CharacterRange::ClampToOneByte(ranges);
+
+  const int ranges_length = ranges->length();
+  if (ranges_length == 0) {
+    if (!cr->is_negated()) {
+      macro_assembler->GoTo(on_failure);
+    }
+    if (check_offset) {
+      macro_assembler->CheckPosition(cp_offset, on_failure);
+    }
+    return;
+  }
+
+  const base::uc32 max_char = MaxCodeUnit(one_byte);
+  if (ranges_length == 1 && ranges->at(0).IsEverything(max_char)) {
+    if (cr->is_negated()) {
+      macro_assembler->GoTo(on_failure);
+    } else {
+      // This is a common case hit by non-anchored expressions.
+      if (check_offset) {
+        macro_assembler->CheckPosition(cp_offset, on_failure);
+      }
+    }
+    return;
+  }
+
+  if (!preloaded) {
+    macro_assembler->LoadCurrentCharacter(cp_offset, on_failure, check_offset);
+  }
+
+  if (cr->is_standard(zone) && macro_assembler->CheckSpecialClassRanges(
+                                   cr->standard_type(), on_failure)) {
+    return;
+  }
+
+  static constexpr int kMaxRangesForInlineBranchGeneration = 16;
+  if (ranges_length > kMaxRangesForInlineBranchGeneration) {
+    // For large range sets, emit a more compact instruction sequence to avoid
+    // a potentially problematic increase in code size.
+    // Note the flipped logic below (we check InRange if negated, NotInRange if
+    // not negated); this is necessary since the method falls through on
+    // failure whereas we want to fall through on success.
+    if (cr->is_negated()) {
+      if (macro_assembler->CheckCharacterInRangeArray(ranges, on_failure)) {
+        return;
+      }
+    } else {
+      if (macro_assembler->CheckCharacterNotInRangeArray(ranges, on_failure)) {
+        return;
+      }
+    }
+  }
+
+  // Generate a flat list of range boundaries for consumption by
+  // GenerateBranches. See the comment on that function for how the list should
+  // be structured
+  ZoneList<base::uc32>* range_boundaries =
+      zone->New<ZoneList<base::uc32>>(ranges_length * 2, zone);
+
+  bool zeroth_entry_is_failure = !cr->is_negated();
+
+  for (int i = 0; i < ranges_length; i++) {
+    CharacterRange& range = ranges->at(i);
+    if (range.from() == 0) {
+      DCHECK_EQ(i, 0);
+      zeroth_entry_is_failure = !zeroth_entry_is_failure;
+    } else {
+      range_boundaries->Add(range.from(), zone);
+    }
+    // `+ 1` to convert from inclusive to exclusive `to`.
+    // [from, to] == [from, to+1[.
+    range_boundaries->Add(range.to() + 1, zone);
+  }
+  int end_index = range_boundaries->length() - 1;
+  if (range_boundaries->at(end_index) > max_char) {
+    end_index--;
+  }
+
+  Label fall_through;
+  GenerateBranches(macro_assembler, range_boundaries,
+                   0,  // start_index.
+                   end_index,
+                   0,  // min_char.
+                   max_char, &fall_through,
+                   zeroth_entry_is_failure ? &fall_through : on_failure,
+                   zeroth_entry_is_failure ? on_failure : &fall_through);
+  macro_assembler->Bind(&fall_through);
+}
+
+}  // namespace
+
+RegExpNode::~RegExpNode() = default;
+
+RegExpNode::LimitResult RegExpNode::LimitVersions(RegExpCompiler* compiler,
+                                                  Trace* trace) {
+  // If we are generating a greedy loop then don't stop and don't reuse code.
+  if (trace->stop_node() != nullptr) {
+    return CONTINUE;
+  }
+
+  RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
+  if (trace->is_trivial()) {
+    if (label_.is_bound() || on_work_list() || !KeepRecursing(compiler)) {
+      // If a generic version is already scheduled to be generated or we have
+      // recursed too deeply then just generate a jump to that code.
+      macro_assembler->GoTo(&label_);
+      // This will queue it up for generation of a generic version if it hasn't
+      // already been queued.
+      compiler->AddWork(this);
+      return DONE;
+    }
+    // Generate generic version of the node and bind the label for later use.
+    macro_assembler->Bind(&label_);
+    return CONTINUE;
+  }
+
+  // We are being asked to make a non-generic version.  Keep track of how many
+  // non-generic versions we generate so as not to overdo it.
+  trace_count_++;
+  if (KeepRecursing(compiler) && compiler->optimize() &&
+      trace_count_ < kMaxCopiesCodeGenerated) {
+    return CONTINUE;
+  }
+
+  // If we get here code has been generated for this node too many times or
+  // recursion is too deep.  Time to switch to a generic version.  The code for
+  // generic versions above can handle deep recursion properly.
+  bool was_limiting = compiler->limiting_recursion();
+  compiler->set_limiting_recursion(true);
+  trace->Flush(compiler, this);
+  compiler->set_limiting_recursion(was_limiting);
+  return DONE;
+}
+
+bool RegExpNode::KeepRecursing(RegExpCompiler* compiler) {
+  return !compiler->limiting_recursion() &&
+         compiler->recursion_depth() <= RegExpCompiler::kMaxRecursion;
+}
+
+void ActionNode::FillInBMInfo(Isolate* isolate, int offset, int budget,
+                              BoyerMooreLookahead* bm, bool not_at_start) {
+  if (action_type_ == POSITIVE_SUBMATCH_SUCCESS) {
+    // Anything may follow a positive submatch success, thus we need to accept
+    // all characters from this position onwards.
+    bm->SetRest(offset);
+  } else {
+    on_success()->FillInBMInfo(isolate, offset, budget - 1, bm, not_at_start);
+  }
+  SaveBMInfo(bm, not_at_start, offset);
+}
+
+void ActionNode::GetQuickCheckDetails(QuickCheckDetails* details,
+                                      RegExpCompiler* compiler, int filled_in,
+                                      bool not_at_start) {
+  if (action_type_ == SET_REGISTER_FOR_LOOP) {
+    on_success()->GetQuickCheckDetailsFromLoopEntry(details, compiler,
+                                                    filled_in, not_at_start);
+  } else {
+    on_success()->GetQuickCheckDetails(details, compiler, filled_in,
+                                       not_at_start);
+  }
+}
+
+void AssertionNode::FillInBMInfo(Isolate* isolate, int offset, int budget,
+                                 BoyerMooreLookahead* bm, bool not_at_start) {
+  // Match the behaviour of EatsAtLeast on this node.
+  if (assertion_type() == AT_START && not_at_start) return;
+  on_success()->FillInBMInfo(isolate, offset, budget - 1, bm, not_at_start);
+  SaveBMInfo(bm, not_at_start, offset);
+}
+
+void NegativeLookaroundChoiceNode::GetQuickCheckDetails(
+    QuickCheckDetails* details, RegExpCompiler* compiler, int filled_in,
+    bool not_at_start) {
+  RegExpNode* node = continue_node();
+  return node->GetQuickCheckDetails(details, compiler, filled_in, not_at_start);
+}
+
+namespace {
+
+// Takes the left-most 1-bit and smears it out, setting all bits to its right.
+inline uint32_t SmearBitsRight(uint32_t v) {
+  v |= v >> 1;
+  v |= v >> 2;
+  v |= v >> 4;
+  v |= v >> 8;
+  v |= v >> 16;
+  return v;
+}
+
+}  // namespace
+
+bool QuickCheckDetails::Rationalize(bool asc) {
+  bool found_useful_op = false;
+  const uint32_t char_mask = CharMask(asc);
+  mask_ = 0;
+  value_ = 0;
+  int char_shift = 0;
+  for (int i = 0; i < characters_; i++) {
+    Position* pos = &positions_[i];
+    if ((pos->mask & String::kMaxOneByteCharCode) != 0) {
+      found_useful_op = true;
+    }
+    mask_ |= (pos->mask & char_mask) << char_shift;
+    value_ |= (pos->value & char_mask) << char_shift;
+    char_shift += asc ? 8 : 16;
+  }
+  return found_useful_op;
+}
+
+int RegExpNode::EatsAtLeast(bool not_at_start) {
+  return not_at_start ? eats_at_least_.eats_at_least_from_not_start
+                      : eats_at_least_.eats_at_least_from_possibly_start;
+}
+
+EatsAtLeastInfo RegExpNode::EatsAtLeastFromLoopEntry() {
+  // SET_REGISTER_FOR_LOOP is only used to initialize loop counters, and it
+  // implies that the following node must be a LoopChoiceNode. If we need to
+  // set registers to constant values for other reasons, we could introduce a
+  // new action type SET_REGISTER that doesn't imply anything about its
+  // successor.
+  UNREACHABLE();
+}
+
+void RegExpNode::GetQuickCheckDetailsFromLoopEntry(QuickCheckDetails* details,
+                                                   RegExpCompiler* compiler,
+                                                   int characters_filled_in,
+                                                   bool not_at_start) {
+  // See comment in RegExpNode::EatsAtLeastFromLoopEntry.
+  UNREACHABLE();
+}
+
+EatsAtLeastInfo LoopChoiceNode::EatsAtLeastFromLoopEntry() {
+  DCHECK_EQ(alternatives_->length(), 2);  // There's just loop and continue.
+
+  if (read_backward()) {
+    // The eats_at_least value is not used if reading backward. The
+    // EatsAtLeastPropagator should've zeroed it as well.
+    DCHECK_EQ(eats_at_least_info()->eats_at_least_from_possibly_start, 0);
+    DCHECK_EQ(eats_at_least_info()->eats_at_least_from_not_start, 0);
+    return {};
+  }
+
+  // Figure out how much the loop body itself eats, not including anything in
+  // the continuation case. In general, the nodes in the loop body should report
+  // that they eat at least the number eaten by the continuation node, since any
+  // successful match in the loop body must also include the continuation node.
+  // However, in some cases involving positive lookaround, the loop body under-
+  // reports its appetite, so use saturated math here to avoid negative numbers.
+  uint8_t loop_body_from_not_start = base::saturated_cast<uint8_t>(
+      loop_node_->EatsAtLeast(true) - continue_node_->EatsAtLeast(true));
+  uint8_t loop_body_from_possibly_start = base::saturated_cast<uint8_t>(
+      loop_node_->EatsAtLeast(false) - continue_node_->EatsAtLeast(true));
+
+  // Limit the number of loop iterations to avoid overflow in subsequent steps.
+  int loop_iterations = base::saturated_cast<uint8_t>(min_loop_iterations());
+
+  EatsAtLeastInfo result;
+  result.eats_at_least_from_not_start =
+      base::saturated_cast<uint8_t>(loop_iterations * loop_body_from_not_start +
+                                    continue_node_->EatsAtLeast(true));
+  if (loop_iterations > 0 && loop_body_from_possibly_start > 0) {
+    // First loop iteration eats at least one, so all subsequent iterations
+    // and the after-loop chunk are guaranteed to not be at the start.
+    result.eats_at_least_from_possibly_start = base::saturated_cast<uint8_t>(
+        loop_body_from_possibly_start +
+        (loop_iterations - 1) * loop_body_from_not_start +
+        continue_node_->EatsAtLeast(true));
+  } else {
+    // Loop body might eat nothing, so only continue node contributes.
+    result.eats_at_least_from_possibly_start =
+        continue_node_->EatsAtLeast(false);
+  }
+  return result;
+}
+
+bool RegExpNode::EmitQuickCheck(RegExpCompiler* compiler,
+                                Trace* bounds_check_trace, Trace* trace,
+                                bool preload_has_checked_bounds,
+                                Label* on_possible_success,
+                                QuickCheckDetails* details,
+                                bool fall_through_on_failure,
+                                ChoiceNode* predecessor) {
+  DCHECK_NOT_NULL(predecessor);
+  if (details->characters() == 0) return false;
+  GetQuickCheckDetails(details, compiler, 0,
+                       trace->at_start() == Trace::FALSE_VALUE);
+  if (details->cannot_match()) return false;
+  if (!details->Rationalize(compiler->one_byte())) return false;
+  DCHECK(details->characters() == 1 ||
+         compiler->macro_assembler()->CanReadUnaligned());
+  uint32_t mask = details->mask();
+  uint32_t value = details->value();
+
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+
+  if (trace->characters_preloaded() != details->characters()) {
+    DCHECK(trace->cp_offset() == bounds_check_trace->cp_offset());
+    // The bounds check is performed using the minimum number of characters
+    // any choice would eat, so if the bounds check fails, then none of the
+    // choices can succeed, so we can just immediately backtrack, rather
+    // than go to the next choice. The number of characters preloaded may be
+    // less than the number used for the bounds check.
+    int eats_at_least = predecessor->EatsAtLeast(
+        bounds_check_trace->at_start() == Trace::FALSE_VALUE);
+    DCHECK_GE(eats_at_least, details->characters());
+    assembler->LoadCurrentCharacter(
+        trace->cp_offset(), bounds_check_trace->backtrack(),
+        !preload_has_checked_bounds, details->characters(), eats_at_least);
+  }
+
+  bool need_mask = true;
+
+  if (details->characters() == 1) {
+    // If number of characters preloaded is 1 then we used a byte or 16 bit
+    // load so the value is already masked down.
+    const uint32_t char_mask = CharMask(compiler->one_byte());
+    if ((mask & char_mask) == char_mask) need_mask = false;
+    mask &= char_mask;
+  } else {
+    // For 2-character preloads in one-byte mode or 1-character preloads in
+    // two-byte mode we also use a 16 bit load with zero extend.
+    static const uint32_t kTwoByteMask = 0xFFFF;
+    static const uint32_t kFourByteMask = 0xFFFFFFFF;
+    if (details->characters() == 2 && compiler->one_byte()) {
+      if ((mask & kTwoByteMask) == kTwoByteMask) need_mask = false;
+    } else if (details->characters() == 1 && !compiler->one_byte()) {
+      if ((mask & kTwoByteMask) == kTwoByteMask) need_mask = false;
+    } else {
+      if (mask == kFourByteMask) need_mask = false;
+    }
+  }
+
+  if (fall_through_on_failure) {
+    if (need_mask) {
+      assembler->CheckCharacterAfterAnd(value, mask, on_possible_success);
+    } else {
+      assembler->CheckCharacter(value, on_possible_success);
+    }
+  } else {
+    if (need_mask) {
+      assembler->CheckNotCharacterAfterAnd(value, mask, trace->backtrack());
+    } else {
+      assembler->CheckNotCharacter(value, trace->backtrack());
+    }
+  }
+  return true;
+}
+
+// Here is the meat of GetQuickCheckDetails (see also the comment on the
+// super-class in the .h file).
+//
+// We iterate along the text object, building up for each character a
+// mask and value that can be used to test for a quick failure to match.
+// The masks and values for the positions will be combined into a single
+// machine word for the current character width in order to be used in
+// generating a quick check.
+void TextNode::GetQuickCheckDetails(QuickCheckDetails* details,
+                                    RegExpCompiler* compiler,
+                                    int characters_filled_in,
+                                    bool not_at_start) {
+  // Do not collect any quick check details if the text node reads backward,
+  // since it reads in the opposite direction than we use for quick checks.
+  if (read_backward()) return;
+  Isolate* isolate = compiler->macro_assembler()->isolate();
+  DCHECK(characters_filled_in < details->characters());
+  int characters = details->characters();
+  const uint32_t char_mask = CharMask(compiler->one_byte());
+  for (int k = 0; k < elements()->length(); k++) {
+    TextElement elm = elements()->at(k);
+    if (elm.text_type() == TextElement::ATOM) {
+      base::Vector<const base::uc16> quarks = elm.atom()->data();
+      for (int i = 0; i < characters && i < quarks.length(); i++) {
+        QuickCheckDetails::Position* pos =
+            details->positions(characters_filled_in);
+        base::uc16 c = quarks[i];
+        if (IsIgnoreCase(compiler->flags())) {
+          unibrow::uchar chars[4];
+          int length = GetCaseIndependentLetters(
+              isolate, c, compiler->one_byte(), chars, 4);
+          if (length == 0) {
+            // This can happen because all case variants are non-Latin1, but we
+            // know the input is Latin1.
+            details->set_cannot_match();
+            pos->determines_perfectly = false;
+            return;
+          }
+          if (length == 1) {
+            // This letter has no case equivalents, so it's nice and simple
+            // and the mask-compare will determine definitely whether we have
+            // a match at this character position.
+            pos->mask = char_mask;
+            pos->value = chars[0];
+            pos->determines_perfectly = true;
+          } else {
+            uint32_t common_bits = char_mask;
+            uint32_t bits = chars[0];
+            for (int j = 1; j < length; j++) {
+              uint32_t differing_bits = ((chars[j] & common_bits) ^ bits);
+              common_bits ^= differing_bits;
+              bits &= common_bits;
+            }
+            // If length is 2 and common bits has only one zero in it then
+            // our mask and compare instruction will determine definitely
+            // whether we have a match at this character position.  Otherwise
+            // it can only be an approximate check.
+            uint32_t one_zero = (common_bits | ~char_mask);
+            if (length == 2 && ((~one_zero) & ((~one_zero) - 1)) == 0) {
+              pos->determines_perfectly = true;
+            }
+            pos->mask = common_bits;
+            pos->value = bits;
+          }
+        } else {
+          // Don't ignore case.  Nice simple case where the mask-compare will
+          // determine definitely whether we have a match at this character
+          // position.
+          if (c > char_mask) {
+            details->set_cannot_match();
+            pos->determines_perfectly = false;
+            return;
+          }
+          pos->mask = char_mask;
+          pos->value = c;
+          pos->determines_perfectly = true;
+        }
+        characters_filled_in++;
+        DCHECK(characters_filled_in <= details->characters());
+        if (characters_filled_in == details->characters()) {
+          return;
+        }
+      }
+    } else {
+      QuickCheckDetails::Position* pos =
+          details->positions(characters_filled_in);
+      RegExpClassRanges* tree = elm.class_ranges();
+      ZoneList<CharacterRange>* ranges = tree->ranges(zone());
+      if (tree->is_negated() || ranges->is_empty()) {
+        // A quick check uses multi-character mask and compare.  There is no
+        // useful way to incorporate a negative char class into this scheme
+        // so we just conservatively create a mask and value that will always
+        // succeed.
+        // Likewise for empty ranges (empty ranges can occur e.g. when
+        // compiling for one-byte subjects and impossible (non-one-byte) ranges
+        // have been removed).
+        pos->mask = 0;
+        pos->value = 0;
+      } else {
+        int first_range = 0;
+        while (ranges->at(first_range).from() > char_mask) {
+          first_range++;
+          if (first_range == ranges->length()) {
+            details->set_cannot_match();
+            pos->determines_perfectly = false;
+            return;
+          }
+        }
+        CharacterRange range = ranges->at(first_range);
+        const base::uc32 first_from = range.from();
+        const base::uc32 first_to =
+            (range.to() > char_mask) ? char_mask : range.to();
+        const uint32_t differing_bits = (first_from ^ first_to);
+        // A mask and compare is only perfect if the differing bits form a
+        // number like 00011111 with one single block of trailing 1s.
+        if ((differing_bits & (differing_bits + 1)) == 0 &&
+            first_from + differing_bits == first_to) {
+          pos->determines_perfectly = true;
+        }
+        uint32_t common_bits = ~SmearBitsRight(differing_bits);
+        uint32_t bits = (first_from & common_bits);
+        for (int i = first_range + 1; i < ranges->length(); i++) {
+          range = ranges->at(i);
+          const base::uc32 from = range.from();
+          if (from > char_mask) continue;
+          const base::uc32 to =
+              (range.to() > char_mask) ? char_mask : range.to();
+          // Here we are combining more ranges into the mask and compare
+          // value.  With each new range the mask becomes more sparse and
+          // so the chances of a false positive rise.  A character class
+          // with multiple ranges is assumed never to be equivalent to a
+          // mask and compare operation.
+          pos->determines_perfectly = false;
+          uint32_t new_common_bits = (from ^ to);
+          new_common_bits = ~SmearBitsRight(new_common_bits);
+          common_bits &= new_common_bits;
+          bits &= new_common_bits;
+          uint32_t new_differing_bits = (from & common_bits) ^ bits;
+          common_bits ^= new_differing_bits;
+          bits &= common_bits;
+        }
+        pos->mask = common_bits;
+        pos->value = bits;
+      }
+      characters_filled_in++;
+      DCHECK(characters_filled_in <= details->characters());
+      if (characters_filled_in == details->characters()) return;
+    }
+  }
+  DCHECK(characters_filled_in != details->characters());
+  if (!details->cannot_match()) {
+    on_success()->GetQuickCheckDetails(details, compiler, characters_filled_in,
+                                       true);
+  }
+}
+
+void QuickCheckDetails::Clear() {
+  for (int i = 0; i < characters_; i++) {
+    positions_[i].mask = 0;
+    positions_[i].value = 0;
+    positions_[i].determines_perfectly = false;
+  }
+  characters_ = 0;
+}
+
+void QuickCheckDetails::Advance(int by, bool one_byte) {
+  if (by >= characters_ || by < 0) {
+    DCHECK_IMPLIES(by < 0, characters_ == 0);
+    Clear();
+    return;
+  }
+  DCHECK_LE(characters_ - by, 4);
+  DCHECK_LE(characters_, 4);
+  for (int i = 0; i < characters_ - by; i++) {
+    positions_[i] = positions_[by + i];
+  }
+  for (int i = characters_ - by; i < characters_; i++) {
+    positions_[i].mask = 0;
+    positions_[i].value = 0;
+    positions_[i].determines_perfectly = false;
+  }
+  characters_ -= by;
+  // We could change mask_ and value_ here but we would never advance unless
+  // they had already been used in a check and they won't be used again because
+  // it would gain us nothing.  So there's no point.
+}
+
+void QuickCheckDetails::Merge(QuickCheckDetails* other, int from_index) {
+  DCHECK(characters_ == other->characters_);
+  if (other->cannot_match_) {
+    return;
+  }
+  if (cannot_match_) {
+    *this = *other;
+    return;
+  }
+  for (int i = from_index; i < characters_; i++) {
+    QuickCheckDetails::Position* pos = positions(i);
+    QuickCheckDetails::Position* other_pos = other->positions(i);
+    if (pos->mask != other_pos->mask || pos->value != other_pos->value ||
+        !other_pos->determines_perfectly) {
+      // Our mask-compare operation will be approximate unless we have the
+      // exact same operation on both sides of the alternation.
+      pos->determines_perfectly = false;
+    }
+    pos->mask &= other_pos->mask;
+    pos->value &= pos->mask;
+    other_pos->value &= pos->mask;
+    uint32_t differing_bits = (pos->value ^ other_pos->value);
+    pos->mask &= ~differing_bits;
+    pos->value &= pos->mask;
+  }
+}
+
+class VisitMarker {
+ public:
+  explicit VisitMarker(NodeInfo* info) : info_(info) {
+    DCHECK(!info->visited);
+    info->visited = true;
+  }
+  ~VisitMarker() { info_->visited = false; }
+
+ private:
+  NodeInfo* info_;
+};
+
+// Temporarily sets traversed_loop_initialization_node_.
+class LoopInitializationMarker {
+ public:
+  explicit LoopInitializationMarker(LoopChoiceNode* node) : node_(node) {
+    DCHECK(!node_->traversed_loop_initialization_node_);
+    node_->traversed_loop_initialization_node_ = true;
+  }
+  ~LoopInitializationMarker() {
+    DCHECK(node_->traversed_loop_initialization_node_);
+    node_->traversed_loop_initialization_node_ = false;
+  }
+  LoopInitializationMarker(const LoopInitializationMarker&) = delete;
+  LoopInitializationMarker& operator=(const LoopInitializationMarker&) = delete;
+
+ private:
+  LoopChoiceNode* node_;
+};
+
+// Temporarily decrements min_loop_iterations_.
+class IterationDecrementer {
+ public:
+  explicit IterationDecrementer(LoopChoiceNode* node) : node_(node) {
+    DCHECK_GT(node_->min_loop_iterations_, 0);
+    --node_->min_loop_iterations_;
+  }
+  ~IterationDecrementer() { ++node_->min_loop_iterations_; }
+  IterationDecrementer(const IterationDecrementer&) = delete;
+  IterationDecrementer& operator=(const IterationDecrementer&) = delete;
+
+ private:
+  LoopChoiceNode* node_;
+};
+
+RegExpNode* SeqRegExpNode::FilterOneByte(int depth, RegExpFlags flags) {
+  if (info()->replacement_calculated) return replacement();
+  if (depth < 0) return this;
+  DCHECK(!info()->visited);
+  VisitMarker marker(info());
+  return FilterSuccessor(depth - 1, flags);
+}
+
+RegExpNode* SeqRegExpNode::FilterSuccessor(int depth, RegExpFlags flags) {
+  RegExpNode* next = on_success_->FilterOneByte(depth - 1, flags);
+  if (next == nullptr) return set_replacement(nullptr);
+  on_success_ = next;
+  return set_replacement(this);
+}
+
+// We need to check for the following characters: 0x39C 0x3BC 0x178.
+bool RangeContainsLatin1Equivalents(CharacterRange range) {
+  // TODO(dcarney): this could be a lot more efficient.
+  return range.Contains(0x039C) || range.Contains(0x03BC) ||
+         range.Contains(0x0178);
+}
+
+namespace {
+
+bool RangesContainLatin1Equivalents(ZoneList<CharacterRange>* ranges) {
+  for (int i = 0; i < ranges->length(); i++) {
+    // TODO(dcarney): this could be a lot more efficient.
+    if (RangeContainsLatin1Equivalents(ranges->at(i))) return true;
+  }
+  return false;
+}
+
+}  // namespace
+
+RegExpNode* TextNode::FilterOneByte(int depth, RegExpFlags flags) {
+  if (info()->replacement_calculated) return replacement();
+  if (depth < 0) return this;
+  DCHECK(!info()->visited);
+  VisitMarker marker(info());
+  int element_count = elements()->length();
+  for (int i = 0; i < element_count; i++) {
+    TextElement elm = elements()->at(i);
+    if (elm.text_type() == TextElement::ATOM) {
+      base::Vector<const base::uc16> quarks = elm.atom()->data();
+      for (int j = 0; j < quarks.length(); j++) {
+        base::uc16 c = quarks[j];
+        if (IsIgnoreCase(flags)) {
+          c = unibrow::Latin1::TryConvertToLatin1(c);
+        }
+        if (c > unibrow::Latin1::kMaxChar) return set_replacement(nullptr);
+        // Replace quark in case we converted to Latin-1.
+        base::uc16* writable_quarks = const_cast<base::uc16*>(quarks.begin());
+        writable_quarks[j] = c;
+      }
+    } else {
+      DCHECK(elm.text_type() == TextElement::CLASS_RANGES);
+      RegExpClassRanges* cr = elm.class_ranges();
+      ZoneList<CharacterRange>* ranges = cr->ranges(zone());
+      CharacterRange::Canonicalize(ranges);
+      // Now they are in order so we only need to look at the first.
+      int range_count = ranges->length();
+      if (cr->is_negated()) {
+        if (range_count != 0 && ranges->at(0).from() == 0 &&
+            ranges->at(0).to() >= String::kMaxOneByteCharCode) {
+          // This will be handled in a later filter.
+          if (IsIgnoreCase(flags) && RangesContainLatin1Equivalents(ranges)) {
+            continue;
+          }
+          return set_replacement(nullptr);
+        }
+      } else {
+        if (range_count == 0 ||
+            ranges->at(0).from() > String::kMaxOneByteCharCode) {
+          // This will be handled in a later filter.
+          if (IsIgnoreCase(flags) && RangesContainLatin1Equivalents(ranges)) {
+            continue;
+          }
+          return set_replacement(nullptr);
+        }
+      }
+    }
+  }
+  return FilterSuccessor(depth - 1, flags);
+}
+
+RegExpNode* LoopChoiceNode::FilterOneByte(int depth, RegExpFlags flags) {
+  if (info()->replacement_calculated) return replacement();
+  if (depth < 0) return this;
+  if (info()->visited) return this;
+  {
+    VisitMarker marker(info());
+
+    RegExpNode* continue_replacement =
+        continue_node_->FilterOneByte(depth - 1, flags);
+    // If we can't continue after the loop then there is no sense in doing the
+    // loop.
+    if (continue_replacement == nullptr) return set_replacement(nullptr);
+  }
+
+  return ChoiceNode::FilterOneByte(depth - 1, flags);
+}
+
+RegExpNode* ChoiceNode::FilterOneByte(int depth, RegExpFlags flags) {
+  if (info()->replacement_calculated) return replacement();
+  if (depth < 0) return this;
+  if (info()->visited) return this;
+  VisitMarker marker(info());
+  int choice_count = alternatives_->length();
+
+  for (int i = 0; i < choice_count; i++) {
+    GuardedAlternative alternative = alternatives_->at(i);
+    if (alternative.guards() != nullptr &&
+        alternative.guards()->length() != 0) {
+      set_replacement(this);
+      return this;
+    }
+  }
+
+  int surviving = 0;
+  RegExpNode* survivor = nullptr;
+  for (int i = 0; i < choice_count; i++) {
+    GuardedAlternative alternative = alternatives_->at(i);
+    RegExpNode* replacement =
+        alternative.node()->FilterOneByte(depth - 1, flags);
+    DCHECK(replacement != this);  // No missing EMPTY_MATCH_CHECK.
+    if (replacement != nullptr) {
+      alternatives_->at(i).set_node(replacement);
+      surviving++;
+      survivor = replacement;
+    }
+  }
+  if (surviving < 2) return set_replacement(survivor);
+
+  set_replacement(this);
+  if (surviving == choice_count) {
+    return this;
+  }
+  // Only some of the nodes survived the filtering.  We need to rebuild the
+  // alternatives list.
+  ZoneList<GuardedAlternative>* new_alternatives =
+      zone()->New<ZoneList<GuardedAlternative>>(surviving, zone());
+  for (int i = 0; i < choice_count; i++) {
+    RegExpNode* replacement =
+        alternatives_->at(i).node()->FilterOneByte(depth - 1, flags);
+    if (replacement != nullptr) {
+      alternatives_->at(i).set_node(replacement);
+      new_alternatives->Add(alternatives_->at(i), zone());
+    }
+  }
+  alternatives_ = new_alternatives;
+  return this;
+}
+
+RegExpNode* NegativeLookaroundChoiceNode::FilterOneByte(int depth,
+                                                        RegExpFlags flags) {
+  if (info()->replacement_calculated) return replacement();
+  if (depth < 0) return this;
+  if (info()->visited) return this;
+  VisitMarker marker(info());
+  // Alternative 0 is the negative lookahead, alternative 1 is what comes
+  // afterwards.
+  RegExpNode* node = continue_node();
+  RegExpNode* replacement = node->FilterOneByte(depth - 1, flags);
+  if (replacement == nullptr) return set_replacement(nullptr);
+  alternatives_->at(kContinueIndex).set_node(replacement);
+
+  RegExpNode* neg_node = lookaround_node();
+  RegExpNode* neg_replacement = neg_node->FilterOneByte(depth - 1, flags);
+  // If the negative lookahead is always going to fail then
+  // we don't need to check it.
+  if (neg_replacement == nullptr) return set_replacement(replacement);
+  alternatives_->at(kLookaroundIndex).set_node(neg_replacement);
+  return set_replacement(this);
+}
+
+void LoopChoiceNode::GetQuickCheckDetails(QuickCheckDetails* details,
+                                          RegExpCompiler* compiler,
+                                          int characters_filled_in,
+                                          bool not_at_start) {
+  if (body_can_be_zero_length_ || info()->visited) return;
+  not_at_start = not_at_start || this->not_at_start();
+  DCHECK_EQ(alternatives_->length(), 2);  // There's just loop and continue.
+  if (traversed_loop_initialization_node_ && min_loop_iterations_ > 0 &&
+      loop_node_->EatsAtLeast(not_at_start) >
+          continue_node_->EatsAtLeast(true)) {
+    // Loop body is guaranteed to execute at least once, and consume characters
+    // when it does, meaning the only possible quick checks from this point
+    // begin with the loop body. We may recursively visit this LoopChoiceNode,
+    // but we temporarily decrease its minimum iteration counter so we know when
+    // to check the continue case.
+    IterationDecrementer next_iteration(this);
+    loop_node_->GetQuickCheckDetails(details, compiler, characters_filled_in,
+                                     not_at_start);
+  } else {
+    // Might not consume anything in the loop body, so treat it like a normal
+    // ChoiceNode (and don't recursively visit this node again).
+    VisitMarker marker(info());
+    ChoiceNode::GetQuickCheckDetails(details, compiler, characters_filled_in,
+                                     not_at_start);
+  }
+}
+
+void LoopChoiceNode::GetQuickCheckDetailsFromLoopEntry(
+    QuickCheckDetails* details, RegExpCompiler* compiler,
+    int characters_filled_in, bool not_at_start) {
+  if (traversed_loop_initialization_node_) {
+    // We already entered this loop once, exited via its continuation node, and
+    // followed an outer loop's back-edge to before the loop entry point. We
+    // could try to reset the minimum iteration count to its starting value at
+    // this point, but that seems like more trouble than it's worth. It's safe
+    // to keep going with the current (possibly reduced) minimum iteration
+    // count.
+    GetQuickCheckDetails(details, compiler, characters_filled_in, not_at_start);
+  } else {
+    // We are entering a loop via its counter initialization action, meaning we
+    // are guaranteed to run the loop body at least some minimum number of times
+    // before running the continuation node. Set a flag so that this node knows
+    // (now and any times we visit it again recursively) that it was entered
+    // from the top.
+    LoopInitializationMarker marker(this);
+    GetQuickCheckDetails(details, compiler, characters_filled_in, not_at_start);
+  }
+}
+
+void LoopChoiceNode::FillInBMInfo(Isolate* isolate, int offset, int budget,
+                                  BoyerMooreLookahead* bm, bool not_at_start) {
+  if (body_can_be_zero_length_ || budget <= 0) {
+    bm->SetRest(offset);
+    SaveBMInfo(bm, not_at_start, offset);
+    return;
+  }
+  ChoiceNode::FillInBMInfo(isolate, offset, budget - 1, bm, not_at_start);
+  SaveBMInfo(bm, not_at_start, offset);
+}
+
+void ChoiceNode::GetQuickCheckDetails(QuickCheckDetails* details,
+                                      RegExpCompiler* compiler,
+                                      int characters_filled_in,
+                                      bool not_at_start) {
+  not_at_start = (not_at_start || not_at_start_);
+  int choice_count = alternatives_->length();
+  DCHECK_LT(0, choice_count);
+  alternatives_->at(0).node()->GetQuickCheckDetails(
+      details, compiler, characters_filled_in, not_at_start);
+  for (int i = 1; i < choice_count; i++) {
+    QuickCheckDetails new_details(details->characters());
+    RegExpNode* node = alternatives_->at(i).node();
+    node->GetQuickCheckDetails(&new_details, compiler, characters_filled_in,
+                               not_at_start);
+    // Here we merge the quick match details of the two branches.
+    details->Merge(&new_details, characters_filled_in);
+  }
+}
+
+namespace {
+
+// Check for [0-9A-Z_a-z].
+void EmitWordCheck(RegExpMacroAssembler* assembler, Label* word,
+                   Label* non_word, bool fall_through_on_word) {
+  if (assembler->CheckSpecialClassRanges(
+          fall_through_on_word ? StandardCharacterSet::kWord
+                               : StandardCharacterSet::kNotWord,
+          fall_through_on_word ? non_word : word)) {
+    // Optimized implementation available.
+    return;
+  }
+  assembler->CheckCharacterGT('z', non_word);
+  assembler->CheckCharacterLT('0', non_word);
+  assembler->CheckCharacterGT('a' - 1, word);
+  assembler->CheckCharacterLT('9' + 1, word);
+  assembler->CheckCharacterLT('A', non_word);
+  assembler->CheckCharacterLT('Z' + 1, word);
+  if (fall_through_on_word) {
+    assembler->CheckNotCharacter('_', non_word);
+  } else {
+    assembler->CheckCharacter('_', word);
+  }
+}
+
+// Emit the code to check for a ^ in multiline mode (1-character lookbehind
+// that matches newline or the start of input).
+void EmitHat(RegExpCompiler* compiler, RegExpNode* on_success, Trace* trace) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+
+  // We will load the previous character into the current character register.
+  Trace new_trace(*trace);
+  new_trace.InvalidateCurrentCharacter();
+
+  // A positive (> 0) cp_offset means we've already successfully matched a
+  // non-empty-width part of the pattern, and thus cannot be at or before the
+  // start of the subject string. We can thus skip both at-start and
+  // bounds-checks when loading the one-character lookbehind.
+  const bool may_be_at_or_before_subject_string_start =
+      new_trace.cp_offset() <= 0;
+
+  Label ok;
+  if (may_be_at_or_before_subject_string_start) {
+    // The start of input counts as a newline in this context, so skip to ok if
+    // we are at the start.
+    assembler->CheckAtStart(new_trace.cp_offset(), &ok);
+  }
+
+  // If we've already checked that we are not at the start of input, it's okay
+  // to load the previous character without bounds checks.
+  const bool can_skip_bounds_check = !may_be_at_or_before_subject_string_start;
+  assembler->LoadCurrentCharacter(new_trace.cp_offset() - 1,
+                                  new_trace.backtrack(), can_skip_bounds_check);
+  if (!assembler->CheckSpecialClassRanges(StandardCharacterSet::kLineTerminator,
+                                          new_trace.backtrack())) {
+    // Newline means \n, \r, 0x2028 or 0x2029.
+    if (!compiler->one_byte()) {
+      assembler->CheckCharacterAfterAnd(0x2028, 0xFFFE, &ok);
+    }
+    assembler->CheckCharacter('\n', &ok);
+    assembler->CheckNotCharacter('\r', new_trace.backtrack());
+  }
+  assembler->Bind(&ok);
+  on_success->Emit(compiler, &new_trace);
+}
+
+}  // namespace
+
+// Emit the code to handle \b and \B (word-boundary or non-word-boundary).
+void AssertionNode::EmitBoundaryCheck(RegExpCompiler* compiler, Trace* trace) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+  Isolate* isolate = assembler->isolate();
+  Trace::TriBool next_is_word_character = Trace::UNKNOWN;
+  bool not_at_start = (trace->at_start() == Trace::FALSE_VALUE);
+  BoyerMooreLookahead* lookahead = bm_info(not_at_start);
+  if (lookahead == nullptr) {
+    int eats_at_least =
+        std::min(kMaxLookaheadForBoyerMoore, EatsAtLeast(not_at_start));
+    if (eats_at_least >= 1) {
+      BoyerMooreLookahead* bm =
+          zone()->New<BoyerMooreLookahead>(eats_at_least, compiler, zone());
+      FillInBMInfo(isolate, 0, kRecursionBudget, bm, not_at_start);
+      if (bm->at(0)->is_non_word()) next_is_word_character = Trace::FALSE_VALUE;
+      if (bm->at(0)->is_word()) next_is_word_character = Trace::TRUE_VALUE;
+    }
+  } else {
+    if (lookahead->at(0)->is_non_word())
+      next_is_word_character = Trace::FALSE_VALUE;
+    if (lookahead->at(0)->is_word()) next_is_word_character = Trace::TRUE_VALUE;
+  }
+  bool at_boundary = (assertion_type_ == AssertionNode::AT_BOUNDARY);
+  if (next_is_word_character == Trace::UNKNOWN) {
+    Label before_non_word;
+    Label before_word;
+    if (trace->characters_preloaded() != 1) {
+      assembler->LoadCurrentCharacter(trace->cp_offset(), &before_non_word);
+    }
+    // Fall through on non-word.
+    EmitWordCheck(assembler, &before_word, &before_non_word, false);
+    // Next character is not a word character.
+    assembler->Bind(&before_non_word);
+    Label ok;
+    BacktrackIfPrevious(compiler, trace, at_boundary ? kIsNonWord : kIsWord);
+    assembler->GoTo(&ok);
+
+    assembler->Bind(&before_word);
+    BacktrackIfPrevious(compiler, trace, at_boundary ? kIsWord : kIsNonWord);
+    assembler->Bind(&ok);
+  } else if (next_is_word_character == Trace::TRUE_VALUE) {
+    BacktrackIfPrevious(compiler, trace, at_boundary ? kIsWord : kIsNonWord);
+  } else {
+    DCHECK(next_is_word_character == Trace::FALSE_VALUE);
+    BacktrackIfPrevious(compiler, trace, at_boundary ? kIsNonWord : kIsWord);
+  }
+}
+
+void AssertionNode::BacktrackIfPrevious(
+    RegExpCompiler* compiler, Trace* trace,
+    AssertionNode::IfPrevious backtrack_if_previous) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+  Trace new_trace(*trace);
+  new_trace.InvalidateCurrentCharacter();
+
+  Label fall_through;
+  Label* non_word = backtrack_if_previous == kIsNonWord ? new_trace.backtrack()
+                                                        : &fall_through;
+  Label* word = backtrack_if_previous == kIsNonWord ? &fall_through
+                                                    : new_trace.backtrack();
+
+  // A positive (> 0) cp_offset means we've already successfully matched a
+  // non-empty-width part of the pattern, and thus cannot be at or before the
+  // start of the subject string. We can thus skip both at-start and
+  // bounds-checks when loading the one-character lookbehind.
+  const bool may_be_at_or_before_subject_string_start =
+      new_trace.cp_offset() <= 0;
+
+  if (may_be_at_or_before_subject_string_start) {
+    // The start of input counts as a non-word character, so the question is
+    // decided if we are at the start.
+    assembler->CheckAtStart(new_trace.cp_offset(), non_word);
+  }
+
+  // If we've already checked that we are not at the start of input, it's okay
+  // to load the previous character without bounds checks.
+  const bool can_skip_bounds_check = !may_be_at_or_before_subject_string_start;
+  assembler->LoadCurrentCharacter(new_trace.cp_offset() - 1, non_word,
+                                  can_skip_bounds_check);
+  EmitWordCheck(assembler, word, non_word, backtrack_if_previous == kIsNonWord);
+
+  assembler->Bind(&fall_through);
+  on_success()->Emit(compiler, &new_trace);
+}
+
+void AssertionNode::GetQuickCheckDetails(QuickCheckDetails* details,
+                                         RegExpCompiler* compiler,
+                                         int filled_in, bool not_at_start) {
+  if (assertion_type_ == AT_START && not_at_start) {
+    details->set_cannot_match();
+    return;
+  }
+  return on_success()->GetQuickCheckDetails(details, compiler, filled_in,
+                                            not_at_start);
+}
+
+void AssertionNode::Emit(RegExpCompiler* compiler, Trace* trace) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+  switch (assertion_type_) {
+    case AT_END: {
+      Label ok;
+      assembler->CheckPosition(trace->cp_offset(), &ok);
+      assembler->GoTo(trace->backtrack());
+      assembler->Bind(&ok);
+      break;
+    }
+    case AT_START: {
+      if (trace->at_start() == Trace::FALSE_VALUE) {
+        assembler->GoTo(trace->backtrack());
+        return;
+      }
+      if (trace->at_start() == Trace::UNKNOWN) {
+        assembler->CheckNotAtStart(trace->cp_offset(), trace->backtrack());
+        Trace at_start_trace = *trace;
+        at_start_trace.set_at_start(Trace::TRUE_VALUE);
+        on_success()->Emit(compiler, &at_start_trace);
+        return;
+      }
+    } break;
+    case AFTER_NEWLINE:
+      EmitHat(compiler, on_success(), trace);
+      return;
+    case AT_BOUNDARY:
+    case AT_NON_BOUNDARY: {
+      EmitBoundaryCheck(compiler, trace);
+      return;
+    }
+  }
+  on_success()->Emit(compiler, trace);
+}
+
+namespace {
+
+bool DeterminedAlready(QuickCheckDetails* quick_check, int offset) {
+  if (quick_check == nullptr) return false;
+  if (offset >= quick_check->characters()) return false;
+  return quick_check->positions(offset)->determines_perfectly;
+}
+
+void UpdateBoundsCheck(int index, int* checked_up_to) {
+  if (index > *checked_up_to) {
+    *checked_up_to = index;
+  }
+}
+
+}  // namespace
+
+// We call this repeatedly to generate code for each pass over the text node.
+// The passes are in increasing order of difficulty because we hope one
+// of the first passes will fail in which case we are saved the work of the
+// later passes.  for example for the case independent regexp /%[asdfghjkl]a/
+// we will check the '%' in the first pass, the case independent 'a' in the
+// second pass and the character class in the last pass.
+//
+// The passes are done from right to left, so for example to test for /bar/
+// we will first test for an 'r' with offset 2, then an 'a' with offset 1
+// and then a 'b' with offset 0.  This means we can avoid the end-of-input
+// bounds check most of the time.  In the example we only need to check for
+// end-of-input when loading the putative 'r'.
+//
+// A slight complication involves the fact that the first character may already
+// be fetched into a register by the previous node.  In this case we want to
+// do the test for that character first.  We do this in separate passes.  The
+// 'preloaded' argument indicates that we are doing such a 'pass'.  If such a
+// pass has been performed then subsequent passes will have true in
+// first_element_checked to indicate that that character does not need to be
+// checked again.
+//
+// In addition to all this we are passed a Trace, which can
+// contain an AlternativeGeneration object.  In this AlternativeGeneration
+// object we can see details of any quick check that was already passed in
+// order to get to the code we are now generating.  The quick check can involve
+// loading characters, which means we do not need to recheck the bounds
+// up to the limit the quick check already checked.  In addition the quick
+// check can have involved a mask and compare operation which may simplify
+// or obviate the need for further checks at some character positions.
+void TextNode::TextEmitPass(RegExpCompiler* compiler, TextEmitPassType pass,
+                            bool preloaded, Trace* trace,
+                            bool first_element_checked, int* checked_up_to) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+  Isolate* isolate = assembler->isolate();
+  bool one_byte = compiler->one_byte();
+  Label* backtrack = trace->backtrack();
+  QuickCheckDetails* quick_check = trace->quick_check_performed();
+  int element_count = elements()->length();
+  int backward_offset = read_backward() ? -Length() : 0;
+  for (int i = preloaded ? 0 : element_count - 1; i >= 0; i--) {
+    TextElement elm = elements()->at(i);
+    int cp_offset = trace->cp_offset() + elm.cp_offset() + backward_offset;
+    if (elm.text_type() == TextElement::ATOM) {
+      if (SkipPass(pass, IsIgnoreCase(compiler->flags()))) continue;
+      base::Vector<const base::uc16> quarks = elm.atom()->data();
+      for (int j = preloaded ? 0 : quarks.length() - 1; j >= 0; j--) {
+        if (first_element_checked && i == 0 && j == 0) continue;
+        if (DeterminedAlready(quick_check, elm.cp_offset() + j)) continue;
+        base::uc16 quark = quarks[j];
+        if (IsIgnoreCase(compiler->flags())) {
+          // Everywhere else we assume that a non-Latin-1 character cannot match
+          // a Latin-1 character. Avoid the cases where this is assumption is
+          // invalid by using the Latin1 equivalent instead.
+          quark = unibrow::Latin1::TryConvertToLatin1(quark);
+        }
+        bool needs_bounds_check =
+            *checked_up_to < cp_offset + j || read_backward();
+        bool bounds_checked = false;
+        switch (pass) {
+          case NON_LATIN1_MATCH:
+            DCHECK(one_byte);
+            if (quark > String::kMaxOneByteCharCode) {
+              assembler->GoTo(backtrack);
+              return;
+            }
+            break;
+          case NON_LETTER_CHARACTER_MATCH:
+            bounds_checked =
+                EmitAtomNonLetter(isolate, compiler, quark, backtrack,
+                                  cp_offset + j, needs_bounds_check, preloaded);
+            break;
+          case SIMPLE_CHARACTER_MATCH:
+            bounds_checked = EmitSimpleCharacter(isolate, compiler, quark,
+                                                 backtrack, cp_offset + j,
+                                                 needs_bounds_check, preloaded);
+            break;
+          case CASE_CHARACTER_MATCH:
+            bounds_checked =
+                EmitAtomLetter(isolate, compiler, quark, backtrack,
+                               cp_offset + j, needs_bounds_check, preloaded);
+            break;
+          default:
+            break;
+        }
+        if (bounds_checked) UpdateBoundsCheck(cp_offset + j, checked_up_to);
+      }
+    } else {
+      DCHECK_EQ(TextElement::CLASS_RANGES, elm.text_type());
+      if (pass == CHARACTER_CLASS_MATCH) {
+        if (first_element_checked && i == 0) continue;
+        if (DeterminedAlready(quick_check, elm.cp_offset())) continue;
+        RegExpClassRanges* cr = elm.class_ranges();
+        bool bounds_check = *checked_up_to < cp_offset || read_backward();
+        EmitClassRanges(assembler, cr, one_byte, backtrack, cp_offset,
+                        bounds_check, preloaded, zone());
+        UpdateBoundsCheck(cp_offset, checked_up_to);
+      }
+    }
+  }
+}
+
+int TextNode::Length() {
+  TextElement elm = elements()->last();
+  DCHECK_LE(0, elm.cp_offset());
+  return elm.cp_offset() + elm.length();
+}
+
+bool TextNode::SkipPass(TextEmitPassType pass, bool ignore_case) {
+  if (ignore_case) {
+    return pass == SIMPLE_CHARACTER_MATCH;
+  } else {
+    return pass == NON_LETTER_CHARACTER_MATCH || pass == CASE_CHARACTER_MATCH;
+  }
+}
+
+TextNode* TextNode::CreateForCharacterRanges(Zone* zone,
+                                             ZoneList<CharacterRange>* ranges,
+                                             bool read_backward,
+                                             RegExpNode* on_success) {
+  DCHECK_NOT_NULL(ranges);
+  // TODO(jgruber): There's no fundamental need to create this
+  // RegExpClassRanges; we could refactor to avoid the allocation.
+  return zone->New<TextNode>(zone->New<RegExpClassRanges>(zone, ranges),
+                             read_backward, on_success);
+}
+
+TextNode* TextNode::CreateForSurrogatePair(
+    Zone* zone, CharacterRange lead, ZoneList<CharacterRange>* trail_ranges,
+    bool read_backward, RegExpNode* on_success) {
+  ZoneList<CharacterRange>* lead_ranges = CharacterRange::List(zone, lead);
+  ZoneList<TextElement>* elms = zone->New<ZoneList<TextElement>>(2, zone);
+  elms->Add(
+      TextElement::ClassRanges(zone->New<RegExpClassRanges>(zone, lead_ranges)),
+      zone);
+  elms->Add(TextElement::ClassRanges(
+                zone->New<RegExpClassRanges>(zone, trail_ranges)),
+            zone);
+  return zone->New<TextNode>(elms, read_backward, on_success);
+}
+
+TextNode* TextNode::CreateForSurrogatePair(
+    Zone* zone, ZoneList<CharacterRange>* lead_ranges, CharacterRange trail,
+    bool read_backward, RegExpNode* on_success) {
+  ZoneList<CharacterRange>* trail_ranges = CharacterRange::List(zone, trail);
+  ZoneList<TextElement>* elms = zone->New<ZoneList<TextElement>>(2, zone);
+  elms->Add(
+      TextElement::ClassRanges(zone->New<RegExpClassRanges>(zone, lead_ranges)),
+      zone);
+  elms->Add(TextElement::ClassRanges(
+                zone->New<RegExpClassRanges>(zone, trail_ranges)),
+            zone);
+  return zone->New<TextNode>(elms, read_backward, on_success);
+}
+
+// This generates the code to match a text node.  A text node can contain
+// straight character sequences (possibly to be matched in a case-independent
+// way) and character classes.  For efficiency we do not do this in a single
+// pass from left to right.  Instead we pass over the text node several times,
+// emitting code for some character positions every time.  See the comment on
+// TextEmitPass for details.
+void TextNode::Emit(RegExpCompiler* compiler, Trace* trace) {
+  LimitResult limit_result = LimitVersions(compiler, trace);
+  if (limit_result == DONE) return;
+  DCHECK(limit_result == CONTINUE);
+
+  if (trace->cp_offset() + Length() > RegExpMacroAssembler::kMaxCPOffset) {
+    compiler->SetRegExpTooBig();
+    return;
+  }
+
+  if (compiler->one_byte()) {
+    int dummy = 0;
+    TextEmitPass(compiler, NON_LATIN1_MATCH, false, trace, false, &dummy);
+  }
+
+  bool first_elt_done = false;
+  int bound_checked_to = trace->cp_offset() - 1;
+  bound_checked_to += trace->bound_checked_up_to();
+
+  // If a character is preloaded into the current character register then
+  // check that now.
+  if (trace->characters_preloaded() == 1) {
+    for (int pass = kFirstRealPass; pass <= kLastPass; pass++) {
+      TextEmitPass(compiler, static_cast<TextEmitPassType>(pass), true, trace,
+                   false, &bound_checked_to);
+    }
+    first_elt_done = true;
+  }
+
+  for (int pass = kFirstRealPass; pass <= kLastPass; pass++) {
+    TextEmitPass(compiler, static_cast<TextEmitPassType>(pass), false, trace,
+                 first_elt_done, &bound_checked_to);
+  }
+
+  Trace successor_trace(*trace);
+  // If we advance backward, we may end up at the start.
+  successor_trace.AdvanceCurrentPositionInTrace(
+      read_backward() ? -Length() : Length(), compiler);
+  successor_trace.set_at_start(read_backward() ? Trace::UNKNOWN
+                                               : Trace::FALSE_VALUE);
+  RecursionCheck rc(compiler);
+  on_success()->Emit(compiler, &successor_trace);
+}
+
+void Trace::InvalidateCurrentCharacter() { characters_preloaded_ = 0; }
+
+void Trace::AdvanceCurrentPositionInTrace(int by, RegExpCompiler* compiler) {
+  // We don't have an instruction for shifting the current character register
+  // down or for using a shifted value for anything so lets just forget that
+  // we preloaded any characters into it.
+  characters_preloaded_ = 0;
+  // Adjust the offsets of the quick check performed information.  This
+  // information is used to find out what we already determined about the
+  // characters by means of mask and compare.
+  quick_check_performed_.Advance(by, compiler->one_byte());
+  cp_offset_ += by;
+  if (cp_offset_ > RegExpMacroAssembler::kMaxCPOffset) {
+    compiler->SetRegExpTooBig();
+    cp_offset_ = 0;
+  }
+  bound_checked_up_to_ = std::max(0, bound_checked_up_to_ - by);
+}
+
+void TextNode::MakeCaseIndependent(Isolate* isolate, bool is_one_byte,
+                                   RegExpFlags flags) {
+  if (!IsIgnoreCase(flags)) return;
+#ifdef V8_INTL_SUPPORT
+  if (NeedsUnicodeCaseEquivalents(flags)) return;
+#endif
+
+  int element_count = elements()->length();
+  for (int i = 0; i < element_count; i++) {
+    TextElement elm = elements()->at(i);
+    if (elm.text_type() == TextElement::CLASS_RANGES) {
+      RegExpClassRanges* cr = elm.class_ranges();
+      // None of the standard character classes is different in the case
+      // independent case and it slows us down if we don't know that.
+      if (cr->is_standard(zone())) continue;
+      ZoneList<CharacterRange>* ranges = cr->ranges(zone());
+      CharacterRange::AddCaseEquivalents(isolate, zone(), ranges, is_one_byte);
+    }
+  }
+}
+
+int TextNode::GreedyLoopTextLength() { return Length(); }
+
+RegExpNode* TextNode::GetSuccessorOfOmnivorousTextNode(
+    RegExpCompiler* compiler) {
+  if (read_backward()) return nullptr;
+  if (elements()->length() != 1) return nullptr;
+  TextElement elm = elements()->at(0);
+  if (elm.text_type() != TextElement::CLASS_RANGES) return nullptr;
+  RegExpClassRanges* node = elm.class_ranges();
+  ZoneList<CharacterRange>* ranges = node->ranges(zone());
+  CharacterRange::Canonicalize(ranges);
+  if (node->is_negated()) {
+    return ranges->length() == 0 ? on_success() : nullptr;
+  }
+  if (ranges->length() != 1) return nullptr;
+  const base::uc32 max_char = MaxCodeUnit(compiler->one_byte());
+  return ranges->at(0).IsEverything(max_char) ? on_success() : nullptr;
+}
+
+// Finds the fixed match length of a sequence of nodes that goes from
+// this alternative and back to this choice node.  If there are variable
+// length nodes or other complications in the way then return a sentinel
+// value indicating that a greedy loop cannot be constructed.
+int ChoiceNode::GreedyLoopTextLengthForAlternative(
+    GuardedAlternative* alternative) {
+  int length = 0;
+  RegExpNode* node = alternative->node();
+  // Later we will generate code for all these text nodes using recursion
+  // so we have to limit the max number.
+  int recursion_depth = 0;
+  while (node != this) {
+    if (recursion_depth++ > RegExpCompiler::kMaxRecursion) {
+      return kNodeIsTooComplexForGreedyLoops;
+    }
+    int node_length = node->GreedyLoopTextLength();
+    if (node_length == kNodeIsTooComplexForGreedyLoops) {
+      return kNodeIsTooComplexForGreedyLoops;
+    }
+    length += node_length;
+    SeqRegExpNode* seq_node = static_cast<SeqRegExpNode*>(node);
+    node = seq_node->on_success();
+  }
+  if (read_backward()) {
+    length = -length;
+  }
+  // Check that we can jump by the whole text length. If not, return sentinel
+  // to indicate the we can't construct a greedy loop.
+  if (length < RegExpMacroAssembler::kMinCPOffset ||
+      length > RegExpMacroAssembler::kMaxCPOffset) {
+    return kNodeIsTooComplexForGreedyLoops;
+  }
+  return length;
+}
+
+void LoopChoiceNode::AddLoopAlternative(GuardedAlternative alt) {
+  DCHECK_NULL(loop_node_);
+  AddAlternative(alt);
+  loop_node_ = alt.node();
+}
+
+void LoopChoiceNode::AddContinueAlternative(GuardedAlternative alt) {
+  DCHECK_NULL(continue_node_);
+  AddAlternative(alt);
+  continue_node_ = alt.node();
+}
+
+void LoopChoiceNode::Emit(RegExpCompiler* compiler, Trace* trace) {
+  RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
+  if (trace->stop_node() == this) {
+    // Back edge of greedy optimized loop node graph.
+    int text_length =
+        GreedyLoopTextLengthForAlternative(&(alternatives_->at(0)));
+    DCHECK_NE(kNodeIsTooComplexForGreedyLoops, text_length);
+    // Update the counter-based backtracking info on the stack.  This is an
+    // optimization for greedy loops (see below).
+    DCHECK(trace->cp_offset() == text_length);
+    macro_assembler->AdvanceCurrentPosition(text_length);
+    macro_assembler->GoTo(trace->loop_label());
+    return;
+  }
+  DCHECK_NULL(trace->stop_node());
+  if (!trace->is_trivial()) {
+    trace->Flush(compiler, this);
+    return;
+  }
+  ChoiceNode::Emit(compiler, trace);
+}
+
+int ChoiceNode::CalculatePreloadCharacters(RegExpCompiler* compiler,
+                                           int eats_at_least) {
+  int preload_characters = std::min(4, eats_at_least);
+  DCHECK_LE(preload_characters, 4);
+  if (compiler->macro_assembler()->CanReadUnaligned()) {
+    bool one_byte = compiler->one_byte();
+    if (one_byte) {
+      // We can't preload 3 characters because there is no machine instruction
+      // to do that.  We can't just load 4 because we could be reading
+      // beyond the end of the string, which could cause a memory fault.
+      if (preload_characters == 3) preload_characters = 2;
+    } else {
+      if (preload_characters > 2) preload_characters = 2;
+    }
+  } else {
+    if (preload_characters > 1) preload_characters = 1;
+  }
+  return preload_characters;
+}
+
+// This class is used when generating the alternatives in a choice node.  It
+// records the way the alternative is being code generated.
+class AlternativeGeneration : public Malloced {
+ public:
+  AlternativeGeneration()
+      : possible_success(),
+        expects_preload(false),
+        after(),
+        quick_check_details() {}
+  Label possible_success;
+  bool expects_preload;
+  Label after;
+  QuickCheckDetails quick_check_details;
+};
+
+// Creates a list of AlternativeGenerations.  If the list has a reasonable
+// size then it is on the stack, otherwise the excess is on the heap.
+class AlternativeGenerationList {
+ public:
+  AlternativeGenerationList(int count, Zone* zone) : alt_gens_(count, zone) {
+    for (int i = 0; i < count && i < kAFew; i++) {
+      alt_gens_.Add(a_few_alt_gens_ + i, zone);
+    }
+    for (int i = kAFew; i < count; i++) {
+      alt_gens_.Add(new AlternativeGeneration(), zone);
+    }
+  }
+  ~AlternativeGenerationList() {
+    for (int i = kAFew; i < alt_gens_.length(); i++) {
+      delete alt_gens_[i];
+      alt_gens_[i] = nullptr;
+    }
+  }
+
+  AlternativeGeneration* at(int i) { return alt_gens_[i]; }
+
+ private:
+  static const int kAFew = 10;
+  ZoneList<AlternativeGeneration*> alt_gens_;
+  AlternativeGeneration a_few_alt_gens_[kAFew];
+};
+
+void BoyerMoorePositionInfo::Set(int character) {
+  SetInterval(Interval(character, character));
+}
+
+namespace {
+
+ContainedInLattice AddRange(ContainedInLattice containment, const int* ranges,
+                            int ranges_length, Interval new_range) {
+  DCHECK_EQ(1, ranges_length & 1);
+  DCHECK_EQ(String::kMaxCodePoint + 1, ranges[ranges_length - 1]);
+  if (containment == kLatticeUnknown) return containment;
+  bool inside = false;
+  int last = 0;
+  for (int i = 0; i < ranges_length; inside = !inside, last = ranges[i], i++) {
+    // Consider the range from last to ranges[i].
+    // We haven't got to the new range yet.
+    if (ranges[i] <= new_range.from()) continue;
+    // New range is wholly inside last-ranges[i].  Note that new_range.to() is
+    // inclusive, but the values in ranges are not.
+    if (last <= new_range.from() && new_range.to() < ranges[i]) {
+      return Combine(containment, inside ? kLatticeIn : kLatticeOut);
+    }
+    return kLatticeUnknown;
+  }
+  return containment;
+}
+
+int BitsetFirstSetBit(BoyerMoorePositionInfo::Bitset bitset) {
+  static_assert(BoyerMoorePositionInfo::kMapSize ==
+                2 * kInt64Size * kBitsPerByte);
+
+  // Slight fiddling is needed here, since the bitset is of length 128 while
+  // CountTrailingZeros requires an integral type and std::bitset can only
+  // convert to unsigned long long. So we handle the most- and least-significant
+  // bits separately.
+
+  {
+    static constexpr BoyerMoorePositionInfo::Bitset mask(~uint64_t{0});
+    BoyerMoorePositionInfo::Bitset masked_bitset = bitset & mask;
+    static_assert(kInt64Size >= sizeof(decltype(masked_bitset.to_ullong())));
+    uint64_t lsb = masked_bitset.to_ullong();
+    if (lsb != 0) return base::bits::CountTrailingZeros(lsb);
+  }
+
+  {
+    BoyerMoorePositionInfo::Bitset masked_bitset = bitset >> 64;
+    uint64_t msb = masked_bitset.to_ullong();
+    if (msb != 0) return 64 + base::bits::CountTrailingZeros(msb);
+  }
+
+  return -1;
+}
+
+}  // namespace
+
+void BoyerMoorePositionInfo::SetInterval(const Interval& interval) {
+  w_ = AddRange(w_, kWordRanges, kWordRangeCount, interval);
+
+  if (interval.size() >= kMapSize) {
+    map_count_ = kMapSize;
+    map_.set();
+    return;
+  }
+
+  for (int i = interval.from(); i <= interval.to(); i++) {
+    int mod_character = (i & kMask);
+    if (!map_[mod_character]) {
+      map_count_++;
+      map_.set(mod_character);
+    }
+    if (map_count_ == kMapSize) return;
+  }
+}
+
+void BoyerMoorePositionInfo::SetAll() {
+  w_ = kLatticeUnknown;
+  if (map_count_ != kMapSize) {
+    map_count_ = kMapSize;
+    map_.set();
+  }
+}
+
+BoyerMooreLookahead::BoyerMooreLookahead(int length, RegExpCompiler* compiler,
+                                         Zone* zone)
+    : length_(length),
+      compiler_(compiler),
+      max_char_(MaxCodeUnit(compiler->one_byte())) {
+  bitmaps_ = zone->New<ZoneList<BoyerMoorePositionInfo*>>(length, zone);
+  for (int i = 0; i < length; i++) {
+    bitmaps_->Add(zone->New<BoyerMoorePositionInfo>(), zone);
+  }
+}
+
+// Find the longest range of lookahead that has the fewest number of different
+// characters that can occur at a given position.  Since we are optimizing two
+// different parameters at once this is a tradeoff.
+bool BoyerMooreLookahead::FindWorthwhileInterval(int* from, int* to) {
+  int biggest_points = 0;
+  // If more than 32 characters out of 128 can occur it is unlikely that we can
+  // be lucky enough to step forwards much of the time.
+  const int kMaxMax = 32;
+  for (int max_number_of_chars = 4; max_number_of_chars < kMaxMax;
+       max_number_of_chars *= 2) {
+    biggest_points =
+        FindBestInterval(max_number_of_chars, biggest_points, from, to);
+  }
+  if (biggest_points == 0) return false;
+  return true;
+}
+
+// Find the highest-points range between 0 and length_ where the character
+// information is not too vague.  'Too vague' means that there are more than
+// max_number_of_chars that can occur at this position.  Calculates the number
+// of points as the product of width-of-the-range and
+// probability-of-finding-one-of-the-characters, where the probability is
+// calculated using the frequency distribution of the sample subject string.
+int BoyerMooreLookahead::FindBestInterval(int max_number_of_chars,
+                                          int old_biggest_points, int* from,
+                                          int* to) {
+  int biggest_points = old_biggest_points;
+  static const int kSize = RegExpMacroAssembler::kTableSize;
+  for (int i = 0; i < length_;) {
+    while (i < length_ && Count(i) > max_number_of_chars) i++;
+    if (i == length_) break;
+    int remembered_from = i;
+
+    BoyerMoorePositionInfo::Bitset union_bitset;
+    for (; i < length_ && Count(i) <= max_number_of_chars; i++) {
+      union_bitset |= bitmaps_->at(i)->raw_bitset();
+    }
+
+    int frequency = 0;
+
+    // Iterate only over set bits.
+    int j;
+    while ((j = BitsetFirstSetBit(union_bitset)) != -1) {
+      DCHECK(union_bitset[j]);  // Sanity check.
+      // Add 1 to the frequency to give a small per-character boost for
+      // the cases where our sampling is not good enough and many
+      // characters have a frequency of zero.  This means the frequency
+      // can theoretically be up to 2*kSize though we treat it mostly as
+      // a fraction of kSize.
+      frequency += compiler_->frequency_collator()->Frequency(j) + 1;
+      union_bitset.reset(j);
+    }
+
+    // We use the probability of skipping times the distance we are skipping to
+    // judge the effectiveness of this.  Actually we have a cut-off:  By
+    // dividing by 2 we switch off the skipping if the probability of skipping
+    // is less than 50%.  This is because the multibyte mask-and-compare
+    // skipping in quickcheck is more likely to do well on this case.
+    bool in_quickcheck_range =
+        ((i - remembered_from < 4) ||
+         (compiler_->one_byte() ? remembered_from <= 4 : remembered_from <= 2));
+    // Called 'probability' but it is only a rough estimate and can actually
+    // be outside the 0-kSize range.
+    int probability = (in_quickcheck_range ? kSize / 2 : kSize) - frequency;
+    int points = (i - remembered_from) * probability;
+    if (points > biggest_points) {
+      *from = remembered_from;
+      *to = i - 1;
+      biggest_points = points;
+    }
+  }
+  return biggest_points;
+}
+
+// Take all the characters that will not prevent a successful match if they
+// occur in the subject string in the range between min_lookahead and
+// max_lookahead (inclusive) measured from the current position.  If the
+// character at max_lookahead offset is not one of these characters, then we
+// can safely skip forwards by the number of characters in the range.
+int BoyerMooreLookahead::GetSkipTable(int min_lookahead, int max_lookahead,
+                                      Handle<ByteArray> boolean_skip_table) {
+  const int kSkipArrayEntry = 0;
+  const int kDontSkipArrayEntry = 1;
+
+  std::memset(boolean_skip_table->GetDataStartAddress(), kSkipArrayEntry,
+              boolean_skip_table->length());
+
+  for (int i = max_lookahead; i >= min_lookahead; i--) {
+    BoyerMoorePositionInfo::Bitset bitset = bitmaps_->at(i)->raw_bitset();
+
+    // Iterate only over set bits.
+    int j;
+    while ((j = BitsetFirstSetBit(bitset)) != -1) {
+      DCHECK(bitset[j]);  // Sanity check.
+      boolean_skip_table->set(j, kDontSkipArrayEntry);
+      bitset.reset(j);
+    }
+  }
+
+  const int skip = max_lookahead + 1 - min_lookahead;
+  return skip;
+}
+
+// See comment above on the implementation of GetSkipTable.
+void BoyerMooreLookahead::EmitSkipInstructions(RegExpMacroAssembler* masm) {
+  const int kSize = RegExpMacroAssembler::kTableSize;
+
+  int min_lookahead = 0;
+  int max_lookahead = 0;
+
+  if (!FindWorthwhileInterval(&min_lookahead, &max_lookahead)) return;
+
+  // Check if we only have a single non-empty position info, and that info
+  // contains precisely one character.
+  bool found_single_character = false;
+  int single_character = 0;
+  for (int i = max_lookahead; i >= min_lookahead; i--) {
+    BoyerMoorePositionInfo* map = bitmaps_->at(i);
+    if (map->map_count() == 0) continue;
+
+    if (found_single_character || map->map_count() > 1) {
+      found_single_character = false;
+      break;
+    }
+
+    DCHECK(!found_single_character);
+    DCHECK_EQ(map->map_count(), 1);
+
+    found_single_character = true;
+    single_character = BitsetFirstSetBit(map->raw_bitset());
+
+    DCHECK_NE(single_character, -1);
+  }
+
+  int lookahead_width = max_lookahead + 1 - min_lookahead;
+
+  if (found_single_character && lookahead_width == 1 && max_lookahead < 3) {
+    // The mask-compare can probably handle this better.
+    return;
+  }
+
+  if (found_single_character) {
+    Label cont, again;
+    masm->Bind(&again);
+    masm->LoadCurrentCharacter(max_lookahead, &cont, true);
+    if (max_char_ > kSize) {
+      masm->CheckCharacterAfterAnd(single_character,
+                                   RegExpMacroAssembler::kTableMask, &cont);
+    } else {
+      masm->CheckCharacter(single_character, &cont);
+    }
+    masm->AdvanceCurrentPosition(lookahead_width);
+    masm->GoTo(&again);
+    masm->Bind(&cont);
+    return;
+  }
+
+  Factory* factory = masm->isolate()->factory();
+  Handle<ByteArray> boolean_skip_table =
+      factory->NewByteArray(kSize, AllocationType::kOld);
+  int skip_distance =
+      GetSkipTable(min_lookahead, max_lookahead, boolean_skip_table);
+  DCHECK_NE(0, skip_distance);
+
+  Label cont, again;
+  masm->Bind(&again);
+  masm->LoadCurrentCharacter(max_lookahead, &cont, true);
+  masm->CheckBitInTable(boolean_skip_table, &cont);
+  masm->AdvanceCurrentPosition(skip_distance);
+  masm->GoTo(&again);
+  masm->Bind(&cont);
+}
+
+/* Code generation for choice nodes.
+ *
+ * We generate quick checks that do a mask and compare to eliminate a
+ * choice.  If the quick check succeeds then it jumps to the continuation to
+ * do slow checks and check subsequent nodes.  If it fails (the common case)
+ * it falls through to the next choice.
+ *
+ * Here is the desired flow graph.  Nodes directly below each other imply
+ * fallthrough.  Alternatives 1 and 2 have quick checks.  Alternative
+ * 3 doesn't have a quick check so we have to call the slow check.
+ * Nodes are marked Qn for quick checks and Sn for slow checks.  The entire
+ * regexp continuation is generated directly after the Sn node, up to the
+ * next GoTo if we decide to reuse some already generated code.  Some
+ * nodes expect preload_characters to be preloaded into the current
+ * character register.  R nodes do this preloading.  Vertices are marked
+ * F for failures and S for success (possible success in the case of quick
+ * nodes).  L, V, < and > are used as arrow heads.
+ *
+ * ----------> R
+ *             |
+ *             V
+ *            Q1 -----> S1
+ *             |   S   /
+ *            F|      /
+ *             |    F/
+ *             |    /
+ *             |   R
+ *             |  /
+ *             V L
+ *            Q2 -----> S2
+ *             |   S   /
+ *            F|      /
+ *             |    F/
+ *             |    /
+ *             |   R
+ *             |  /
+ *             V L
+ *            S3
+ *             |
+ *            F|
+ *             |
+ *             R
+ *             |
+ * backtrack   V
+ * <----------Q4
+ *   \    F    |
+ *    \        |S
+ *     \   F   V
+ *      \-----S4
+ *
+ * For greedy loops we push the current position, then generate the code that
+ * eats the input specially in EmitGreedyLoop.  The other choice (the
+ * continuation) is generated by the normal code in EmitChoices, and steps back
+ * in the input to the starting position when it fails to match.  The loop code
+ * looks like this (U is the unwind code that steps back in the greedy loop).
+ *
+ *              _____
+ *             /     \
+ *             V     |
+ * ----------> S1    |
+ *            /|     |
+ *           / |S    |
+ *         F/  \_____/
+ *         /
+ *        |<-----
+ *        |      \
+ *        V       |S
+ *        Q2 ---> U----->backtrack
+ *        |  F   /
+ *       S|     /
+ *        V  F /
+ *        S2--/
+ */
+
+GreedyLoopState::GreedyLoopState(bool not_at_start) {
+  counter_backtrack_trace_.set_backtrack(&label_);
+  if (not_at_start) counter_backtrack_trace_.set_at_start(Trace::FALSE_VALUE);
+}
+
+void ChoiceNode::AssertGuardsMentionRegisters(Trace* trace) {
+#ifdef DEBUG
+  int choice_count = alternatives_->length();
+  for (int i = 0; i < choice_count - 1; i++) {
+    GuardedAlternative alternative = alternatives_->at(i);
+    ZoneList<Guard*>* guards = alternative.guards();
+    int guard_count = (guards == nullptr) ? 0 : guards->length();
+    for (int j = 0; j < guard_count; j++) {
+      DCHECK(!trace->mentions_reg(guards->at(j)->reg()));
+    }
+  }
+#endif
+}
+
+void ChoiceNode::SetUpPreLoad(RegExpCompiler* compiler, Trace* current_trace,
+                              PreloadState* state) {
+  if (state->eats_at_least_ == PreloadState::kEatsAtLeastNotYetInitialized) {
+    // Save some time by looking at most one machine word ahead.
+    state->eats_at_least_ =
+        EatsAtLeast(current_trace->at_start() == Trace::FALSE_VALUE);
+  }
+  state->preload_characters_ =
+      CalculatePreloadCharacters(compiler, state->eats_at_least_);
+
+  state->preload_is_current_ =
+      (current_trace->characters_preloaded() == state->preload_characters_);
+  state->preload_has_checked_bounds_ = state->preload_is_current_;
+}
+
+void ChoiceNode::Emit(RegExpCompiler* compiler, Trace* trace) {
+  int choice_count = alternatives_->length();
+
+  if (choice_count == 1 && alternatives_->at(0).guards() == nullptr) {
+    alternatives_->at(0).node()->Emit(compiler, trace);
+    return;
+  }
+
+  AssertGuardsMentionRegisters(trace);
+
+  LimitResult limit_result = LimitVersions(compiler, trace);
+  if (limit_result == DONE) return;
+  DCHECK(limit_result == CONTINUE);
+
+  // For loop nodes we already flushed (see LoopChoiceNode::Emit), but for
+  // other choice nodes we only flush if we are out of code size budget.
+  if (trace->flush_budget() == 0 && trace->actions() != nullptr) {
+    trace->Flush(compiler, this);
+    return;
+  }
+
+  RecursionCheck rc(compiler);
+
+  PreloadState preload;
+  preload.init();
+  GreedyLoopState greedy_loop_state(not_at_start());
+
+  int text_length = GreedyLoopTextLengthForAlternative(&alternatives_->at(0));
+  AlternativeGenerationList alt_gens(choice_count, zone());
+
+  if (choice_count > 1 && text_length != kNodeIsTooComplexForGreedyLoops) {
+    trace = EmitGreedyLoop(compiler, trace, &alt_gens, &preload,
+                           &greedy_loop_state, text_length);
+  } else {
+    // TODO(erikcorry): Delete this.  We don't need this label, but it makes us
+    // match the traces produced pre-cleanup.
+    Label second_choice;
+    compiler->macro_assembler()->Bind(&second_choice);
+
+    preload.eats_at_least_ = EmitOptimizedUnanchoredSearch(compiler, trace);
+
+    EmitChoices(compiler, &alt_gens, 0, trace, &preload);
+  }
+
+  // At this point we need to generate slow checks for the alternatives where
+  // the quick check was inlined.  We can recognize these because the associated
+  // label was bound.
+  int new_flush_budget = trace->flush_budget() / choice_count;
+  for (int i = 0; i < choice_count; i++) {
+    AlternativeGeneration* alt_gen = alt_gens.at(i);
+    Trace new_trace(*trace);
+    // If there are actions to be flushed we have to limit how many times
+    // they are flushed.  Take the budget of the parent trace and distribute
+    // it fairly amongst the children.
+    if (new_trace.actions() != nullptr) {
+      new_trace.set_flush_budget(new_flush_budget);
+    }
+    bool next_expects_preload =
+        i == choice_count - 1 ? false : alt_gens.at(i + 1)->expects_preload;
+    EmitOutOfLineContinuation(compiler, &new_trace, alternatives_->at(i),
+                              alt_gen, preload.preload_characters_,
+                              next_expects_preload);
+  }
+}
+
+Trace* ChoiceNode::EmitGreedyLoop(RegExpCompiler* compiler, Trace* trace,
+                                  AlternativeGenerationList* alt_gens,
+                                  PreloadState* preload,
+                                  GreedyLoopState* greedy_loop_state,
+                                  int text_length) {
+  RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
+  // Here we have special handling for greedy loops containing only text nodes
+  // and other simple nodes.  These are handled by pushing the current
+  // position on the stack and then incrementing the current position each
+  // time around the switch.  On backtrack we decrement the current position
+  // and check it against the pushed value.  This avoids pushing backtrack
+  // information for each iteration of the loop, which could take up a lot of
+  // space.
+  DCHECK(trace->stop_node() == nullptr);
+  macro_assembler->PushCurrentPosition();
+  Label greedy_match_failed;
+  Trace greedy_match_trace;
+  if (not_at_start()) greedy_match_trace.set_at_start(Trace::FALSE_VALUE);
+  greedy_match_trace.set_backtrack(&greedy_match_failed);
+  Label loop_label;
+  macro_assembler->Bind(&loop_label);
+  greedy_match_trace.set_stop_node(this);
+  greedy_match_trace.set_loop_label(&loop_label);
+  alternatives_->at(0).node()->Emit(compiler, &greedy_match_trace);
+  macro_assembler->Bind(&greedy_match_failed);
+
+  Label second_choice;  // For use in greedy matches.
+  macro_assembler->Bind(&second_choice);
+
+  Trace* new_trace = greedy_loop_state->counter_backtrack_trace();
+
+  EmitChoices(compiler, alt_gens, 1, new_trace, preload);
+
+  macro_assembler->Bind(greedy_loop_state->label());
+  // If we have unwound to the bottom then backtrack.
+  macro_assembler->CheckGreedyLoop(trace->backtrack());
+  // Otherwise try the second priority at an earlier position.
+  macro_assembler->AdvanceCurrentPosition(-text_length);
+  macro_assembler->GoTo(&second_choice);
+  return new_trace;
+}
+
+int ChoiceNode::EmitOptimizedUnanchoredSearch(RegExpCompiler* compiler,
+                                              Trace* trace) {
+  int eats_at_least = PreloadState::kEatsAtLeastNotYetInitialized;
+  if (alternatives_->length() != 2) return eats_at_least;
+
+  GuardedAlternative alt1 = alternatives_->at(1);
+  if (alt1.guards() != nullptr && alt1.guards()->length() != 0) {
+    return eats_at_least;
+  }
+  RegExpNode* eats_anything_node = alt1.node();
+  if (eats_anything_node->GetSuccessorOfOmnivorousTextNode(compiler) != this) {
+    return eats_at_least;
+  }
+
+  // Really we should be creating a new trace when we execute this function,
+  // but there is no need, because the code it generates cannot backtrack, and
+  // we always arrive here with a trivial trace (since it's the entry to a
+  // loop.  That also implies that there are no preloaded characters, which is
+  // good, because it means we won't be violating any assumptions by
+  // overwriting those characters with new load instructions.
+  DCHECK(trace->is_trivial());
+
+  RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
+  Isolate* isolate = macro_assembler->isolate();
+  // At this point we know that we are at a non-greedy loop that will eat
+  // any character one at a time.  Any non-anchored regexp has such a
+  // loop prepended to it in order to find where it starts.  We look for
+  // a pattern of the form ...abc... where we can look 6 characters ahead
+  // and step forwards 3 if the character is not one of abc.  Abc need
+  // not be atoms, they can be any reasonably limited character class or
+  // small alternation.
+  BoyerMooreLookahead* bm = bm_info(false);
+  if (bm == nullptr) {
+    eats_at_least = std::min(kMaxLookaheadForBoyerMoore, EatsAtLeast(false));
+    if (eats_at_least >= 1) {
+      bm = zone()->New<BoyerMooreLookahead>(eats_at_least, compiler, zone());
+      GuardedAlternative alt0 = alternatives_->at(0);
+      alt0.node()->FillInBMInfo(isolate, 0, kRecursionBudget, bm, false);
+    }
+  }
+  if (bm != nullptr) {
+    bm->EmitSkipInstructions(macro_assembler);
+  }
+  return eats_at_least;
+}
+
+void ChoiceNode::EmitChoices(RegExpCompiler* compiler,
+                             AlternativeGenerationList* alt_gens,
+                             int first_choice, Trace* trace,
+                             PreloadState* preload) {
+  RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
+  SetUpPreLoad(compiler, trace, preload);
+
+  // For now we just call all choices one after the other.  The idea ultimately
+  // is to use the Dispatch table to try only the relevant ones.
+  int choice_count = alternatives_->length();
+
+  int new_flush_budget = trace->flush_budget() / choice_count;
+
+  for (int i = first_choice; i < choice_count; i++) {
+    bool is_last = i == choice_count - 1;
+    bool fall_through_on_failure = !is_last;
+    GuardedAlternative alternative = alternatives_->at(i);
+    AlternativeGeneration* alt_gen = alt_gens->at(i);
+    alt_gen->quick_check_details.set_characters(preload->preload_characters_);
+    ZoneList<Guard*>* guards = alternative.guards();
+    int guard_count = (guards == nullptr) ? 0 : guards->length();
+    Trace new_trace(*trace);
+    new_trace.set_characters_preloaded(
+        preload->preload_is_current_ ? preload->preload_characters_ : 0);
+    if (preload->preload_has_checked_bounds_) {
+      new_trace.set_bound_checked_up_to(preload->preload_characters_);
+    }
+    new_trace.quick_check_performed()->Clear();
+    if (not_at_start_) new_trace.set_at_start(Trace::FALSE_VALUE);
+    if (!is_last) {
+      new_trace.set_backtrack(&alt_gen->after);
+    }
+    alt_gen->expects_preload = preload->preload_is_current_;
+    bool generate_full_check_inline = false;
+    if (compiler->optimize() &&
+        try_to_emit_quick_check_for_alternative(i == 0) &&
+        alternative.node()->EmitQuickCheck(
+            compiler, trace, &new_trace, preload->preload_has_checked_bounds_,
+            &alt_gen->possible_success, &alt_gen->quick_check_details,
+            fall_through_on_failure, this)) {
+      // Quick check was generated for this choice.
+      preload->preload_is_current_ = true;
+      preload->preload_has_checked_bounds_ = true;
+      // If we generated the quick check to fall through on possible success,
+      // we now need to generate the full check inline.
+      if (!fall_through_on_failure) {
+        macro_assembler->Bind(&alt_gen->possible_success);
+        new_trace.set_quick_check_performed(&alt_gen->quick_check_details);
+        new_trace.set_characters_preloaded(preload->preload_characters_);
+        new_trace.set_bound_checked_up_to(preload->preload_characters_);
+        generate_full_check_inline = true;
+      }
+    } else if (alt_gen->quick_check_details.cannot_match()) {
+      if (!fall_through_on_failure) {
+        macro_assembler->GoTo(trace->backtrack());
+      }
+      continue;
+    } else {
+      // No quick check was generated.  Put the full code here.
+      // If this is not the first choice then there could be slow checks from
+      // previous cases that go here when they fail.  There's no reason to
+      // insist that they preload characters since the slow check we are about
+      // to generate probably can't use it.
+      if (i != first_choice) {
+        alt_gen->expects_preload = false;
+        new_trace.InvalidateCurrentCharacter();
+      }
+      generate_full_check_inline = true;
+    }
+    if (generate_full_check_inline) {
+      if (new_trace.actions() != nullptr) {
+        new_trace.set_flush_budget(new_flush_budget);
+      }
+      for (int j = 0; j < guard_count; j++) {
+        GenerateGuard(macro_assembler, guards->at(j), &new_trace);
+      }
+      alternative.node()->Emit(compiler, &new_trace);
+      preload->preload_is_current_ = false;
+    }
+    macro_assembler->Bind(&alt_gen->after);
+  }
+}
+
+void ChoiceNode::EmitOutOfLineContinuation(RegExpCompiler* compiler,
+                                           Trace* trace,
+                                           GuardedAlternative alternative,
+                                           AlternativeGeneration* alt_gen,
+                                           int preload_characters,
+                                           bool next_expects_preload) {
+  if (!alt_gen->possible_success.is_linked()) return;
+
+  RegExpMacroAssembler* macro_assembler = compiler->macro_assembler();
+  macro_assembler->Bind(&alt_gen->possible_success);
+  Trace out_of_line_trace(*trace);
+  out_of_line_trace.set_characters_preloaded(preload_characters);
+  out_of_line_trace.set_quick_check_performed(&alt_gen->quick_check_details);
+  if (not_at_start_) out_of_line_trace.set_at_start(Trace::FALSE_VALUE);
+  ZoneList<Guard*>* guards = alternative.guards();
+  int guard_count = (guards == nullptr) ? 0 : guards->length();
+  if (next_expects_preload) {
+    Label reload_current_char;
+    out_of_line_trace.set_backtrack(&reload_current_char);
+    for (int j = 0; j < guard_count; j++) {
+      GenerateGuard(macro_assembler, guards->at(j), &out_of_line_trace);
+    }
+    alternative.node()->Emit(compiler, &out_of_line_trace);
+    macro_assembler->Bind(&reload_current_char);
+    // Reload the current character, since the next quick check expects that.
+    // We don't need to check bounds here because we only get into this
+    // code through a quick check which already did the checked load.
+    macro_assembler->LoadCurrentCharacter(trace->cp_offset(), nullptr, false,
+                                          preload_characters);
+    macro_assembler->GoTo(&(alt_gen->after));
+  } else {
+    out_of_line_trace.set_backtrack(&(alt_gen->after));
+    for (int j = 0; j < guard_count; j++) {
+      GenerateGuard(macro_assembler, guards->at(j), &out_of_line_trace);
+    }
+    alternative.node()->Emit(compiler, &out_of_line_trace);
+  }
+}
+
+void ActionNode::Emit(RegExpCompiler* compiler, Trace* trace) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+  LimitResult limit_result = LimitVersions(compiler, trace);
+  if (limit_result == DONE) return;
+  DCHECK(limit_result == CONTINUE);
+
+  RecursionCheck rc(compiler);
+
+  switch (action_type_) {
+    case STORE_POSITION: {
+      Trace::DeferredCapture new_capture(data_.u_position_register.reg,
+                                         data_.u_position_register.is_capture,
+                                         trace);
+      Trace new_trace = *trace;
+      new_trace.add_action(&new_capture);
+      on_success()->Emit(compiler, &new_trace);
+      break;
+    }
+    case INCREMENT_REGISTER: {
+      Trace::DeferredIncrementRegister new_increment(
+          data_.u_increment_register.reg);
+      Trace new_trace = *trace;
+      new_trace.add_action(&new_increment);
+      on_success()->Emit(compiler, &new_trace);
+      break;
+    }
+    case SET_REGISTER_FOR_LOOP: {
+      Trace::DeferredSetRegisterForLoop new_set(data_.u_store_register.reg,
+                                                data_.u_store_register.value);
+      Trace new_trace = *trace;
+      new_trace.add_action(&new_set);
+      on_success()->Emit(compiler, &new_trace);
+      break;
+    }
+    case CLEAR_CAPTURES: {
+      Trace::DeferredClearCaptures new_capture(Interval(
+          data_.u_clear_captures.range_from, data_.u_clear_captures.range_to));
+      Trace new_trace = *trace;
+      new_trace.add_action(&new_capture);
+      on_success()->Emit(compiler, &new_trace);
+      break;
+    }
+    case BEGIN_POSITIVE_SUBMATCH:
+    case BEGIN_NEGATIVE_SUBMATCH:
+      if (!trace->is_trivial()) {
+        trace->Flush(compiler, this);
+      } else {
+        assembler->WriteCurrentPositionToRegister(
+            data_.u_submatch.current_position_register, 0);
+        assembler->WriteStackPointerToRegister(
+            data_.u_submatch.stack_pointer_register);
+        on_success()->Emit(compiler, trace);
+      }
+      break;
+    case EMPTY_MATCH_CHECK: {
+      int start_pos_reg = data_.u_empty_match_check.start_register;
+      int stored_pos = 0;
+      int rep_reg = data_.u_empty_match_check.repetition_register;
+      bool has_minimum = (rep_reg != RegExpCompiler::kNoRegister);
+      bool know_dist = trace->GetStoredPosition(start_pos_reg, &stored_pos);
+      if (know_dist && !has_minimum && stored_pos == trace->cp_offset()) {
+        // If we know we haven't advanced and there is no minimum we
+        // can just backtrack immediately.
+        assembler->GoTo(trace->backtrack());
+      } else if (know_dist && stored_pos < trace->cp_offset()) {
+        // If we know we've advanced we can generate the continuation
+        // immediately.
+        on_success()->Emit(compiler, trace);
+      } else if (!trace->is_trivial()) {
+        trace->Flush(compiler, this);
+      } else {
+        Label skip_empty_check;
+        // If we have a minimum number of repetitions we check the current
+        // number first and skip the empty check if it's not enough.
+        if (has_minimum) {
+          int limit = data_.u_empty_match_check.repetition_limit;
+          assembler->IfRegisterLT(rep_reg, limit, &skip_empty_check);
+        }
+        // If the match is empty we bail out, otherwise we fall through
+        // to the on-success continuation.
+        assembler->IfRegisterEqPos(data_.u_empty_match_check.start_register,
+                                   trace->backtrack());
+        assembler->Bind(&skip_empty_check);
+        on_success()->Emit(compiler, trace);
+      }
+      break;
+    }
+    case POSITIVE_SUBMATCH_SUCCESS: {
+      if (!trace->is_trivial()) {
+        trace->Flush(compiler, this);
+        return;
+      }
+      assembler->ReadCurrentPositionFromRegister(
+          data_.u_submatch.current_position_register);
+      assembler->ReadStackPointerFromRegister(
+          data_.u_submatch.stack_pointer_register);
+      int clear_register_count = data_.u_submatch.clear_register_count;
+      if (clear_register_count == 0) {
+        on_success()->Emit(compiler, trace);
+        return;
+      }
+      int clear_registers_from = data_.u_submatch.clear_register_from;
+      Label clear_registers_backtrack;
+      Trace new_trace = *trace;
+      new_trace.set_backtrack(&clear_registers_backtrack);
+      on_success()->Emit(compiler, &new_trace);
+
+      assembler->Bind(&clear_registers_backtrack);
+      int clear_registers_to = clear_registers_from + clear_register_count - 1;
+      assembler->ClearRegisters(clear_registers_from, clear_registers_to);
+
+      DCHECK(trace->backtrack() == nullptr);
+      assembler->Backtrack();
+      return;
+    }
+    default:
+      UNREACHABLE();
+  }
+}
+
+void BackReferenceNode::Emit(RegExpCompiler* compiler, Trace* trace) {
+  RegExpMacroAssembler* assembler = compiler->macro_assembler();
+  if (!trace->is_trivial()) {
+    trace->Flush(compiler, this);
+    return;
+  }
+
+  LimitResult limit_result = LimitVersions(compiler, trace);
+  if (limit_result == DONE) return;
+  DCHECK(limit_result == CONTINUE);
+
+  RecursionCheck rc(compiler);
+
+  DCHECK_EQ(start_reg_ + 1, end_reg_);
+  if (IsIgnoreCase(flags_)) {
+    bool unicode = IsEitherUnicode(flags_);
+    assembler->CheckNotBackReferenceIgnoreCase(start_reg_, read_backward(),
+                                               unicode, trace->backtrack());
+  } else {
+    assembler->CheckNotBackReference(start_reg_, read_backward(),
+                                     trace->backtrack());
+  }
+  // We are going to advance backward, so we may end up at the start.
+  if (read_backward()) trace->set_at_start(Trace::UNKNOWN);
+
+  // Check that the back reference does not end inside a surrogate pair.
+  if (IsEitherUnicode(flags_) && !compiler->one_byte()) {
+    assembler->CheckNotInSurrogatePair(trace->cp_offset(), trace->backtrack());
+  }
+  on_success()->Emit(compiler, trace);
+}
+
+void TextNode::CalculateOffsets() {
+  int element_count = elements()->length();
+  // Set up the offsets of the elements relative to the start.  This is a fixed
+  // quantity since a TextNode can only contain fixed-width things.
+  int cp_offset = 0;
+  for (int i = 0; i < element_count; i++) {
+    TextElement& elm = elements()->at(i);
+    elm.set_cp_offset(cp_offset);
+    cp_offset += elm.length();
+  }
+}
+
+namespace {
+
+// Assertion propagation moves information about assertions such as
+// \b to the affected nodes.  For instance, in /.\b./ information must
+// be propagated to the first '.' that whatever follows needs to know
+// if it matched a word or a non-word, and to the second '.' that it
+// has to check if it succeeds a word or non-word.  In this case the
+// result will be something like:
+//
+//   +-------+        +------------+
+//   |   .   |        |      .     |
+//   +-------+  --->  +------------+
+//   | word? |        | check word |
+//   +-------+        +------------+
+class AssertionPropagator : public AllStatic {
+ public:
+  static void VisitText(TextNode* that) {}
+
+  static void VisitAction(ActionNode* that) {
+    // If the next node is interested in what it follows then this node
+    // has to be interested too so it can pass the information on.
+    that->info()->AddFromFollowing(that->on_success()->info());
+  }
+
+  static void VisitChoice(ChoiceNode* that, int i) {
+    // Anything the following nodes need to know has to be known by
+    // this node also, so it can pass it on.
+    that->info()->AddFromFollowing(that->alternatives()->at(i).node()->info());
+  }
+
+  static void VisitLoopChoiceContinueNode(LoopChoiceNode* that) {
+    that->info()->AddFromFollowing(that->continue_node()->info());
+  }
+
+  static void VisitLoopChoiceLoopNode(LoopChoiceNode* that) {
+    that->info()->AddFromFollowing(that->loop_node()->info());
+  }
+
+  static void VisitNegativeLookaroundChoiceLookaroundNode(
+      NegativeLookaroundChoiceNode* that) {
+    VisitChoice(that, NegativeLookaroundChoiceNode::kLookaroundIndex);
+  }
+
+  static void VisitNegativeLookaroundChoiceContinueNode(
+      NegativeLookaroundChoiceNode* that) {
+    VisitChoice(that, NegativeLookaroundChoiceNode::kContinueIndex);
+  }
+
+  static void VisitBackReference(BackReferenceNode* that) {}
+
+  static void VisitAssertion(AssertionNode* that) {}
+};
+
+// Propagates information about the minimum size of successful matches from
+// successor nodes to their predecessors. Note that all eats_at_least values
+// are initialized to zero before analysis.
+class EatsAtLeastPropagator : public AllStatic {
+ public:
+  static void VisitText(TextNode* that) {
+    // The eats_at_least value is not used if reading backward.
+    if (!that->read_backward()) {
+      // We are not at the start after this node, and thus we can use the
+      // successor's eats_at_least_from_not_start value.
+      uint8_t eats_at_least = base::saturated_cast<uint8_t>(
+          that->Length() + that->on_success()
+                               ->eats_at_least_info()
+                               ->eats_at_least_from_not_start);
+      that->set_eats_at_least_info(EatsAtLeastInfo(eats_at_least));
+    }
+  }
+
+  static void VisitAction(ActionNode* that) {
+    switch (that->action_type()) {
+      case ActionNode::BEGIN_POSITIVE_SUBMATCH:
+      case ActionNode::POSITIVE_SUBMATCH_SUCCESS:
+        // We do not propagate eats_at_least data through positive lookarounds,
+        // because they rewind input.
+        // TODO(v8:11859) Potential approaches for fixing this include:
+        // 1. Add a dedicated choice node for positive lookaround, similar to
+        //    NegativeLookaroundChoiceNode.
+        // 2. Add an eats_at_least_inside_loop field to EatsAtLeastInfo, which
+        //    is <= eats_at_least_from_possibly_start, and use that value in
+        //    EatsAtLeastFromLoopEntry.
+        DCHECK(that->eats_at_least_info()->IsZero());
+        break;
+      case ActionNode::SET_REGISTER_FOR_LOOP:
+        // SET_REGISTER_FOR_LOOP indicates a loop entry point, which means the
+        // loop body will run at least the minimum number of times before the
+        // continuation case can run.
+        that->set_eats_at_least_info(
+            that->on_success()->EatsAtLeastFromLoopEntry());
+        break;
+      case ActionNode::BEGIN_NEGATIVE_SUBMATCH:
+      default:
+        // Otherwise, the current node eats at least as much as its successor.
+        // Note: we can propagate eats_at_least data for BEGIN_NEGATIVE_SUBMATCH
+        // because NegativeLookaroundChoiceNode ignores its lookaround successor
+        // when computing eats-at-least and quick check information.
+        that->set_eats_at_least_info(*that->on_success()->eats_at_least_info());
+        break;
+    }
+  }
+
+  static void VisitChoice(ChoiceNode* that, int i) {
+    // The minimum possible match from a choice node is the minimum of its
+    // successors.
+    EatsAtLeastInfo eats_at_least =
+        i == 0 ? EatsAtLeastInfo(UINT8_MAX) : *that->eats_at_least_info();
+    eats_at_least.SetMin(
+        *that->alternatives()->at(i).node()->eats_at_least_info());
+    that->set_eats_at_least_info(eats_at_least);
+  }
+
+  static void VisitLoopChoiceContinueNode(LoopChoiceNode* that) {
+    if (!that->read_backward()) {
+      that->set_eats_at_least_info(
+          *that->continue_node()->eats_at_least_info());
+    }
+  }
+
+  static void VisitLoopChoiceLoopNode(LoopChoiceNode* that) {}
+
+  static void VisitNegativeLookaroundChoiceLookaroundNode(
+      NegativeLookaroundChoiceNode* that) {}
+
+  static void VisitNegativeLookaroundChoiceContinueNode(
+      NegativeLookaroundChoiceNode* that) {
+    that->set_eats_at_least_info(*that->continue_node()->eats_at_least_info());
+  }
+
+  static void VisitBackReference(BackReferenceNode* that) {
+    if (!that->read_backward()) {
+      that->set_eats_at_least_info(*that->on_success()->eats_at_least_info());
+    }
+  }
+
+  static void VisitAssertion(AssertionNode* that) {
+    EatsAtLeastInfo eats_at_least = *that->on_success()->eats_at_least_info();
+    if (that->assertion_type() == AssertionNode::AT_START) {
+      // If we know we are not at the start and we are asked "how many
+      // characters will you match if you succeed?" then we can answer anything
+      // since false implies false.  So let's just set the max answer
+      // (UINT8_MAX) since that won't prevent us from preloading a lot of
+      // characters for the other branches in the node graph.
+      eats_at_least.eats_at_least_from_not_start = UINT8_MAX;
+    }
+    that->set_eats_at_least_info(eats_at_least);
+  }
+};
+
+}  // namespace
+
+// -------------------------------------------------------------------
+// Analysis
+
+// Iterates the node graph and provides the opportunity for propagators to set
+// values that depend on successor nodes.
+template <typename... Propagators>
+class Analysis : public NodeVisitor {
+ public:
+  Analysis(Isolate* isolate, bool is_one_byte, RegExpFlags flags)
+      : isolate_(isolate),
+        is_one_byte_(is_one_byte),
+        flags_(flags),
+        error_(RegExpError::kNone) {}
+
+  void EnsureAnalyzed(RegExpNode* that) {
+    StackLimitCheck check(isolate());
+    if (check.HasOverflowed()) {
+      if (v8_flags.correctness_fuzzer_suppressions) {
+        FATAL("Analysis: Aborting on stack overflow");
+      }
+      fail(RegExpError::kAnalysisStackOverflow);
+      return;
+    }
+    if (that->info()->been_analyzed || that->info()->being_analyzed) return;
+    that->info()->being_analyzed = true;
+    that->Accept(this);
+    that->info()->being_analyzed = false;
+    that->info()->been_analyzed = true;
+  }
+
+  bool has_failed() { return error_ != RegExpError::kNone; }
+  RegExpError error() {
+    DCHECK(error_ != RegExpError::kNone);
+    return error_;
+  }
+  void fail(RegExpError error) { error_ = error; }
+
+  Isolate* isolate() const { return isolate_; }
+
+  void VisitEnd(EndNode* that) override {
+    // nothing to do
+  }
+
+// Used to call the given static function on each propagator / variadic template
+// argument.
+#define STATIC_FOR_EACH(expr)       \
+  do {                              \
+    int dummy[] = {((expr), 0)...}; \
+    USE(dummy);                     \
+  } while (false)
+
+  void VisitText(TextNode* that) override {
+    that->MakeCaseIndependent(isolate(), is_one_byte_, flags_);
+    EnsureAnalyzed(that->on_success());
+    if (has_failed()) return;
+    that->CalculateOffsets();
+    STATIC_FOR_EACH(Propagators::VisitText(that));
+  }
+
+  void VisitAction(ActionNode* that) override {
+    EnsureAnalyzed(that->on_success());
+    if (has_failed()) return;
+    STATIC_FOR_EACH(Propagators::VisitAction(that));
+  }
+
+  void VisitChoice(ChoiceNode* that) override {
+    for (int i = 0; i < that->alternatives()->length(); i++) {
+      EnsureAnalyzed(that->alternatives()->at(i).node());
+      if (has_failed()) return;
+      STATIC_FOR_EACH(Propagators::VisitChoice(that, i));
+    }
+  }
+
+  void VisitLoopChoice(LoopChoiceNode* that) override {
+    DCHECK_EQ(that->alternatives()->length(), 2);  // Just loop and continue.
+
+    // First propagate all information from the continuation node.
+    EnsureAnalyzed(that->continue_node());
+    if (has_failed()) return;
+    STATIC_FOR_EACH(Propagators::VisitLoopChoiceContinueNode(that));
+
+    // Check the loop last since it may need the value of this node
+    // to get a correct result.
+    EnsureAnalyzed(that->loop_node());
+    if (has_failed()) return;
+    STATIC_FOR_EACH(Propagators::VisitLoopChoiceLoopNode(that));
+  }
+
+  void VisitNegativeLookaroundChoice(
+      NegativeLookaroundChoiceNode* that) override {
+    DCHECK_EQ(that->alternatives()->length(), 2);  // Lookaround and continue.
+
+    EnsureAnalyzed(that->lookaround_node());
+    if (has_failed()) return;
+    STATIC_FOR_EACH(
+        Propagators::VisitNegativeLookaroundChoiceLookaroundNode(that));
+
+    EnsureAnalyzed(that->continue_node());
+    if (has_failed()) return;
+    STATIC_FOR_EACH(
+        Propagators::VisitNegativeLookaroundChoiceContinueNode(that));
+  }
+
+  void VisitBackReference(BackReferenceNode* that) override {
+    EnsureAnalyzed(that->on_success());
+    if (has_failed()) return;
+    STATIC_FOR_EACH(Propagators::VisitBackReference(that));
+  }
+
+  void VisitAssertion(AssertionNode* that) override {
+    EnsureAnalyzed(that->on_success());
+    if (has_failed()) return;
+    STATIC_FOR_EACH(Propagators::VisitAssertion(that));
+  }
+
+#undef STATIC_FOR_EACH
+
+ private:
+  Isolate* isolate_;
+  const bool is_one_byte_;
+  const RegExpFlags flags_;
+  RegExpError error_;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(Analysis);
+};
+
+RegExpError AnalyzeRegExp(Isolate* isolate, bool is_one_byte, RegExpFlags flags,
+                          RegExpNode* node) {
+  Analysis<AssertionPropagator, EatsAtLeastPropagator> analysis(
+      isolate, is_one_byte, flags);
+  DCHECK_EQ(node->info()->been_analyzed, false);
+  analysis.EnsureAnalyzed(node);
+  DCHECK_IMPLIES(analysis.has_failed(), analysis.error() != RegExpError::kNone);
+  return analysis.has_failed() ? analysis.error() : RegExpError::kNone;
+}
+
+void BackReferenceNode::FillInBMInfo(Isolate* isolate, int offset, int budget,
+                                     BoyerMooreLookahead* bm,
+                                     bool not_at_start) {
+  // Working out the set of characters that a backreference can match is too
+  // hard, so we just say that any character can match.
+  bm->SetRest(offset);
+  SaveBMInfo(bm, not_at_start, offset);
+}
+
+static_assert(BoyerMoorePositionInfo::kMapSize ==
+              RegExpMacroAssembler::kTableSize);
+
+void ChoiceNode::FillInBMInfo(Isolate* isolate, int offset, int budget,
+                              BoyerMooreLookahead* bm, bool not_at_start) {
+  ZoneList<GuardedAlternative>* alts = alternatives();
+  budget = (budget - 1) / alts->length();
+  for (int i = 0; i < alts->length(); i++) {
+    GuardedAlternative& alt = alts->at(i);
+    if (alt.guards() != nullptr && alt.guards()->length() != 0) {
+      bm->SetRest(offset);  // Give up trying to fill in info.
+      SaveBMInfo(bm, not_at_start, offset);
+      return;
+    }
+    alt.node()->FillInBMInfo(isolate, offset, budget, bm, not_at_start);
+  }
+  SaveBMInfo(bm, not_at_start, offset);
+}
+
+void TextNode::FillInBMInfo(Isolate* isolate, int initial_offset, int budget,
+                            BoyerMooreLookahead* bm, bool not_at_start) {
+  if (initial_offset >= bm->length()) return;
+  int offset = initial_offset;
+  int max_char = bm->max_char();
+  for (int i = 0; i < elements()->length(); i++) {
+    if (offset >= bm->length()) {
+      if (initial_offset == 0) set_bm_info(not_at_start, bm);
+      return;
+    }
+    TextElement text = elements()->at(i);
+    if (text.text_type() == TextElement::ATOM) {
+      RegExpAtom* atom = text.atom();
+      for (int j = 0; j < atom->length(); j++, offset++) {
+        if (offset >= bm->length()) {
+          if (initial_offset == 0) set_bm_info(not_at_start, bm);
+          return;
+        }
+        base::uc16 character = atom->data()[j];
+        if (IsIgnoreCase(bm->compiler()->flags())) {
+          unibrow::uchar chars[4];
+          int length = GetCaseIndependentLetters(
+              isolate, character, bm->max_char() == String::kMaxOneByteCharCode,
+              chars, 4);
+          for (int k = 0; k < length; k++) {
+            bm->Set(offset, chars[k]);
+          }
+        } else {
+          if (character <= max_char) bm->Set(offset, character);
+        }
+      }
+    } else {
+      DCHECK_EQ(TextElement::CLASS_RANGES, text.text_type());
+      RegExpClassRanges* class_ranges = text.class_ranges();
+      ZoneList<CharacterRange>* ranges = class_ranges->ranges(zone());
+      if (class_ranges->is_negated()) {
+        bm->SetAll(offset);
+      } else {
+        for (int k = 0; k < ranges->length(); k++) {
+          CharacterRange& range = ranges->at(k);
+          if (static_cast<int>(range.from()) > max_char) continue;
+          int to = std::min(max_char, static_cast<int>(range.to()));
+          bm->SetInterval(offset, Interval(range.from(), to));
+        }
+      }
+      offset++;
+    }
+  }
+  if (offset >= bm->length()) {
+    if (initial_offset == 0) set_bm_info(not_at_start, bm);
+    return;
+  }
+  on_success()->FillInBMInfo(isolate, offset, budget - 1, bm,
+                             true);  // Not at start after a text node.
+  if (initial_offset == 0) set_bm_info(not_at_start, bm);
+}
+
+RegExpNode* RegExpCompiler::OptionallyStepBackToLeadSurrogate(
+    RegExpNode* on_success) {
+  DCHECK(!read_backward());
+  ZoneList<CharacterRange>* lead_surrogates = CharacterRange::List(
+      zone(), CharacterRange::Range(kLeadSurrogateStart, kLeadSurrogateEnd));
+  ZoneList<CharacterRange>* trail_surrogates = CharacterRange::List(
+      zone(), CharacterRange::Range(kTrailSurrogateStart, kTrailSurrogateEnd));
+
+  ChoiceNode* optional_step_back = zone()->New<ChoiceNode>(2, zone());
+
+  int stack_register = UnicodeLookaroundStackRegister();
+  int position_register = UnicodeLookaroundPositionRegister();
+  RegExpNode* step_back = TextNode::CreateForCharacterRanges(
+      zone(), lead_surrogates, true, on_success);
+  RegExpLookaround::Builder builder(true, step_back, stack_register,
+                                    position_register);
+  RegExpNode* match_trail = TextNode::CreateForCharacterRanges(
+      zone(), trail_surrogates, false, builder.on_match_success());
+
+  optional_step_back->AddAlternative(
+      GuardedAlternative(builder.ForMatch(match_trail)));
+  optional_step_back->AddAlternative(GuardedAlternative(on_success));
+
+  return optional_step_back;
+}
+
+RegExpNode* RegExpCompiler::PreprocessRegExp(RegExpCompileData* data,
+                                             RegExpFlags flags,
+                                             bool is_one_byte) {
+  // Wrap the body of the regexp in capture #0.
+  RegExpNode* captured_body =
+      RegExpCapture::ToNode(data->tree, 0, this, accept());
+  RegExpNode* node = captured_body;
+  if (!data->tree->IsAnchoredAtStart() && !IsSticky(flags)) {
+    // Add a .*? at the beginning, outside the body capture, unless
+    // this expression is anchored at the beginning or sticky.
+    RegExpNode* loop_node = RegExpQuantifier::ToNode(
+        0, RegExpTree::kInfinity, false,
+        zone()->New<RegExpClassRanges>(StandardCharacterSet::kEverything), this,
+        captured_body, data->contains_anchor);
+
+    if (data->contains_anchor) {
+      // Unroll loop once, to take care of the case that might start
+      // at the start of input.
+      ChoiceNode* first_step_node = zone()->New<ChoiceNode>(2, zone());
+      first_step_node->AddAlternative(GuardedAlternative(captured_body));
+      first_step_node->AddAlternative(GuardedAlternative(zone()->New<TextNode>(
+          zone()->New<RegExpClassRanges>(StandardCharacterSet::kEverything),
+          false, loop_node)));
+      node = first_step_node;
+    } else {
+      node = loop_node;
+    }
+  }
+  if (is_one_byte) {
+    node = node->FilterOneByte(RegExpCompiler::kMaxRecursion, flags);
+    // Do it again to propagate the new nodes to places where they were not
+    // put because they had not been calculated yet.
+    if (node != nullptr) {
+      node = node->FilterOneByte(RegExpCompiler::kMaxRecursion, flags);
+    }
+  } else if (IsEitherUnicode(flags) && (IsGlobal(flags) || IsSticky(flags))) {
+    node = OptionallyStepBackToLeadSurrogate(node);
+  }
+
+  if (node == nullptr) node = zone()->New<EndNode>(EndNode::BACKTRACK, zone());
+  return node;
+}
+
+void RegExpCompiler::ToNodeCheckForStackOverflow() {
+  if (StackLimitCheck{isolate()}.HasOverflowed()) {
+    V8::FatalProcessOutOfMemory(isolate(), "RegExpCompiler");
+  }
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/irregexp/imported/regexp-compiler.h b/js/src/irregexp/imported/regexp-compiler.h
new file mode 100644
index 0000000000..91dd43ab8a
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-compiler.h
@@ -0,0 +1,621 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_COMPILER_H_
+#define V8_REGEXP_REGEXP_COMPILER_H_
+
+#include <bitset>
+
+#include "irregexp/imported/regexp-nodes.h"
+
+namespace v8 {
+namespace internal {
+
+class DynamicBitSet;
+class Isolate;
+
+namespace regexp_compiler_constants {
+
+// The '2' variant is has inclusive from and exclusive to.
+// This covers \s as defined in ECMA-262 5.1, 15.10.2.12,
+// which include WhiteSpace (7.2) or LineTerminator (7.3) values.
+constexpr base::uc32 kRangeEndMarker = 0x110000;
+constexpr int kSpaceRanges[] = {
+    '\t',   '\r' + 1, ' ',    ' ' + 1, 0x00A0, 0x00A1, 0x1680,
+    0x1681, 0x2000,   0x200B, 0x2028,  0x202A, 0x202F, 0x2030,
+    0x205F, 0x2060,   0x3000, 0x3001,  0xFEFF, 0xFF00, kRangeEndMarker};
+constexpr int kSpaceRangeCount = arraysize(kSpaceRanges);
+
+constexpr int kWordRanges[] = {'0',     '9' + 1, 'A',     'Z' + 1,        '_',
+                               '_' + 1, 'a',     'z' + 1, kRangeEndMarker};
+constexpr int kWordRangeCount = arraysize(kWordRanges);
+constexpr int kDigitRanges[] = {'0', '9' + 1, kRangeEndMarker};
+constexpr int kDigitRangeCount = arraysize(kDigitRanges);
+constexpr int kSurrogateRanges[] = {kLeadSurrogateStart,
+                                    kLeadSurrogateStart + 1, kRangeEndMarker};
+constexpr int kSurrogateRangeCount = arraysize(kSurrogateRanges);
+constexpr int kLineTerminatorRanges[] = {0x000A, 0x000B, 0x000D,         0x000E,
+                                         0x2028, 0x202A, kRangeEndMarker};
+constexpr int kLineTerminatorRangeCount = arraysize(kLineTerminatorRanges);
+
+// More makes code generation slower, less makes V8 benchmark score lower.
+constexpr int kMaxLookaheadForBoyerMoore = 8;
+// In a 3-character pattern you can maximally step forwards 3 characters
+// at a time, which is not always enough to pay for the extra logic.
+constexpr int kPatternTooShortForBoyerMoore = 2;
+
+}  // namespace regexp_compiler_constants
+
+inline bool NeedsUnicodeCaseEquivalents(RegExpFlags flags) {
+  // Both unicode (or unicode sets) and ignore_case flags are set. We need to
+  // use ICU to find the closure over case equivalents.
+  return IsEitherUnicode(flags) && IsIgnoreCase(flags);
+}
+
+// Details of a quick mask-compare check that can look ahead in the
+// input stream.
+class QuickCheckDetails {
+ public:
+  QuickCheckDetails()
+      : characters_(0), mask_(0), value_(0), cannot_match_(false) {}
+  explicit QuickCheckDetails(int characters)
+      : characters_(characters), mask_(0), value_(0), cannot_match_(false) {}
+  bool Rationalize(bool one_byte);
+  // Merge in the information from another branch of an alternation.
+  void Merge(QuickCheckDetails* other, int from_index);
+  // Advance the current position by some amount.
+  void Advance(int by, bool one_byte);
+  void Clear();
+  bool cannot_match() { return cannot_match_; }
+  void set_cannot_match() { cannot_match_ = true; }
+  struct Position {
+    Position() : mask(0), value(0), determines_perfectly(false) {}
+    base::uc32 mask;
+    base::uc32 value;
+    bool determines_perfectly;
+  };
+  int characters() { return characters_; }
+  void set_characters(int characters) { characters_ = characters; }
+  Position* positions(int index) {
+    DCHECK_LE(0, index);
+    DCHECK_GT(characters_, index);
+    return positions_ + index;
+  }
+  uint32_t mask() { return mask_; }
+  uint32_t value() { return value_; }
+
+ private:
+  // How many characters do we have quick check information from.  This is
+  // the same for all branches of a choice node.
+  int characters_;
+  Position positions_[4];
+  // These values are the condensate of the above array after Rationalize().
+  uint32_t mask_;
+  uint32_t value_;
+  // If set to true, there is no way this quick check can match at all.
+  // E.g., if it requires to be at the start of the input, and isn't.
+  bool cannot_match_;
+};
+
+// Improve the speed that we scan for an initial point where a non-anchored
+// regexp can match by using a Boyer-Moore-like table. This is done by
+// identifying non-greedy non-capturing loops in the nodes that eat any
+// character one at a time.  For example in the middle of the regexp
+// /foo[\s\S]*?bar/ we find such a loop.  There is also such a loop implicitly
+// inserted at the start of any non-anchored regexp.
+//
+// When we have found such a loop we look ahead in the nodes to find the set of
+// characters that can come at given distances. For example for the regexp
+// /.?foo/ we know that there are at least 3 characters ahead of us, and the
+// sets of characters that can occur are [any, [f, o], [o]]. We find a range in
+// the lookahead info where the set of characters is reasonably constrained. In
+// our example this is from index 1 to 2 (0 is not constrained). We can now
+// look 3 characters ahead and if we don't find one of [f, o] (the union of
+// [f, o] and [o]) then we can skip forwards by the range size (in this case 2).
+//
+// For Unicode input strings we do the same, but modulo 128.
+//
+// We also look at the first string fed to the regexp and use that to get a hint
+// of the character frequencies in the inputs. This affects the assessment of
+// whether the set of characters is 'reasonably constrained'.
+//
+// We also have another lookahead mechanism (called quick check in the code),
+// which uses a wide load of multiple characters followed by a mask and compare
+// to determine whether a match is possible at this point.
+enum ContainedInLattice {
+  kNotYet = 0,
+  kLatticeIn = 1,
+  kLatticeOut = 2,
+  kLatticeUnknown = 3  // Can also mean both in and out.
+};
+
+inline ContainedInLattice Combine(ContainedInLattice a, ContainedInLattice b) {
+  return static_cast<ContainedInLattice>(a | b);
+}
+
+class BoyerMoorePositionInfo : public ZoneObject {
+ public:
+  bool at(int i) const { return map_[i]; }
+
+  static constexpr int kMapSize = 128;
+  static constexpr int kMask = kMapSize - 1;
+
+  int map_count() const { return map_count_; }
+
+  void Set(int character);
+  void SetInterval(const Interval& interval);
+  void SetAll();
+
+  bool is_non_word() { return w_ == kLatticeOut; }
+  bool is_word() { return w_ == kLatticeIn; }
+
+  using Bitset = std::bitset<kMapSize>;
+  Bitset raw_bitset() const { return map_; }
+
+ private:
+  Bitset map_;
+  int map_count_ = 0;               // Number of set bits in the map.
+  ContainedInLattice w_ = kNotYet;  // The \w character class.
+};
+
+class BoyerMooreLookahead : public ZoneObject {
+ public:
+  BoyerMooreLookahead(int length, RegExpCompiler* compiler, Zone* zone);
+
+  int length() { return length_; }
+  int max_char() { return max_char_; }
+  RegExpCompiler* compiler() { return compiler_; }
+
+  int Count(int map_number) { return bitmaps_->at(map_number)->map_count(); }
+
+  BoyerMoorePositionInfo* at(int i) { return bitmaps_->at(i); }
+
+  void Set(int map_number, int character) {
+    if (character > max_char_) return;
+    BoyerMoorePositionInfo* info = bitmaps_->at(map_number);
+    info->Set(character);
+  }
+
+  void SetInterval(int map_number, const Interval& interval) {
+    if (interval.from() > max_char_) return;
+    BoyerMoorePositionInfo* info = bitmaps_->at(map_number);
+    if (interval.to() > max_char_) {
+      info->SetInterval(Interval(interval.from(), max_char_));
+    } else {
+      info->SetInterval(interval);
+    }
+  }
+
+  void SetAll(int map_number) { bitmaps_->at(map_number)->SetAll(); }
+
+  void SetRest(int from_map) {
+    for (int i = from_map; i < length_; i++) SetAll(i);
+  }
+  void EmitSkipInstructions(RegExpMacroAssembler* masm);
+
+ private:
+  // This is the value obtained by EatsAtLeast.  If we do not have at least this
+  // many characters left in the sample string then the match is bound to fail.
+  // Therefore it is OK to read a character this far ahead of the current match
+  // point.
+  int length_;
+  RegExpCompiler* compiler_;
+  // 0xff for Latin1, 0xffff for UTF-16.
+  int max_char_;
+  ZoneList<BoyerMoorePositionInfo*>* bitmaps_;
+
+  int GetSkipTable(int min_lookahead, int max_lookahead,
+                   Handle<ByteArray> boolean_skip_table);
+  bool FindWorthwhileInterval(int* from, int* to);
+  int FindBestInterval(int max_number_of_chars, int old_biggest_points,
+                       int* from, int* to);
+};
+
+// There are many ways to generate code for a node.  This class encapsulates
+// the current way we should be generating.  In other words it encapsulates
+// the current state of the code generator.  The effect of this is that we
+// generate code for paths that the matcher can take through the regular
+// expression.  A given node in the regexp can be code-generated several times
+// as it can be part of several traces.  For example for the regexp:
+// /foo(bar|ip)baz/ the code to match baz will be generated twice, once as part
+// of the foo-bar-baz trace and once as part of the foo-ip-baz trace.  The code
+// to match foo is generated only once (the traces have a common prefix).  The
+// code to store the capture is deferred and generated (twice) after the places
+// where baz has been matched.
+class Trace {
+ public:
+  // A value for a property that is either known to be true, know to be false,
+  // or not known.
+  enum TriBool { UNKNOWN = -1, FALSE_VALUE = 0, TRUE_VALUE = 1 };
+
+  class DeferredAction {
+   public:
+    DeferredAction(ActionNode::ActionType action_type, int reg)
+        : action_type_(action_type), reg_(reg), next_(nullptr) {}
+    DeferredAction* next() { return next_; }
+    bool Mentions(int reg);
+    int reg() { return reg_; }
+    ActionNode::ActionType action_type() { return action_type_; }
+
+   private:
+    ActionNode::ActionType action_type_;
+    int reg_;
+    DeferredAction* next_;
+    friend class Trace;
+  };
+
+  class DeferredCapture : public DeferredAction {
+   public:
+    DeferredCapture(int reg, bool is_capture, Trace* trace)
+        : DeferredAction(ActionNode::STORE_POSITION, reg),
+          cp_offset_(trace->cp_offset()),
+          is_capture_(is_capture) {}
+    int cp_offset() { return cp_offset_; }
+    bool is_capture() { return is_capture_; }
+
+   private:
+    int cp_offset_;
+    bool is_capture_;
+    void set_cp_offset(int cp_offset) { cp_offset_ = cp_offset; }
+  };
+
+  class DeferredSetRegisterForLoop : public DeferredAction {
+   public:
+    DeferredSetRegisterForLoop(int reg, int value)
+        : DeferredAction(ActionNode::SET_REGISTER_FOR_LOOP, reg),
+          value_(value) {}
+    int value() { return value_; }
+
+   private:
+    int value_;
+  };
+
+  class DeferredClearCaptures : public DeferredAction {
+   public:
+    explicit DeferredClearCaptures(Interval range)
+        : DeferredAction(ActionNode::CLEAR_CAPTURES, -1), range_(range) {}
+    Interval range() { return range_; }
+
+   private:
+    Interval range_;
+  };
+
+  class DeferredIncrementRegister : public DeferredAction {
+   public:
+    explicit DeferredIncrementRegister(int reg)
+        : DeferredAction(ActionNode::INCREMENT_REGISTER, reg) {}
+  };
+
+  Trace()
+      : cp_offset_(0),
+        actions_(nullptr),
+        backtrack_(nullptr),
+        stop_node_(nullptr),
+        loop_label_(nullptr),
+        characters_preloaded_(0),
+        bound_checked_up_to_(0),
+        flush_budget_(100),
+        at_start_(UNKNOWN) {}
+
+  // End the trace.  This involves flushing the deferred actions in the trace
+  // and pushing a backtrack location onto the backtrack stack.  Once this is
+  // done we can start a new trace or go to one that has already been
+  // generated.
+  void Flush(RegExpCompiler* compiler, RegExpNode* successor);
+  int cp_offset() { return cp_offset_; }
+  DeferredAction* actions() { return actions_; }
+  // A trivial trace is one that has no deferred actions or other state that
+  // affects the assumptions used when generating code.  There is no recorded
+  // backtrack location in a trivial trace, so with a trivial trace we will
+  // generate code that, on a failure to match, gets the backtrack location
+  // from the backtrack stack rather than using a direct jump instruction.  We
+  // always start code generation with a trivial trace and non-trivial traces
+  // are created as we emit code for nodes or add to the list of deferred
+  // actions in the trace.  The location of the code generated for a node using
+  // a trivial trace is recorded in a label in the node so that gotos can be
+  // generated to that code.
+  bool is_trivial() {
+    return backtrack_ == nullptr && actions_ == nullptr && cp_offset_ == 0 &&
+           characters_preloaded_ == 0 && bound_checked_up_to_ == 0 &&
+           quick_check_performed_.characters() == 0 && at_start_ == UNKNOWN;
+  }
+  TriBool at_start() { return at_start_; }
+  void set_at_start(TriBool at_start) { at_start_ = at_start; }
+  Label* backtrack() { return backtrack_; }
+  Label* loop_label() { return loop_label_; }
+  RegExpNode* stop_node() { return stop_node_; }
+  int characters_preloaded() { return characters_preloaded_; }
+  int bound_checked_up_to() { return bound_checked_up_to_; }
+  int flush_budget() { return flush_budget_; }
+  QuickCheckDetails* quick_check_performed() { return &quick_check_performed_; }
+  bool mentions_reg(int reg);
+  // Returns true if a deferred position store exists to the specified
+  // register and stores the offset in the out-parameter.  Otherwise
+  // returns false.
+  bool GetStoredPosition(int reg, int* cp_offset);
+  // These set methods and AdvanceCurrentPositionInTrace should be used only on
+  // new traces - the intention is that traces are immutable after creation.
+  void add_action(DeferredAction* new_action) {
+    DCHECK(new_action->next_ == nullptr);
+    new_action->next_ = actions_;
+    actions_ = new_action;
+  }
+  void set_backtrack(Label* backtrack) { backtrack_ = backtrack; }
+  void set_stop_node(RegExpNode* node) { stop_node_ = node; }
+  void set_loop_label(Label* label) { loop_label_ = label; }
+  void set_characters_preloaded(int count) { characters_preloaded_ = count; }
+  void set_bound_checked_up_to(int to) { bound_checked_up_to_ = to; }
+  void set_flush_budget(int to) { flush_budget_ = to; }
+  void set_quick_check_performed(QuickCheckDetails* d) {
+    quick_check_performed_ = *d;
+  }
+  void InvalidateCurrentCharacter();
+  void AdvanceCurrentPositionInTrace(int by, RegExpCompiler* compiler);
+
+ private:
+  int FindAffectedRegisters(DynamicBitSet* affected_registers, Zone* zone);
+  void PerformDeferredActions(RegExpMacroAssembler* macro, int max_register,
+                              const DynamicBitSet& affected_registers,
+                              DynamicBitSet* registers_to_pop,
+                              DynamicBitSet* registers_to_clear, Zone* zone);
+  void RestoreAffectedRegisters(RegExpMacroAssembler* macro, int max_register,
+                                const DynamicBitSet& registers_to_pop,
+                                const DynamicBitSet& registers_to_clear);
+  int cp_offset_;
+  DeferredAction* actions_;
+  Label* backtrack_;
+  RegExpNode* stop_node_;
+  Label* loop_label_;
+  int characters_preloaded_;
+  int bound_checked_up_to_;
+  QuickCheckDetails quick_check_performed_;
+  int flush_budget_;
+  TriBool at_start_;
+};
+
+class GreedyLoopState {
+ public:
+  explicit GreedyLoopState(bool not_at_start);
+
+  Label* label() { return &label_; }
+  Trace* counter_backtrack_trace() { return &counter_backtrack_trace_; }
+
+ private:
+  Label label_;
+  Trace counter_backtrack_trace_;
+};
+
+struct PreloadState {
+  static const int kEatsAtLeastNotYetInitialized = -1;
+  bool preload_is_current_;
+  bool preload_has_checked_bounds_;
+  int preload_characters_;
+  int eats_at_least_;
+  void init() { eats_at_least_ = kEatsAtLeastNotYetInitialized; }
+};
+
+// Analysis performs assertion propagation and computes eats_at_least_ values.
+// See the comments on AssertionPropagator and EatsAtLeastPropagator for more
+// details.
+RegExpError AnalyzeRegExp(Isolate* isolate, bool is_one_byte, RegExpFlags flags,
+                          RegExpNode* node);
+
+class FrequencyCollator {
+ public:
+  FrequencyCollator() : total_samples_(0) {
+    for (int i = 0; i < RegExpMacroAssembler::kTableSize; i++) {
+      frequencies_[i] = CharacterFrequency(i);
+    }
+  }
+
+  void CountCharacter(int character) {
+    int index = (character & RegExpMacroAssembler::kTableMask);
+    frequencies_[index].Increment();
+    total_samples_++;
+  }
+
+  // Does not measure in percent, but rather per-128 (the table size from the
+  // regexp macro assembler).
+  int Frequency(int in_character) {
+    DCHECK((in_character & RegExpMacroAssembler::kTableMask) == in_character);
+    if (total_samples_ < 1) return 1;  // Division by zero.
+    int freq_in_per128 =
+        (frequencies_[in_character].counter() * 128) / total_samples_;
+    return freq_in_per128;
+  }
+
+ private:
+  class CharacterFrequency {
+   public:
+    CharacterFrequency() : counter_(0), character_(-1) {}
+    explicit CharacterFrequency(int character)
+        : counter_(0), character_(character) {}
+
+    void Increment() { counter_++; }
+    int counter() { return counter_; }
+    int character() { return character_; }
+
+   private:
+    int counter_;
+    int character_;
+  };
+
+ private:
+  CharacterFrequency frequencies_[RegExpMacroAssembler::kTableSize];
+  int total_samples_;
+};
+
+class RegExpCompiler {
+ public:
+  RegExpCompiler(Isolate* isolate, Zone* zone, int capture_count,
+                 RegExpFlags flags, bool is_one_byte);
+
+  int AllocateRegister() {
+    if (next_register_ >= RegExpMacroAssembler::kMaxRegister) {
+      reg_exp_too_big_ = true;
+      return next_register_;
+    }
+    return next_register_++;
+  }
+
+  // Lookarounds to match lone surrogates for unicode character class matches
+  // are never nested. We can therefore reuse registers.
+  int UnicodeLookaroundStackRegister() {
+    if (unicode_lookaround_stack_register_ == kNoRegister) {
+      unicode_lookaround_stack_register_ = AllocateRegister();
+    }
+    return unicode_lookaround_stack_register_;
+  }
+
+  int UnicodeLookaroundPositionRegister() {
+    if (unicode_lookaround_position_register_ == kNoRegister) {
+      unicode_lookaround_position_register_ = AllocateRegister();
+    }
+    return unicode_lookaround_position_register_;
+  }
+
+  struct CompilationResult final {
+    explicit CompilationResult(RegExpError err) : error(err) {}
+    CompilationResult(Handle<Object> code, int registers)
+        : code(code), num_registers(registers) {}
+
+    static CompilationResult RegExpTooBig() {
+      return CompilationResult(RegExpError::kTooLarge);
+    }
+
+    bool Succeeded() const { return error == RegExpError::kNone; }
+
+    const RegExpError error = RegExpError::kNone;
+    Handle<Object> code;
+    int num_registers = 0;
+  };
+
+  CompilationResult Assemble(Isolate* isolate, RegExpMacroAssembler* assembler,
+                             RegExpNode* start, int capture_count,
+                             Handle<String> pattern);
+
+  // Preprocessing is the final step of node creation before analysis
+  // and assembly. It includes:
+  // - Wrapping the body of the regexp in capture 0.
+  // - Inserting the implicit .* before/after the regexp if necessary.
+  // - If the input is a one-byte string, filtering out nodes that can't match.
+  // - Fixing up regexp matches that start within a surrogate pair.
+  RegExpNode* PreprocessRegExp(RegExpCompileData* data, RegExpFlags flags,
+                               bool is_one_byte);
+
+  // If the regexp matching starts within a surrogate pair, step back to the
+  // lead surrogate and start matching from there.
+  RegExpNode* OptionallyStepBackToLeadSurrogate(RegExpNode* on_success);
+
+  inline void AddWork(RegExpNode* node) {
+    if (!node->on_work_list() && !node->label()->is_bound()) {
+      node->set_on_work_list(true);
+      work_list_->push_back(node);
+    }
+  }
+
+  static const int kImplementationOffset = 0;
+  static const int kNumberOfRegistersOffset = 0;
+  static const int kCodeOffset = 1;
+
+  RegExpMacroAssembler* macro_assembler() { return macro_assembler_; }
+  EndNode* accept() { return accept_; }
+
+  static const int kMaxRecursion = 100;
+  inline int recursion_depth() { return recursion_depth_; }
+  inline void IncrementRecursionDepth() { recursion_depth_++; }
+  inline void DecrementRecursionDepth() { recursion_depth_--; }
+
+  RegExpFlags flags() const { return flags_; }
+
+  void SetRegExpTooBig() { reg_exp_too_big_ = true; }
+
+  inline bool one_byte() { return one_byte_; }
+  inline bool optimize() { return optimize_; }
+  inline void set_optimize(bool value) { optimize_ = value; }
+  inline bool limiting_recursion() { return limiting_recursion_; }
+  inline void set_limiting_recursion(bool value) {
+    limiting_recursion_ = value;
+  }
+  bool read_backward() { return read_backward_; }
+  void set_read_backward(bool value) { read_backward_ = value; }
+  FrequencyCollator* frequency_collator() { return &frequency_collator_; }
+
+  int current_expansion_factor() { return current_expansion_factor_; }
+  void set_current_expansion_factor(int value) {
+    current_expansion_factor_ = value;
+  }
+
+  // The recursive nature of ToNode node generation means we may run into stack
+  // overflow issues. We introduce periodic checks to detect these, and the
+  // tick counter helps limit overhead of these checks.
+  // TODO(jgruber): This is super hacky and should be replaced by an abort
+  // mechanism or iterative node generation.
+  void ToNodeMaybeCheckForStackOverflow() {
+    if ((to_node_overflow_check_ticks_++ % 16 == 0)) {
+      ToNodeCheckForStackOverflow();
+    }
+  }
+  void ToNodeCheckForStackOverflow();
+
+  Isolate* isolate() const { return isolate_; }
+  Zone* zone() const { return zone_; }
+
+  static const int kNoRegister = -1;
+
+ private:
+  EndNode* accept_;
+  int next_register_;
+  int unicode_lookaround_stack_register_;
+  int unicode_lookaround_position_register_;
+  ZoneVector<RegExpNode*>* work_list_;
+  int recursion_depth_;
+  const RegExpFlags flags_;
+  RegExpMacroAssembler* macro_assembler_;
+  bool one_byte_;
+  bool reg_exp_too_big_;
+  bool limiting_recursion_;
+  int to_node_overflow_check_ticks_ = 0;
+  bool optimize_;
+  bool read_backward_;
+  int current_expansion_factor_;
+  FrequencyCollator frequency_collator_;
+  Isolate* isolate_;
+  Zone* zone_;
+};
+
+// Categorizes character ranges into BMP, non-BMP, lead, and trail surrogates.
+class UnicodeRangeSplitter {
+ public:
+  V8_EXPORT_PRIVATE UnicodeRangeSplitter(ZoneList<CharacterRange>* base);
+
+  static constexpr int kInitialSize = 8;
+  using CharacterRangeVector = base::SmallVector<CharacterRange, kInitialSize>;
+
+  const CharacterRangeVector* bmp() const { return &bmp_; }
+  const CharacterRangeVector* lead_surrogates() const {
+    return &lead_surrogates_;
+  }
+  const CharacterRangeVector* trail_surrogates() const {
+    return &trail_surrogates_;
+  }
+  const CharacterRangeVector* non_bmp() const { return &non_bmp_; }
+
+ private:
+  void AddRange(CharacterRange range);
+
+  CharacterRangeVector bmp_;
+  CharacterRangeVector lead_surrogates_;
+  CharacterRangeVector trail_surrogates_;
+  CharacterRangeVector non_bmp_;
+};
+
+// We need to check for the following characters: 0x39C 0x3BC 0x178.
+// TODO(jgruber): Move to CharacterRange.
+bool RangeContainsLatin1Equivalents(CharacterRange range);
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_COMPILER_H_
diff --git a/js/src/irregexp/imported/regexp-dotprinter.cc b/js/src/irregexp/imported/regexp-dotprinter.cc
new file mode 100644
index 0000000000..6746992a0a
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-dotprinter.cc
@@ -0,0 +1,249 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "irregexp/imported/regexp-dotprinter.h"
+
+#include "irregexp/imported/regexp-compiler.h"
+
+namespace v8 {
+namespace internal {
+
+// -------------------------------------------------------------------
+// Dot/dotty output
+
+class DotPrinterImpl : public NodeVisitor {
+ public:
+  explicit DotPrinterImpl(std::ostream& os) : os_(os) {}
+  void PrintNode(const char* label, RegExpNode* node);
+  void Visit(RegExpNode* node);
+  void PrintAttributes(RegExpNode* from);
+  void PrintOnFailure(RegExpNode* from, RegExpNode* to);
+#define DECLARE_VISIT(Type) virtual void Visit##Type(Type##Node* that);
+  FOR_EACH_NODE_TYPE(DECLARE_VISIT)
+#undef DECLARE_VISIT
+ private:
+  std::ostream& os_;
+};
+
+void DotPrinterImpl::PrintNode(const char* label, RegExpNode* node) {
+  os_ << "digraph G {\n  graph [label=\"";
+  for (int i = 0; label[i]; i++) {
+    switch (label[i]) {
+      case '\\':
+        os_ << "\\\\";
+        break;
+      case '"':
+        os_ << "\"";
+        break;
+      default:
+        os_ << label[i];
+        break;
+    }
+  }
+  os_ << "\"];\n";
+  Visit(node);
+  os_ << "}" << std::endl;
+}
+
+void DotPrinterImpl::Visit(RegExpNode* node) {
+  if (node->info()->visited) return;
+  node->info()->visited = true;
+  node->Accept(this);
+}
+
+void DotPrinterImpl::PrintOnFailure(RegExpNode* from, RegExpNode* on_failure) {
+  os_ << "  n" << from << " -> n" << on_failure << " [style=dotted];\n";
+  Visit(on_failure);
+}
+
+class AttributePrinter {
+ public:
+  explicit AttributePrinter(std::ostream& os) : os_(os), first_(true) {}
+  void PrintSeparator() {
+    if (first_) {
+      first_ = false;
+    } else {
+      os_ << "|";
+    }
+  }
+  void PrintBit(const char* name, bool value) {
+    if (!value) return;
+    PrintSeparator();
+    os_ << "{" << name << "}";
+  }
+  void PrintPositive(const char* name, int value) {
+    if (value < 0) return;
+    PrintSeparator();
+    os_ << "{" << name << "|" << value << "}";
+  }
+
+ private:
+  std::ostream& os_;
+  bool first_;
+};
+
+void DotPrinterImpl::PrintAttributes(RegExpNode* that) {
+  os_ << "  a" << that << " [shape=Mrecord, color=grey, fontcolor=grey, "
+      << "margin=0.1, fontsize=10, label=\"{";
+  AttributePrinter printer(os_);
+  NodeInfo* info = that->info();
+  printer.PrintBit("NI", info->follows_newline_interest);
+  printer.PrintBit("WI", info->follows_word_interest);
+  printer.PrintBit("SI", info->follows_start_interest);
+  Label* label = that->label();
+  if (label->is_bound()) printer.PrintPositive("@", label->pos());
+  os_ << "}\"];\n"
+      << "  a" << that << " -> n" << that
+      << " [style=dashed, color=grey, arrowhead=none];\n";
+}
+
+void DotPrinterImpl::VisitChoice(ChoiceNode* that) {
+  os_ << "  n" << that << " [shape=Mrecord, label=\"?\"];\n";
+  for (int i = 0; i < that->alternatives()->length(); i++) {
+    GuardedAlternative alt = that->alternatives()->at(i);
+    os_ << "  n" << that << " -> n" << alt.node();
+  }
+  for (int i = 0; i < that->alternatives()->length(); i++) {
+    GuardedAlternative alt = that->alternatives()->at(i);
+    alt.node()->Accept(this);
+  }
+}
+
+void DotPrinterImpl::VisitLoopChoice(LoopChoiceNode* that) {
+  VisitChoice(that);
+}
+
+void DotPrinterImpl::VisitNegativeLookaroundChoice(
+    NegativeLookaroundChoiceNode* that) {
+  VisitChoice(that);
+}
+
+void DotPrinterImpl::VisitText(TextNode* that) {
+  Zone* zone = that->zone();
+  os_ << "  n" << that << " [label=\"";
+  for (int i = 0; i < that->elements()->length(); i++) {
+    if (i > 0) os_ << " ";
+    TextElement elm = that->elements()->at(i);
+    switch (elm.text_type()) {
+      case TextElement::ATOM: {
+        base::Vector<const base::uc16> data = elm.atom()->data();
+        for (int j = 0; j < data.length(); j++) {
+          os_ << static_cast<char>(data[j]);
+        }
+        break;
+      }
+      case TextElement::CLASS_RANGES: {
+        RegExpClassRanges* node = elm.class_ranges();
+        os_ << "[";
+        if (node->is_negated()) os_ << "^";
+        for (int j = 0; j < node->ranges(zone)->length(); j++) {
+          CharacterRange range = node->ranges(zone)->at(j);
+          os_ << AsUC32(range.from()) << "-" << AsUC32(range.to());
+        }
+        os_ << "]";
+        break;
+      }
+      default:
+        UNREACHABLE();
+    }
+  }
+  os_ << "\", shape=box, peripheries=2];\n";
+  PrintAttributes(that);
+  os_ << "  n" << that << " -> n" << that->on_success() << ";\n";
+  Visit(that->on_success());
+}
+
+void DotPrinterImpl::VisitBackReference(BackReferenceNode* that) {
+  os_ << "  n" << that << " [label=\"$" << that->start_register() << "..$"
+      << that->end_register() << "\", shape=doubleoctagon];\n";
+  PrintAttributes(that);
+  os_ << "  n" << that << " -> n" << that->on_success() << ";\n";
+  Visit(that->on_success());
+}
+
+void DotPrinterImpl::VisitEnd(EndNode* that) {
+  os_ << "  n" << that << " [style=bold, shape=point];\n";
+  PrintAttributes(that);
+}
+
+void DotPrinterImpl::VisitAssertion(AssertionNode* that) {
+  os_ << "  n" << that << " [";
+  switch (that->assertion_type()) {
+    case AssertionNode::AT_END:
+      os_ << "label=\"$\", shape=septagon";
+      break;
+    case AssertionNode::AT_START:
+      os_ << "label=\"^\", shape=septagon";
+      break;
+    case AssertionNode::AT_BOUNDARY:
+      os_ << "label=\"\\b\", shape=septagon";
+      break;
+    case AssertionNode::AT_NON_BOUNDARY:
+      os_ << "label=\"\\B\", shape=septagon";
+      break;
+    case AssertionNode::AFTER_NEWLINE:
+      os_ << "label=\"(?<=\\n)\", shape=septagon";
+      break;
+  }
+  os_ << "];\n";
+  PrintAttributes(that);
+  RegExpNode* successor = that->on_success();
+  os_ << "  n" << that << " -> n" << successor << ";\n";
+  Visit(successor);
+}
+
+void DotPrinterImpl::VisitAction(ActionNode* that) {
+  os_ << "  n" << that << " [";
+  switch (that->action_type_) {
+    case ActionNode::SET_REGISTER_FOR_LOOP:
+      os_ << "label=\"$" << that->data_.u_store_register.reg
+          << ":=" << that->data_.u_store_register.value << "\", shape=octagon";
+      break;
+    case ActionNode::INCREMENT_REGISTER:
+      os_ << "label=\"$" << that->data_.u_increment_register.reg
+          << "++\", shape=octagon";
+      break;
+    case ActionNode::STORE_POSITION:
+      os_ << "label=\"$" << that->data_.u_position_register.reg
+          << ":=$pos\", shape=octagon";
+      break;
+    case ActionNode::BEGIN_POSITIVE_SUBMATCH:
+      os_ << "label=\"$" << that->data_.u_submatch.current_position_register
+          << ":=$pos,begin-positive\", shape=septagon";
+      break;
+    case ActionNode::BEGIN_NEGATIVE_SUBMATCH:
+      os_ << "label=\"$" << that->data_.u_submatch.current_position_register
+          << ":=$pos,begin-negative\", shape=septagon";
+      break;
+    case ActionNode::POSITIVE_SUBMATCH_SUCCESS:
+      os_ << "label=\"escape\", shape=septagon";
+      break;
+    case ActionNode::EMPTY_MATCH_CHECK:
+      os_ << "label=\"$" << that->data_.u_empty_match_check.start_register
+          << "=$pos?,$" << that->data_.u_empty_match_check.repetition_register
+          << "<" << that->data_.u_empty_match_check.repetition_limit
+          << "?\", shape=septagon";
+      break;
+    case ActionNode::CLEAR_CAPTURES: {
+      os_ << "label=\"clear $" << that->data_.u_clear_captures.range_from
+          << " to $" << that->data_.u_clear_captures.range_to
+          << "\", shape=septagon";
+      break;
+    }
+  }
+  os_ << "];\n";
+  PrintAttributes(that);
+  RegExpNode* successor = that->on_success();
+  os_ << "  n" << that << " -> n" << successor << ";\n";
+  Visit(successor);
+}
+
+void DotPrinter::DotPrint(const char* label, RegExpNode* node) {
+  StdoutStream os;
+  DotPrinterImpl printer(os);
+  printer.PrintNode(label, node);
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/irregexp/imported/regexp-dotprinter.h b/js/src/irregexp/imported/regexp-dotprinter.h
new file mode 100644
index 0000000000..7fcece6e1a
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-dotprinter.h
@@ -0,0 +1,23 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_DOTPRINTER_H_
+#define V8_REGEXP_REGEXP_DOTPRINTER_H_
+
+#include "irregexp/RegExpShim.h"
+
+namespace v8 {
+namespace internal {
+
+class RegExpNode;
+
+class DotPrinter final : public AllStatic {
+ public:
+  static void DotPrint(const char* label, RegExpNode* node);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_DOTPRINTER_H_
diff --git a/js/src/irregexp/imported/regexp-error.cc b/js/src/irregexp/imported/regexp-error.cc
new file mode 100644
index 0000000000..d0b4c263a4
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-error.cc
@@ -0,0 +1,22 @@
+// Copyright 2020 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "irregexp/imported/regexp-error.h"
+
+namespace v8 {
+namespace internal {
+
+const char* const kRegExpErrorStrings[] = {
+#define TEMPLATE(NAME, STRING) STRING,
+    REGEXP_ERROR_MESSAGES(TEMPLATE)
+#undef TEMPLATE
+};
+
+const char* RegExpErrorString(RegExpError error) {
+  DCHECK_LT(error, RegExpError::NumErrors);
+  return kRegExpErrorStrings[static_cast<int>(error)];
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/irregexp/imported/regexp-error.h b/js/src/irregexp/imported/regexp-error.h
new file mode 100644
index 0000000000..ff4fe41cd5
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-error.h
@@ -0,0 +1,67 @@
+// Copyright 2020 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_ERROR_H_
+#define V8_REGEXP_REGEXP_ERROR_H_
+
+#include "irregexp/RegExpShim.h"
+
+namespace v8 {
+namespace internal {
+
+#define REGEXP_ERROR_MESSAGES(T)                                          \
+  T(None, "")                                                             \
+  T(StackOverflow, "Maximum call stack size exceeded")                    \
+  T(AnalysisStackOverflow, "Stack overflow")                              \
+  T(TooLarge, "Regular expression too large")                             \
+  T(UnterminatedGroup, "Unterminated group")                              \
+  T(UnmatchedParen, "Unmatched ')'")                                      \
+  T(EscapeAtEndOfPattern, "\\ at end of pattern")                         \
+  T(InvalidPropertyName, "Invalid property name")                         \
+  T(InvalidEscape, "Invalid escape")                                      \
+  T(InvalidDecimalEscape, "Invalid decimal escape")                       \
+  T(InvalidUnicodeEscape, "Invalid Unicode escape")                       \
+  T(NothingToRepeat, "Nothing to repeat")                                 \
+  T(LoneQuantifierBrackets, "Lone quantifier brackets")                   \
+  T(RangeOutOfOrder, "numbers out of order in {} quantifier")             \
+  T(IncompleteQuantifier, "Incomplete quantifier")                        \
+  T(InvalidQuantifier, "Invalid quantifier")                              \
+  T(InvalidGroup, "Invalid group")                                        \
+  T(MultipleFlagDashes, "Multiple dashes in flag group")                  \
+  T(NotLinear, "Cannot be executed in linear time")                       \
+  T(RepeatedFlag, "Repeated flag in flag group")                          \
+  T(InvalidFlagGroup, "Invalid flag group")                               \
+  T(TooManyCaptures, "Too many captures")                                 \
+  T(InvalidCaptureGroupName, "Invalid capture group name")                \
+  T(DuplicateCaptureGroupName, "Duplicate capture group name")            \
+  T(InvalidNamedReference, "Invalid named reference")                     \
+  T(InvalidNamedCaptureReference, "Invalid named capture referenced")     \
+  T(InvalidClassEscape, "Invalid class escape")                           \
+  T(InvalidClassPropertyName, "Invalid property name in character class") \
+  T(InvalidCharacterClass, "Invalid character class")                     \
+  T(UnterminatedCharacterClass, "Unterminated character class")           \
+  T(OutOfOrderCharacterClass, "Range out of order in character class")    \
+  T(InvalidClassSetOperation, "Invalid set operation in character class") \
+  T(InvalidCharacterInClass, "Invalid character in character class")      \
+  T(NegatedCharacterClassWithStrings,                                     \
+    "Negated character class may contain strings")
+
+enum class RegExpError : uint32_t {
+#define TEMPLATE(NAME, STRING) k##NAME,
+  REGEXP_ERROR_MESSAGES(TEMPLATE)
+#undef TEMPLATE
+      NumErrors
+};
+
+V8_EXPORT_PRIVATE const char* RegExpErrorString(RegExpError error);
+
+inline constexpr bool RegExpErrorIsStackOverflow(RegExpError error) {
+  return error == RegExpError::kStackOverflow ||
+         error == RegExpError::kAnalysisStackOverflow;
+}
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_ERROR_H_
diff --git a/js/src/irregexp/imported/regexp-interpreter.cc b/js/src/irregexp/imported/regexp-interpreter.cc
new file mode 100644
index 0000000000..859fa53c0b
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-interpreter.cc
@@ -0,0 +1,1147 @@
+// Copyright 2011 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// A simple interpreter for the Irregexp byte code.
+
+#include "irregexp/imported/regexp-interpreter.h"
+
+#include "irregexp/imported/regexp-bytecodes.h"
+#include "irregexp/imported/regexp-macro-assembler.h"
+#include "irregexp/imported/regexp-stack.h"  // For kMaximumStackSize.
+#include "irregexp/imported/regexp.h"
+
+#ifdef V8_INTL_SUPPORT
+#include "unicode/uchar.h"
+#endif  // V8_INTL_SUPPORT
+
+// Use token threaded dispatch iff the compiler supports computed gotos and the
+// build argument v8_enable_regexp_interpreter_threaded_dispatch was set.
+#if V8_HAS_COMPUTED_GOTO && \
+    defined(V8_ENABLE_REGEXP_INTERPRETER_THREADED_DISPATCH)
+#define V8_USE_COMPUTED_GOTO 1
+#endif  // V8_HAS_COMPUTED_GOTO
+
+namespace v8 {
+namespace internal {
+
+namespace {
+
+bool BackRefMatchesNoCase(Isolate* isolate, int from, int current, int len,
+                          base::Vector<const base::uc16> subject,
+                          bool unicode) {
+  Address offset_a =
+      reinterpret_cast<Address>(const_cast<base::uc16*>(&subject.at(from)));
+  Address offset_b =
+      reinterpret_cast<Address>(const_cast<base::uc16*>(&subject.at(current)));
+  size_t length = len * base::kUC16Size;
+
+  bool result = unicode
+                    ? RegExpMacroAssembler::CaseInsensitiveCompareUnicode(
+                          offset_a, offset_b, length, isolate)
+                    : RegExpMacroAssembler::CaseInsensitiveCompareNonUnicode(
+                          offset_a, offset_b, length, isolate);
+  return result == 1;
+}
+
+bool BackRefMatchesNoCase(Isolate* isolate, int from, int current, int len,
+                          base::Vector<const uint8_t> subject, bool unicode) {
+  // For Latin1 characters the unicode flag makes no difference.
+  for (int i = 0; i < len; i++) {
+    unsigned int old_char = subject[from++];
+    unsigned int new_char = subject[current++];
+    if (old_char == new_char) continue;
+    // Convert both characters to lower case.
+    old_char |= 0x20;
+    new_char |= 0x20;
+    if (old_char != new_char) return false;
+    // Not letters in the ASCII range and Latin-1 range.
+    if (!(old_char - 'a' <= 'z' - 'a') &&
+        !(old_char - 224 <= 254 - 224 && old_char != 247)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+#ifdef DEBUG
+void MaybeTraceInterpreter(const byte* code_base, const byte* pc,
+                           int stack_depth, int current_position,
+                           uint32_t current_char, int bytecode_length,
+                           const char* bytecode_name) {
+  if (v8_flags.trace_regexp_bytecodes) {
+    const bool printable = std::isprint(current_char);
+    const char* format =
+        printable
+            ? "pc = %02x, sp = %d, curpos = %d, curchar = %08x (%c), bc = "
+            : "pc = %02x, sp = %d, curpos = %d, curchar = %08x .%c., bc = ";
+    PrintF(format, pc - code_base, stack_depth, current_position, current_char,
+           printable ? current_char : '.');
+
+    RegExpBytecodeDisassembleSingle(code_base, pc);
+  }
+}
+#endif  // DEBUG
+
+int32_t Load32Aligned(const byte* pc) {
+  DCHECK_EQ(0, reinterpret_cast<intptr_t>(pc) & 3);
+  return *reinterpret_cast<const int32_t*>(pc);
+}
+
+// TODO(jgruber): Rename to Load16AlignedUnsigned.
+uint32_t Load16Aligned(const byte* pc) {
+  DCHECK_EQ(0, reinterpret_cast<intptr_t>(pc) & 1);
+  return *reinterpret_cast<const uint16_t*>(pc);
+}
+
+int32_t Load16AlignedSigned(const byte* pc) {
+  DCHECK_EQ(0, reinterpret_cast<intptr_t>(pc) & 1);
+  return *reinterpret_cast<const int16_t*>(pc);
+}
+
+// Helpers to access the packed argument. Takes the 32 bits containing the
+// current bytecode, where the 8 LSB contain the bytecode and the rest contains
+// a packed 24-bit argument.
+// TODO(jgruber): Specify signed-ness in bytecode signature declarations, and
+// police restrictions during bytecode generation.
+int32_t LoadPacked24Signed(int32_t bytecode_and_packed_arg) {
+  return bytecode_and_packed_arg >> BYTECODE_SHIFT;
+}
+uint32_t LoadPacked24Unsigned(int32_t bytecode_and_packed_arg) {
+  return static_cast<uint32_t>(bytecode_and_packed_arg) >> BYTECODE_SHIFT;
+}
+
+// A simple abstraction over the backtracking stack used by the interpreter.
+//
+// Despite the name 'backtracking' stack, it's actually used as a generic stack
+// that stores both program counters (= offsets into the bytecode) and generic
+// integer values.
+class BacktrackStack {
+ public:
+  BacktrackStack() = default;
+  BacktrackStack(const BacktrackStack&) = delete;
+  BacktrackStack& operator=(const BacktrackStack&) = delete;
+
+  V8_WARN_UNUSED_RESULT bool push(int v) {
+    data_.emplace_back(v);
+    return (static_cast<int>(data_.size()) <= kMaxSize);
+  }
+  int peek() const {
+    DCHECK(!data_.empty());
+    return data_.back();
+  }
+  int pop() {
+    int v = peek();
+    data_.pop_back();
+    return v;
+  }
+
+  // The 'sp' is the index of the first empty element in the stack.
+  int sp() const { return static_cast<int>(data_.size()); }
+  void set_sp(int new_sp) {
+    DCHECK_LE(new_sp, sp());
+    data_.resize_no_init(new_sp);
+  }
+
+ private:
+  // Semi-arbitrary. Should be large enough for common cases to remain in the
+  // static stack-allocated backing store, but small enough not to waste space.
+  static constexpr int kStaticCapacity = 64;
+
+  using ValueT = int;
+  base::SmallVector<ValueT, kStaticCapacity> data_;
+
+  static constexpr int kMaxSize =
+      RegExpStack::kMaximumStackSize / sizeof(ValueT);
+};
+
+// Registers used during interpreter execution. These consist of output
+// registers in indices [0, output_register_count[ which will contain matcher
+// results as a {start,end} index tuple for each capture (where the whole match
+// counts as implicit capture 0); and internal registers in indices
+// [output_register_count, total_register_count[.
+class InterpreterRegisters {
+ public:
+  using RegisterT = int;
+
+  InterpreterRegisters(int total_register_count, RegisterT* output_registers,
+                       int output_register_count)
+      : registers_(total_register_count),
+        output_registers_(output_registers),
+        output_register_count_(output_register_count) {
+    // TODO(jgruber): Use int32_t consistently for registers. Currently, CSA
+    // uses int32_t while runtime uses int.
+    static_assert(sizeof(int) == sizeof(int32_t));
+    DCHECK_GE(output_register_count, 2);  // At least 2 for the match itself.
+    DCHECK_GE(total_register_count, output_register_count);
+    DCHECK_LE(total_register_count, RegExpMacroAssembler::kMaxRegisterCount);
+    DCHECK_NOT_NULL(output_registers);
+
+    // Initialize the output register region to -1 signifying 'no match'.
+    std::memset(registers_.data(), -1,
+                output_register_count * sizeof(RegisterT));
+  }
+
+  const RegisterT& operator[](size_t index) const { return registers_[index]; }
+  RegisterT& operator[](size_t index) { return registers_[index]; }
+
+  void CopyToOutputRegisters() {
+    MemCopy(output_registers_, registers_.data(),
+            output_register_count_ * sizeof(RegisterT));
+  }
+
+ private:
+  static constexpr int kStaticCapacity = 64;  // Arbitrary.
+  base::SmallVector<RegisterT, kStaticCapacity> registers_;
+  RegisterT* const output_registers_;
+  const int output_register_count_;
+};
+
+IrregexpInterpreter::Result ThrowStackOverflow(Isolate* isolate,
+                                               RegExp::CallOrigin call_origin) {
+  CHECK(call_origin == RegExp::CallOrigin::kFromRuntime);
+  // We abort interpreter execution after the stack overflow is thrown, and thus
+  // allow allocation here despite the outer DisallowGarbageCollectionScope.
+  AllowGarbageCollection yes_gc;
+  isolate->StackOverflow();
+  return IrregexpInterpreter::EXCEPTION;
+}
+
+// Only throws if called from the runtime, otherwise just returns the EXCEPTION
+// status code.
+IrregexpInterpreter::Result MaybeThrowStackOverflow(
+    Isolate* isolate, RegExp::CallOrigin call_origin) {
+  if (call_origin == RegExp::CallOrigin::kFromRuntime) {
+    return ThrowStackOverflow(isolate, call_origin);
+  } else {
+    return IrregexpInterpreter::EXCEPTION;
+  }
+}
+
+template <typename Char>
+void UpdateCodeAndSubjectReferences(
+    Isolate* isolate, Handle<ByteArray> code_array,
+    Handle<String> subject_string, ByteArray* code_array_out,
+    const byte** code_base_out, const byte** pc_out, String* subject_string_out,
+    base::Vector<const Char>* subject_string_vector_out) {
+  DisallowGarbageCollection no_gc;
+
+  if (*code_base_out != code_array->GetDataStartAddress()) {
+    *code_array_out = *code_array;
+    const intptr_t pc_offset = *pc_out - *code_base_out;
+    DCHECK_GT(pc_offset, 0);
+    *code_base_out = code_array->GetDataStartAddress();
+    *pc_out = *code_base_out + pc_offset;
+  }
+
+  DCHECK(subject_string->IsFlat());
+  *subject_string_out = *subject_string;
+  *subject_string_vector_out = subject_string->GetCharVector<Char>(no_gc);
+}
+
+// Runs all pending interrupts and updates unhandlified object references if
+// necessary.
+template <typename Char>
+IrregexpInterpreter::Result HandleInterrupts(
+    Isolate* isolate, RegExp::CallOrigin call_origin, ByteArray* code_array_out,
+    String* subject_string_out, const byte** code_base_out,
+    base::Vector<const Char>* subject_string_vector_out, const byte** pc_out) {
+  DisallowGarbageCollection no_gc;
+
+  StackLimitCheck check(isolate);
+  bool js_has_overflowed = check.JsHasOverflowed();
+
+  if (call_origin == RegExp::CallOrigin::kFromJs) {
+    // Direct calls from JavaScript can be interrupted in two ways:
+    // 1. A real stack overflow, in which case we let the caller throw the
+    //    exception.
+    // 2. The stack guard was used to interrupt execution for another purpose,
+    //    forcing the call through the runtime system.
+    if (js_has_overflowed) {
+      return IrregexpInterpreter::EXCEPTION;
+    } else if (check.InterruptRequested()) {
+      return IrregexpInterpreter::RETRY;
+    }
+  } else {
+    DCHECK(call_origin == RegExp::CallOrigin::kFromRuntime);
+    // Prepare for possible GC.
+    HandleScope handles(isolate);
+    Handle<ByteArray> code_handle(*code_array_out, isolate);
+    Handle<String> subject_handle(*subject_string_out, isolate);
+
+    if (js_has_overflowed) {
+      return ThrowStackOverflow(isolate, call_origin);
+    } else if (check.InterruptRequested()) {
+      const bool was_one_byte =
+          String::IsOneByteRepresentationUnderneath(*subject_string_out);
+      Object result;
+      {
+        AllowGarbageCollection yes_gc;
+        result = isolate->stack_guard()->HandleInterrupts();
+      }
+      if (result.IsException(isolate)) {
+        return IrregexpInterpreter::EXCEPTION;
+      }
+
+      // If we changed between a LATIN1 and a UC16 string, we need to
+      // restart regexp matching with the appropriate template instantiation of
+      // RawMatch.
+      if (String::IsOneByteRepresentationUnderneath(*subject_handle) !=
+          was_one_byte) {
+        return IrregexpInterpreter::RETRY;
+      }
+
+      UpdateCodeAndSubjectReferences(
+          isolate, code_handle, subject_handle, code_array_out, code_base_out,
+          pc_out, subject_string_out, subject_string_vector_out);
+    }
+  }
+
+  return IrregexpInterpreter::SUCCESS;
+}
+
+bool CheckBitInTable(const uint32_t current_char, const byte* const table) {
+  int mask = RegExpMacroAssembler::kTableMask;
+  int b = table[(current_char & mask) >> kBitsPerByteLog2];
+  int bit = (current_char & (kBitsPerByte - 1));
+  return (b & (1 << bit)) != 0;
+}
+
+// Returns true iff 0 <= index < length.
+bool IndexIsInBounds(int index, int length) {
+  DCHECK_GE(length, 0);
+  return static_cast<uintptr_t>(index) < static_cast<uintptr_t>(length);
+}
+
+// If computed gotos are supported by the compiler, we can get addresses to
+// labels directly in C/C++. Every bytecode handler has its own label and we
+// store the addresses in a dispatch table indexed by bytecode. To execute the
+// next handler we simply jump (goto) directly to its address.
+#if V8_USE_COMPUTED_GOTO
+#define BC_LABEL(name) BC_##name:
+#define DECODE()                                                   \
+  do {                                                             \
+    next_insn = Load32Aligned(next_pc);                            \
+    next_handler_addr = dispatch_table[next_insn & BYTECODE_MASK]; \
+  } while (false)
+#define DISPATCH()  \
+  pc = next_pc;     \
+  insn = next_insn; \
+  goto* next_handler_addr
+// Without computed goto support, we fall back to a simple switch-based
+// dispatch (A large switch statement inside a loop with a case for every
+// bytecode).
+#else  // V8_USE_COMPUTED_GOTO
+#define BC_LABEL(name) case BC_##name:
+#define DECODE() next_insn = Load32Aligned(next_pc)
+#define DISPATCH()  \
+  pc = next_pc;     \
+  insn = next_insn; \
+  goto switch_dispatch_continuation
+#endif  // V8_USE_COMPUTED_GOTO
+
+// ADVANCE/SET_PC_FROM_OFFSET are separated from DISPATCH, because ideally some
+// instructions can be executed between ADVANCE/SET_PC_FROM_OFFSET and DISPATCH.
+// We want those two macros as far apart as possible, because the goto in
+// DISPATCH is dependent on a memory load in ADVANCE/SET_PC_FROM_OFFSET. If we
+// don't hit the cache and have to fetch the next handler address from physical
+// memory, instructions between ADVANCE/SET_PC_FROM_OFFSET and DISPATCH can
+// potentially be executed unconditionally, reducing memory stall.
+#define ADVANCE(name)                             \
+  next_pc = pc + RegExpBytecodeLength(BC_##name); \
+  DECODE()
+#define SET_PC_FROM_OFFSET(offset) \
+  next_pc = code_base + offset;    \
+  DECODE()
+
+// Current position mutations.
+#define SET_CURRENT_POSITION(value)                        \
+  do {                                                     \
+    current = (value);                                     \
+    DCHECK(base::IsInRange(current, 0, subject.length())); \
+  } while (false)
+#define ADVANCE_CURRENT_POSITION(by) SET_CURRENT_POSITION(current + (by))
+
+#ifdef DEBUG
+#define BYTECODE(name)                                                \
+  BC_LABEL(name)                                                      \
+  MaybeTraceInterpreter(code_base, pc, backtrack_stack.sp(), current, \
+                        current_char, RegExpBytecodeLength(BC_##name), #name);
+#else
+#define BYTECODE(name) BC_LABEL(name)
+#endif  // DEBUG
+
+template <typename Char>
+IrregexpInterpreter::Result RawMatch(
+    Isolate* isolate, ByteArray code_array, String subject_string,
+    base::Vector<const Char> subject, int* output_registers,
+    int output_register_count, int total_register_count, int current,
+    uint32_t current_char, RegExp::CallOrigin call_origin,
+    const uint32_t backtrack_limit) {
+  DisallowGarbageCollection no_gc;
+
+#if V8_USE_COMPUTED_GOTO
+
+// We have to make sure that no OOB access to the dispatch table is possible and
+// all values are valid label addresses.
+// Otherwise jumps to arbitrary addresses could potentially happen.
+// This is ensured as follows:
+// Every index to the dispatch table gets masked using BYTECODE_MASK in
+// DECODE(). This way we can only get values between 0 (only the least
+// significant byte of an integer is used) and kRegExpPaddedBytecodeCount - 1
+// (BYTECODE_MASK is defined to be exactly this value).
+// All entries from kRegExpBytecodeCount to kRegExpPaddedBytecodeCount have to
+// be filled with BREAKs (invalid operation).
+
+// Fill dispatch table from last defined bytecode up to the next power of two
+// with BREAK (invalid operation).
+// TODO(pthier): Find a way to fill up automatically (at compile time)
+// 59 real bytecodes -> 5 fillers
+#define BYTECODE_FILLER_ITERATOR(V) \
+  V(BREAK) /* 1 */                  \
+  V(BREAK) /* 2 */                  \
+  V(BREAK) /* 3 */                  \
+  V(BREAK) /* 4 */                  \
+  V(BREAK) /* 5 */
+
+#define COUNT(...) +1
+  static constexpr int kRegExpBytecodeFillerCount =
+      BYTECODE_FILLER_ITERATOR(COUNT);
+#undef COUNT
+
+  // Make sure kRegExpPaddedBytecodeCount is actually the closest possible power
+  // of two.
+  DCHECK_EQ(kRegExpPaddedBytecodeCount,
+            base::bits::RoundUpToPowerOfTwo32(kRegExpBytecodeCount));
+
+  // Make sure every bytecode we get by using BYTECODE_MASK is well defined.
+  static_assert(kRegExpBytecodeCount <= kRegExpPaddedBytecodeCount);
+  static_assert(kRegExpBytecodeCount + kRegExpBytecodeFillerCount ==
+                kRegExpPaddedBytecodeCount);
+
+#define DECLARE_DISPATCH_TABLE_ENTRY(name, ...) &&BC_##name,
+  static const void* const dispatch_table[kRegExpPaddedBytecodeCount] = {
+      BYTECODE_ITERATOR(DECLARE_DISPATCH_TABLE_ENTRY)
+          BYTECODE_FILLER_ITERATOR(DECLARE_DISPATCH_TABLE_ENTRY)};
+#undef DECLARE_DISPATCH_TABLE_ENTRY
+#undef BYTECODE_FILLER_ITERATOR
+
+#endif  // V8_USE_COMPUTED_GOTO
+
+  const byte* pc = code_array.GetDataStartAddress();
+  const byte* code_base = pc;
+
+  InterpreterRegisters registers(total_register_count, output_registers,
+                                 output_register_count);
+  BacktrackStack backtrack_stack;
+
+  uint32_t backtrack_count = 0;
+
+#ifdef DEBUG
+  if (v8_flags.trace_regexp_bytecodes) {
+    PrintF("\n\nStart bytecode interpreter\n\n");
+  }
+#endif
+
+  while (true) {
+    const byte* next_pc = pc;
+    int32_t insn;
+    int32_t next_insn;
+#if V8_USE_COMPUTED_GOTO
+    const void* next_handler_addr;
+    DECODE();
+    DISPATCH();
+#else
+    insn = Load32Aligned(pc);
+    switch (insn & BYTECODE_MASK) {
+#endif  // V8_USE_COMPUTED_GOTO
+    BYTECODE(BREAK) { UNREACHABLE(); }
+    BYTECODE(PUSH_CP) {
+      ADVANCE(PUSH_CP);
+      if (!backtrack_stack.push(current)) {
+        return MaybeThrowStackOverflow(isolate, call_origin);
+      }
+      DISPATCH();
+    }
+    BYTECODE(PUSH_BT) {
+      ADVANCE(PUSH_BT);
+      if (!backtrack_stack.push(Load32Aligned(pc + 4))) {
+        return MaybeThrowStackOverflow(isolate, call_origin);
+      }
+      DISPATCH();
+    }
+    BYTECODE(PUSH_REGISTER) {
+      ADVANCE(PUSH_REGISTER);
+      if (!backtrack_stack.push(registers[LoadPacked24Unsigned(insn)])) {
+        return MaybeThrowStackOverflow(isolate, call_origin);
+      }
+      DISPATCH();
+    }
+    BYTECODE(SET_REGISTER) {
+      ADVANCE(SET_REGISTER);
+      registers[LoadPacked24Unsigned(insn)] = Load32Aligned(pc + 4);
+      DISPATCH();
+    }
+    BYTECODE(ADVANCE_REGISTER) {
+      ADVANCE(ADVANCE_REGISTER);
+      registers[LoadPacked24Unsigned(insn)] += Load32Aligned(pc + 4);
+      DISPATCH();
+    }
+    BYTECODE(SET_REGISTER_TO_CP) {
+      ADVANCE(SET_REGISTER_TO_CP);
+      registers[LoadPacked24Unsigned(insn)] = current + Load32Aligned(pc + 4);
+      DISPATCH();
+    }
+    BYTECODE(SET_CP_TO_REGISTER) {
+      ADVANCE(SET_CP_TO_REGISTER);
+      SET_CURRENT_POSITION(registers[LoadPacked24Unsigned(insn)]);
+      DISPATCH();
+    }
+    BYTECODE(SET_REGISTER_TO_SP) {
+      ADVANCE(SET_REGISTER_TO_SP);
+      registers[LoadPacked24Unsigned(insn)] = backtrack_stack.sp();
+      DISPATCH();
+    }
+    BYTECODE(SET_SP_TO_REGISTER) {
+      ADVANCE(SET_SP_TO_REGISTER);
+      backtrack_stack.set_sp(registers[LoadPacked24Unsigned(insn)]);
+      DISPATCH();
+    }
+    BYTECODE(POP_CP) {
+      ADVANCE(POP_CP);
+      SET_CURRENT_POSITION(backtrack_stack.pop());
+      DISPATCH();
+    }
+    BYTECODE(POP_BT) {
+      static_assert(JSRegExp::kNoBacktrackLimit == 0);
+      if (++backtrack_count == backtrack_limit) {
+        int return_code = LoadPacked24Signed(insn);
+        return static_cast<IrregexpInterpreter::Result>(return_code);
+      }
+
+      IrregexpInterpreter::Result return_code =
+          HandleInterrupts(isolate, call_origin, &code_array, &subject_string,
+                           &code_base, &subject, &pc);
+      if (return_code != IrregexpInterpreter::SUCCESS) return return_code;
+
+      SET_PC_FROM_OFFSET(backtrack_stack.pop());
+      DISPATCH();
+    }
+    BYTECODE(POP_REGISTER) {
+      ADVANCE(POP_REGISTER);
+      registers[LoadPacked24Unsigned(insn)] = backtrack_stack.pop();
+      DISPATCH();
+    }
+    BYTECODE(FAIL) {
+      isolate->counters()->regexp_backtracks()->AddSample(
+          static_cast<int>(backtrack_count));
+      return IrregexpInterpreter::FAILURE;
+    }
+    BYTECODE(SUCCEED) {
+      isolate->counters()->regexp_backtracks()->AddSample(
+          static_cast<int>(backtrack_count));
+      registers.CopyToOutputRegisters();
+      return IrregexpInterpreter::SUCCESS;
+    }
+    BYTECODE(ADVANCE_CP) {
+      ADVANCE(ADVANCE_CP);
+      ADVANCE_CURRENT_POSITION(LoadPacked24Signed(insn));
+      DISPATCH();
+    }
+    BYTECODE(GOTO) {
+      SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      DISPATCH();
+    }
+    BYTECODE(ADVANCE_CP_AND_GOTO) {
+      SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      ADVANCE_CURRENT_POSITION(LoadPacked24Signed(insn));
+      DISPATCH();
+    }
+    BYTECODE(CHECK_GREEDY) {
+      if (current == backtrack_stack.peek()) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+        backtrack_stack.pop();
+      } else {
+        ADVANCE(CHECK_GREEDY);
+      }
+      DISPATCH();
+    }
+    BYTECODE(LOAD_CURRENT_CHAR) {
+      int pos = current + LoadPacked24Signed(insn);
+      if (pos >= subject.length() || pos < 0) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(LOAD_CURRENT_CHAR);
+        current_char = subject[pos];
+      }
+      DISPATCH();
+    }
+    BYTECODE(LOAD_CURRENT_CHAR_UNCHECKED) {
+      ADVANCE(LOAD_CURRENT_CHAR_UNCHECKED);
+      int pos = current + LoadPacked24Signed(insn);
+      current_char = subject[pos];
+      DISPATCH();
+    }
+    BYTECODE(LOAD_2_CURRENT_CHARS) {
+      int pos = current + LoadPacked24Signed(insn);
+      if (pos + 2 > subject.length() || pos < 0) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(LOAD_2_CURRENT_CHARS);
+        Char next = subject[pos + 1];
+        current_char = (subject[pos] | (next << (kBitsPerByte * sizeof(Char))));
+      }
+      DISPATCH();
+    }
+    BYTECODE(LOAD_2_CURRENT_CHARS_UNCHECKED) {
+      ADVANCE(LOAD_2_CURRENT_CHARS_UNCHECKED);
+      int pos = current + LoadPacked24Signed(insn);
+      Char next = subject[pos + 1];
+      current_char = (subject[pos] | (next << (kBitsPerByte * sizeof(Char))));
+      DISPATCH();
+    }
+    BYTECODE(LOAD_4_CURRENT_CHARS) {
+      DCHECK_EQ(1, sizeof(Char));
+      int pos = current + LoadPacked24Signed(insn);
+      if (pos + 4 > subject.length() || pos < 0) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(LOAD_4_CURRENT_CHARS);
+        Char next1 = subject[pos + 1];
+        Char next2 = subject[pos + 2];
+        Char next3 = subject[pos + 3];
+        current_char =
+            (subject[pos] | (next1 << 8) | (next2 << 16) | (next3 << 24));
+      }
+      DISPATCH();
+    }
+    BYTECODE(LOAD_4_CURRENT_CHARS_UNCHECKED) {
+      ADVANCE(LOAD_4_CURRENT_CHARS_UNCHECKED);
+      DCHECK_EQ(1, sizeof(Char));
+      int pos = current + LoadPacked24Signed(insn);
+      Char next1 = subject[pos + 1];
+      Char next2 = subject[pos + 2];
+      Char next3 = subject[pos + 3];
+      current_char =
+          (subject[pos] | (next1 << 8) | (next2 << 16) | (next3 << 24));
+      DISPATCH();
+    }
+    BYTECODE(CHECK_4_CHARS) {
+      uint32_t c = Load32Aligned(pc + 4);
+      if (c == current_char) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(CHECK_4_CHARS);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_CHAR) {
+      uint32_t c = LoadPacked24Unsigned(insn);
+      if (c == current_char) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(CHECK_CHAR);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_4_CHARS) {
+      uint32_t c = Load32Aligned(pc + 4);
+      if (c != current_char) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(CHECK_NOT_4_CHARS);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_CHAR) {
+      uint32_t c = LoadPacked24Unsigned(insn);
+      if (c != current_char) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(CHECK_NOT_CHAR);
+      }
+      DISPATCH();
+    }
+    BYTECODE(AND_CHECK_4_CHARS) {
+      uint32_t c = Load32Aligned(pc + 4);
+      if (c == (current_char & Load32Aligned(pc + 8))) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 12));
+      } else {
+        ADVANCE(AND_CHECK_4_CHARS);
+      }
+      DISPATCH();
+    }
+    BYTECODE(AND_CHECK_CHAR) {
+      uint32_t c = LoadPacked24Unsigned(insn);
+      if (c == (current_char & Load32Aligned(pc + 4))) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(AND_CHECK_CHAR);
+      }
+      DISPATCH();
+    }
+    BYTECODE(AND_CHECK_NOT_4_CHARS) {
+      uint32_t c = Load32Aligned(pc + 4);
+      if (c != (current_char & Load32Aligned(pc + 8))) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 12));
+      } else {
+        ADVANCE(AND_CHECK_NOT_4_CHARS);
+      }
+      DISPATCH();
+    }
+    BYTECODE(AND_CHECK_NOT_CHAR) {
+      uint32_t c = LoadPacked24Unsigned(insn);
+      if (c != (current_char & Load32Aligned(pc + 4))) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(AND_CHECK_NOT_CHAR);
+      }
+      DISPATCH();
+    }
+    BYTECODE(MINUS_AND_CHECK_NOT_CHAR) {
+      uint32_t c = LoadPacked24Unsigned(insn);
+      uint32_t minus = Load16Aligned(pc + 4);
+      uint32_t mask = Load16Aligned(pc + 6);
+      if (c != ((current_char - minus) & mask)) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(MINUS_AND_CHECK_NOT_CHAR);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_CHAR_IN_RANGE) {
+      uint32_t from = Load16Aligned(pc + 4);
+      uint32_t to = Load16Aligned(pc + 6);
+      if (from <= current_char && current_char <= to) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(CHECK_CHAR_IN_RANGE);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_CHAR_NOT_IN_RANGE) {
+      uint32_t from = Load16Aligned(pc + 4);
+      uint32_t to = Load16Aligned(pc + 6);
+      if (from > current_char || current_char > to) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(CHECK_CHAR_NOT_IN_RANGE);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_BIT_IN_TABLE) {
+      if (CheckBitInTable(current_char, pc + 8)) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(CHECK_BIT_IN_TABLE);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_LT) {
+      uint32_t limit = LoadPacked24Unsigned(insn);
+      if (current_char < limit) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(CHECK_LT);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_GT) {
+      uint32_t limit = LoadPacked24Unsigned(insn);
+      if (current_char > limit) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(CHECK_GT);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_REGISTER_LT) {
+      if (registers[LoadPacked24Unsigned(insn)] < Load32Aligned(pc + 4)) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(CHECK_REGISTER_LT);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_REGISTER_GE) {
+      if (registers[LoadPacked24Unsigned(insn)] >= Load32Aligned(pc + 4)) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      } else {
+        ADVANCE(CHECK_REGISTER_GE);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_REGISTER_EQ_POS) {
+      if (registers[LoadPacked24Unsigned(insn)] == current) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(CHECK_REGISTER_EQ_POS);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_REGS_EQUAL) {
+      if (registers[LoadPacked24Unsigned(insn)] ==
+          registers[Load32Aligned(pc + 4)]) {
+        ADVANCE(CHECK_NOT_REGS_EQUAL);
+      } else {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_BACK_REF) {
+      int from = registers[LoadPacked24Unsigned(insn)];
+      int len = registers[LoadPacked24Unsigned(insn) + 1] - from;
+      if (from >= 0 && len > 0) {
+        if (current + len > subject.length() ||
+            !CompareCharsEqual(&subject[from], &subject[current], len)) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+          DISPATCH();
+        }
+        ADVANCE_CURRENT_POSITION(len);
+      }
+      ADVANCE(CHECK_NOT_BACK_REF);
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_BACK_REF_BACKWARD) {
+      int from = registers[LoadPacked24Unsigned(insn)];
+      int len = registers[LoadPacked24Unsigned(insn) + 1] - from;
+      if (from >= 0 && len > 0) {
+        if (current - len < 0 ||
+            !CompareCharsEqual(&subject[from], &subject[current - len], len)) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+          DISPATCH();
+        }
+        SET_CURRENT_POSITION(current - len);
+      }
+      ADVANCE(CHECK_NOT_BACK_REF_BACKWARD);
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_BACK_REF_NO_CASE_UNICODE) {
+      int from = registers[LoadPacked24Unsigned(insn)];
+      int len = registers[LoadPacked24Unsigned(insn) + 1] - from;
+      if (from >= 0 && len > 0) {
+        if (current + len > subject.length() ||
+            !BackRefMatchesNoCase(isolate, from, current, len, subject, true)) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+          DISPATCH();
+        }
+        ADVANCE_CURRENT_POSITION(len);
+      }
+      ADVANCE(CHECK_NOT_BACK_REF_NO_CASE_UNICODE);
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_BACK_REF_NO_CASE) {
+      int from = registers[LoadPacked24Unsigned(insn)];
+      int len = registers[LoadPacked24Unsigned(insn) + 1] - from;
+      if (from >= 0 && len > 0) {
+        if (current + len > subject.length() ||
+            !BackRefMatchesNoCase(isolate, from, current, len, subject,
+                                  false)) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+          DISPATCH();
+        }
+        ADVANCE_CURRENT_POSITION(len);
+      }
+      ADVANCE(CHECK_NOT_BACK_REF_NO_CASE);
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_BACK_REF_NO_CASE_UNICODE_BACKWARD) {
+      int from = registers[LoadPacked24Unsigned(insn)];
+      int len = registers[LoadPacked24Unsigned(insn) + 1] - from;
+      if (from >= 0 && len > 0) {
+        if (current - len < 0 ||
+            !BackRefMatchesNoCase(isolate, from, current - len, len, subject,
+                                  true)) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+          DISPATCH();
+        }
+        SET_CURRENT_POSITION(current - len);
+      }
+      ADVANCE(CHECK_NOT_BACK_REF_NO_CASE_UNICODE_BACKWARD);
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_BACK_REF_NO_CASE_BACKWARD) {
+      int from = registers[LoadPacked24Unsigned(insn)];
+      int len = registers[LoadPacked24Unsigned(insn) + 1] - from;
+      if (from >= 0 && len > 0) {
+        if (current - len < 0 ||
+            !BackRefMatchesNoCase(isolate, from, current - len, len, subject,
+                                  false)) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+          DISPATCH();
+        }
+        SET_CURRENT_POSITION(current - len);
+      }
+      ADVANCE(CHECK_NOT_BACK_REF_NO_CASE_BACKWARD);
+      DISPATCH();
+    }
+    BYTECODE(CHECK_AT_START) {
+      if (current + LoadPacked24Signed(insn) == 0) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(CHECK_AT_START);
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_NOT_AT_START) {
+      if (current + LoadPacked24Signed(insn) == 0) {
+        ADVANCE(CHECK_NOT_AT_START);
+      } else {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      }
+      DISPATCH();
+    }
+    BYTECODE(SET_CURRENT_POSITION_FROM_END) {
+      ADVANCE(SET_CURRENT_POSITION_FROM_END);
+      int by = LoadPacked24Unsigned(insn);
+      if (subject.length() - current > by) {
+        SET_CURRENT_POSITION(subject.length() - by);
+        current_char = subject[current - 1];
+      }
+      DISPATCH();
+    }
+    BYTECODE(CHECK_CURRENT_POSITION) {
+      int pos = current + LoadPacked24Signed(insn);
+      if (pos > subject.length() || pos < 0) {
+        SET_PC_FROM_OFFSET(Load32Aligned(pc + 4));
+      } else {
+        ADVANCE(CHECK_CURRENT_POSITION);
+      }
+      DISPATCH();
+    }
+    BYTECODE(SKIP_UNTIL_CHAR) {
+      int32_t load_offset = LoadPacked24Signed(insn);
+      int32_t advance = Load16AlignedSigned(pc + 4);
+      uint32_t c = Load16Aligned(pc + 6);
+      while (IndexIsInBounds(current + load_offset, subject.length())) {
+        current_char = subject[current + load_offset];
+        if (c == current_char) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 8));
+          DISPATCH();
+        }
+        ADVANCE_CURRENT_POSITION(advance);
+      }
+      SET_PC_FROM_OFFSET(Load32Aligned(pc + 12));
+      DISPATCH();
+    }
+    BYTECODE(SKIP_UNTIL_CHAR_AND) {
+      int32_t load_offset = LoadPacked24Signed(insn);
+      int32_t advance = Load16AlignedSigned(pc + 4);
+      uint16_t c = Load16Aligned(pc + 6);
+      uint32_t mask = Load32Aligned(pc + 8);
+      int32_t maximum_offset = Load32Aligned(pc + 12);
+      while (static_cast<uintptr_t>(current + maximum_offset) <=
+             static_cast<uintptr_t>(subject.length())) {
+        current_char = subject[current + load_offset];
+        if (c == (current_char & mask)) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 16));
+          DISPATCH();
+        }
+        ADVANCE_CURRENT_POSITION(advance);
+      }
+      SET_PC_FROM_OFFSET(Load32Aligned(pc + 20));
+      DISPATCH();
+    }
+    BYTECODE(SKIP_UNTIL_CHAR_POS_CHECKED) {
+      int32_t load_offset = LoadPacked24Signed(insn);
+      int32_t advance = Load16AlignedSigned(pc + 4);
+      uint16_t c = Load16Aligned(pc + 6);
+      int32_t maximum_offset = Load32Aligned(pc + 8);
+      while (static_cast<uintptr_t>(current + maximum_offset) <=
+             static_cast<uintptr_t>(subject.length())) {
+        current_char = subject[current + load_offset];
+        if (c == current_char) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 12));
+          DISPATCH();
+        }
+        ADVANCE_CURRENT_POSITION(advance);
+      }
+      SET_PC_FROM_OFFSET(Load32Aligned(pc + 16));
+      DISPATCH();
+    }
+    BYTECODE(SKIP_UNTIL_BIT_IN_TABLE) {
+      int32_t load_offset = LoadPacked24Signed(insn);
+      int32_t advance = Load16AlignedSigned(pc + 4);
+      const byte* table = pc + 8;
+      while (IndexIsInBounds(current + load_offset, subject.length())) {
+        current_char = subject[current + load_offset];
+        if (CheckBitInTable(current_char, table)) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 24));
+          DISPATCH();
+        }
+        ADVANCE_CURRENT_POSITION(advance);
+      }
+      SET_PC_FROM_OFFSET(Load32Aligned(pc + 28));
+      DISPATCH();
+    }
+    BYTECODE(SKIP_UNTIL_GT_OR_NOT_BIT_IN_TABLE) {
+      int32_t load_offset = LoadPacked24Signed(insn);
+      int32_t advance = Load16AlignedSigned(pc + 4);
+      uint16_t limit = Load16Aligned(pc + 6);
+      const byte* table = pc + 8;
+      while (IndexIsInBounds(current + load_offset, subject.length())) {
+        current_char = subject[current + load_offset];
+        if (current_char > limit) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 24));
+          DISPATCH();
+        }
+        if (!CheckBitInTable(current_char, table)) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 24));
+          DISPATCH();
+        }
+        ADVANCE_CURRENT_POSITION(advance);
+      }
+      SET_PC_FROM_OFFSET(Load32Aligned(pc + 28));
+      DISPATCH();
+    }
+    BYTECODE(SKIP_UNTIL_CHAR_OR_CHAR) {
+      int32_t load_offset = LoadPacked24Signed(insn);
+      int32_t advance = Load32Aligned(pc + 4);
+      uint16_t c = Load16Aligned(pc + 8);
+      uint16_t c2 = Load16Aligned(pc + 10);
+      while (IndexIsInBounds(current + load_offset, subject.length())) {
+        current_char = subject[current + load_offset];
+        // The two if-statements below are split up intentionally, as combining
+        // them seems to result in register allocation behaving quite
+        // differently and slowing down the resulting code.
+        if (c == current_char) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 12));
+          DISPATCH();
+        }
+        if (c2 == current_char) {
+          SET_PC_FROM_OFFSET(Load32Aligned(pc + 12));
+          DISPATCH();
+        }
+        ADVANCE_CURRENT_POSITION(advance);
+      }
+      SET_PC_FROM_OFFSET(Load32Aligned(pc + 16));
+      DISPATCH();
+    }
+#if V8_USE_COMPUTED_GOTO
+// Lint gets confused a lot if we just use !V8_USE_COMPUTED_GOTO or ifndef
+// V8_USE_COMPUTED_GOTO here.
+#else
+      default:
+        UNREACHABLE();
+    }
+  // Label we jump to in DISPATCH(). There must be no instructions between the
+  // end of the switch, this label and the end of the loop.
+  switch_dispatch_continuation : {}
+#endif  // V8_USE_COMPUTED_GOTO
+  }
+}
+
+#undef BYTECODE
+#undef ADVANCE_CURRENT_POSITION
+#undef SET_CURRENT_POSITION
+#undef DISPATCH
+#undef DECODE
+#undef SET_PC_FROM_OFFSET
+#undef ADVANCE
+#undef BC_LABEL
+#undef V8_USE_COMPUTED_GOTO
+
+}  // namespace
+
+// static
+IrregexpInterpreter::Result IrregexpInterpreter::Match(
+    Isolate* isolate, JSRegExp regexp, String subject_string,
+    int* output_registers, int output_register_count, int start_position,
+    RegExp::CallOrigin call_origin) {
+  if (v8_flags.regexp_tier_up) regexp.TierUpTick();
+
+  bool is_one_byte = String::IsOneByteRepresentationUnderneath(subject_string);
+  ByteArray code_array = ByteArray::cast(regexp.bytecode(is_one_byte));
+  int total_register_count = regexp.max_register_count();
+
+  return MatchInternal(isolate, code_array, subject_string, output_registers,
+                       output_register_count, total_register_count,
+                       start_position, call_origin, regexp.backtrack_limit());
+}
+
+IrregexpInterpreter::Result IrregexpInterpreter::MatchInternal(
+    Isolate* isolate, ByteArray code_array, String subject_string,
+    int* output_registers, int output_register_count, int total_register_count,
+    int start_position, RegExp::CallOrigin call_origin,
+    uint32_t backtrack_limit) {
+  DCHECK(subject_string.IsFlat());
+
+  // TODO(chromium:1262676): Remove this CHECK once fixed.
+  CHECK(code_array.IsByteArray());
+
+  // Note: Heap allocation *is* allowed in two situations if calling from
+  // Runtime:
+  // 1. When creating & throwing a stack overflow exception. The interpreter
+  //    aborts afterwards, and thus possible-moved objects are never used.
+  // 2. When handling interrupts. We manually relocate unhandlified references
+  //    after interrupts have run.
+  DisallowGarbageCollection no_gc;
+
+  base::uc16 previous_char = '\n';
+  String::FlatContent subject_content = subject_string.GetFlatContent(no_gc);
+  // Because interrupts can result in GC and string content relocation, the
+  // checksum verification in FlatContent may fail even though this code is
+  // safe. See (2) above.
+  subject_content.UnsafeDisableChecksumVerification();
+  if (subject_content.IsOneByte()) {
+    base::Vector<const uint8_t> subject_vector =
+        subject_content.ToOneByteVector();
+    if (start_position != 0) previous_char = subject_vector[start_position - 1];
+    return RawMatch(isolate, code_array, subject_string, subject_vector,
+                    output_registers, output_register_count,
+                    total_register_count, start_position, previous_char,
+                    call_origin, backtrack_limit);
+  } else {
+    DCHECK(subject_content.IsTwoByte());
+    base::Vector<const base::uc16> subject_vector =
+        subject_content.ToUC16Vector();
+    if (start_position != 0) previous_char = subject_vector[start_position - 1];
+    return RawMatch(isolate, code_array, subject_string, subject_vector,
+                    output_registers, output_register_count,
+                    total_register_count, start_position, previous_char,
+                    call_origin, backtrack_limit);
+  }
+}
+
+#ifndef COMPILING_IRREGEXP_FOR_EXTERNAL_EMBEDDER
+
+// This method is called through an external reference from RegExpExecInternal
+// builtin.
+IrregexpInterpreter::Result IrregexpInterpreter::MatchForCallFromJs(
+    Address subject, int32_t start_position, Address, Address,
+    int* output_registers, int32_t output_register_count,
+    RegExp::CallOrigin call_origin, Isolate* isolate, Address regexp) {
+  DCHECK_NOT_NULL(isolate);
+  DCHECK_NOT_NULL(output_registers);
+  DCHECK(call_origin == RegExp::CallOrigin::kFromJs);
+
+  DisallowGarbageCollection no_gc;
+  DisallowJavascriptExecution no_js(isolate);
+  DisallowHandleAllocation no_handles;
+  DisallowHandleDereference no_deref;
+
+  String subject_string = String::cast(Object(subject));
+  JSRegExp regexp_obj = JSRegExp::cast(Object(regexp));
+
+  if (regexp_obj.MarkedForTierUp()) {
+    // Returning RETRY will re-enter through runtime, where actual recompilation
+    // for tier-up takes place.
+    return IrregexpInterpreter::RETRY;
+  }
+
+  return Match(isolate, regexp_obj, subject_string, output_registers,
+               output_register_count, start_position, call_origin);
+}
+
+#endif  // !COMPILING_IRREGEXP_FOR_EXTERNAL_EMBEDDER
+
+IrregexpInterpreter::Result IrregexpInterpreter::MatchForCallFromRuntime(
+    Isolate* isolate, Handle<JSRegExp> regexp, Handle<String> subject_string,
+    int* output_registers, int output_register_count, int start_position) {
+  return Match(isolate, *regexp, *subject_string, output_registers,
+               output_register_count, start_position,
+               RegExp::CallOrigin::kFromRuntime);
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/irregexp/imported/regexp-interpreter.h b/js/src/irregexp/imported/regexp-interpreter.h
new file mode 100644
index 0000000000..bc55be2b8c
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-interpreter.h
@@ -0,0 +1,68 @@
+// Copyright 2011 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// A simple interpreter for the Irregexp byte code.
+
+#ifndef V8_REGEXP_REGEXP_INTERPRETER_H_
+#define V8_REGEXP_REGEXP_INTERPRETER_H_
+
+#include "irregexp/imported/regexp.h"
+
+namespace v8 {
+namespace internal {
+
+class ByteArray;
+
+class V8_EXPORT_PRIVATE IrregexpInterpreter : public AllStatic {
+ public:
+  enum Result {
+    FAILURE = RegExp::kInternalRegExpFailure,
+    SUCCESS = RegExp::kInternalRegExpSuccess,
+    EXCEPTION = RegExp::kInternalRegExpException,
+    RETRY = RegExp::kInternalRegExpRetry,
+    FALLBACK_TO_EXPERIMENTAL = RegExp::kInternalRegExpFallbackToExperimental,
+  };
+
+  // In case a StackOverflow occurs, a StackOverflowException is created and
+  // EXCEPTION is returned.
+  static Result MatchForCallFromRuntime(
+      Isolate* isolate, Handle<JSRegExp> regexp, Handle<String> subject_string,
+      int* output_registers, int output_register_count, int start_position);
+
+  // In case a StackOverflow occurs, EXCEPTION is returned. The caller is
+  // responsible for creating the exception.
+  //
+  // RETRY is returned if a retry through the runtime is needed (e.g. when
+  // interrupts have been scheduled or the regexp is marked for tier-up).
+  //
+  // Arguments input_start and input_end are unused. They are only passed to
+  // match the signature of the native irregex code.
+  //
+  // Arguments output_registers and output_register_count describe the results
+  // array, which will contain register values of all captures if SUCCESS is
+  // returned. For all other return codes, the results array remains unmodified.
+  static Result MatchForCallFromJs(Address subject, int32_t start_position,
+                                   Address input_start, Address input_end,
+                                   int* output_registers,
+                                   int32_t output_register_count,
+                                   RegExp::CallOrigin call_origin,
+                                   Isolate* isolate, Address regexp);
+
+  static Result MatchInternal(Isolate* isolate, ByteArray code_array,
+                              String subject_string, int* output_registers,
+                              int output_register_count,
+                              int total_register_count, int start_position,
+                              RegExp::CallOrigin call_origin,
+                              uint32_t backtrack_limit);
+
+ private:
+  static Result Match(Isolate* isolate, JSRegExp regexp, String subject_string,
+                      int* output_registers, int output_register_count,
+                      int start_position, RegExp::CallOrigin call_origin);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_INTERPRETER_H_
diff --git a/js/src/irregexp/imported/regexp-macro-assembler-arch.h b/js/src/irregexp/imported/regexp-macro-assembler-arch.h
new file mode 100644
index 0000000000..a755e7c1b3
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-macro-assembler-arch.h
@@ -0,0 +1,7 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "irregexp/RegExpNativeMacroAssembler.h"
diff --git a/js/src/irregexp/imported/regexp-macro-assembler-tracer.cc b/js/src/irregexp/imported/regexp-macro-assembler-tracer.cc
new file mode 100644
index 0000000000..6444ca3c60
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-macro-assembler-tracer.cc
@@ -0,0 +1,438 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "irregexp/imported/regexp-macro-assembler-tracer.h"
+
+
+namespace v8 {
+namespace internal {
+
+RegExpMacroAssemblerTracer::RegExpMacroAssemblerTracer(
+    Isolate* isolate, RegExpMacroAssembler* assembler)
+    : RegExpMacroAssembler(isolate, assembler->zone()), assembler_(assembler) {
+  PrintF("RegExpMacroAssembler%s();\n",
+         ImplementationToString(assembler->Implementation()));
+}
+
+RegExpMacroAssemblerTracer::~RegExpMacroAssemblerTracer() = default;
+
+void RegExpMacroAssemblerTracer::AbortedCodeGeneration() {
+  PrintF(" AbortedCodeGeneration\n");
+  assembler_->AbortedCodeGeneration();
+}
+
+
+// This is used for printing out debugging information.  It makes an integer
+// that is closely related to the address of an object.
+static int LabelToInt(Label* label) {
+  return static_cast<int>(reinterpret_cast<intptr_t>(label));
+}
+
+
+void RegExpMacroAssemblerTracer::Bind(Label* label) {
+  PrintF("label[%08x]: (Bind)\n", LabelToInt(label));
+  assembler_->Bind(label);
+}
+
+
+void RegExpMacroAssemblerTracer::AdvanceCurrentPosition(int by) {
+  PrintF(" AdvanceCurrentPosition(by=%d);\n", by);
+  assembler_->AdvanceCurrentPosition(by);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckGreedyLoop(Label* label) {
+  PrintF(" CheckGreedyLoop(label[%08x]);\n\n", LabelToInt(label));
+  assembler_->CheckGreedyLoop(label);
+}
+
+
+void RegExpMacroAssemblerTracer::PopCurrentPosition() {
+  PrintF(" PopCurrentPosition();\n");
+  assembler_->PopCurrentPosition();
+}
+
+
+void RegExpMacroAssemblerTracer::PushCurrentPosition() {
+  PrintF(" PushCurrentPosition();\n");
+  assembler_->PushCurrentPosition();
+}
+
+
+void RegExpMacroAssemblerTracer::Backtrack() {
+  PrintF(" Backtrack();\n");
+  assembler_->Backtrack();
+}
+
+
+void RegExpMacroAssemblerTracer::GoTo(Label* label) {
+  PrintF(" GoTo(label[%08x]);\n\n", LabelToInt(label));
+  assembler_->GoTo(label);
+}
+
+
+void RegExpMacroAssemblerTracer::PushBacktrack(Label* label) {
+  PrintF(" PushBacktrack(label[%08x]);\n", LabelToInt(label));
+  assembler_->PushBacktrack(label);
+}
+
+
+bool RegExpMacroAssemblerTracer::Succeed() {
+  bool restart = assembler_->Succeed();
+  PrintF(" Succeed();%s\n", restart ? " [restart for global match]" : "");
+  return restart;
+}
+
+
+void RegExpMacroAssemblerTracer::Fail() {
+  PrintF(" Fail();");
+  assembler_->Fail();
+}
+
+
+void RegExpMacroAssemblerTracer::PopRegister(int register_index) {
+  PrintF(" PopRegister(register=%d);\n", register_index);
+  assembler_->PopRegister(register_index);
+}
+
+
+void RegExpMacroAssemblerTracer::PushRegister(
+    int register_index,
+    StackCheckFlag check_stack_limit) {
+  PrintF(" PushRegister(register=%d, %s);\n",
+         register_index,
+         check_stack_limit ? "check stack limit" : "");
+  assembler_->PushRegister(register_index, check_stack_limit);
+}
+
+
+void RegExpMacroAssemblerTracer::AdvanceRegister(int reg, int by) {
+  PrintF(" AdvanceRegister(register=%d, by=%d);\n", reg, by);
+  assembler_->AdvanceRegister(reg, by);
+}
+
+
+void RegExpMacroAssemblerTracer::SetCurrentPositionFromEnd(int by) {
+  PrintF(" SetCurrentPositionFromEnd(by=%d);\n", by);
+  assembler_->SetCurrentPositionFromEnd(by);
+}
+
+
+void RegExpMacroAssemblerTracer::SetRegister(int register_index, int to) {
+  PrintF(" SetRegister(register=%d, to=%d);\n", register_index, to);
+  assembler_->SetRegister(register_index, to);
+}
+
+
+void RegExpMacroAssemblerTracer::WriteCurrentPositionToRegister(int reg,
+                                                                int cp_offset) {
+  PrintF(" WriteCurrentPositionToRegister(register=%d,cp_offset=%d);\n",
+         reg,
+         cp_offset);
+  assembler_->WriteCurrentPositionToRegister(reg, cp_offset);
+}
+
+
+void RegExpMacroAssemblerTracer::ClearRegisters(int reg_from, int reg_to) {
+  PrintF(" ClearRegister(from=%d, to=%d);\n", reg_from, reg_to);
+  assembler_->ClearRegisters(reg_from, reg_to);
+}
+
+
+void RegExpMacroAssemblerTracer::ReadCurrentPositionFromRegister(int reg) {
+  PrintF(" ReadCurrentPositionFromRegister(register=%d);\n", reg);
+  assembler_->ReadCurrentPositionFromRegister(reg);
+}
+
+
+void RegExpMacroAssemblerTracer::WriteStackPointerToRegister(int reg) {
+  PrintF(" WriteStackPointerToRegister(register=%d);\n", reg);
+  assembler_->WriteStackPointerToRegister(reg);
+}
+
+
+void RegExpMacroAssemblerTracer::ReadStackPointerFromRegister(int reg) {
+  PrintF(" ReadStackPointerFromRegister(register=%d);\n", reg);
+  assembler_->ReadStackPointerFromRegister(reg);
+}
+
+void RegExpMacroAssemblerTracer::LoadCurrentCharacterImpl(
+    int cp_offset, Label* on_end_of_input, bool check_bounds, int characters,
+    int eats_at_least) {
+  const char* check_msg = check_bounds ? "" : " (unchecked)";
+  PrintF(
+      " LoadCurrentCharacter(cp_offset=%d, label[%08x]%s (%d chars) (eats at "
+      "least %d));\n",
+      cp_offset, LabelToInt(on_end_of_input), check_msg, characters,
+      eats_at_least);
+  assembler_->LoadCurrentCharacter(cp_offset, on_end_of_input, check_bounds,
+                                   characters, eats_at_least);
+}
+
+namespace {
+
+class PrintablePrinter {
+ public:
+  explicit PrintablePrinter(base::uc16 character) : character_(character) {}
+
+  const char* operator*() {
+    if (character_ >= ' ' && character_ <= '~') {
+      buffer_[0] = '(';
+      buffer_[1] = static_cast<char>(character_);
+      buffer_[2] = ')';
+      buffer_[3] = '\0';
+    } else {
+      buffer_[0] = '\0';
+    }
+    return &buffer_[0];
+  }
+
+ private:
+  base::uc16 character_;
+  char buffer_[4];
+};
+
+}  // namespace
+
+void RegExpMacroAssemblerTracer::CheckCharacterLT(base::uc16 limit,
+                                                  Label* on_less) {
+  PrintablePrinter printable(limit);
+  PrintF(" CheckCharacterLT(c=0x%04x%s, label[%08x]);\n",
+         limit,
+         *printable,
+         LabelToInt(on_less));
+  assembler_->CheckCharacterLT(limit, on_less);
+}
+
+void RegExpMacroAssemblerTracer::CheckCharacterGT(base::uc16 limit,
+                                                  Label* on_greater) {
+  PrintablePrinter printable(limit);
+  PrintF(" CheckCharacterGT(c=0x%04x%s, label[%08x]);\n",
+         limit,
+         *printable,
+         LabelToInt(on_greater));
+  assembler_->CheckCharacterGT(limit, on_greater);
+}
+
+void RegExpMacroAssemblerTracer::CheckCharacter(unsigned c, Label* on_equal) {
+  PrintablePrinter printable(c);
+  PrintF(" CheckCharacter(c=0x%04x%s, label[%08x]);\n",
+         c,
+         *printable,
+         LabelToInt(on_equal));
+  assembler_->CheckCharacter(c, on_equal);
+}
+
+void RegExpMacroAssemblerTracer::CheckAtStart(int cp_offset,
+                                              Label* on_at_start) {
+  PrintF(" CheckAtStart(cp_offset=%d, label[%08x]);\n", cp_offset,
+         LabelToInt(on_at_start));
+  assembler_->CheckAtStart(cp_offset, on_at_start);
+}
+
+void RegExpMacroAssemblerTracer::CheckNotAtStart(int cp_offset,
+                                                 Label* on_not_at_start) {
+  PrintF(" CheckNotAtStart(cp_offset=%d, label[%08x]);\n", cp_offset,
+         LabelToInt(on_not_at_start));
+  assembler_->CheckNotAtStart(cp_offset, on_not_at_start);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckNotCharacter(unsigned c,
+                                                   Label* on_not_equal) {
+  PrintablePrinter printable(c);
+  PrintF(" CheckNotCharacter(c=0x%04x%s, label[%08x]);\n",
+         c,
+         *printable,
+         LabelToInt(on_not_equal));
+  assembler_->CheckNotCharacter(c, on_not_equal);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckCharacterAfterAnd(
+    unsigned c,
+    unsigned mask,
+    Label* on_equal) {
+  PrintablePrinter printable(c);
+  PrintF(" CheckCharacterAfterAnd(c=0x%04x%s, mask=0x%04x, label[%08x]);\n",
+         c,
+         *printable,
+         mask,
+         LabelToInt(on_equal));
+  assembler_->CheckCharacterAfterAnd(c, mask, on_equal);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckNotCharacterAfterAnd(
+    unsigned c,
+    unsigned mask,
+    Label* on_not_equal) {
+  PrintablePrinter printable(c);
+  PrintF(" CheckNotCharacterAfterAnd(c=0x%04x%s, mask=0x%04x, label[%08x]);\n",
+         c,
+         *printable,
+         mask,
+         LabelToInt(on_not_equal));
+  assembler_->CheckNotCharacterAfterAnd(c, mask, on_not_equal);
+}
+
+void RegExpMacroAssemblerTracer::CheckNotCharacterAfterMinusAnd(
+    base::uc16 c, base::uc16 minus, base::uc16 mask, Label* on_not_equal) {
+  PrintF(" CheckNotCharacterAfterMinusAnd(c=0x%04x, minus=%04x, mask=0x%04x, "
+             "label[%08x]);\n",
+         c,
+         minus,
+         mask,
+         LabelToInt(on_not_equal));
+  assembler_->CheckNotCharacterAfterMinusAnd(c, minus, mask, on_not_equal);
+}
+
+void RegExpMacroAssemblerTracer::CheckCharacterInRange(base::uc16 from,
+                                                       base::uc16 to,
+                                                       Label* on_not_in_range) {
+  PrintablePrinter printable_from(from);
+  PrintablePrinter printable_to(to);
+  PrintF(" CheckCharacterInRange(from=0x%04x%s, to=0x%04x%s, label[%08x]);\n",
+         from,
+         *printable_from,
+         to,
+         *printable_to,
+         LabelToInt(on_not_in_range));
+  assembler_->CheckCharacterInRange(from, to, on_not_in_range);
+}
+
+void RegExpMacroAssemblerTracer::CheckCharacterNotInRange(base::uc16 from,
+                                                          base::uc16 to,
+                                                          Label* on_in_range) {
+  PrintablePrinter printable_from(from);
+  PrintablePrinter printable_to(to);
+  PrintF(
+      " CheckCharacterNotInRange(from=0x%04x%s," " to=%04x%s, label[%08x]);\n",
+      from,
+      *printable_from,
+      to,
+      *printable_to,
+      LabelToInt(on_in_range));
+  assembler_->CheckCharacterNotInRange(from, to, on_in_range);
+}
+
+namespace {
+
+void PrintRangeArray(const ZoneList<CharacterRange>* ranges) {
+  for (int i = 0; i < ranges->length(); i++) {
+    base::uc16 from = ranges->at(i).from();
+    base::uc16 to = ranges->at(i).to();
+    PrintablePrinter printable_from(from);
+    PrintablePrinter printable_to(to);
+    PrintF("        [from=0x%04x%s, to=%04x%s],\n", from, *printable_from, to,
+           *printable_to);
+  }
+}
+
+}  // namespace
+
+bool RegExpMacroAssemblerTracer::CheckCharacterInRangeArray(
+    const ZoneList<CharacterRange>* ranges, Label* on_in_range) {
+  PrintF(
+      " CheckCharacterInRangeArray(\n"
+      "        label[%08x]);\n",
+      LabelToInt(on_in_range));
+  PrintRangeArray(ranges);
+  return assembler_->CheckCharacterInRangeArray(ranges, on_in_range);
+}
+
+bool RegExpMacroAssemblerTracer::CheckCharacterNotInRangeArray(
+    const ZoneList<CharacterRange>* ranges, Label* on_not_in_range) {
+  PrintF(
+      " CheckCharacterNotInRangeArray(\n"
+      "        label[%08x]);\n",
+      LabelToInt(on_not_in_range));
+  PrintRangeArray(ranges);
+  return assembler_->CheckCharacterNotInRangeArray(ranges, on_not_in_range);
+}
+
+void RegExpMacroAssemblerTracer::CheckBitInTable(
+    Handle<ByteArray> table, Label* on_bit_set) {
+  PrintF(" CheckBitInTable(label[%08x] ", LabelToInt(on_bit_set));
+  for (int i = 0; i < kTableSize; i++) {
+    PrintF("%c", table->get(i) != 0 ? 'X' : '.');
+    if (i % 32 == 31 && i != kTableMask) {
+      PrintF("\n                                 ");
+    }
+  }
+  PrintF(");\n");
+  assembler_->CheckBitInTable(table, on_bit_set);
+}
+
+
+void RegExpMacroAssemblerTracer::CheckNotBackReference(int start_reg,
+                                                       bool read_backward,
+                                                       Label* on_no_match) {
+  PrintF(" CheckNotBackReference(register=%d, %s, label[%08x]);\n", start_reg,
+         read_backward ? "backward" : "forward", LabelToInt(on_no_match));
+  assembler_->CheckNotBackReference(start_reg, read_backward, on_no_match);
+}
+
+void RegExpMacroAssemblerTracer::CheckNotBackReferenceIgnoreCase(
+    int start_reg, bool read_backward, bool unicode, Label* on_no_match) {
+  PrintF(" CheckNotBackReferenceIgnoreCase(register=%d, %s %s, label[%08x]);\n",
+         start_reg, read_backward ? "backward" : "forward",
+         unicode ? "unicode" : "non-unicode", LabelToInt(on_no_match));
+  assembler_->CheckNotBackReferenceIgnoreCase(start_reg, read_backward, unicode,
+                                              on_no_match);
+}
+
+void RegExpMacroAssemblerTracer::CheckPosition(int cp_offset,
+                                               Label* on_outside_input) {
+  PrintF(" CheckPosition(cp_offset=%d, label[%08x]);\n", cp_offset,
+         LabelToInt(on_outside_input));
+  assembler_->CheckPosition(cp_offset, on_outside_input);
+}
+
+bool RegExpMacroAssemblerTracer::CheckSpecialClassRanges(
+    StandardCharacterSet type, Label* on_no_match) {
+  bool supported = assembler_->CheckSpecialClassRanges(type, on_no_match);
+  PrintF(" CheckSpecialClassRanges(type='%c', label[%08x]): %s;\n",
+         static_cast<char>(type), LabelToInt(on_no_match),
+         supported ? "true" : "false");
+  return supported;
+}
+
+void RegExpMacroAssemblerTracer::IfRegisterLT(int register_index,
+                                              int comparand, Label* if_lt) {
+  PrintF(" IfRegisterLT(register=%d, number=%d, label[%08x]);\n",
+         register_index, comparand, LabelToInt(if_lt));
+  assembler_->IfRegisterLT(register_index, comparand, if_lt);
+}
+
+
+void RegExpMacroAssemblerTracer::IfRegisterEqPos(int register_index,
+                                                 Label* if_eq) {
+  PrintF(" IfRegisterEqPos(register=%d, label[%08x]);\n",
+         register_index, LabelToInt(if_eq));
+  assembler_->IfRegisterEqPos(register_index, if_eq);
+}
+
+
+void RegExpMacroAssemblerTracer::IfRegisterGE(int register_index,
+                                              int comparand, Label* if_ge) {
+  PrintF(" IfRegisterGE(register=%d, number=%d, label[%08x]);\n",
+         register_index, comparand, LabelToInt(if_ge));
+  assembler_->IfRegisterGE(register_index, comparand, if_ge);
+}
+
+
+RegExpMacroAssembler::IrregexpImplementation
+    RegExpMacroAssemblerTracer::Implementation() {
+  return assembler_->Implementation();
+}
+
+
+Handle<HeapObject> RegExpMacroAssemblerTracer::GetCode(Handle<String> source) {
+  PrintF(" GetCode(%s);\n", source->ToCString().get());
+  return assembler_->GetCode(source);
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/irregexp/imported/regexp-macro-assembler-tracer.h b/js/src/irregexp/imported/regexp-macro-assembler-tracer.h
new file mode 100644
index 0000000000..3fadf1a893
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-macro-assembler-tracer.h
@@ -0,0 +1,90 @@
+// Copyright 2008 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_MACRO_ASSEMBLER_TRACER_H_
+#define V8_REGEXP_REGEXP_MACRO_ASSEMBLER_TRACER_H_
+
+#include "irregexp/imported/regexp-macro-assembler.h"
+
+namespace v8 {
+namespace internal {
+
+// Decorator on a RegExpMacroAssembler that write all calls.
+class RegExpMacroAssemblerTracer: public RegExpMacroAssembler {
+ public:
+  RegExpMacroAssemblerTracer(Isolate* isolate, RegExpMacroAssembler* assembler);
+  ~RegExpMacroAssemblerTracer() override;
+  void AbortedCodeGeneration() override;
+  int stack_limit_slack() override { return assembler_->stack_limit_slack(); }
+  bool CanReadUnaligned() const override {
+    return assembler_->CanReadUnaligned();
+  }
+  void AdvanceCurrentPosition(int by) override;    // Signed cp change.
+  void AdvanceRegister(int reg, int by) override;  // r[reg] += by.
+  void Backtrack() override;
+  void Bind(Label* label) override;
+  void CheckCharacter(unsigned c, Label* on_equal) override;
+  void CheckCharacterAfterAnd(unsigned c, unsigned and_with,
+                              Label* on_equal) override;
+  void CheckCharacterGT(base::uc16 limit, Label* on_greater) override;
+  void CheckCharacterLT(base::uc16 limit, Label* on_less) override;
+  void CheckGreedyLoop(Label* on_tos_equals_current_position) override;
+  void CheckAtStart(int cp_offset, Label* on_at_start) override;
+  void CheckNotAtStart(int cp_offset, Label* on_not_at_start) override;
+  void CheckNotBackReference(int start_reg, bool read_backward,
+                             Label* on_no_match) override;
+  void CheckNotBackReferenceIgnoreCase(int start_reg, bool read_backward,
+                                       bool unicode,
+                                       Label* on_no_match) override;
+  void CheckNotCharacter(unsigned c, Label* on_not_equal) override;
+  void CheckNotCharacterAfterAnd(unsigned c, unsigned and_with,
+                                 Label* on_not_equal) override;
+  void CheckNotCharacterAfterMinusAnd(base::uc16 c, base::uc16 minus,
+                                      base::uc16 and_with,
+                                      Label* on_not_equal) override;
+  void CheckCharacterInRange(base::uc16 from, base::uc16 to,
+                             Label* on_in_range) override;
+  void CheckCharacterNotInRange(base::uc16 from, base::uc16 to,
+                                Label* on_not_in_range) override;
+  bool CheckCharacterInRangeArray(const ZoneList<CharacterRange>* ranges,
+                                  Label* on_in_range) override;
+  bool CheckCharacterNotInRangeArray(const ZoneList<CharacterRange>* ranges,
+                                     Label* on_not_in_range) override;
+  void CheckBitInTable(Handle<ByteArray> table, Label* on_bit_set) override;
+  void CheckPosition(int cp_offset, Label* on_outside_input) override;
+  bool CheckSpecialClassRanges(StandardCharacterSet type,
+                               Label* on_no_match) override;
+  void Fail() override;
+  Handle<HeapObject> GetCode(Handle<String> source) override;
+  void GoTo(Label* label) override;
+  void IfRegisterGE(int reg, int comparand, Label* if_ge) override;
+  void IfRegisterLT(int reg, int comparand, Label* if_lt) override;
+  void IfRegisterEqPos(int reg, Label* if_eq) override;
+  IrregexpImplementation Implementation() override;
+  void LoadCurrentCharacterImpl(int cp_offset, Label* on_end_of_input,
+                                bool check_bounds, int characters,
+                                int eats_at_least) override;
+  void PopCurrentPosition() override;
+  void PopRegister(int register_index) override;
+  void PushBacktrack(Label* label) override;
+  void PushCurrentPosition() override;
+  void PushRegister(int register_index,
+                    StackCheckFlag check_stack_limit) override;
+  void ReadCurrentPositionFromRegister(int reg) override;
+  void ReadStackPointerFromRegister(int reg) override;
+  void SetCurrentPositionFromEnd(int by) override;
+  void SetRegister(int register_index, int to) override;
+  bool Succeed() override;
+  void WriteCurrentPositionToRegister(int reg, int cp_offset) override;
+  void ClearRegisters(int reg_from, int reg_to) override;
+  void WriteStackPointerToRegister(int reg) override;
+
+ private:
+  RegExpMacroAssembler* assembler_;
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_MACRO_ASSEMBLER_TRACER_H_
diff --git a/js/src/irregexp/imported/regexp-macro-assembler.cc b/js/src/irregexp/imported/regexp-macro-assembler.cc
new file mode 100644
index 0000000000..0592338229
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-macro-assembler.cc
@@ -0,0 +1,520 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "irregexp/imported/regexp-macro-assembler.h"
+
+#include "irregexp/imported/regexp-stack.h"
+#include "irregexp/imported/special-case.h"
+
+#ifdef V8_INTL_SUPPORT
+#include "unicode/uchar.h"
+#include "unicode/unistr.h"
+#endif  // V8_INTL_SUPPORT
+
+namespace v8 {
+namespace internal {
+
+RegExpMacroAssembler::RegExpMacroAssembler(Isolate* isolate, Zone* zone)
+    : slow_safe_compiler_(false),
+      backtrack_limit_(JSRegExp::kNoBacktrackLimit),
+      global_mode_(NOT_GLOBAL),
+      isolate_(isolate),
+      zone_(zone) {}
+
+bool RegExpMacroAssembler::has_backtrack_limit() const {
+  return backtrack_limit_ != JSRegExp::kNoBacktrackLimit;
+}
+
+// static
+int RegExpMacroAssembler::CaseInsensitiveCompareNonUnicode(Address byte_offset1,
+                                                           Address byte_offset2,
+                                                           size_t byte_length,
+                                                           Isolate* isolate) {
+#ifdef V8_INTL_SUPPORT
+  // This function is not allowed to cause a garbage collection.
+  // A GC might move the calling generated code and invalidate the
+  // return address on the stack.
+  DisallowGarbageCollection no_gc;
+  DCHECK_EQ(0, byte_length % 2);
+  size_t length = byte_length / 2;
+  base::uc16* substring1 = reinterpret_cast<base::uc16*>(byte_offset1);
+  base::uc16* substring2 = reinterpret_cast<base::uc16*>(byte_offset2);
+
+  for (size_t i = 0; i < length; i++) {
+    UChar32 c1 = RegExpCaseFolding::Canonicalize(substring1[i]);
+    UChar32 c2 = RegExpCaseFolding::Canonicalize(substring2[i]);
+    if (c1 != c2) {
+      return 0;
+    }
+  }
+  return 1;
+#else
+  return CaseInsensitiveCompareUnicode(byte_offset1, byte_offset2, byte_length,
+                                       isolate);
+#endif
+}
+
+// static
+int RegExpMacroAssembler::CaseInsensitiveCompareUnicode(Address byte_offset1,
+                                                        Address byte_offset2,
+                                                        size_t byte_length,
+                                                        Isolate* isolate) {
+  // This function is not allowed to cause a garbage collection.
+  // A GC might move the calling generated code and invalidate the
+  // return address on the stack.
+  DisallowGarbageCollection no_gc;
+  DCHECK_EQ(0, byte_length % 2);
+
+#ifdef V8_INTL_SUPPORT
+  int32_t length = static_cast<int32_t>(byte_length >> 1);
+  icu::UnicodeString uni_str_1(reinterpret_cast<const char16_t*>(byte_offset1),
+                               length);
+  return uni_str_1.caseCompare(reinterpret_cast<const char16_t*>(byte_offset2),
+                               length, U_FOLD_CASE_DEFAULT) == 0;
+#else
+  base::uc16* substring1 = reinterpret_cast<base::uc16*>(byte_offset1);
+  base::uc16* substring2 = reinterpret_cast<base::uc16*>(byte_offset2);
+  size_t length = byte_length >> 1;
+  DCHECK_NOT_NULL(isolate);
+  unibrow::Mapping<unibrow::Ecma262Canonicalize>* canonicalize =
+      isolate->regexp_macro_assembler_canonicalize();
+  for (size_t i = 0; i < length; i++) {
+    unibrow::uchar c1 = substring1[i];
+    unibrow::uchar c2 = substring2[i];
+    if (c1 != c2) {
+      unibrow::uchar s1[1] = {c1};
+      canonicalize->get(c1, '\0', s1);
+      if (s1[0] != c2) {
+        unibrow::uchar s2[1] = {c2};
+        canonicalize->get(c2, '\0', s2);
+        if (s1[0] != s2[0]) {
+          return 0;
+        }
+      }
+    }
+  }
+  return 1;
+#endif  // V8_INTL_SUPPORT
+}
+
+namespace {
+
+uint32_t Hash(const ZoneList<CharacterRange>* ranges) {
+  size_t seed = 0;
+  for (int i = 0; i < ranges->length(); i++) {
+    const CharacterRange& r = ranges->at(i);
+    seed = base::hash_combine(seed, r.from(), r.to());
+  }
+  return static_cast<uint32_t>(seed);
+}
+
+constexpr base::uc32 MaskEndOfRangeMarker(base::uc32 c) {
+  // CharacterRanges may use 0x10ffff as the end-of-range marker irrespective
+  // of whether the regexp IsUnicode or not; translate the marker value here.
+  DCHECK_IMPLIES(c > kMaxUInt16, c == String::kMaxCodePoint);
+  return c & 0xffff;
+}
+
+int RangeArrayLengthFor(const ZoneList<CharacterRange>* ranges) {
+  const int ranges_length = ranges->length();
+  return MaskEndOfRangeMarker(ranges->at(ranges_length - 1).to()) == kMaxUInt16
+             ? ranges_length * 2 - 1
+             : ranges_length * 2;
+}
+
+bool Equals(const ZoneList<CharacterRange>* lhs,
+            const Handle<FixedUInt16Array>& rhs) {
+  const int rhs_length = rhs->length();
+  if (rhs_length != RangeArrayLengthFor(lhs)) return false;
+  for (int i = 0; i < lhs->length(); i++) {
+    const CharacterRange& r = lhs->at(i);
+    if (rhs->get(i * 2 + 0) != r.from()) return false;
+    if (i * 2 + 1 == rhs_length) break;
+    if (rhs->get(i * 2 + 1) != r.to() + 1) return false;
+  }
+  return true;
+}
+
+Handle<FixedUInt16Array> MakeRangeArray(
+    Isolate* isolate, const ZoneList<CharacterRange>* ranges) {
+  const int ranges_length = ranges->length();
+  const int range_array_length = RangeArrayLengthFor(ranges);
+  Handle<FixedUInt16Array> range_array =
+      FixedUInt16Array::New(isolate, range_array_length);
+  for (int i = 0; i < ranges_length; i++) {
+    const CharacterRange& r = ranges->at(i);
+    DCHECK_LE(r.from(), kMaxUInt16);
+    range_array->set(i * 2 + 0, r.from());
+    const base::uc32 to = MaskEndOfRangeMarker(r.to());
+    if (i == ranges_length - 1 && to == kMaxUInt16) {
+      DCHECK_EQ(range_array_length, ranges_length * 2 - 1);
+      break;  // Avoid overflow by leaving the last range open-ended.
+    }
+    DCHECK_LT(to, kMaxUInt16);
+    range_array->set(i * 2 + 1, to + 1);  // Exclusive.
+  }
+  return range_array;
+}
+
+}  // namespace
+
+Handle<ByteArray> NativeRegExpMacroAssembler::GetOrAddRangeArray(
+    const ZoneList<CharacterRange>* ranges) {
+  const uint32_t hash = Hash(ranges);
+
+  if (range_array_cache_.count(hash) != 0) {
+    Handle<FixedUInt16Array> range_array = range_array_cache_[hash];
+    if (Equals(ranges, range_array)) return range_array;
+  }
+
+  Handle<FixedUInt16Array> range_array = MakeRangeArray(isolate(), ranges);
+  range_array_cache_[hash] = range_array;
+  return range_array;
+}
+
+// static
+uint32_t RegExpMacroAssembler::IsCharacterInRangeArray(uint32_t current_char,
+                                                       Address raw_byte_array,
+                                                       Isolate* isolate) {
+  // Use uint32_t to avoid complexity around bool return types (which may be
+  // optimized to use only the least significant byte).
+  static constexpr uint32_t kTrue = 1;
+  static constexpr uint32_t kFalse = 0;
+
+  FixedUInt16Array ranges = FixedUInt16Array::cast(Object(raw_byte_array));
+  DCHECK_GE(ranges.length(), 1);
+
+  // Shortcut for fully out of range chars.
+  if (current_char < ranges.get(0)) return kFalse;
+  if (current_char >= ranges.get(ranges.length() - 1)) {
+    // The last range may be open-ended.
+    return (ranges.length() % 2) == 0 ? kFalse : kTrue;
+  }
+
+  // Binary search for the matching range. `ranges` is encoded as
+  // [from0, to0, from1, to1, ..., fromN, toN], or
+  // [from0, to0, from1, to1, ..., fromN] (open-ended last interval).
+
+  int mid, lower = 0, upper = ranges.length();
+  do {
+    mid = lower + (upper - lower) / 2;
+    const base::uc16 elem = ranges.get(mid);
+    if (current_char < elem) {
+      upper = mid;
+    } else if (current_char > elem) {
+      lower = mid + 1;
+    } else {
+      DCHECK_EQ(current_char, elem);
+      break;
+    }
+  } while (lower < upper);
+
+  const bool current_char_ge_last_elem = current_char >= ranges.get(mid);
+  const int current_range_start_index =
+      current_char_ge_last_elem ? mid : mid - 1;
+
+  // Ranges start at even indices and end at odd indices.
+  return (current_range_start_index % 2) == 0 ? kTrue : kFalse;
+}
+
+void RegExpMacroAssembler::CheckNotInSurrogatePair(int cp_offset,
+                                                   Label* on_failure) {
+  Label ok;
+  // Check that current character is not a trail surrogate.
+  LoadCurrentCharacter(cp_offset, &ok);
+  CheckCharacterNotInRange(kTrailSurrogateStart, kTrailSurrogateEnd, &ok);
+  // Check that previous character is not a lead surrogate.
+  LoadCurrentCharacter(cp_offset - 1, &ok);
+  CheckCharacterInRange(kLeadSurrogateStart, kLeadSurrogateEnd, on_failure);
+  Bind(&ok);
+}
+
+void RegExpMacroAssembler::CheckPosition(int cp_offset,
+                                         Label* on_outside_input) {
+  LoadCurrentCharacter(cp_offset, on_outside_input, true);
+}
+
+void RegExpMacroAssembler::LoadCurrentCharacter(int cp_offset,
+                                                Label* on_end_of_input,
+                                                bool check_bounds,
+                                                int characters,
+                                                int eats_at_least) {
+  // By default, eats_at_least = characters.
+  if (eats_at_least == kUseCharactersValue) {
+    eats_at_least = characters;
+  }
+
+  LoadCurrentCharacterImpl(cp_offset, on_end_of_input, check_bounds, characters,
+                           eats_at_least);
+}
+
+void NativeRegExpMacroAssembler::LoadCurrentCharacterImpl(
+    int cp_offset, Label* on_end_of_input, bool check_bounds, int characters,
+    int eats_at_least) {
+  // It's possible to preload a small number of characters when each success
+  // path requires a large number of characters, but not the reverse.
+  DCHECK_GE(eats_at_least, characters);
+
+  DCHECK(base::IsInRange(cp_offset, kMinCPOffset, kMaxCPOffset));
+  if (check_bounds) {
+    if (cp_offset >= 0) {
+      CheckPosition(cp_offset + eats_at_least - 1, on_end_of_input);
+    } else {
+      CheckPosition(cp_offset, on_end_of_input);
+    }
+  }
+  LoadCurrentCharacterUnchecked(cp_offset, characters);
+}
+
+bool NativeRegExpMacroAssembler::CanReadUnaligned() const {
+  return v8_flags.enable_regexp_unaligned_accesses && !slow_safe();
+}
+
+#ifndef COMPILING_IRREGEXP_FOR_EXTERNAL_EMBEDDER
+
+// This method may only be called after an interrupt.
+// static
+int NativeRegExpMacroAssembler::CheckStackGuardState(
+    Isolate* isolate, int start_index, RegExp::CallOrigin call_origin,
+    Address* return_address, InstructionStream re_code, Address* subject,
+    const byte** input_start, const byte** input_end) {
+  DisallowGarbageCollection no_gc;
+  Address old_pc = PointerAuthentication::AuthenticatePC(return_address, 0);
+  DCHECK_LE(re_code.instruction_start(), old_pc);
+  DCHECK_LE(old_pc, re_code.code(kAcquireLoad).instruction_end());
+
+  StackLimitCheck check(isolate);
+  bool js_has_overflowed = check.JsHasOverflowed();
+
+  if (call_origin == RegExp::CallOrigin::kFromJs) {
+    // Direct calls from JavaScript can be interrupted in two ways:
+    // 1. A real stack overflow, in which case we let the caller throw the
+    //    exception.
+    // 2. The stack guard was used to interrupt execution for another purpose,
+    //    forcing the call through the runtime system.
+
+    // Bug(v8:9540) Investigate why this method is called from JS although no
+    // stackoverflow or interrupt is pending on ARM64. We return 0 in this case
+    // to continue execution normally.
+    if (js_has_overflowed) {
+      return EXCEPTION;
+    } else if (check.InterruptRequested()) {
+      return RETRY;
+    } else {
+      return 0;
+    }
+  }
+  DCHECK(call_origin == RegExp::CallOrigin::kFromRuntime);
+
+  // Prepare for possible GC.
+  HandleScope handles(isolate);
+  Handle<InstructionStream> code_handle(re_code, isolate);
+  Handle<String> subject_handle(String::cast(Object(*subject)), isolate);
+  bool is_one_byte = String::IsOneByteRepresentationUnderneath(*subject_handle);
+  int return_value = 0;
+
+  {
+    DisableGCMole no_gc_mole;
+    if (js_has_overflowed) {
+      AllowGarbageCollection yes_gc;
+      isolate->StackOverflow();
+      return_value = EXCEPTION;
+    } else if (check.InterruptRequested()) {
+      AllowGarbageCollection yes_gc;
+      Object result = isolate->stack_guard()->HandleInterrupts();
+      if (result.IsException(isolate)) return_value = EXCEPTION;
+    }
+
+    // We are not using operator == here because it does a slow DCHECK
+    // CheckObjectComparisonAllowed() which might crash when trying to access
+    // the page header of the stale pointer.
+    if (!code_handle->SafeEquals(re_code)) {  // Return address no longer valid
+      // Overwrite the return address on the stack.
+      intptr_t delta = code_handle->address() - re_code.address();
+      Address new_pc = old_pc + delta;
+      // TODO(v8:10026): avoid replacing a signed pointer.
+      PointerAuthentication::ReplacePC(return_address, new_pc, 0);
+    }
+  }
+
+  // If we continue, we need to update the subject string addresses.
+  if (return_value == 0) {
+    // String encoding might have changed.
+    if (String::IsOneByteRepresentationUnderneath(*subject_handle) !=
+        is_one_byte) {
+      // If we changed between an LATIN1 and an UC16 string, the specialized
+      // code cannot be used, and we need to restart regexp matching from
+      // scratch (including, potentially, compiling a new version of the code).
+      return_value = RETRY;
+    } else {
+      *subject = subject_handle->ptr();
+      intptr_t byte_length = *input_end - *input_start;
+      *input_start = subject_handle->AddressOfCharacterAt(start_index, no_gc);
+      *input_end = *input_start + byte_length;
+    }
+  }
+  return return_value;
+}
+
+// Returns a {Result} sentinel, or the number of successful matches.
+int NativeRegExpMacroAssembler::Match(Handle<JSRegExp> regexp,
+                                      Handle<String> subject,
+                                      int* offsets_vector,
+                                      int offsets_vector_length,
+                                      int previous_index, Isolate* isolate) {
+  DCHECK(subject->IsFlat());
+  DCHECK_LE(0, previous_index);
+  DCHECK_LE(previous_index, subject->length());
+
+  // No allocations before calling the regexp, but we can't use
+  // DisallowGarbageCollection, since regexps might be preempted, and another
+  // thread might do allocation anyway.
+
+  String subject_ptr = *subject;
+  // Character offsets into string.
+  int start_offset = previous_index;
+  int char_length = subject_ptr.length() - start_offset;
+  int slice_offset = 0;
+
+  // The string has been flattened, so if it is a cons string it contains the
+  // full string in the first part.
+  if (StringShape(subject_ptr).IsCons()) {
+    DCHECK_EQ(0, ConsString::cast(subject_ptr).second().length());
+    subject_ptr = ConsString::cast(subject_ptr).first();
+  } else if (StringShape(subject_ptr).IsSliced()) {
+    SlicedString slice = SlicedString::cast(subject_ptr);
+    subject_ptr = slice.parent();
+    slice_offset = slice.offset();
+  }
+  if (StringShape(subject_ptr).IsThin()) {
+    subject_ptr = ThinString::cast(subject_ptr).actual();
+  }
+  // Ensure that an underlying string has the same representation.
+  bool is_one_byte = subject_ptr.IsOneByteRepresentation();
+  DCHECK(subject_ptr.IsExternalString() || subject_ptr.IsSeqString());
+  // String is now either Sequential or External
+  int char_size_shift = is_one_byte ? 0 : 1;
+
+  DisallowGarbageCollection no_gc;
+  const byte* input_start =
+      subject_ptr.AddressOfCharacterAt(start_offset + slice_offset, no_gc);
+  int byte_length = char_length << char_size_shift;
+  const byte* input_end = input_start + byte_length;
+  return Execute(*subject, start_offset, input_start, input_end, offsets_vector,
+                 offsets_vector_length, isolate, *regexp);
+}
+
+// static
+int NativeRegExpMacroAssembler::ExecuteForTesting(
+    String input, int start_offset, const byte* input_start,
+    const byte* input_end, int* output, int output_size, Isolate* isolate,
+    JSRegExp regexp) {
+  return Execute(input, start_offset, input_start, input_end, output,
+                 output_size, isolate, regexp);
+}
+
+// Returns a {Result} sentinel, or the number of successful matches.
+// TODO(pthier): The JSRegExp object is passed to native irregexp code to match
+// the signature of the interpreter. We should get rid of JS objects passed to
+// internal methods.
+int NativeRegExpMacroAssembler::Execute(
+    String input,  // This needs to be the unpacked (sliced, cons) string.
+    int start_offset, const byte* input_start, const byte* input_end,
+    int* output, int output_size, Isolate* isolate, JSRegExp regexp) {
+  RegExpStackScope stack_scope(isolate);
+
+  bool is_one_byte = String::IsOneByteRepresentationUnderneath(input);
+  Code code = Code::cast(regexp.code(is_one_byte));
+  RegExp::CallOrigin call_origin = RegExp::CallOrigin::kFromRuntime;
+
+  using RegexpMatcherSig =
+      // NOLINTNEXTLINE(readability/casting)
+      int(Address input_string, int start_offset, const byte* input_start,
+          const byte* input_end, int* output, int output_size, int call_origin,
+          Isolate* isolate, Address regexp);
+
+  auto fn = GeneratedCode<RegexpMatcherSig>::FromCode(isolate, code);
+  int result = fn.Call(input.ptr(), start_offset, input_start, input_end,
+                       output, output_size, call_origin, isolate, regexp.ptr());
+  DCHECK_GE(result, SMALLEST_REGEXP_RESULT);
+
+  if (result == EXCEPTION && !isolate->has_pending_exception()) {
+    // We detected a stack overflow (on the backtrack stack) in RegExp code,
+    // but haven't created the exception yet. Additionally, we allow heap
+    // allocation because even though it invalidates {input_start} and
+    // {input_end}, we are about to return anyway.
+    AllowGarbageCollection allow_allocation;
+    isolate->StackOverflow();
+  }
+  return result;
+}
+
+#endif  // !COMPILING_IRREGEXP_FOR_EXTERNAL_EMBEDDER
+
+// clang-format off
+const byte NativeRegExpMacroAssembler::word_character_map[] = {
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu,  // '0' - '7'
+    0xFFu, 0xFFu, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,  // '8' - '9'
+
+    0x00u, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu,  // 'A' - 'G'
+    0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu,  // 'H' - 'O'
+    0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu,  // 'P' - 'W'
+    0xFFu, 0xFFu, 0xFFu, 0x00u, 0x00u, 0x00u, 0x00u, 0xFFu,  // 'X' - 'Z', '_'
+
+    0x00u, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu,  // 'a' - 'g'
+    0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu,  // 'h' - 'o'
+    0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu, 0xFFu,  // 'p' - 'w'
+    0xFFu, 0xFFu, 0xFFu, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,  // 'x' - 'z'
+    // Latin-1 range
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+    0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,
+};
+// clang-format on
+
+// static
+Address NativeRegExpMacroAssembler::GrowStack(Isolate* isolate) {
+  DisallowGarbageCollection no_gc;
+
+  RegExpStack* regexp_stack = isolate->regexp_stack();
+  const size_t old_size = regexp_stack->memory_size();
+
+#ifdef DEBUG
+  const Address old_stack_top = regexp_stack->memory_top();
+  const Address old_stack_pointer = regexp_stack->stack_pointer();
+  CHECK_LE(old_stack_pointer, old_stack_top);
+  CHECK_LE(static_cast<size_t>(old_stack_top - old_stack_pointer), old_size);
+#endif  // DEBUG
+
+  Address new_stack_base = regexp_stack->EnsureCapacity(old_size * 2);
+  if (new_stack_base == kNullAddress) return kNullAddress;
+
+  return regexp_stack->stack_pointer();
+}
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/irregexp/imported/regexp-macro-assembler.h b/js/src/irregexp/imported/regexp-macro-assembler.h
new file mode 100644
index 0000000000..651f6cb580
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-macro-assembler.h
@@ -0,0 +1,361 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_MACRO_ASSEMBLER_H_
+#define V8_REGEXP_REGEXP_MACRO_ASSEMBLER_H_
+
+#include "irregexp/imported/regexp-ast.h"
+#include "irregexp/imported/regexp.h"
+#include "irregexp/RegExpShim.h"
+
+namespace v8 {
+namespace internal {
+
+class ByteArray;
+class JSRegExp;
+class Label;
+class String;
+
+static const base::uc32 kLeadSurrogateStart = 0xd800;
+static const base::uc32 kLeadSurrogateEnd = 0xdbff;
+static const base::uc32 kTrailSurrogateStart = 0xdc00;
+static const base::uc32 kTrailSurrogateEnd = 0xdfff;
+static const base::uc32 kNonBmpStart = 0x10000;
+static const base::uc32 kNonBmpEnd = 0x10ffff;
+
+class RegExpMacroAssembler {
+ public:
+  // The implementation must be able to handle at least:
+  static constexpr int kMaxRegisterCount = (1 << 16);
+  static constexpr int kMaxRegister = kMaxRegisterCount - 1;
+  static constexpr int kMaxCaptures = (kMaxRegister - 1) / 2;
+  static constexpr int kMaxCPOffset = (1 << 15) - 1;
+  static constexpr int kMinCPOffset = -(1 << 15);
+
+  static constexpr int kTableSizeBits = 7;
+  static constexpr int kTableSize = 1 << kTableSizeBits;
+  static constexpr int kTableMask = kTableSize - 1;
+
+  static constexpr int kUseCharactersValue = -1;
+
+  RegExpMacroAssembler(Isolate* isolate, Zone* zone);
+  virtual ~RegExpMacroAssembler() = default;
+
+  virtual Handle<HeapObject> GetCode(Handle<String> source) = 0;
+
+  // This function is called when code generation is aborted, so that
+  // the assembler could clean up internal data structures.
+  virtual void AbortedCodeGeneration() {}
+  // The maximal number of pushes between stack checks. Users must supply
+  // kCheckStackLimit flag to push operations (instead of kNoStackLimitCheck)
+  // at least once for every stack_limit() pushes that are executed.
+  virtual int stack_limit_slack() = 0;
+  virtual bool CanReadUnaligned() const = 0;
+
+  virtual void AdvanceCurrentPosition(int by) = 0;  // Signed cp change.
+  virtual void AdvanceRegister(int reg, int by) = 0;  // r[reg] += by.
+  // Continues execution from the position pushed on the top of the backtrack
+  // stack by an earlier PushBacktrack(Label*).
+  virtual void Backtrack() = 0;
+  virtual void Bind(Label* label) = 0;
+  // Dispatch after looking the current character up in a 2-bits-per-entry
+  // map.  The destinations vector has up to 4 labels.
+  virtual void CheckCharacter(unsigned c, Label* on_equal) = 0;
+  // Bitwise and the current character with the given constant and then
+  // check for a match with c.
+  virtual void CheckCharacterAfterAnd(unsigned c,
+                                      unsigned and_with,
+                                      Label* on_equal) = 0;
+  virtual void CheckCharacterGT(base::uc16 limit, Label* on_greater) = 0;
+  virtual void CheckCharacterLT(base::uc16 limit, Label* on_less) = 0;
+  virtual void CheckGreedyLoop(Label* on_tos_equals_current_position) = 0;
+  virtual void CheckAtStart(int cp_offset, Label* on_at_start) = 0;
+  virtual void CheckNotAtStart(int cp_offset, Label* on_not_at_start) = 0;
+  virtual void CheckNotBackReference(int start_reg, bool read_backward,
+                                     Label* on_no_match) = 0;
+  virtual void CheckNotBackReferenceIgnoreCase(int start_reg,
+                                               bool read_backward, bool unicode,
+                                               Label* on_no_match) = 0;
+  // Check the current character for a match with a literal character.  If we
+  // fail to match then goto the on_failure label.  End of input always
+  // matches.  If the label is nullptr then we should pop a backtrack address
+  // off the stack and go to that.
+  virtual void CheckNotCharacter(unsigned c, Label* on_not_equal) = 0;
+  virtual void CheckNotCharacterAfterAnd(unsigned c,
+                                         unsigned and_with,
+                                         Label* on_not_equal) = 0;
+  // Subtract a constant from the current character, then and with the given
+  // constant and then check for a match with c.
+  virtual void CheckNotCharacterAfterMinusAnd(base::uc16 c, base::uc16 minus,
+                                              base::uc16 and_with,
+                                              Label* on_not_equal) = 0;
+  virtual void CheckCharacterInRange(base::uc16 from,
+                                     base::uc16 to,  // Both inclusive.
+                                     Label* on_in_range) = 0;
+  virtual void CheckCharacterNotInRange(base::uc16 from,
+                                        base::uc16 to,  // Both inclusive.
+                                        Label* on_not_in_range) = 0;
+  // Returns true if the check was emitted, false otherwise.
+  virtual bool CheckCharacterInRangeArray(
+      const ZoneList<CharacterRange>* ranges, Label* on_in_range) = 0;
+  virtual bool CheckCharacterNotInRangeArray(
+      const ZoneList<CharacterRange>* ranges, Label* on_not_in_range) = 0;
+
+  // The current character (modulus the kTableSize) is looked up in the byte
+  // array, and if the found byte is non-zero, we jump to the on_bit_set label.
+  virtual void CheckBitInTable(Handle<ByteArray> table, Label* on_bit_set) = 0;
+
+  // Checks whether the given offset from the current position is before
+  // the end of the string.  May overwrite the current character.
+  virtual void CheckPosition(int cp_offset, Label* on_outside_input);
+  // Check whether a standard/default character class matches the current
+  // character. Returns false if the type of special character class does
+  // not have custom support.
+  // May clobber the current loaded character.
+  virtual bool CheckSpecialClassRanges(StandardCharacterSet type,
+                                       Label* on_no_match) {
+    return false;
+  }
+
+  // Control-flow integrity:
+  // Define a jump target and bind a label.
+  virtual void BindJumpTarget(Label* label) { Bind(label); }
+
+  virtual void Fail() = 0;
+  virtual void GoTo(Label* label) = 0;
+  // Check whether a register is >= a given constant and go to a label if it
+  // is.  Backtracks instead if the label is nullptr.
+  virtual void IfRegisterGE(int reg, int comparand, Label* if_ge) = 0;
+  // Check whether a register is < a given constant and go to a label if it is.
+  // Backtracks instead if the label is nullptr.
+  virtual void IfRegisterLT(int reg, int comparand, Label* if_lt) = 0;
+  // Check whether a register is == to the current position and go to a
+  // label if it is.
+  virtual void IfRegisterEqPos(int reg, Label* if_eq) = 0;
+  V8_EXPORT_PRIVATE void LoadCurrentCharacter(
+      int cp_offset, Label* on_end_of_input, bool check_bounds = true,
+      int characters = 1, int eats_at_least = kUseCharactersValue);
+  virtual void LoadCurrentCharacterImpl(int cp_offset, Label* on_end_of_input,
+                                        bool check_bounds, int characters,
+                                        int eats_at_least) = 0;
+  virtual void PopCurrentPosition() = 0;
+  virtual void PopRegister(int register_index) = 0;
+  // Pushes the label on the backtrack stack, so that a following Backtrack
+  // will go to this label. Always checks the backtrack stack limit.
+  virtual void PushBacktrack(Label* label) = 0;
+  virtual void PushCurrentPosition() = 0;
+  enum StackCheckFlag { kNoStackLimitCheck = false, kCheckStackLimit = true };
+  virtual void PushRegister(int register_index,
+                            StackCheckFlag check_stack_limit) = 0;
+  virtual void ReadCurrentPositionFromRegister(int reg) = 0;
+  virtual void ReadStackPointerFromRegister(int reg) = 0;
+  virtual void SetCurrentPositionFromEnd(int by) = 0;
+  virtual void SetRegister(int register_index, int to) = 0;
+  // Return whether the matching (with a global regexp) will be restarted.
+  virtual bool Succeed() = 0;
+  virtual void WriteCurrentPositionToRegister(int reg, int cp_offset) = 0;
+  virtual void ClearRegisters(int reg_from, int reg_to) = 0;
+  virtual void WriteStackPointerToRegister(int reg) = 0;
+
+  // Check that we are not in the middle of a surrogate pair.
+  void CheckNotInSurrogatePair(int cp_offset, Label* on_failure);
+
+#define IMPLEMENTATIONS_LIST(V) \
+  V(IA32)                       \
+  V(ARM)                        \
+  V(ARM64)                      \
+  V(MIPS)                       \
+  V(LOONG64)                    \
+  V(RISCV)                      \
+  V(RISCV32)                    \
+  V(S390)                       \
+  V(PPC)                        \
+  V(X64)                        \
+  V(Bytecode)
+
+  enum IrregexpImplementation {
+#define V(Name) k##Name##Implementation,
+    IMPLEMENTATIONS_LIST(V)
+#undef V
+  };
+
+  inline const char* ImplementationToString(IrregexpImplementation impl) {
+    static const char* const kNames[] = {
+#define V(Name) #Name,
+        IMPLEMENTATIONS_LIST(V)
+#undef V
+    };
+    return kNames[impl];
+  }
+#undef IMPLEMENTATIONS_LIST
+  virtual IrregexpImplementation Implementation() = 0;
+
+  // Compare two-byte strings case insensitively.
+  //
+  // Called from generated code.
+  static int CaseInsensitiveCompareNonUnicode(Address byte_offset1,
+                                              Address byte_offset2,
+                                              size_t byte_length,
+                                              Isolate* isolate);
+  static int CaseInsensitiveCompareUnicode(Address byte_offset1,
+                                           Address byte_offset2,
+                                           size_t byte_length,
+                                           Isolate* isolate);
+
+  // `raw_byte_array` is a ByteArray containing a set of character ranges,
+  // where ranges are encoded as uint16_t elements:
+  //
+  //  [from0, to0, from1, to1, ..., fromN, toN], or
+  //  [from0, to0, from1, to1, ..., fromN]  (open-ended last interval).
+  //
+  // fromN is inclusive, toN is exclusive. Returns zero if not in a range,
+  // non-zero otherwise.
+  //
+  // Called from generated code.
+  static uint32_t IsCharacterInRangeArray(uint32_t current_char,
+                                          Address raw_byte_array,
+                                          Isolate* isolate);
+
+  // Controls the generation of large inlined constants in the code.
+  void set_slow_safe(bool ssc) { slow_safe_compiler_ = ssc; }
+  bool slow_safe() const { return slow_safe_compiler_; }
+
+  // Controls after how many backtracks irregexp should abort execution.  If it
+  // can fall back to the experimental engine (see `set_can_fallback`), it will
+  // return the appropriate error code, otherwise it will return the number of
+  // matches found so far (perhaps none).
+  void set_backtrack_limit(uint32_t backtrack_limit) {
+    backtrack_limit_ = backtrack_limit;
+  }
+
+  // Set whether or not irregexp can fall back to the experimental engine on
+  // excessive backtracking.  The number of backtracks considered excessive can
+  // be controlled with set_backtrack_limit.
+  void set_can_fallback(bool val) { can_fallback_ = val; }
+
+  enum GlobalMode {
+    NOT_GLOBAL,
+    GLOBAL_NO_ZERO_LENGTH_CHECK,
+    GLOBAL,
+    GLOBAL_UNICODE
+  };
+  // Set whether the regular expression has the global flag.  Exiting due to
+  // a failure in a global regexp may still mean success overall.
+  inline void set_global_mode(GlobalMode mode) { global_mode_ = mode; }
+  inline bool global() const { return global_mode_ != NOT_GLOBAL; }
+  inline bool global_with_zero_length_check() const {
+    return global_mode_ == GLOBAL || global_mode_ == GLOBAL_UNICODE;
+  }
+  inline bool global_unicode() const { return global_mode_ == GLOBAL_UNICODE; }
+
+  Isolate* isolate() const { return isolate_; }
+  Zone* zone() const { return zone_; }
+
+ protected:
+  bool has_backtrack_limit() const;
+  uint32_t backtrack_limit() const { return backtrack_limit_; }
+
+  bool can_fallback() const { return can_fallback_; }
+
+ private:
+  bool slow_safe_compiler_;
+  uint32_t backtrack_limit_;
+  bool can_fallback_ = false;
+  GlobalMode global_mode_;
+  Isolate* const isolate_;
+  Zone* const zone_;
+};
+
+class NativeRegExpMacroAssembler: public RegExpMacroAssembler {
+ public:
+  // Type of input string to generate code for.
+  enum Mode { LATIN1 = 1, UC16 = 2 };
+
+  // Result of calling generated native RegExp code.
+  // RETRY: Something significant changed during execution, and the matching
+  //        should be retried from scratch.
+  // EXCEPTION: Something failed during execution. If no exception has been
+  //            thrown, it's an internal out-of-memory, and the caller should
+  //            throw the exception.
+  // FAILURE: Matching failed.
+  // SUCCESS: Matching succeeded, and the output array has been filled with
+  //          capture positions.
+  // FALLBACK_TO_EXPERIMENTAL: Execute the regexp on this subject using the
+  //                           experimental engine instead.
+  enum Result {
+    FAILURE = RegExp::kInternalRegExpFailure,
+    SUCCESS = RegExp::kInternalRegExpSuccess,
+    EXCEPTION = RegExp::kInternalRegExpException,
+    RETRY = RegExp::kInternalRegExpRetry,
+    FALLBACK_TO_EXPERIMENTAL = RegExp::kInternalRegExpFallbackToExperimental,
+    SMALLEST_REGEXP_RESULT = RegExp::kInternalRegExpSmallestResult,
+  };
+
+  NativeRegExpMacroAssembler(Isolate* isolate, Zone* zone)
+      : RegExpMacroAssembler(isolate, zone), range_array_cache_(zone) {}
+  ~NativeRegExpMacroAssembler() override = default;
+
+  // Returns a {Result} sentinel, or the number of successful matches.
+  static int Match(Handle<JSRegExp> regexp, Handle<String> subject,
+                   int* offsets_vector, int offsets_vector_length,
+                   int previous_index, Isolate* isolate);
+
+  V8_EXPORT_PRIVATE static int ExecuteForTesting(String input, int start_offset,
+                                                 const byte* input_start,
+                                                 const byte* input_end,
+                                                 int* output, int output_size,
+                                                 Isolate* isolate,
+                                                 JSRegExp regexp);
+
+  bool CanReadUnaligned() const override;
+
+  void LoadCurrentCharacterImpl(int cp_offset, Label* on_end_of_input,
+                                bool check_bounds, int characters,
+                                int eats_at_least) override;
+  // Load a number of characters at the given offset from the
+  // current position, into the current-character register.
+  virtual void LoadCurrentCharacterUnchecked(int cp_offset,
+                                             int character_count) = 0;
+
+  // Called from RegExp if the backtrack stack limit is hit. Tries to expand
+  // the stack. Returns the new stack-pointer if successful, or returns 0 if
+  // unable to grow the stack.
+  // This function must not trigger a garbage collection.
+  //
+  // Called from generated code.
+  static Address GrowStack(Isolate* isolate);
+
+  // Called from generated code.
+  static int CheckStackGuardState(Isolate* isolate, int start_index,
+                                  RegExp::CallOrigin call_origin,
+                                  Address* return_address,
+                                  InstructionStream re_code, Address* subject,
+                                  const byte** input_start,
+                                  const byte** input_end);
+
+  static Address word_character_map_address() {
+    return reinterpret_cast<Address>(&word_character_map[0]);
+  }
+
+ protected:
+  // Byte map of one byte characters with a 0xff if the character is a word
+  // character (digit, letter or underscore) and 0x00 otherwise.
+  // Used by generated RegExp code.
+  static const byte word_character_map[256];
+
+  Handle<ByteArray> GetOrAddRangeArray(const ZoneList<CharacterRange>* ranges);
+
+ private:
+  // Returns a {Result} sentinel, or the number of successful matches.
+  static int Execute(String input, int start_offset, const byte* input_start,
+                     const byte* input_end, int* output, int output_size,
+                     Isolate* isolate, JSRegExp regexp);
+
+  ZoneUnorderedMap<uint32_t, Handle<FixedUInt16Array>> range_array_cache_;
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_MACRO_ASSEMBLER_H_
diff --git a/js/src/irregexp/imported/regexp-nodes.h b/js/src/irregexp/imported/regexp-nodes.h
new file mode 100644
index 0000000000..9407f1c5ec
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-nodes.h
@@ -0,0 +1,775 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_NODES_H_
+#define V8_REGEXP_REGEXP_NODES_H_
+
+#include "irregexp/imported/regexp-macro-assembler.h"
+
+namespace v8 {
+namespace internal {
+
+class AlternativeGenerationList;
+class BoyerMooreLookahead;
+class GreedyLoopState;
+class NodeVisitor;
+class QuickCheckDetails;
+class RegExpCompiler;
+class Trace;
+struct PreloadState;
+class ChoiceNode;
+
+#define FOR_EACH_NODE_TYPE(VISIT) \
+  VISIT(End)                      \
+  VISIT(Action)                   \
+  VISIT(Choice)                   \
+  VISIT(LoopChoice)               \
+  VISIT(NegativeLookaroundChoice) \
+  VISIT(BackReference)            \
+  VISIT(Assertion)                \
+  VISIT(Text)
+
+struct NodeInfo final {
+  NodeInfo()
+      : being_analyzed(false),
+        been_analyzed(false),
+        follows_word_interest(false),
+        follows_newline_interest(false),
+        follows_start_interest(false),
+        at_end(false),
+        visited(false),
+        replacement_calculated(false) {}
+
+  // Returns true if the interests and assumptions of this node
+  // matches the given one.
+  bool Matches(NodeInfo* that) {
+    return (at_end == that->at_end) &&
+           (follows_word_interest == that->follows_word_interest) &&
+           (follows_newline_interest == that->follows_newline_interest) &&
+           (follows_start_interest == that->follows_start_interest);
+  }
+
+  // Updates the interests of this node given the interests of the
+  // node preceding it.
+  void AddFromPreceding(NodeInfo* that) {
+    at_end |= that->at_end;
+    follows_word_interest |= that->follows_word_interest;
+    follows_newline_interest |= that->follows_newline_interest;
+    follows_start_interest |= that->follows_start_interest;
+  }
+
+  bool HasLookbehind() {
+    return follows_word_interest || follows_newline_interest ||
+           follows_start_interest;
+  }
+
+  // Sets the interests of this node to include the interests of the
+  // following node.
+  void AddFromFollowing(NodeInfo* that) {
+    follows_word_interest |= that->follows_word_interest;
+    follows_newline_interest |= that->follows_newline_interest;
+    follows_start_interest |= that->follows_start_interest;
+  }
+
+  void ResetCompilationState() {
+    being_analyzed = false;
+    been_analyzed = false;
+  }
+
+  bool being_analyzed : 1;
+  bool been_analyzed : 1;
+
+  // These bits are set of this node has to know what the preceding
+  // character was.
+  bool follows_word_interest : 1;
+  bool follows_newline_interest : 1;
+  bool follows_start_interest : 1;
+
+  bool at_end : 1;
+  bool visited : 1;
+  bool replacement_calculated : 1;
+};
+
+struct EatsAtLeastInfo final {
+  EatsAtLeastInfo() : EatsAtLeastInfo(0) {}
+  explicit EatsAtLeastInfo(uint8_t eats)
+      : eats_at_least_from_possibly_start(eats),
+        eats_at_least_from_not_start(eats) {}
+  void SetMin(const EatsAtLeastInfo& other) {
+    if (other.eats_at_least_from_possibly_start <
+        eats_at_least_from_possibly_start) {
+      eats_at_least_from_possibly_start =
+          other.eats_at_least_from_possibly_start;
+    }
+    if (other.eats_at_least_from_not_start < eats_at_least_from_not_start) {
+      eats_at_least_from_not_start = other.eats_at_least_from_not_start;
+    }
+  }
+
+  bool IsZero() const {
+    return eats_at_least_from_possibly_start == 0 &&
+           eats_at_least_from_not_start == 0;
+  }
+
+  // Any successful match starting from the current node will consume at least
+  // this many characters. This does not necessarily mean that there is a
+  // possible match with exactly this many characters, but we generally try to
+  // get this number as high as possible to allow for early exit on failure.
+  uint8_t eats_at_least_from_possibly_start;
+
+  // Like eats_at_least_from_possibly_start, but with the additional assumption
+  // that start-of-string assertions (^) can't match. This value is greater than
+  // or equal to eats_at_least_from_possibly_start.
+  uint8_t eats_at_least_from_not_start;
+};
+
+class RegExpNode : public ZoneObject {
+ public:
+  explicit RegExpNode(Zone* zone)
+      : replacement_(nullptr),
+        on_work_list_(false),
+        trace_count_(0),
+        zone_(zone) {
+    bm_info_[0] = bm_info_[1] = nullptr;
+  }
+  virtual ~RegExpNode();
+  virtual void Accept(NodeVisitor* visitor) = 0;
+  // Generates a goto to this node or actually generates the code at this point.
+  virtual void Emit(RegExpCompiler* compiler, Trace* trace) = 0;
+  // How many characters must this node consume at a minimum in order to
+  // succeed.  The not_at_start argument is used to indicate that we know we are
+  // not at the start of the input.  In this case anchored branches will always
+  // fail and can be ignored when determining how many characters are consumed
+  // on success.  If this node has not been analyzed yet, EatsAtLeast returns 0.
+  int EatsAtLeast(bool not_at_start);
+  // Returns how many characters this node must consume in order to succeed,
+  // given that this is a LoopChoiceNode whose counter register is in a
+  // newly-initialized state at the current position in the generated code. For
+  // example, consider /a{6,8}/. Absent any extra information, the
+  // LoopChoiceNode for the repetition must report that it consumes at least
+  // zero characters, because it may have already looped several times. However,
+  // with a newly-initialized counter, it can report that it consumes at least
+  // six characters.
+  virtual EatsAtLeastInfo EatsAtLeastFromLoopEntry();
+  // Emits some quick code that checks whether the preloaded characters match.
+  // Falls through on certain failure, jumps to the label on possible success.
+  // If the node cannot make a quick check it does nothing and returns false.
+  bool EmitQuickCheck(RegExpCompiler* compiler, Trace* bounds_check_trace,
+                      Trace* trace, bool preload_has_checked_bounds,
+                      Label* on_possible_success,
+                      QuickCheckDetails* details_return,
+                      bool fall_through_on_failure, ChoiceNode* predecessor);
+  // For a given number of characters this returns a mask and a value.  The
+  // next n characters are anded with the mask and compared with the value.
+  // A comparison failure indicates the node cannot match the next n characters.
+  // A comparison success indicates the node may match.
+  virtual void GetQuickCheckDetails(QuickCheckDetails* details,
+                                    RegExpCompiler* compiler,
+                                    int characters_filled_in,
+                                    bool not_at_start) = 0;
+  // Fills in quick check details for this node, given that this is a
+  // LoopChoiceNode whose counter register is in a newly-initialized state at
+  // the current position in the generated code. For example, consider /a{6,8}/.
+  // Absent any extra information, the LoopChoiceNode for the repetition cannot
+  // generate any useful quick check because a match might be the (empty)
+  // continuation node. However, with a newly-initialized counter, it can
+  // generate a quick check for several 'a' characters at once.
+  virtual void GetQuickCheckDetailsFromLoopEntry(QuickCheckDetails* details,
+                                                 RegExpCompiler* compiler,
+                                                 int characters_filled_in,
+                                                 bool not_at_start);
+  static const int kNodeIsTooComplexForGreedyLoops = kMinInt;
+  virtual int GreedyLoopTextLength() { return kNodeIsTooComplexForGreedyLoops; }
+  // Only returns the successor for a text node of length 1 that matches any
+  // character and that has no guards on it.
+  virtual RegExpNode* GetSuccessorOfOmnivorousTextNode(
+      RegExpCompiler* compiler) {
+    return nullptr;
+  }
+
+  // Collects information on the possible code units (mod 128) that can match if
+  // we look forward.  This is used for a Boyer-Moore-like string searching
+  // implementation.  TODO(erikcorry):  This should share more code with
+  // EatsAtLeast, GetQuickCheckDetails.  The budget argument is used to limit
+  // the number of nodes we are willing to look at in order to create this data.
+  static const int kRecursionBudget = 200;
+  bool KeepRecursing(RegExpCompiler* compiler);
+  virtual void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                            BoyerMooreLookahead* bm, bool not_at_start) {
+    UNREACHABLE();
+  }
+
+  // If we know that the input is one-byte then there are some nodes that can
+  // never match.  This method returns a node that can be substituted for
+  // itself, or nullptr if the node can never match.
+  virtual RegExpNode* FilterOneByte(int depth, RegExpFlags flags) {
+    return this;
+  }
+  // Helper for FilterOneByte.
+  RegExpNode* replacement() {
+    DCHECK(info()->replacement_calculated);
+    return replacement_;
+  }
+  RegExpNode* set_replacement(RegExpNode* replacement) {
+    info()->replacement_calculated = true;
+    replacement_ = replacement;
+    return replacement;  // For convenience.
+  }
+
+  // We want to avoid recalculating the lookahead info, so we store it on the
+  // node.  Only info that is for this node is stored.  We can tell that the
+  // info is for this node when offset == 0, so the information is calculated
+  // relative to this node.
+  void SaveBMInfo(BoyerMooreLookahead* bm, bool not_at_start, int offset) {
+    if (offset == 0) set_bm_info(not_at_start, bm);
+  }
+
+  Label* label() { return &label_; }
+  // If non-generic code is generated for a node (i.e. the node is not at the
+  // start of the trace) then it cannot be reused.  This variable sets a limit
+  // on how often we allow that to happen before we insist on starting a new
+  // trace and generating generic code for a node that can be reused by flushing
+  // the deferred actions in the current trace and generating a goto.
+  static const int kMaxCopiesCodeGenerated = 10;
+
+  bool on_work_list() { return on_work_list_; }
+  void set_on_work_list(bool value) { on_work_list_ = value; }
+
+  NodeInfo* info() { return &info_; }
+  const EatsAtLeastInfo* eats_at_least_info() const { return &eats_at_least_; }
+  void set_eats_at_least_info(const EatsAtLeastInfo& eats_at_least) {
+    eats_at_least_ = eats_at_least;
+  }
+
+  // TODO(v8:10441): This is a hacky way to avoid exponential code size growth
+  // for very large choice nodes that can be generated by unicode property
+  // escapes. In order to avoid inlining (i.e. trace recursion), we pretend to
+  // have generated the maximum count of code copies already.
+  // We should instead fix this properly, e.g. by using the code size budget
+  // (flush_budget) or by generating property escape matches as calls to a C
+  // function.
+  void SetDoNotInline() { trace_count_ = kMaxCopiesCodeGenerated; }
+
+  BoyerMooreLookahead* bm_info(bool not_at_start) {
+    return bm_info_[not_at_start ? 1 : 0];
+  }
+
+  Zone* zone() const { return zone_; }
+
+ protected:
+  enum LimitResult { DONE, CONTINUE };
+  RegExpNode* replacement_;
+
+  LimitResult LimitVersions(RegExpCompiler* compiler, Trace* trace);
+
+  void set_bm_info(bool not_at_start, BoyerMooreLookahead* bm) {
+    bm_info_[not_at_start ? 1 : 0] = bm;
+  }
+
+ private:
+  static const int kFirstCharBudget = 10;
+  Label label_;
+  bool on_work_list_;
+  NodeInfo info_;
+
+  // Saved values for EatsAtLeast results, to avoid recomputation. Filled in
+  // during analysis (valid if info_.been_analyzed is true).
+  EatsAtLeastInfo eats_at_least_;
+
+  // This variable keeps track of how many times code has been generated for
+  // this node (in different traces).  We don't keep track of where the
+  // generated code is located unless the code is generated at the start of
+  // a trace, in which case it is generic and can be reused by flushing the
+  // deferred operations in the current trace and generating a goto.
+  int trace_count_;
+  BoyerMooreLookahead* bm_info_[2];
+
+  Zone* zone_;
+};
+
+class SeqRegExpNode : public RegExpNode {
+ public:
+  explicit SeqRegExpNode(RegExpNode* on_success)
+      : RegExpNode(on_success->zone()), on_success_(on_success) {}
+  RegExpNode* on_success() { return on_success_; }
+  void set_on_success(RegExpNode* node) { on_success_ = node; }
+  RegExpNode* FilterOneByte(int depth, RegExpFlags flags) override;
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override {
+    on_success_->FillInBMInfo(isolate, offset, budget - 1, bm, not_at_start);
+    if (offset == 0) set_bm_info(not_at_start, bm);
+  }
+
+ protected:
+  RegExpNode* FilterSuccessor(int depth, RegExpFlags flags);
+
+ private:
+  RegExpNode* on_success_;
+};
+
+class ActionNode : public SeqRegExpNode {
+ public:
+  enum ActionType {
+    SET_REGISTER_FOR_LOOP,
+    INCREMENT_REGISTER,
+    STORE_POSITION,
+    BEGIN_POSITIVE_SUBMATCH,
+    BEGIN_NEGATIVE_SUBMATCH,
+    POSITIVE_SUBMATCH_SUCCESS,
+    EMPTY_MATCH_CHECK,
+    CLEAR_CAPTURES
+  };
+  static ActionNode* SetRegisterForLoop(int reg, int val,
+                                        RegExpNode* on_success);
+  static ActionNode* IncrementRegister(int reg, RegExpNode* on_success);
+  static ActionNode* StorePosition(int reg, bool is_capture,
+                                   RegExpNode* on_success);
+  static ActionNode* ClearCaptures(Interval range, RegExpNode* on_success);
+  static ActionNode* BeginPositiveSubmatch(int stack_pointer_reg,
+                                           int position_reg,
+                                           RegExpNode* on_success);
+  static ActionNode* BeginNegativeSubmatch(int stack_pointer_reg,
+                                           int position_reg,
+                                           RegExpNode* on_success);
+  static ActionNode* PositiveSubmatchSuccess(int stack_pointer_reg,
+                                             int restore_reg,
+                                             int clear_capture_count,
+                                             int clear_capture_from,
+                                             RegExpNode* on_success);
+  static ActionNode* EmptyMatchCheck(int start_register,
+                                     int repetition_register,
+                                     int repetition_limit,
+                                     RegExpNode* on_success);
+  void Accept(NodeVisitor* visitor) override;
+  void Emit(RegExpCompiler* compiler, Trace* trace) override;
+  void GetQuickCheckDetails(QuickCheckDetails* details,
+                            RegExpCompiler* compiler, int filled_in,
+                            bool not_at_start) override;
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override;
+  ActionType action_type() { return action_type_; }
+  // TODO(erikcorry): We should allow some action nodes in greedy loops.
+  int GreedyLoopTextLength() override {
+    return kNodeIsTooComplexForGreedyLoops;
+  }
+
+ private:
+  union {
+    struct {
+      int reg;
+      int value;
+    } u_store_register;
+    struct {
+      int reg;
+    } u_increment_register;
+    struct {
+      int reg;
+      bool is_capture;
+    } u_position_register;
+    struct {
+      int stack_pointer_register;
+      int current_position_register;
+      int clear_register_count;
+      int clear_register_from;
+    } u_submatch;
+    struct {
+      int start_register;
+      int repetition_register;
+      int repetition_limit;
+    } u_empty_match_check;
+    struct {
+      int range_from;
+      int range_to;
+    } u_clear_captures;
+  } data_;
+  ActionNode(ActionType action_type, RegExpNode* on_success)
+      : SeqRegExpNode(on_success), action_type_(action_type) {}
+  ActionType action_type_;
+  friend class DotPrinterImpl;
+  friend Zone;
+};
+
+class TextNode : public SeqRegExpNode {
+ public:
+  TextNode(ZoneList<TextElement>* elms, bool read_backward,
+           RegExpNode* on_success)
+      : SeqRegExpNode(on_success), elms_(elms), read_backward_(read_backward) {}
+  TextNode(RegExpClassRanges* that, bool read_backward, RegExpNode* on_success)
+      : SeqRegExpNode(on_success),
+        elms_(zone()->New<ZoneList<TextElement>>(1, zone())),
+        read_backward_(read_backward) {
+    elms_->Add(TextElement::ClassRanges(that), zone());
+  }
+  // Create TextNode for a single character class for the given ranges.
+  static TextNode* CreateForCharacterRanges(Zone* zone,
+                                            ZoneList<CharacterRange>* ranges,
+                                            bool read_backward,
+                                            RegExpNode* on_success);
+  // Create TextNode for a surrogate pair (i.e. match a sequence of two uc16
+  // code unit ranges).
+  static TextNode* CreateForSurrogatePair(
+      Zone* zone, CharacterRange lead, ZoneList<CharacterRange>* trail_ranges,
+      bool read_backward, RegExpNode* on_success);
+  static TextNode* CreateForSurrogatePair(Zone* zone,
+                                          ZoneList<CharacterRange>* lead_ranges,
+                                          CharacterRange trail,
+                                          bool read_backward,
+                                          RegExpNode* on_success);
+  void Accept(NodeVisitor* visitor) override;
+  void Emit(RegExpCompiler* compiler, Trace* trace) override;
+  void GetQuickCheckDetails(QuickCheckDetails* details,
+                            RegExpCompiler* compiler, int characters_filled_in,
+                            bool not_at_start) override;
+  ZoneList<TextElement>* elements() { return elms_; }
+  bool read_backward() { return read_backward_; }
+  void MakeCaseIndependent(Isolate* isolate, bool is_one_byte,
+                           RegExpFlags flags);
+  int GreedyLoopTextLength() override;
+  RegExpNode* GetSuccessorOfOmnivorousTextNode(
+      RegExpCompiler* compiler) override;
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override;
+  void CalculateOffsets();
+  RegExpNode* FilterOneByte(int depth, RegExpFlags flags) override;
+  int Length();
+
+ private:
+  enum TextEmitPassType {
+    NON_LATIN1_MATCH,            // Check for characters that can't match.
+    SIMPLE_CHARACTER_MATCH,      // Case-dependent single character check.
+    NON_LETTER_CHARACTER_MATCH,  // Check characters that have no case equivs.
+    CASE_CHARACTER_MATCH,        // Case-independent single character check.
+    CHARACTER_CLASS_MATCH        // Character class.
+  };
+  static bool SkipPass(TextEmitPassType pass, bool ignore_case);
+  static const int kFirstRealPass = SIMPLE_CHARACTER_MATCH;
+  static const int kLastPass = CHARACTER_CLASS_MATCH;
+  void TextEmitPass(RegExpCompiler* compiler, TextEmitPassType pass,
+                    bool preloaded, Trace* trace, bool first_element_checked,
+                    int* checked_up_to);
+  ZoneList<TextElement>* elms_;
+  bool read_backward_;
+};
+
+class AssertionNode : public SeqRegExpNode {
+ public:
+  enum AssertionType {
+    AT_END,
+    AT_START,
+    AT_BOUNDARY,
+    AT_NON_BOUNDARY,
+    AFTER_NEWLINE
+  };
+  static AssertionNode* AtEnd(RegExpNode* on_success) {
+    return on_success->zone()->New<AssertionNode>(AT_END, on_success);
+  }
+  static AssertionNode* AtStart(RegExpNode* on_success) {
+    return on_success->zone()->New<AssertionNode>(AT_START, on_success);
+  }
+  static AssertionNode* AtBoundary(RegExpNode* on_success) {
+    return on_success->zone()->New<AssertionNode>(AT_BOUNDARY, on_success);
+  }
+  static AssertionNode* AtNonBoundary(RegExpNode* on_success) {
+    return on_success->zone()->New<AssertionNode>(AT_NON_BOUNDARY, on_success);
+  }
+  static AssertionNode* AfterNewline(RegExpNode* on_success) {
+    return on_success->zone()->New<AssertionNode>(AFTER_NEWLINE, on_success);
+  }
+  void Accept(NodeVisitor* visitor) override;
+  void Emit(RegExpCompiler* compiler, Trace* trace) override;
+  void GetQuickCheckDetails(QuickCheckDetails* details,
+                            RegExpCompiler* compiler, int filled_in,
+                            bool not_at_start) override;
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override;
+  AssertionType assertion_type() { return assertion_type_; }
+
+ private:
+  friend Zone;
+
+  void EmitBoundaryCheck(RegExpCompiler* compiler, Trace* trace);
+  enum IfPrevious { kIsNonWord, kIsWord };
+  void BacktrackIfPrevious(RegExpCompiler* compiler, Trace* trace,
+                           IfPrevious backtrack_if_previous);
+  AssertionNode(AssertionType t, RegExpNode* on_success)
+      : SeqRegExpNode(on_success), assertion_type_(t) {}
+  AssertionType assertion_type_;
+};
+
+class BackReferenceNode : public SeqRegExpNode {
+ public:
+  BackReferenceNode(int start_reg, int end_reg, RegExpFlags flags,
+                    bool read_backward, RegExpNode* on_success)
+      : SeqRegExpNode(on_success),
+        start_reg_(start_reg),
+        end_reg_(end_reg),
+        flags_(flags),
+        read_backward_(read_backward) {}
+  void Accept(NodeVisitor* visitor) override;
+  int start_register() { return start_reg_; }
+  int end_register() { return end_reg_; }
+  bool read_backward() { return read_backward_; }
+  void Emit(RegExpCompiler* compiler, Trace* trace) override;
+  void GetQuickCheckDetails(QuickCheckDetails* details,
+                            RegExpCompiler* compiler, int characters_filled_in,
+                            bool not_at_start) override {
+    return;
+  }
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override;
+
+ private:
+  int start_reg_;
+  int end_reg_;
+  RegExpFlags flags_;
+  bool read_backward_;
+};
+
+class EndNode : public RegExpNode {
+ public:
+  enum Action { ACCEPT, BACKTRACK, NEGATIVE_SUBMATCH_SUCCESS };
+  EndNode(Action action, Zone* zone) : RegExpNode(zone), action_(action) {}
+  void Accept(NodeVisitor* visitor) override;
+  void Emit(RegExpCompiler* compiler, Trace* trace) override;
+  void GetQuickCheckDetails(QuickCheckDetails* details,
+                            RegExpCompiler* compiler, int characters_filled_in,
+                            bool not_at_start) override {
+    // Returning 0 from EatsAtLeast should ensure we never get here.
+    UNREACHABLE();
+  }
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override {
+    // Returning 0 from EatsAtLeast should ensure we never get here.
+    UNREACHABLE();
+  }
+
+ private:
+  Action action_;
+};
+
+class NegativeSubmatchSuccess : public EndNode {
+ public:
+  NegativeSubmatchSuccess(int stack_pointer_reg, int position_reg,
+                          int clear_capture_count, int clear_capture_start,
+                          Zone* zone)
+      : EndNode(NEGATIVE_SUBMATCH_SUCCESS, zone),
+        stack_pointer_register_(stack_pointer_reg),
+        current_position_register_(position_reg),
+        clear_capture_count_(clear_capture_count),
+        clear_capture_start_(clear_capture_start) {}
+  void Emit(RegExpCompiler* compiler, Trace* trace) override;
+
+ private:
+  int stack_pointer_register_;
+  int current_position_register_;
+  int clear_capture_count_;
+  int clear_capture_start_;
+};
+
+class Guard : public ZoneObject {
+ public:
+  enum Relation { LT, GEQ };
+  Guard(int reg, Relation op, int value) : reg_(reg), op_(op), value_(value) {}
+  int reg() { return reg_; }
+  Relation op() { return op_; }
+  int value() { return value_; }
+
+ private:
+  int reg_;
+  Relation op_;
+  int value_;
+};
+
+class GuardedAlternative {
+ public:
+  explicit GuardedAlternative(RegExpNode* node)
+      : node_(node), guards_(nullptr) {}
+  void AddGuard(Guard* guard, Zone* zone);
+  RegExpNode* node() { return node_; }
+  void set_node(RegExpNode* node) { node_ = node; }
+  ZoneList<Guard*>* guards() { return guards_; }
+
+ private:
+  RegExpNode* node_;
+  ZoneList<Guard*>* guards_;
+};
+
+class AlternativeGeneration;
+
+class ChoiceNode : public RegExpNode {
+ public:
+  explicit ChoiceNode(int expected_size, Zone* zone)
+      : RegExpNode(zone),
+        alternatives_(
+            zone->New<ZoneList<GuardedAlternative>>(expected_size, zone)),
+        not_at_start_(false),
+        being_calculated_(false) {}
+  void Accept(NodeVisitor* visitor) override;
+  void AddAlternative(GuardedAlternative node) {
+    alternatives()->Add(node, zone());
+  }
+  ZoneList<GuardedAlternative>* alternatives() { return alternatives_; }
+  void Emit(RegExpCompiler* compiler, Trace* trace) override;
+  void GetQuickCheckDetails(QuickCheckDetails* details,
+                            RegExpCompiler* compiler, int characters_filled_in,
+                            bool not_at_start) override;
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override;
+
+  bool being_calculated() { return being_calculated_; }
+  bool not_at_start() { return not_at_start_; }
+  void set_not_at_start() { not_at_start_ = true; }
+  void set_being_calculated(bool b) { being_calculated_ = b; }
+  virtual bool try_to_emit_quick_check_for_alternative(bool is_first) {
+    return true;
+  }
+  RegExpNode* FilterOneByte(int depth, RegExpFlags flags) override;
+  virtual bool read_backward() { return false; }
+
+ protected:
+  int GreedyLoopTextLengthForAlternative(GuardedAlternative* alternative);
+  ZoneList<GuardedAlternative>* alternatives_;
+
+ private:
+  template <typename...>
+  friend class Analysis;
+
+  void GenerateGuard(RegExpMacroAssembler* macro_assembler, Guard* guard,
+                     Trace* trace);
+  int CalculatePreloadCharacters(RegExpCompiler* compiler, int eats_at_least);
+  void EmitOutOfLineContinuation(RegExpCompiler* compiler, Trace* trace,
+                                 GuardedAlternative alternative,
+                                 AlternativeGeneration* alt_gen,
+                                 int preload_characters,
+                                 bool next_expects_preload);
+  void SetUpPreLoad(RegExpCompiler* compiler, Trace* current_trace,
+                    PreloadState* preloads);
+  void AssertGuardsMentionRegisters(Trace* trace);
+  int EmitOptimizedUnanchoredSearch(RegExpCompiler* compiler, Trace* trace);
+  Trace* EmitGreedyLoop(RegExpCompiler* compiler, Trace* trace,
+                        AlternativeGenerationList* alt_gens,
+                        PreloadState* preloads,
+                        GreedyLoopState* greedy_loop_state, int text_length);
+  void EmitChoices(RegExpCompiler* compiler,
+                   AlternativeGenerationList* alt_gens, int first_choice,
+                   Trace* trace, PreloadState* preloads);
+
+  // If true, this node is never checked at the start of the input.
+  // Allows a new trace to start with at_start() set to false.
+  bool not_at_start_;
+  bool being_calculated_;
+};
+
+class NegativeLookaroundChoiceNode : public ChoiceNode {
+ public:
+  explicit NegativeLookaroundChoiceNode(GuardedAlternative this_must_fail,
+                                        GuardedAlternative then_do_this,
+                                        Zone* zone)
+      : ChoiceNode(2, zone) {
+    AddAlternative(this_must_fail);
+    AddAlternative(then_do_this);
+  }
+  void GetQuickCheckDetails(QuickCheckDetails* details,
+                            RegExpCompiler* compiler, int characters_filled_in,
+                            bool not_at_start) override;
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override {
+    continue_node()->FillInBMInfo(isolate, offset, budget - 1, bm,
+                                  not_at_start);
+    if (offset == 0) set_bm_info(not_at_start, bm);
+  }
+  static constexpr int kLookaroundIndex = 0;
+  static constexpr int kContinueIndex = 1;
+  RegExpNode* lookaround_node() {
+    return alternatives()->at(kLookaroundIndex).node();
+  }
+  RegExpNode* continue_node() {
+    return alternatives()->at(kContinueIndex).node();
+  }
+  // For a negative lookahead we don't emit the quick check for the
+  // alternative that is expected to fail.  This is because quick check code
+  // starts by loading enough characters for the alternative that takes fewest
+  // characters, but on a negative lookahead the negative branch did not take
+  // part in that calculation (EatsAtLeast) so the assumptions don't hold.
+  bool try_to_emit_quick_check_for_alternative(bool is_first) override {
+    return !is_first;
+  }
+  void Accept(NodeVisitor* visitor) override;
+  RegExpNode* FilterOneByte(int depth, RegExpFlags flags) override;
+};
+
+class LoopChoiceNode : public ChoiceNode {
+ public:
+  LoopChoiceNode(bool body_can_be_zero_length, bool read_backward,
+                 int min_loop_iterations, Zone* zone)
+      : ChoiceNode(2, zone),
+        loop_node_(nullptr),
+        continue_node_(nullptr),
+        body_can_be_zero_length_(body_can_be_zero_length),
+        read_backward_(read_backward),
+        traversed_loop_initialization_node_(false),
+        min_loop_iterations_(min_loop_iterations) {}
+  void AddLoopAlternative(GuardedAlternative alt);
+  void AddContinueAlternative(GuardedAlternative alt);
+  void Emit(RegExpCompiler* compiler, Trace* trace) override;
+  void GetQuickCheckDetails(QuickCheckDetails* details,
+                            RegExpCompiler* compiler, int characters_filled_in,
+                            bool not_at_start) override;
+  void GetQuickCheckDetailsFromLoopEntry(QuickCheckDetails* details,
+                                         RegExpCompiler* compiler,
+                                         int characters_filled_in,
+                                         bool not_at_start) override;
+  void FillInBMInfo(Isolate* isolate, int offset, int budget,
+                    BoyerMooreLookahead* bm, bool not_at_start) override;
+  EatsAtLeastInfo EatsAtLeastFromLoopEntry() override;
+  RegExpNode* loop_node() { return loop_node_; }
+  RegExpNode* continue_node() { return continue_node_; }
+  bool body_can_be_zero_length() { return body_can_be_zero_length_; }
+  int min_loop_iterations() const { return min_loop_iterations_; }
+  bool read_backward() override { return read_backward_; }
+  void Accept(NodeVisitor* visitor) override;
+  RegExpNode* FilterOneByte(int depth, RegExpFlags flags) override;
+
+ private:
+  // AddAlternative is made private for loop nodes because alternatives
+  // should not be added freely, we need to keep track of which node
+  // goes back to the node itself.
+  void AddAlternative(GuardedAlternative node) {
+    ChoiceNode::AddAlternative(node);
+  }
+
+  RegExpNode* loop_node_;
+  RegExpNode* continue_node_;
+  bool body_can_be_zero_length_;
+  bool read_backward_;
+
+  // Temporary marker set only while generating quick check details. Represents
+  // whether GetQuickCheckDetails traversed the initialization node for this
+  // loop's counter. If so, we may be able to generate stricter quick checks
+  // because we know the loop node must match at least min_loop_iterations_
+  // times before the continuation node can match.
+  bool traversed_loop_initialization_node_;
+
+  // The minimum number of times the loop_node_ must match before the
+  // continue_node_ might be considered. This value can be temporarily decreased
+  // while generating quick check details, to represent the remaining iterations
+  // after the completed portion of the quick check details.
+  int min_loop_iterations_;
+
+  friend class IterationDecrementer;
+  friend class LoopInitializationMarker;
+};
+
+class NodeVisitor {
+ public:
+  virtual ~NodeVisitor() = default;
+#define DECLARE_VISIT(Type) virtual void Visit##Type(Type##Node* that) = 0;
+  FOR_EACH_NODE_TYPE(DECLARE_VISIT)
+#undef DECLARE_VISIT
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_NODES_H_
diff --git a/js/src/irregexp/imported/regexp-parser.cc b/js/src/irregexp/imported/regexp-parser.cc
new file mode 100644
index 0000000000..57f4c12fc5
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-parser.cc
@@ -0,0 +1,3131 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "irregexp/imported/regexp-parser.h"
+
+#include "irregexp/imported/regexp-ast.h"
+#include "irregexp/imported/regexp-macro-assembler.h"
+#include "irregexp/imported/regexp.h"
+
+#ifdef V8_INTL_SUPPORT
+#include "unicode/uniset.h"
+#include "unicode/unistr.h"
+#include "unicode/usetiter.h"
+#include "unicode/utf16.h"  // For U16_NEXT
+#endif  // V8_INTL_SUPPORT
+
+namespace v8 {
+namespace internal {
+
+namespace {
+
+// Whether we're currently inside the ClassEscape production
+// (tc39.es/ecma262/#prod-annexB-CharacterEscape).
+enum class InClassEscapeState {
+  kInClass,
+  kNotInClass,
+};
+
+// The production used to derive ClassSetOperand.
+enum class ClassSetOperandType {
+  kClassSetCharacter,
+  kClassStringDisjunction,
+  kNestedClass,
+  kCharacterClassEscape,  // \ CharacterClassEscape is a special nested class,
+                          // as we can fold it directly into another range.
+  kClassSetRange
+};
+
+class RegExpTextBuilder {
+ public:
+  using SmallRegExpTreeVector =
+      base::SmallVector<RegExpTree*, 8, ZoneAllocator<RegExpTree*>>;
+
+  RegExpTextBuilder(Zone* zone, SmallRegExpTreeVector* terms_storage,
+                    RegExpFlags flags)
+      : zone_(zone),
+        flags_(flags),
+        terms_(terms_storage),
+        text_(ZoneAllocator<RegExpTree*>{zone}) {}
+  void AddCharacter(base::uc16 character);
+  void AddUnicodeCharacter(base::uc32 character);
+  void AddEscapedUnicodeCharacter(base::uc32 character);
+  void AddAtom(RegExpTree* atom);
+  void AddTerm(RegExpTree* term);
+  void AddClassRanges(RegExpClassRanges* cc);
+  void FlushPendingSurrogate();
+  void FlushText();
+  RegExpTree* PopLastAtom();
+  RegExpTree* ToRegExp();
+
+ private:
+  static const base::uc16 kNoPendingSurrogate = 0;
+
+  void AddLeadSurrogate(base::uc16 lead_surrogate);
+  void AddTrailSurrogate(base::uc16 trail_surrogate);
+  void FlushCharacters();
+  bool NeedsDesugaringForUnicode(RegExpClassRanges* cc);
+  bool NeedsDesugaringForIgnoreCase(base::uc32 c);
+  void AddClassRangesForDesugaring(base::uc32 c);
+  bool ignore_case() const { return IsIgnoreCase(flags_); }
+  bool IsUnicodeMode() const {
+    // Either /v or /u enable UnicodeMode
+    // TODO(v8:11935): Change permalink once proposal is in stage 4.
+    // https://arai-a.github.io/ecma262-compare/snapshot.html?pr=2418#sec-parsepattern
+    return IsUnicode(flags_) || IsUnicodeSets(flags_);
+  }
+  Zone* zone() const { return zone_; }
+
+  Zone* const zone_;
+  const RegExpFlags flags_;
+  ZoneList<base::uc16>* characters_ = nullptr;
+  base::uc16 pending_surrogate_ = kNoPendingSurrogate;
+  SmallRegExpTreeVector* terms_;
+  SmallRegExpTreeVector text_;
+};
+
+void RegExpTextBuilder::AddLeadSurrogate(base::uc16 lead_surrogate) {
+  DCHECK(unibrow::Utf16::IsLeadSurrogate(lead_surrogate));
+  FlushPendingSurrogate();
+  // Hold onto the lead surrogate, waiting for a trail surrogate to follow.
+  pending_surrogate_ = lead_surrogate;
+}
+
+void RegExpTextBuilder::AddTrailSurrogate(base::uc16 trail_surrogate) {
+  DCHECK(unibrow::Utf16::IsTrailSurrogate(trail_surrogate));
+  if (pending_surrogate_ != kNoPendingSurrogate) {
+    base::uc16 lead_surrogate = pending_surrogate_;
+    pending_surrogate_ = kNoPendingSurrogate;
+    DCHECK(unibrow::Utf16::IsLeadSurrogate(lead_surrogate));
+    base::uc32 combined =
+        unibrow::Utf16::CombineSurrogatePair(lead_surrogate, trail_surrogate);
+    if (NeedsDesugaringForIgnoreCase(combined)) {
+      AddClassRangesForDesugaring(combined);
+    } else {
+      ZoneList<base::uc16> surrogate_pair(2, zone());
+      surrogate_pair.Add(lead_surrogate, zone());
+      surrogate_pair.Add(trail_surrogate, zone());
+      RegExpAtom* atom =
+          zone()->New<RegExpAtom>(surrogate_pair.ToConstVector());
+      AddAtom(atom);
+    }
+  } else {
+    pending_surrogate_ = trail_surrogate;
+    FlushPendingSurrogate();
+  }
+}
+
+void RegExpTextBuilder::FlushPendingSurrogate() {
+  if (pending_surrogate_ != kNoPendingSurrogate) {
+    DCHECK(IsUnicodeMode());
+    base::uc32 c = pending_surrogate_;
+    pending_surrogate_ = kNoPendingSurrogate;
+    AddClassRangesForDesugaring(c);
+  }
+}
+
+void RegExpTextBuilder::FlushCharacters() {
+  FlushPendingSurrogate();
+  if (characters_ != nullptr) {
+    RegExpTree* atom = zone()->New<RegExpAtom>(characters_->ToConstVector());
+    characters_ = nullptr;
+    text_.emplace_back(atom);
+  }
+}
+
+void RegExpTextBuilder::FlushText() {
+  FlushCharacters();
+  size_t num_text = text_.size();
+  if (num_text == 0) {
+    return;
+  } else if (num_text == 1) {
+    terms_->emplace_back(text_.back());
+  } else {
+    RegExpText* text = zone()->New<RegExpText>(zone());
+    for (size_t i = 0; i < num_text; i++) {
+      text_[i]->AppendToText(text, zone());
+    }
+    terms_->emplace_back(text);
+  }
+  text_.clear();
+}
+
+void RegExpTextBuilder::AddCharacter(base::uc16 c) {
+  FlushPendingSurrogate();
+  if (NeedsDesugaringForIgnoreCase(c)) {
+    AddClassRangesForDesugaring(c);
+  } else {
+    if (characters_ == nullptr) {
+      characters_ = zone()->New<ZoneList<base::uc16>>(4, zone());
+    }
+    characters_->Add(c, zone());
+  }
+}
+
+void RegExpTextBuilder::AddUnicodeCharacter(base::uc32 c) {
+  if (c > static_cast<base::uc32>(unibrow::Utf16::kMaxNonSurrogateCharCode)) {
+    DCHECK(IsUnicodeMode());
+    AddLeadSurrogate(unibrow::Utf16::LeadSurrogate(c));
+    AddTrailSurrogate(unibrow::Utf16::TrailSurrogate(c));
+  } else if (IsUnicodeMode() && unibrow::Utf16::IsLeadSurrogate(c)) {
+    AddLeadSurrogate(c);
+  } else if (IsUnicodeMode() && unibrow::Utf16::IsTrailSurrogate(c)) {
+    AddTrailSurrogate(c);
+  } else {
+    AddCharacter(static_cast<base::uc16>(c));
+  }
+}
+
+void RegExpTextBuilder::AddEscapedUnicodeCharacter(base::uc32 character) {
+  // A lead or trail surrogate parsed via escape sequence will not
+  // pair up with any preceding lead or following trail surrogate.
+  FlushPendingSurrogate();
+  AddUnicodeCharacter(character);
+  FlushPendingSurrogate();
+}
+
+void RegExpTextBuilder::AddClassRanges(RegExpClassRanges* cr) {
+  if (NeedsDesugaringForUnicode(cr)) {
+    // With /u or /v, character class needs to be desugared, so it
+    // must be a standalone term instead of being part of a RegExpText.
+    AddTerm(cr);
+  } else {
+    AddAtom(cr);
+  }
+}
+
+void RegExpTextBuilder::AddClassRangesForDesugaring(base::uc32 c) {
+  AddTerm(zone()->New<RegExpClassRanges>(
+      zone(), CharacterRange::List(zone(), CharacterRange::Singleton(c))));
+}
+
+void RegExpTextBuilder::AddAtom(RegExpTree* atom) {
+  DCHECK(atom->IsTextElement());
+  FlushCharacters();
+  text_.emplace_back(atom);
+}
+
+void RegExpTextBuilder::AddTerm(RegExpTree* term) {
+  DCHECK(term->IsTextElement());
+  FlushText();
+  terms_->emplace_back(term);
+}
+
+bool RegExpTextBuilder::NeedsDesugaringForUnicode(RegExpClassRanges* cc) {
+  if (!IsUnicodeMode()) return false;
+  // TODO(yangguo): we could be smarter than this. Case-insensitivity does not
+  // necessarily mean that we need to desugar. It's probably nicer to have a
+  // separate pass to figure out unicode desugarings.
+  if (ignore_case()) return true;
+  ZoneList<CharacterRange>* ranges = cc->ranges(zone());
+  CharacterRange::Canonicalize(ranges);
+
+  if (cc->is_negated()) {
+    ZoneList<CharacterRange>* negated_ranges =
+        zone()->New<ZoneList<CharacterRange>>(ranges->length(), zone());
+    CharacterRange::Negate(ranges, negated_ranges, zone());
+    ranges = negated_ranges;
+  }
+
+  for (int i = ranges->length() - 1; i >= 0; i--) {
+    base::uc32 from = ranges->at(i).from();
+    base::uc32 to = ranges->at(i).to();
+    // Check for non-BMP characters.
+    if (to >= kNonBmpStart) return true;
+    // Check for lone surrogates.
+    if (from <= kTrailSurrogateEnd && to >= kLeadSurrogateStart) return true;
+  }
+  return false;
+}
+
+bool RegExpTextBuilder::NeedsDesugaringForIgnoreCase(base::uc32 c) {
+#ifdef V8_INTL_SUPPORT
+  if (IsUnicodeMode() && ignore_case()) {
+    icu::UnicodeSet set(c, c);
+    set.closeOver(USET_CASE_INSENSITIVE);
+    set.removeAllStrings();
+    return set.size() > 1;
+  }
+  // In the case where ICU is not included, we act as if the unicode flag is
+  // not set, and do not desugar.
+#endif  // V8_INTL_SUPPORT
+  return false;
+}
+
+RegExpTree* RegExpTextBuilder::PopLastAtom() {
+  FlushPendingSurrogate();
+  RegExpTree* atom;
+  if (characters_ != nullptr) {
+    base::Vector<const base::uc16> char_vector = characters_->ToConstVector();
+    int num_chars = char_vector.length();
+    if (num_chars > 1) {
+      base::Vector<const base::uc16> prefix =
+          char_vector.SubVector(0, num_chars - 1);
+      text_.emplace_back(zone()->New<RegExpAtom>(prefix));
+      char_vector = char_vector.SubVector(num_chars - 1, num_chars);
+    }
+    characters_ = nullptr;
+    atom = zone()->New<RegExpAtom>(char_vector);
+    return atom;
+  } else if (text_.size() > 0) {
+    atom = text_.back();
+    text_.pop_back();
+    return atom;
+  }
+  return nullptr;
+}
+
+RegExpTree* RegExpTextBuilder::ToRegExp() {
+  FlushText();
+  size_t num_alternatives = terms_->size();
+  if (num_alternatives == 0) return zone()->New<RegExpEmpty>();
+  if (num_alternatives == 1) return terms_->back();
+  return zone()->New<RegExpAlternative>(zone()->New<ZoneList<RegExpTree*>>(
+      base::VectorOf(terms_->begin(), terms_->size()), zone()));
+}
+
+// Accumulates RegExp atoms and assertions into lists of terms and alternatives.
+class RegExpBuilder {
+ public:
+  RegExpBuilder(Zone* zone, RegExpFlags flags)
+      : zone_(zone),
+        flags_(flags),
+        terms_(ZoneAllocator<RegExpTree*>{zone}),
+        alternatives_(ZoneAllocator<RegExpTree*>{zone}),
+        text_builder_(RegExpTextBuilder{zone, &terms_, flags}) {}
+  void AddCharacter(base::uc16 character);
+  void AddUnicodeCharacter(base::uc32 character);
+  void AddEscapedUnicodeCharacter(base::uc32 character);
+  // "Adds" an empty expression. Does nothing except consume a
+  // following quantifier
+  void AddEmpty();
+  void AddClassRanges(RegExpClassRanges* cc);
+  void AddAtom(RegExpTree* tree);
+  void AddTerm(RegExpTree* tree);
+  void AddAssertion(RegExpTree* tree);
+  void NewAlternative();  // '|'
+  bool AddQuantifierToAtom(int min, int max,
+                           RegExpQuantifier::QuantifierType type);
+  void FlushText();
+  RegExpTree* ToRegExp();
+  RegExpFlags flags() const { return flags_; }
+
+  bool ignore_case() const { return IsIgnoreCase(flags_); }
+  bool multiline() const { return IsMultiline(flags_); }
+  bool dotall() const { return IsDotAll(flags_); }
+
+ private:
+  void FlushTerms();
+  bool IsUnicodeMode() const {
+    // Either /v or /u enable UnicodeMode
+    // TODO(v8:11935): Change permalink once proposal is in stage 4.
+    // https://arai-a.github.io/ecma262-compare/snapshot.html?pr=2418#sec-parsepattern
+    return IsUnicode(flags_) || IsUnicodeSets(flags_);
+  }
+  Zone* zone() const { return zone_; }
+  RegExpTextBuilder& text_builder() { return text_builder_; }
+
+  Zone* const zone_;
+  bool pending_empty_ = false;
+  const RegExpFlags flags_;
+
+  using SmallRegExpTreeVector =
+      base::SmallVector<RegExpTree*, 8, ZoneAllocator<RegExpTree*>>;
+  SmallRegExpTreeVector terms_;
+  SmallRegExpTreeVector alternatives_;
+  RegExpTextBuilder text_builder_;
+};
+
+enum SubexpressionType {
+  INITIAL,
+  CAPTURE,  // All positive values represent captures.
+  POSITIVE_LOOKAROUND,
+  NEGATIVE_LOOKAROUND,
+  GROUPING
+};
+
+class RegExpParserState : public ZoneObject {
+ public:
+  // Push a state on the stack.
+  RegExpParserState(RegExpParserState* previous_state,
+                    SubexpressionType group_type,
+                    RegExpLookaround::Type lookaround_type,
+                    int disjunction_capture_index,
+                    const ZoneVector<base::uc16>* capture_name,
+                    RegExpFlags flags, Zone* zone)
+      : previous_state_(previous_state),
+        builder_(zone, flags),
+        group_type_(group_type),
+        lookaround_type_(lookaround_type),
+        disjunction_capture_index_(disjunction_capture_index),
+        capture_name_(capture_name) {}
+  // Parser state of containing expression, if any.
+  RegExpParserState* previous_state() const { return previous_state_; }
+  bool IsSubexpression() { return previous_state_ != nullptr; }
+  // RegExpBuilder building this regexp's AST.
+  RegExpBuilder* builder() { return &builder_; }
+  // Type of regexp being parsed (parenthesized group or entire regexp).
+  SubexpressionType group_type() const { return group_type_; }
+  // Lookahead or Lookbehind.
+  RegExpLookaround::Type lookaround_type() const { return lookaround_type_; }
+  // Index in captures array of first capture in this sub-expression, if any.
+  // Also the capture index of this sub-expression itself, if group_type
+  // is CAPTURE.
+  int capture_index() const { return disjunction_capture_index_; }
+  // The name of the current sub-expression, if group_type is CAPTURE. Only
+  // used for named captures.
+  const ZoneVector<base::uc16>* capture_name() const { return capture_name_; }
+
+  bool IsNamedCapture() const { return capture_name_ != nullptr; }
+
+  // Check whether the parser is inside a capture group with the given index.
+  bool IsInsideCaptureGroup(int index) const {
+    for (const RegExpParserState* s = this; s != nullptr;
+         s = s->previous_state()) {
+      if (s->group_type() != CAPTURE) continue;
+      // Return true if we found the matching capture index.
+      if (index == s->capture_index()) return true;
+      // Abort if index is larger than what has been parsed up till this state.
+      if (index > s->capture_index()) return false;
+    }
+    return false;
+  }
+
+  // Check whether the parser is inside a capture group with the given name.
+  bool IsInsideCaptureGroup(const ZoneVector<base::uc16>* name) const {
+    DCHECK_NOT_NULL(name);
+    for (const RegExpParserState* s = this; s != nullptr;
+         s = s->previous_state()) {
+      if (s->capture_name() == nullptr) continue;
+      if (*s->capture_name() == *name) return true;
+    }
+    return false;
+  }
+
+ private:
+  // Linked list implementation of stack of states.
+  RegExpParserState* const previous_state_;
+  // Builder for the stored disjunction.
+  RegExpBuilder builder_;
+  // Stored disjunction type (capture, look-ahead or grouping), if any.
+  const SubexpressionType group_type_;
+  // Stored read direction.
+  const RegExpLookaround::Type lookaround_type_;
+  // Stored disjunction's capture index (if any).
+  const int disjunction_capture_index_;
+  // Stored capture name (if any).
+  const ZoneVector<base::uc16>* const capture_name_;
+};
+
+template <class CharT>
+class RegExpParserImpl final {
+ private:
+  RegExpParserImpl(const CharT* input, int input_length, RegExpFlags flags,
+                   uintptr_t stack_limit, Zone* zone,
+                   const DisallowGarbageCollection& no_gc);
+
+  bool Parse(RegExpCompileData* result);
+
+  RegExpTree* ParsePattern();
+  RegExpTree* ParseDisjunction();
+  RegExpTree* ParseGroup();
+
+  // Parses a {...,...} quantifier and stores the range in the given
+  // out parameters.
+  bool ParseIntervalQuantifier(int* min_out, int* max_out);
+
+  // Checks whether the following is a length-digit hexadecimal number,
+  // and sets the value if it is.
+  bool ParseHexEscape(int length, base::uc32* value);
+  bool ParseUnicodeEscape(base::uc32* value);
+  bool ParseUnlimitedLengthHexNumber(int max_value, base::uc32* value);
+
+  bool ParsePropertyClassName(ZoneVector<char>* name_1,
+                              ZoneVector<char>* name_2);
+  bool AddPropertyClassRange(ZoneList<CharacterRange>* add_to_range,
+                             CharacterClassStrings* add_to_strings, bool negate,
+                             const ZoneVector<char>& name_1,
+                             const ZoneVector<char>& name_2);
+
+  RegExpTree* ParseClassRanges(ZoneList<CharacterRange>* ranges,
+                               bool add_unicode_case_equivalents);
+  // Parse inside a class. Either add escaped class to the range, or return
+  // false and pass parsed single character through |char_out|.
+  void ParseClassEscape(ZoneList<CharacterRange>* ranges, Zone* zone,
+                        bool add_unicode_case_equivalents, base::uc32* char_out,
+                        bool* is_class_escape);
+  // Returns true iff parsing was successful.
+  bool TryParseCharacterClassEscape(base::uc32 next,
+                                    InClassEscapeState in_class_escape_state,
+                                    ZoneList<CharacterRange>* ranges,
+                                    CharacterClassStrings* strings, Zone* zone,
+                                    bool add_unicode_case_equivalents);
+  RegExpTree* ParseClassStringDisjunction(ZoneList<CharacterRange>* ranges,
+                                          CharacterClassStrings* strings);
+  RegExpTree* ParseClassSetOperand(const RegExpBuilder* builder,
+                                   ClassSetOperandType* type_out);
+  RegExpTree* ParseClassSetOperand(const RegExpBuilder* builder,
+                                   ClassSetOperandType* type_out,
+                                   ZoneList<CharacterRange>* ranges,
+                                   CharacterClassStrings* strings);
+  base::uc32 ParseClassSetCharacter();
+  // Parses and returns a single escaped character.
+  base::uc32 ParseCharacterEscape(InClassEscapeState in_class_escape_state,
+                                  bool* is_escaped_unicode_character);
+
+  RegExpTree* ParseClassUnion(const RegExpBuilder* builder, bool is_negated,
+                              RegExpTree* first_operand,
+                              ClassSetOperandType first_operand_type,
+                              ZoneList<CharacterRange>* ranges,
+                              CharacterClassStrings* strings);
+  RegExpTree* ParseClassIntersection(const RegExpBuilder* builder,
+                                     bool is_negated, RegExpTree* first_operand,
+                                     ClassSetOperandType first_operand_type);
+  RegExpTree* ParseClassSubtraction(const RegExpBuilder* builder,
+                                    bool is_negated, RegExpTree* first_operand,
+                                    ClassSetOperandType first_operand_type);
+  RegExpTree* ParseCharacterClass(const RegExpBuilder* state);
+
+  base::uc32 ParseOctalLiteral();
+
+  // Tries to parse the input as a back reference.  If successful it
+  // stores the result in the output parameter and returns true.  If
+  // it fails it will push back the characters read so the same characters
+  // can be reparsed.
+  bool ParseBackReferenceIndex(int* index_out);
+
+  RegExpTree* ReportError(RegExpError error);
+  void Advance();
+  void Advance(int dist);
+  void RewindByOneCodepoint();  // Rewinds to before the previous Advance().
+  void Reset(int pos);
+
+  // Reports whether the pattern might be used as a literal search string.
+  // Only use if the result of the parse is a single atom node.
+  bool simple() const { return simple_; }
+  bool contains_anchor() const { return contains_anchor_; }
+  void set_contains_anchor() { contains_anchor_ = true; }
+  int captures_started() const { return captures_started_; }
+  int position() const { return next_pos_ - 1; }
+  bool failed() const { return failed_; }
+  RegExpFlags flags() const { return top_level_flags_; }
+  bool IsUnicodeMode() const {
+    // Either /v or /u enable UnicodeMode
+    // TODO(v8:11935): Change permalink once proposal is in stage 4.
+    // https://arai-a.github.io/ecma262-compare/snapshot.html?pr=2418#sec-parsepattern
+    return IsUnicode(flags()) || IsUnicodeSets(flags()) || force_unicode_;
+  }
+  bool unicode_sets() const { return IsUnicodeSets(flags()); }
+  bool ignore_case() const { return IsIgnoreCase(flags()); }
+
+  static bool IsSyntaxCharacterOrSlash(base::uc32 c);
+  static bool IsClassSetSyntaxCharacter(base::uc32 c);
+  static bool IsClassSetReservedPunctuator(base::uc32 c);
+  bool IsClassSetReservedDoublePunctuator(base::uc32 c);
+
+  static const base::uc32 kEndMarker = (1 << 21);
+
+ private:
+  // Return the 1-indexed RegExpCapture object, allocate if necessary.
+  RegExpCapture* GetCapture(int index);
+
+  // Creates a new named capture at the specified index. Must be called exactly
+  // once for each named capture. Fails if a capture with the same name is
+  // encountered.
+  bool CreateNamedCaptureAtIndex(const ZoneVector<base::uc16>* name, int index);
+
+  // Parses the name of a capture group (?<name>pattern). The name must adhere
+  // to IdentifierName in the ECMAScript standard.
+  const ZoneVector<base::uc16>* ParseCaptureGroupName();
+
+  bool ParseNamedBackReference(RegExpBuilder* builder,
+                               RegExpParserState* state);
+  RegExpParserState* ParseOpenParenthesis(RegExpParserState* state);
+
+  // After the initial parsing pass, patch corresponding RegExpCapture objects
+  // into all RegExpBackReferences. This is done after initial parsing in order
+  // to avoid complicating cases in which references comes before the capture.
+  void PatchNamedBackReferences();
+
+  ZoneVector<RegExpCapture*>* GetNamedCaptures() const;
+
+  // Returns true iff the pattern contains named captures. May call
+  // ScanForCaptures to look ahead at the remaining pattern.
+  bool HasNamedCaptures(InClassEscapeState in_class_escape_state);
+
+  Zone* zone() const { return zone_; }
+
+  base::uc32 current() const { return current_; }
+  bool has_more() const { return has_more_; }
+  bool has_next() const { return next_pos_ < input_length(); }
+  base::uc32 Next();
+  template <bool update_position>
+  base::uc32 ReadNext();
+  CharT InputAt(int index) const {
+    DCHECK(0 <= index && index < input_length());
+    return input_[index];
+  }
+  int input_length() const { return input_length_; }
+  void ScanForCaptures(InClassEscapeState in_class_escape_state);
+
+  struct RegExpCaptureNameLess {
+    bool operator()(const RegExpCapture* lhs, const RegExpCapture* rhs) const {
+      DCHECK_NOT_NULL(lhs);
+      DCHECK_NOT_NULL(rhs);
+      return *lhs->name() < *rhs->name();
+    }
+  };
+
+  class ForceUnicodeScope final {
+   public:
+    explicit ForceUnicodeScope(RegExpParserImpl<CharT>* parser)
+        : parser_(parser) {
+      DCHECK(!parser_->force_unicode_);
+      parser_->force_unicode_ = true;
+    }
+    ~ForceUnicodeScope() {
+      DCHECK(parser_->force_unicode_);
+      parser_->force_unicode_ = false;
+    }
+
+   private:
+    RegExpParserImpl<CharT>* const parser_;
+  };
+
+  const DisallowGarbageCollection no_gc_;
+  Zone* const zone_;
+  RegExpError error_ = RegExpError::kNone;
+  int error_pos_ = 0;
+  ZoneList<RegExpCapture*>* captures_;
+  ZoneSet<RegExpCapture*, RegExpCaptureNameLess>* named_captures_;
+  ZoneList<RegExpBackReference*>* named_back_references_;
+  const CharT* const input_;
+  const int input_length_;
+  base::uc32 current_;
+  const RegExpFlags top_level_flags_;
+  bool force_unicode_ = false;  // Force parser to act as if unicode were set.
+  int next_pos_;
+  int captures_started_;
+  int capture_count_;  // Only valid after we have scanned for captures.
+  bool has_more_;
+  bool simple_;
+  bool contains_anchor_;
+  bool is_scanned_for_captures_;
+  bool has_named_captures_;  // Only valid after we have scanned for captures.
+  bool failed_;
+  const uintptr_t stack_limit_;
+
+  friend class v8::internal::RegExpParser;
+};
+
+template <class CharT>
+RegExpParserImpl<CharT>::RegExpParserImpl(
+    const CharT* input, int input_length, RegExpFlags flags,
+    uintptr_t stack_limit, Zone* zone, const DisallowGarbageCollection& no_gc)
+    : zone_(zone),
+      captures_(nullptr),
+      named_captures_(nullptr),
+      named_back_references_(nullptr),
+      input_(input),
+      input_length_(input_length),
+      current_(kEndMarker),
+      top_level_flags_(flags),
+      next_pos_(0),
+      captures_started_(0),
+      capture_count_(0),
+      has_more_(true),
+      simple_(false),
+      contains_anchor_(false),
+      is_scanned_for_captures_(false),
+      has_named_captures_(false),
+      failed_(false),
+      stack_limit_(stack_limit) {
+  Advance();
+}
+
+template <>
+template <bool update_position>
+inline base::uc32 RegExpParserImpl<uint8_t>::ReadNext() {
+  int position = next_pos_;
+  base::uc16 c0 = InputAt(position);
+  position++;
+  DCHECK(!unibrow::Utf16::IsLeadSurrogate(c0));
+  if (update_position) next_pos_ = position;
+  return c0;
+}
+
+template <>
+template <bool update_position>
+inline base::uc32 RegExpParserImpl<base::uc16>::ReadNext() {
+  int position = next_pos_;
+  base::uc16 c0 = InputAt(position);
+  base::uc32 result = c0;
+  position++;
+  // Read the whole surrogate pair in case of unicode mode, if possible.
+  if (IsUnicodeMode() && position < input_length() &&
+      unibrow::Utf16::IsLeadSurrogate(c0)) {
+    base::uc16 c1 = InputAt(position);
+    if (unibrow::Utf16::IsTrailSurrogate(c1)) {
+      result = unibrow::Utf16::CombineSurrogatePair(c0, c1);
+      position++;
+    }
+  }
+  if (update_position) next_pos_ = position;
+  return result;
+}
+
+template <class CharT>
+base::uc32 RegExpParserImpl<CharT>::Next() {
+  if (has_next()) {
+    return ReadNext<false>();
+  } else {
+    return kEndMarker;
+  }
+}
+
+template <class CharT>
+void RegExpParserImpl<CharT>::Advance() {
+  if (has_next()) {
+    if (GetCurrentStackPosition() < stack_limit_) {
+      if (v8_flags.correctness_fuzzer_suppressions) {
+        FATAL("Aborting on stack overflow");
+      }
+      ReportError(RegExpError::kStackOverflow);
+    } else {
+      current_ = ReadNext<true>();
+    }
+  } else {
+    current_ = kEndMarker;
+    // Advance so that position() points to 1-after-the-last-character. This is
+    // important so that Reset() to this position works correctly.
+    next_pos_ = input_length() + 1;
+    has_more_ = false;
+  }
+}
+
+template <class CharT>
+void RegExpParserImpl<CharT>::RewindByOneCodepoint() {
+  if (!has_more()) return;
+  // Rewinds by one code point, i.e.: two code units if `current` is outside
+  // the basic multilingual plane (= composed of a lead and trail surrogate),
+  // or one code unit otherwise.
+  const int rewind_by =
+      current() > unibrow::Utf16::kMaxNonSurrogateCharCode ? -2 : -1;
+  Advance(rewind_by);  // Undo the last Advance.
+}
+
+template <class CharT>
+void RegExpParserImpl<CharT>::Reset(int pos) {
+  next_pos_ = pos;
+  has_more_ = (pos < input_length());
+  Advance();
+}
+
+template <class CharT>
+void RegExpParserImpl<CharT>::Advance(int dist) {
+  next_pos_ += dist - 1;
+  Advance();
+}
+
+// static
+template <class CharT>
+bool RegExpParserImpl<CharT>::IsSyntaxCharacterOrSlash(base::uc32 c) {
+  switch (c) {
+    case '^':
+    case '$':
+    case '\\':
+    case '.':
+    case '*':
+    case '+':
+    case '?':
+    case '(':
+    case ')':
+    case '[':
+    case ']':
+    case '{':
+    case '}':
+    case '|':
+    case '/':
+      return true;
+    default:
+      break;
+  }
+  return false;
+}
+
+// static
+template <class CharT>
+bool RegExpParserImpl<CharT>::IsClassSetSyntaxCharacter(base::uc32 c) {
+  switch (c) {
+    case '(':
+    case ')':
+    case '[':
+    case ']':
+    case '{':
+    case '}':
+    case '/':
+    case '-':
+    case '\\':
+    case '|':
+      return true;
+    default:
+      break;
+  }
+  return false;
+}
+
+// static
+template <class CharT>
+bool RegExpParserImpl<CharT>::IsClassSetReservedPunctuator(base::uc32 c) {
+  switch (c) {
+    case '&':
+    case '-':
+    case '!':
+    case '#':
+    case '%':
+    case ',':
+    case ':':
+    case ';':
+    case '<':
+    case '=':
+    case '>':
+    case '@':
+    case '`':
+    case '~':
+      return true;
+    default:
+      break;
+  }
+  return false;
+}
+
+template <class CharT>
+bool RegExpParserImpl<CharT>::IsClassSetReservedDoublePunctuator(base::uc32 c) {
+#define DOUBLE_PUNCTUATOR_CASE(Char) \
+  case Char:                         \
+    return Next() == Char
+
+  switch (c) {
+    DOUBLE_PUNCTUATOR_CASE('&');
+    DOUBLE_PUNCTUATOR_CASE('!');
+    DOUBLE_PUNCTUATOR_CASE('#');
+    DOUBLE_PUNCTUATOR_CASE('$');
+    DOUBLE_PUNCTUATOR_CASE('%');
+    DOUBLE_PUNCTUATOR_CASE('*');
+    DOUBLE_PUNCTUATOR_CASE('+');
+    DOUBLE_PUNCTUATOR_CASE(',');
+    DOUBLE_PUNCTUATOR_CASE('.');
+    DOUBLE_PUNCTUATOR_CASE(':');
+    DOUBLE_PUNCTUATOR_CASE(';');
+    DOUBLE_PUNCTUATOR_CASE('<');
+    DOUBLE_PUNCTUATOR_CASE('=');
+    DOUBLE_PUNCTUATOR_CASE('>');
+    DOUBLE_PUNCTUATOR_CASE('?');
+    DOUBLE_PUNCTUATOR_CASE('@');
+    DOUBLE_PUNCTUATOR_CASE('^');
+    DOUBLE_PUNCTUATOR_CASE('`');
+    DOUBLE_PUNCTUATOR_CASE('~');
+    default:
+      break;
+  }
+#undef DOUBLE_PUNCTUATOR_CASE
+
+  return false;
+}
+
+template <class CharT>
+RegExpTree* RegExpParserImpl<CharT>::ReportError(RegExpError error) {
+  if (failed_) return nullptr;  // Do not overwrite any existing error.
+  failed_ = true;
+  error_ = error;
+  error_pos_ = position();
+  // Zip to the end to make sure no more input is read.
+  current_ = kEndMarker;
+  next_pos_ = input_length();
+  has_more_ = false;
+  return nullptr;
+}
+
+#define CHECK_FAILED /**/);    \
+  if (failed_) return nullptr; \
+  ((void)0
+
+// Pattern ::
+//   Disjunction
+template <class CharT>
+RegExpTree* RegExpParserImpl<CharT>::ParsePattern() {
+  RegExpTree* result = ParseDisjunction(CHECK_FAILED);
+  PatchNamedBackReferences(CHECK_FAILED);
+  DCHECK(!has_more());
+  // If the result of parsing is a literal string atom, and it has the
+  // same length as the input, then the atom is identical to the input.
+  if (result->IsAtom() && result->AsAtom()->length() == input_length()) {
+    simple_ = true;
+  }
+  return result;
+}
+
+// Disjunction ::
+//   Alternative
+//   Alternative | Disjunction
+// Alternative ::
+//   [empty]
+//   Term Alternative
+// Term ::
+//   Assertion
+//   Atom
+//   Atom Quantifier
+template <class CharT>
+RegExpTree* RegExpParserImpl<CharT>::ParseDisjunction() {
+  // Used to store current state while parsing subexpressions.
+  RegExpParserState initial_state(nullptr, INITIAL, RegExpLookaround::LOOKAHEAD,
+                                  0, nullptr, flags(), zone());
+  RegExpParserState* state = &initial_state;
+  // Cache the builder in a local variable for quick access.
+  RegExpBuilder* builder = initial_state.builder();
+  while (true) {
+    switch (current()) {
+      case kEndMarker:
+        if (failed()) return nullptr;  // E.g. the initial Advance failed.
+        if (state->IsSubexpression()) {
+          // Inside a parenthesized group when hitting end of input.
+          return ReportError(RegExpError::kUnterminatedGroup);
+        }
+        DCHECK_EQ(INITIAL, state->group_type());
+        // Parsing completed successfully.
+        return builder->ToRegExp();
+      case ')': {
+        if (!state->IsSubexpression()) {
+          return ReportError(RegExpError::kUnmatchedParen);
+        }
+        DCHECK_NE(INITIAL, state->group_type());
+
+        Advance();
+        // End disjunction parsing and convert builder content to new single
+        // regexp atom.
+        RegExpTree* body = builder->ToRegExp();
+
+        int end_capture_index = captures_started();
+
+        int capture_index = state->capture_index();
+        SubexpressionType group_type = state->group_type();
+
+        // Build result of subexpression.
+        if (group_type == CAPTURE) {
+          if (state->IsNamedCapture()) {
+            CreateNamedCaptureAtIndex(state->capture_name(),
+                                      capture_index CHECK_FAILED);
+          }
+          RegExpCapture* capture = GetCapture(capture_index);
+          capture->set_body(body);
+          body = capture;
+        } else if (group_type == GROUPING) {
+          body = zone()->template New<RegExpGroup>(body);
+        } else {
+          DCHECK(group_type == POSITIVE_LOOKAROUND ||
+                 group_type == NEGATIVE_LOOKAROUND);
+          bool is_positive = (group_type == POSITIVE_LOOKAROUND);
+          body = zone()->template New<RegExpLookaround>(
+              body, is_positive, end_capture_index - capture_index,
+              capture_index, state->lookaround_type());
+        }
+
+        // Restore previous state.
+        state = state->previous_state();
+        builder = state->builder();
+
+        builder->AddAtom(body);
+        // For compatibility with JSC and ES3, we allow quantifiers after
+        // lookaheads, and break in all cases.
+        break;
+      }
+      case '|': {
+        Advance();
+        builder->NewAlternative();
+        continue;
+      }
+      case '*':
+      case '+':
+      case '?':
+        return ReportError(RegExpError::kNothingToRepeat);
+      case '^': {
+        Advance();
+        builder->AddAssertion(zone()->template New<RegExpAssertion>(
+            builder->multiline() ? RegExpAssertion::Type::START_OF_LINE
+                                 : RegExpAssertion::Type::START_OF_INPUT));
+        set_contains_anchor();
+        continue;
+      }
+      case '$': {
+        Advance();
+        RegExpAssertion::Type assertion_type =
+            builder->multiline() ? RegExpAssertion::Type::END_OF_LINE
+                                 : RegExpAssertion::Type::END_OF_INPUT;
+        builder->AddAssertion(
+            zone()->template New<RegExpAssertion>(assertion_type));
+        continue;
+      }
+      case '.': {
+        Advance();
+        ZoneList<CharacterRange>* ranges =
+            zone()->template New<ZoneList<CharacterRange>>(2, zone());
+
+        if (builder->dotall()) {
+          // Everything.
+          CharacterRange::AddClassEscape(StandardCharacterSet::kEverything,
+                                         ranges, false, zone());
+        } else {
+          // Everything except \x0A, \x0D, \u2028 and \u2029.
+          CharacterRange::AddClassEscape(
+              StandardCharacterSet::kNotLineTerminator, ranges, false, zone());
+        }
+
+        RegExpClassRanges* cc =
+            zone()->template New<RegExpClassRanges>(zone(), ranges);
+        builder->AddClassRanges(cc);
+        break;
+      }
+      case '(': {
+        state = ParseOpenParenthesis(state CHECK_FAILED);
+        builder = state->builder();
+        continue;
+      }
+      case '[': {
+        RegExpTree* cc = ParseCharacterClass(builder CHECK_FAILED);
+        if (cc->IsClassRanges()) {
+          builder->AddClassRanges(cc->AsClassRanges());
+        } else {
+          DCHECK(cc->IsClassSetExpression());
+          builder->AddTerm(cc);
+        }
+        break;
+      }
+      // Atom ::
+      //   \ AtomEscape
+      case '\\':
+        switch (Next()) {
+          case kEndMarker:
+            return ReportError(RegExpError::kEscapeAtEndOfPattern);
+          // AtomEscape ::
+          //   [+UnicodeMode] DecimalEscape
+          //   [~UnicodeMode] DecimalEscape but only if the CapturingGroupNumber
+          //                  of DecimalEscape is ≤ NcapturingParens
+          //   CharacterEscape (some cases of this mixed in too)
+          //
+          // TODO(jgruber): It may make sense to disentangle all the different
+          // cases and make the structure mirror the spec, e.g. for AtomEscape:
+          //
+          //  if (TryParseDecimalEscape(...)) return;
+          //  if (TryParseCharacterClassEscape(...)) return;
+          //  if (TryParseCharacterEscape(...)) return;
+          //  if (TryParseGroupName(...)) return;
+          case '1':
+          case '2':
+          case '3':
+          case '4':
+          case '5':
+          case '6':
+          case '7':
+          case '8':
+          case '9': {
+            int index = 0;
+            const bool is_backref =
+                ParseBackReferenceIndex(&index CHECK_FAILED);
+            if (is_backref) {
+              if (state->IsInsideCaptureGroup(index)) {
+                // The back reference is inside the capture group it refers to.
+                // Nothing can possibly have been captured yet, so we use empty
+                // instead. This ensures that, when checking a back reference,
+                // the capture registers of the referenced capture are either
+                // both set or both cleared.
+                builder->AddEmpty();
+              } else {
+                RegExpCapture* capture = GetCapture(index);
+                RegExpTree* atom = zone()->template New<RegExpBackReference>(
+                    capture, builder->flags());
+                builder->AddAtom(atom);
+              }
+              break;
+            }
+            // With /u and /v, no identity escapes except for syntax characters
+            // are allowed. Otherwise, all identity escapes are allowed.
+            if (IsUnicodeMode()) {
+              return ReportError(RegExpError::kInvalidEscape);
+            }
+            base::uc32 first_digit = Next();
+            if (first_digit == '8' || first_digit == '9') {
+              builder->AddCharacter(first_digit);
+              Advance(2);
+              break;
+            }
+            V8_FALLTHROUGH;
+          }
+          case '0': {
+            Advance();
+            if (IsUnicodeMode() && Next() >= '0' && Next() <= '9') {
+              // Decimal escape with leading 0 are not parsed as octal.
+              return ReportError(RegExpError::kInvalidDecimalEscape);
+            }
+            base::uc32 octal = ParseOctalLiteral();
+            builder->AddCharacter(octal);
+            break;
+          }
+          case 'b':
+            Advance(2);
+            builder->AddAssertion(zone()->template New<RegExpAssertion>(
+                RegExpAssertion::Type::BOUNDARY));
+            continue;
+          case 'B':
+            Advance(2);
+            builder->AddAssertion(zone()->template New<RegExpAssertion>(
+                RegExpAssertion::Type::NON_BOUNDARY));
+            continue;
+          // AtomEscape ::
+          //   CharacterClassEscape
+          case 'd':
+          case 'D':
+          case 's':
+          case 'S':
+          case 'w':
+          case 'W': {
+            base::uc32 next = Next();
+            ZoneList<CharacterRange>* ranges =
+                zone()->template New<ZoneList<CharacterRange>>(2, zone());
+            bool add_unicode_case_equivalents =
+                IsUnicodeMode() && ignore_case();
+            bool parsed_character_class_escape = TryParseCharacterClassEscape(
+                next, InClassEscapeState::kNotInClass, ranges, nullptr, zone(),
+                add_unicode_case_equivalents CHECK_FAILED);
+
+            if (parsed_character_class_escape) {
+              RegExpClassRanges* cc =
+                  zone()->template New<RegExpClassRanges>(zone(), ranges);
+              builder->AddClassRanges(cc);
+            } else {
+              CHECK(!IsUnicodeMode());
+              Advance(2);
+              builder->AddCharacter(next);  // IdentityEscape.
+            }
+            break;
+          }
+          case 'p':
+          case 'P': {
+            base::uc32 next = Next();
+            ZoneList<CharacterRange>* ranges =
+                zone()->template New<ZoneList<CharacterRange>>(2, zone());
+            CharacterClassStrings* strings = nullptr;
+            if (unicode_sets()) {
+              strings = zone()->template New<CharacterClassStrings>(zone());
+            }
+            bool add_unicode_case_equivalents = ignore_case();
+            bool parsed_character_class_escape = TryParseCharacterClassEscape(
+                next, InClassEscapeState::kNotInClass, ranges, strings, zone(),
+                add_unicode_case_equivalents CHECK_FAILED);
+
+            if (parsed_character_class_escape) {
+              if (unicode_sets()) {
+                RegExpClassSetOperand* op =
+                    zone()->template New<RegExpClassSetOperand>(ranges,
+                                                                strings);
+                builder->AddTerm(op);
+              } else {
+                RegExpClassRanges* cc =
+                    zone()->template New<RegExpClassRanges>(zone(), ranges);
+                builder->AddClassRanges(cc);
+              }
+            } else {
+              CHECK(!IsUnicodeMode());
+              Advance(2);
+              builder->AddCharacter(next);  // IdentityEscape.
+            }
+            break;
+          }
+          // AtomEscape ::
+          //   k GroupName
+          case 'k': {
+            // Either an identity escape or a named back-reference.  The two
+            // interpretations are mutually exclusive: '\k' is interpreted as
+            // an identity escape for non-Unicode patterns without named
+            // capture groups, and as the beginning of a named back-reference
+            // in all other cases.
+            const bool has_named_captures =
+                HasNamedCaptures(InClassEscapeState::kNotInClass CHECK_FAILED);
+            if (IsUnicodeMode() || has_named_captures) {
+              Advance(2);
+              ParseNamedBackReference(builder, state CHECK_FAILED);
+              break;
+            }
+          }
+            V8_FALLTHROUGH;
+          // AtomEscape ::
+          //   CharacterEscape
+          default: {
+            bool is_escaped_unicode_character = false;
+            base::uc32 c = ParseCharacterEscape(
+                InClassEscapeState::kNotInClass,
+                &is_escaped_unicode_character CHECK_FAILED);
+            if (is_escaped_unicode_character) {
+              builder->AddEscapedUnicodeCharacter(c);
+            } else {
+              builder->AddCharacter(c);
+            }
+            break;
+          }
+        }
+        break;
+      case '{': {
+        int dummy;
+        bool parsed = ParseIntervalQuantifier(&dummy, &dummy CHECK_FAILED);
+        if (parsed) return ReportError(RegExpError::kNothingToRepeat);
+        V8_FALLTHROUGH;
+      }
+      case '}':
+      case ']':
+        if (IsUnicodeMode()) {
+          return ReportError(RegExpError::kLoneQuantifierBrackets);
+        }
+        V8_FALLTHROUGH;
+      default:
+        builder->AddUnicodeCharacter(current());
+        Advance();
+        break;
+    }  // end switch(current())
+
+    int min;
+    int max;
+    switch (current()) {
+      // QuantifierPrefix ::
+      //   *
+      //   +
+      //   ?
+      //   {
+      case '*':
+        min = 0;
+        max = RegExpTree::kInfinity;
+        Advance();
+        break;
+      case '+':
+        min = 1;
+        max = RegExpTree::kInfinity;
+        Advance();
+        break;
+      case '?':
+        min = 0;
+        max = 1;
+        Advance();
+        break;
+      case '{':
+        if (ParseIntervalQuantifier(&min, &max)) {
+          if (max < min) {
+            return ReportError(RegExpError::kRangeOutOfOrder);
+          }
+          break;
+        } else if (IsUnicodeMode()) {
+          // Incomplete quantifiers are not allowed.
+          return ReportError(RegExpError::kIncompleteQuantifier);
+        }
+        continue;
+      default:
+        continue;
+    }
+    RegExpQuantifier::QuantifierType quantifier_type = RegExpQuantifier::GREEDY;
+    if (current() == '?') {
+      quantifier_type = RegExpQuantifier::NON_GREEDY;
+      Advance();
+    } else if (v8_flags.regexp_possessive_quantifier && current() == '+') {
+      // v8_flags.regexp_possessive_quantifier is a debug-only flag.
+      quantifier_type = RegExpQuantifier::POSSESSIVE;
+      Advance();
+    }
+    if (!builder->AddQuantifierToAtom(min, max, quantifier_type)) {
+      return ReportError(RegExpError::kInvalidQuantifier);
+    }
+  }
+}
+
+template <class CharT>
+RegExpParserState* RegExpParserImpl<CharT>::ParseOpenParenthesis(
+    RegExpParserState* state) {
+  RegExpLookaround::Type lookaround_type = state->lookaround_type();
+  bool is_named_capture = false;
+  const ZoneVector<base::uc16>* capture_name = nullptr;
+  SubexpressionType subexpr_type = CAPTURE;
+  Advance();
+  if (current() == '?') {
+    switch (Next()) {
+      case ':':
+        Advance(2);
+        subexpr_type = GROUPING;
+        break;
+      case '=':
+        Advance(2);
+        lookaround_type = RegExpLookaround::LOOKAHEAD;
+        subexpr_type = POSITIVE_LOOKAROUND;
+        break;
+      case '!':
+        Advance(2);
+        lookaround_type = RegExpLookaround::LOOKAHEAD;
+        subexpr_type = NEGATIVE_LOOKAROUND;
+        break;
+      case '<':
+        Advance();
+        if (Next() == '=') {
+          Advance(2);
+          lookaround_type = RegExpLookaround::LOOKBEHIND;
+          subexpr_type = POSITIVE_LOOKAROUND;
+          break;
+        } else if (Next() == '!') {
+          Advance(2);
+          lookaround_type = RegExpLookaround::LOOKBEHIND;
+          subexpr_type = NEGATIVE_LOOKAROUND;
+          break;
+        }
+        is_named_capture = true;
+        has_named_captures_ = true;
+        Advance();
+        break;
+      default:
+        ReportError(RegExpError::kInvalidGroup);
+        return nullptr;
+    }
+  }
+  if (subexpr_type == CAPTURE) {
+    if (captures_started_ >= RegExpMacroAssembler::kMaxCaptures) {
+      ReportError(RegExpError::kTooManyCaptures);
+      return nullptr;
+    }
+    captures_started_++;
+
+    if (is_named_capture) {
+      capture_name = ParseCaptureGroupName(CHECK_FAILED);
+    }
+  }
+  // Store current state and begin new disjunction parsing.
+  return zone()->template New<RegExpParserState>(
+      state, subexpr_type, lookaround_type, captures_started_, capture_name,
+      state->builder()->flags(), zone());
+}
+
+// In order to know whether an escape is a backreference or not we have to scan
+// the entire regexp and find the number of capturing parentheses.  However we
+// don't want to scan the regexp twice unless it is necessary.  This mini-parser
+// is called when needed.  It can see the difference between capturing and
+// noncapturing parentheses and can skip character classes and backslash-escaped
+// characters.
+//
+// Important: The scanner has to be in a consistent state when calling
+// ScanForCaptures, e.g. not in the middle of an escape sequence '\[' or while
+// parsing a nested class.
+template <class CharT>
+void RegExpParserImpl<CharT>::ScanForCaptures(
+    InClassEscapeState in_class_escape_state) {
+  DCHECK(!is_scanned_for_captures_);
+  const int saved_position = position();
+  // Start with captures started previous to current position
+  int capture_count = captures_started();
+  // When we start inside a character class, skip everything inside the class.
+  if (in_class_escape_state == InClassEscapeState::kInClass) {
+    // \k is always invalid within a class in unicode mode, thus we should never
+    // call ScanForCaptures within a class.
+    DCHECK(!IsUnicodeMode());
+    int c;
+    while ((c = current()) != kEndMarker) {
+      Advance();
+      if (c == '\\') {
+        Advance();
+      } else {
+        if (c == ']') break;
+      }
+    }
+  }
+  // Add count of captures after this position.
+  int n;
+  while ((n = current()) != kEndMarker) {
+    Advance();
+    switch (n) {
+      case '\\':
+        Advance();
+        break;
+      case '[': {
+        int class_nest_level = 0;
+        int c;
+        while ((c = current()) != kEndMarker) {
+          Advance();
+          if (c == '\\') {
+            Advance();
+          } else if (c == '[') {
+            // With /v, '[' inside a class is treated as a nested class.
+            // Without /v, '[' is a normal character.
+            if (unicode_sets()) class_nest_level++;
+          } else if (c == ']') {
+            if (class_nest_level == 0) break;
+            class_nest_level--;
+          }
+        }
+        break;
+      }
+      case '(':
+        if (current() == '?') {
+          // At this point we could be in
+          // * a non-capturing group '(:',
+          // * a lookbehind assertion '(?<=' '(?<!'
+          // * or a named capture '(?<'.
+          //
+          // Of these, only named captures are capturing groups.
+
+          Advance();
+          if (current() != '<') break;
+
+          Advance();
+          if (current() == '=' || current() == '!') break;
+
+          // Found a possible named capture. It could turn out to be a syntax
+          // error (e.g. an unterminated or invalid name), but that distinction
+          // does not matter for our purposes.
+          has_named_captures_ = true;
+        }
+        capture_count++;
+        break;
+    }
+  }
+  capture_count_ = capture_count;
+  is_scanned_for_captures_ = true;
+  Reset(saved_position);
+}
+
+template <class CharT>
+bool RegExpParserImpl<CharT>::ParseBackReferenceIndex(int* index_out) {
+  DCHECK_EQ('\\', current());
+  DCHECK('1' <= Next() && Next() <= '9');
+  // Try to parse a decimal literal that is no greater than the total number
+  // of left capturing parentheses in the input.
+  int start = position();
+  int value = Next() - '0';
+  Advance(2);
+  while (true) {
+    base::uc32 c = current();
+    if (IsDecimalDigit(c)) {
+      value = 10 * value + (c - '0');
+      if (value > RegExpMacroAssembler::kMaxCaptures) {
+        Reset(start);
+        return false;
+      }
+      Advance();
+    } else {
+      break;
+    }
+  }
+  if (value > captures_started()) {
+    if (!is_scanned_for_captures_) {
+      ScanForCaptures(InClassEscapeState::kNotInClass);
+    }
+    if (value > capture_count_) {
+      Reset(start);
+      return false;
+    }
+  }
+  *index_out = value;
+  return true;
+}
+
+namespace {
+
+void push_code_unit(ZoneVector<base::uc16>* v, uint32_t code_unit) {
+  if (code_unit <= unibrow::Utf16::kMaxNonSurrogateCharCode) {
+    v->push_back(code_unit);
+  } else {
+    v->push_back(unibrow::Utf16::LeadSurrogate(code_unit));
+    v->push_back(unibrow::Utf16::TrailSurrogate(code_unit));
+  }
+}
+
+}  // namespace
+
+template <class CharT>
+const ZoneVector<base::uc16>* RegExpParserImpl<CharT>::ParseCaptureGroupName() {
+  // Due to special Advance requirements (see the next comment), rewind by one
+  // such that names starting with a surrogate pair are parsed correctly for
+  // patterns where the unicode flag is unset.
+  //
+  // Note that we use this odd pattern of rewinding the last advance in order
+  // to adhere to the common parser behavior of expecting `current` to point at
+  // the first candidate character for a function (e.g. when entering ParseFoo,
+  // `current` should point at the first character of Foo).
+  RewindByOneCodepoint();
+
+  ZoneVector<base::uc16>* name =
+      zone()->template New<ZoneVector<base::uc16>>(zone());
+
+  {
+    // Advance behavior inside this function is tricky since
+    // RegExpIdentifierName explicitly enables unicode (in spec terms, sets +U)
+    // and thus allows surrogate pairs and \u{}-style escapes even in
+    // non-unicode patterns. Therefore Advance within the capture group name
+    // has to force-enable unicode, and outside the name revert to default
+    // behavior.
+    ForceUnicodeScope force_unicode(this);
+
+    bool at_start = true;
+    while (true) {
+      Advance();
+      base::uc32 c = current();
+
+      // Convert unicode escapes.
+      if (c == '\\' && Next() == 'u') {
+        Advance(2);
+        if (!ParseUnicodeEscape(&c)) {
+          ReportError(RegExpError::kInvalidUnicodeEscape);
+          return nullptr;
+        }
+        RewindByOneCodepoint();
+      }
+
+      // The backslash char is misclassified as both ID_Start and ID_Continue.
+      if (c == '\\') {
+        ReportError(RegExpError::kInvalidCaptureGroupName);
+        return nullptr;
+      }
+
+      if (at_start) {
+        if (!IsIdentifierStart(c)) {
+          ReportError(RegExpError::kInvalidCaptureGroupName);
+          return nullptr;
+        }
+        push_code_unit(name, c);
+        at_start = false;
+      } else {
+        if (c == '>') {
+          break;
+        } else if (IsIdentifierPart(c)) {
+          push_code_unit(name, c);
+        } else {
+          ReportError(RegExpError::kInvalidCaptureGroupName);
+          return nullptr;
+        }
+      }
+    }
+  }
+
+  // This final advance goes back into the state of pointing at the next
+  // relevant char, which the rest of the parser expects. See also the previous
+  // comments in this function.
+  Advance();
+  return name;
+}
+
+template <class CharT>
+bool RegExpParserImpl<CharT>::CreateNamedCaptureAtIndex(
+    const ZoneVector<base::uc16>* name, int index) {
+  DCHECK(0 < index && index <= captures_started_);
+  DCHECK_NOT_NULL(name);
+
+  RegExpCapture* capture = GetCapture(index);
+  DCHECK_NULL(capture->name());
+
+  capture->set_name(name);
+
+  if (named_captures_ == nullptr) {
+    named_captures_ =
+        zone_->template New<ZoneSet<RegExpCapture*, RegExpCaptureNameLess>>(
+            zone());
+  } else {
+    // Check for duplicates and bail if we find any.
+
+    const auto& named_capture_it = named_captures_->find(capture);
+    if (named_capture_it != named_captures_->end()) {
+      ReportError(RegExpError::kDuplicateCaptureGroupName);
+      return false;
+    }
+  }
+
+  named_captures_->emplace(capture);
+
+  return true;
+}
+
+template <class CharT>
+bool RegExpParserImpl<CharT>::ParseNamedBackReference(
+    RegExpBuilder* builder, RegExpParserState* state) {
+  // The parser is assumed to be on the '<' in \k<name>.
+  if (current() != '<') {
+    ReportError(RegExpError::kInvalidNamedReference);
+    return false;
+  }
+
+  Advance();
+  const ZoneVector<base::uc16>* name = ParseCaptureGroupName();
+  if (name == nullptr) {
+    return false;
+  }
+
+  if (state->IsInsideCaptureGroup(name)) {
+    builder->AddEmpty();
+  } else {
+    RegExpBackReference* atom =
+        zone()->template New<RegExpBackReference>(builder->flags());
+    atom->set_name(name);
+
+    builder->AddAtom(atom);
+
+    if (named_back_references_ == nullptr) {
+      named_back_references_ =
+          zone()->template New<ZoneList<RegExpBackReference*>>(1, zone());
+    }
+    named_back_references_->Add(atom, zone());
+  }
+
+  return true;
+}
+
+template <class CharT>
+void RegExpParserImpl<CharT>::PatchNamedBackReferences() {
+  if (named_back_references_ == nullptr) return;
+
+  if (named_captures_ == nullptr) {
+    ReportError(RegExpError::kInvalidNamedCaptureReference);
+    return;
+  }
+
+  // Look up and patch the actual capture for each named back reference.
+
+  for (int i = 0; i < named_back_references_->length(); i++) {
+    RegExpBackReference* ref = named_back_references_->at(i);
+
+    // Capture used to search the named_captures_ by name, index of the
+    // capture is never used.
+    static const int kInvalidIndex = 0;
+    RegExpCapture* search_capture =
+        zone()->template New<RegExpCapture>(kInvalidIndex);
+    DCHECK_NULL(search_capture->name());
+    search_capture->set_name(ref->name());
+
+    int index = -1;
+    const auto& capture_it = named_captures_->find(search_capture);
+    if (capture_it != named_captures_->end()) {
+      index = (*capture_it)->index();
+    } else {
+      ReportError(RegExpError::kInvalidNamedCaptureReference);
+      return;
+    }
+
+    ref->set_capture(GetCapture(index));
+  }
+}
+
+template <class CharT>
+RegExpCapture* RegExpParserImpl<CharT>::GetCapture(int index) {
+  // The index for the capture groups are one-based. Its index in the list is
+  // zero-based.
+  const int known_captures =
+      is_scanned_for_captures_ ? capture_count_ : captures_started_;
+  DCHECK(index <= known_captures);
+  if (captures_ == nullptr) {
+    captures_ =
+        zone()->template New<ZoneList<RegExpCapture*>>(known_captures, zone());
+  }
+  while (captures_->length() < known_captures) {
+    captures_->Add(zone()->template New<RegExpCapture>(captures_->length() + 1),
+                   zone());
+  }
+  return captures_->at(index - 1);
+}
+
+template <class CharT>
+ZoneVector<RegExpCapture*>* RegExpParserImpl<CharT>::GetNamedCaptures() const {
+  if (named_captures_ == nullptr || named_captures_->empty()) {
+    return nullptr;
+  }
+
+  return zone()->template New<ZoneVector<RegExpCapture*>>(
+      named_captures_->begin(), named_captures_->end(), zone());
+}
+
+template <class CharT>
+bool RegExpParserImpl<CharT>::HasNamedCaptures(
+    InClassEscapeState in_class_escape_state) {
+  if (has_named_captures_ || is_scanned_for_captures_) {
+    return has_named_captures_;
+  }
+
+  ScanForCaptures(in_class_escape_state);
+  DCHECK(is_scanned_for_captures_);
+  return has_named_captures_;
+}
+
+// QuantifierPrefix ::
+//   { DecimalDigits }
+//   { DecimalDigits , }
+//   { DecimalDigits , DecimalDigits }
+//
+// Returns true if parsing succeeds, and set the min_out and max_out
+// values. Values are truncated to RegExpTree::kInfinity if they overflow.
+template <class CharT>
+bool RegExpParserImpl<CharT>::ParseIntervalQuantifier(int* min_out,
+                                                      int* max_out) {
+  DCHECK_EQ(current(), '{');
+  int start = position();
+  Advance();
+  int min = 0;
+  if (!IsDecimalDigit(current())) {
+    Reset(start);
+    return false;
+  }
+  while (IsDecimalDigit(current())) {
+    int next = current() - '0';
+    if (min > (RegExpTree::kInfinity - next) / 10) {
+      // Overflow. Skip past remaining decimal digits and return -1.
+      do {
+        Advance();
+      } while (IsDecimalDigit(current()));
+      min = RegExpTree::kInfinity;
+      break;
+    }
+    min = 10 * min + next;
+    Advance();
+  }
+  int max = 0;
+  if (current() == '}') {
+    max = min;
+    Advance();
+  } else if (current() == ',') {
+    Advance();
+    if (current() == '}') {
+      max = RegExpTree::kInfinity;
+      Advance();
+    } else {
+      while (IsDecimalDigit(current())) {
+        int next = current() - '0';
+        if (max > (RegExpTree::kInfinity - next) / 10) {
+          do {
+            Advance();
+          } while (IsDecimalDigit(current()));
+          max = RegExpTree::kInfinity;
+          break;
+        }
+        max = 10 * max + next;
+        Advance();
+      }
+      if (current() != '}') {
+        Reset(start);
+        return false;
+      }
+      Advance();
+    }
+  } else {
+    Reset(start);
+    return false;
+  }
+  *min_out = min;
+  *max_out = max;
+  return true;
+}
+
+template <class CharT>
+base::uc32 RegExpParserImpl<CharT>::ParseOctalLiteral() {
+  DCHECK(('0' <= current() && current() <= '7') || !has_more());
+  // For compatibility with some other browsers (not all), we parse
+  // up to three octal digits with a value below 256.
+  // ES#prod-annexB-LegacyOctalEscapeSequence
+  base::uc32 value = current() - '0';
+  Advance();
+  if ('0' <= current() && current() <= '7') {
+    value = value * 8 + current() - '0';
+    Advance();
+    if (value < 32 && '0' <= current() && current() <= '7') {
+      value = value * 8 + current() - '0';
+      Advance();
+    }
+  }
+  return value;
+}
+
+template <class CharT>
+bool RegExpParserImpl<CharT>::ParseHexEscape(int length, base::uc32* value) {
+  int start = position();
+  base::uc32 val = 0;
+  for (int i = 0; i < length; ++i) {
+    base::uc32 c = current();
+    int d = base::HexValue(c);
+    if (d < 0) {
+      Reset(start);
+      return false;
+    }
+    val = val * 16 + d;
+    Advance();
+  }
+  *value = val;
+  return true;
+}
+
+// This parses RegExpUnicodeEscapeSequence as described in ECMA262.
+template <class CharT>
+bool RegExpParserImpl<CharT>::ParseUnicodeEscape(base::uc32* value) {
+  // Accept both \uxxxx and \u{xxxxxx} (if harmony unicode escapes are
+  // allowed). In the latter case, the number of hex digits between { } is
+  // arbitrary. \ and u have already been read.
+  if (current() == '{' && IsUnicodeMode()) {
+    int start = position();
+    Advance();
+    if (ParseUnlimitedLengthHexNumber(0x10FFFF, value)) {
+      if (current() == '}') {
+        Advance();
+        return true;
+      }
+    }
+    Reset(start);
+    return false;
+  }
+  // \u but no {, or \u{...} escapes not allowed.
+  bool result = ParseHexEscape(4, value);
+  if (result && IsUnicodeMode() && unibrow::Utf16::IsLeadSurrogate(*value) &&
+      current() == '\\') {
+    // Attempt to read trail surrogate.
+    int start = position();
+    if (Next() == 'u') {
+      Advance(2);
+      base::uc32 trail;
+      if (ParseHexEscape(4, &trail) &&
+          unibrow::Utf16::IsTrailSurrogate(trail)) {
+        *value = unibrow::Utf16::CombineSurrogatePair(
+            static_cast<base::uc16>(*value), static_cast<base::uc16>(trail));
+        return true;
+      }
+    }
+    Reset(start);
+  }
+  return result;
+}
+
+#ifdef V8_INTL_SUPPORT
+
+namespace {
+
+bool IsExactPropertyAlias(const char* property_name, UProperty property) {
+  const char* short_name = u_getPropertyName(property, U_SHORT_PROPERTY_NAME);
+  if (short_name != nullptr && strcmp(property_name, short_name) == 0)
+    return true;
+  for (int i = 0;; i++) {
+    const char* long_name = u_getPropertyName(
+        property, static_cast<UPropertyNameChoice>(U_LONG_PROPERTY_NAME + i));
+    if (long_name == nullptr) break;
+    if (strcmp(property_name, long_name) == 0) return true;
+  }
+  return false;
+}
+
+bool IsExactPropertyValueAlias(const char* property_value_name,
+                               UProperty property, int32_t property_value) {
+  const char* short_name =
+      u_getPropertyValueName(property, property_value, U_SHORT_PROPERTY_NAME);
+  if (short_name != nullptr && strcmp(property_value_name, short_name) == 0) {
+    return true;
+  }
+  for (int i = 0;; i++) {
+    const char* long_name = u_getPropertyValueName(
+        property, property_value,
+        static_cast<UPropertyNameChoice>(U_LONG_PROPERTY_NAME + i));
+    if (long_name == nullptr) break;
+    if (strcmp(property_value_name, long_name) == 0) return true;
+  }
+  return false;
+}
+
+void ExtractStringsFromUnicodeSet(const icu::UnicodeSet& set,
+                                  CharacterClassStrings* strings,
+                                  RegExpFlags flags, Zone* zone) {
+  DCHECK(set.hasStrings());
+  DCHECK(IsUnicodeSets(flags));
+  DCHECK_NOT_NULL(strings);
+
+  RegExpTextBuilder::SmallRegExpTreeVector string_storage(
+      ZoneAllocator<RegExpTree*>{zone});
+  RegExpTextBuilder string_builder(zone, &string_storage, flags);
+  const bool needs_case_folding = IsIgnoreCase(flags);
+  icu::UnicodeSetIterator iter(set);
+  iter.skipToStrings();
+  while (iter.next()) {
+    const icu::UnicodeString& s = iter.getString();
+    const char16_t* p = s.getBuffer();
+    int32_t length = s.length();
+    ZoneList<base::uc32>* string =
+        zone->template New<ZoneList<base::uc32>>(length, zone);
+    for (int32_t i = 0; i < length;) {
+      UChar32 c;
+      U16_NEXT(p, i, length, c);
+      string_builder.AddUnicodeCharacter(c);
+      if (needs_case_folding) {
+        c = u_foldCase(c, U_FOLD_CASE_DEFAULT);
+      }
+      string->Add(c, zone);
+    }
+    strings->emplace(string->ToVector(), string_builder.ToRegExp());
+    string_storage.clear();
+  }
+}
+
+bool LookupPropertyValueName(UProperty property,
+                             const char* property_value_name, bool negate,
+                             ZoneList<CharacterRange>* result_ranges,
+                             CharacterClassStrings* result_strings,
+                             RegExpFlags flags, Zone* zone) {
+  UProperty property_for_lookup = property;
+  if (property_for_lookup == UCHAR_SCRIPT_EXTENSIONS) {
+    // For the property Script_Extensions, we have to do the property value
+    // name lookup as if the property is Script.
+    property_for_lookup = UCHAR_SCRIPT;
+  }
+  int32_t property_value =
+      u_getPropertyValueEnum(property_for_lookup, property_value_name);
+  if (property_value == UCHAR_INVALID_CODE) return false;
+
+  // We require the property name to match exactly to one of the property value
+  // aliases. However, u_getPropertyValueEnum uses loose matching.
+  if (!IsExactPropertyValueAlias(property_value_name, property_for_lookup,
+                                 property_value)) {
+    return false;
+  }
+
+  UErrorCode ec = U_ZERO_ERROR;
+  icu::UnicodeSet set;
+  set.applyIntPropertyValue(property, property_value, ec);
+  bool success = ec == U_ZERO_ERROR && !set.isEmpty();
+
+  if (success) {
+    if (set.hasStrings()) {
+      ExtractStringsFromUnicodeSet(set, result_strings, flags, zone);
+    }
+    const bool needs_case_folding = IsUnicodeSets(flags) && IsIgnoreCase(flags);
+    if (needs_case_folding) CharacterRange::UnicodeSimpleCloseOver(set);
+    set.removeAllStrings();
+    if (negate) set.complement();
+    for (int i = 0; i < set.getRangeCount(); i++) {
+      result_ranges->Add(
+          CharacterRange::Range(set.getRangeStart(i), set.getRangeEnd(i)),
+          zone);
+    }
+  }
+  return success;
+}
+
+template <size_t N>
+inline bool NameEquals(const char* name, const char (&literal)[N]) {
+  return strncmp(name, literal, N + 1) == 0;
+}
+
+bool LookupSpecialPropertyValueName(const char* name,
+                                    ZoneList<CharacterRange>* result,
+                                    bool negate, RegExpFlags flags,
+                                    Zone* zone) {
+  if (NameEquals(name, "Any")) {
+    if (negate) {
+      // Leave the list of character ranges empty, since the negation of 'Any'
+      // is the empty set.
+    } else {
+      result->Add(CharacterRange::Everything(), zone);
+    }
+  } else if (NameEquals(name, "ASCII")) {
+    result->Add(negate ? CharacterRange::Range(0x80, String::kMaxCodePoint)
+                       : CharacterRange::Range(0x0, 0x7F),
+                zone);
+  } else if (NameEquals(name, "Assigned")) {
+    return LookupPropertyValueName(UCHAR_GENERAL_CATEGORY, "Unassigned",
+                                   !negate, result, nullptr, flags, zone);
+  } else {
+    return false;
+  }
+  return true;
+}
+
+// Explicitly allowlist supported binary properties. The spec forbids supporting
+// properties outside of this set to ensure interoperability.
+bool IsSupportedBinaryProperty(UProperty property, bool unicode_sets) {
+  switch (property) {
+    case UCHAR_ALPHABETIC:
+    // 'Any' is not supported by ICU. See LookupSpecialPropertyValueName.
+    // 'ASCII' is not supported by ICU. See LookupSpecialPropertyValueName.
+    case UCHAR_ASCII_HEX_DIGIT:
+    // 'Assigned' is not supported by ICU. See LookupSpecialPropertyValueName.
+    case UCHAR_BIDI_CONTROL:
+    case UCHAR_BIDI_MIRRORED:
+    case UCHAR_CASE_IGNORABLE:
+    case UCHAR_CASED:
+    case UCHAR_CHANGES_WHEN_CASEFOLDED:
+    case UCHAR_CHANGES_WHEN_CASEMAPPED:
+    case UCHAR_CHANGES_WHEN_LOWERCASED:
+    case UCHAR_CHANGES_WHEN_NFKC_CASEFOLDED:
+    case UCHAR_CHANGES_WHEN_TITLECASED:
+    case UCHAR_CHANGES_WHEN_UPPERCASED:
+    case UCHAR_DASH:
+    case UCHAR_DEFAULT_IGNORABLE_CODE_POINT:
+    case UCHAR_DEPRECATED:
+    case UCHAR_DIACRITIC:
+    case UCHAR_EMOJI:
+    case UCHAR_EMOJI_COMPONENT:
+    case UCHAR_EMOJI_MODIFIER_BASE:
+    case UCHAR_EMOJI_MODIFIER:
+    case UCHAR_EMOJI_PRESENTATION:
+    case UCHAR_EXTENDED_PICTOGRAPHIC:
+    case UCHAR_EXTENDER:
+    case UCHAR_GRAPHEME_BASE:
+    case UCHAR_GRAPHEME_EXTEND:
+    case UCHAR_HEX_DIGIT:
+    case UCHAR_ID_CONTINUE:
+    case UCHAR_ID_START:
+    case UCHAR_IDEOGRAPHIC:
+    case UCHAR_IDS_BINARY_OPERATOR:
+    case UCHAR_IDS_TRINARY_OPERATOR:
+    case UCHAR_JOIN_CONTROL:
+    case UCHAR_LOGICAL_ORDER_EXCEPTION:
+    case UCHAR_LOWERCASE:
+    case UCHAR_MATH:
+    case UCHAR_NONCHARACTER_CODE_POINT:
+    case UCHAR_PATTERN_SYNTAX:
+    case UCHAR_PATTERN_WHITE_SPACE:
+    case UCHAR_QUOTATION_MARK:
+    case UCHAR_RADICAL:
+    case UCHAR_REGIONAL_INDICATOR:
+    case UCHAR_S_TERM:
+    case UCHAR_SOFT_DOTTED:
+    case UCHAR_TERMINAL_PUNCTUATION:
+    case UCHAR_UNIFIED_IDEOGRAPH:
+    case UCHAR_UPPERCASE:
+    case UCHAR_VARIATION_SELECTOR:
+    case UCHAR_WHITE_SPACE:
+    case UCHAR_XID_CONTINUE:
+    case UCHAR_XID_START:
+      return true;
+    case UCHAR_BASIC_EMOJI:
+    case UCHAR_EMOJI_KEYCAP_SEQUENCE:
+    case UCHAR_RGI_EMOJI_MODIFIER_SEQUENCE:
+    case UCHAR_RGI_EMOJI_FLAG_SEQUENCE:
+    case UCHAR_RGI_EMOJI_TAG_SEQUENCE:
+    case UCHAR_RGI_EMOJI_ZWJ_SEQUENCE:
+    case UCHAR_RGI_EMOJI:
+      return unicode_sets;
+    default:
+      break;
+  }
+  return false;
+}
+
+bool IsBinaryPropertyOfStrings(UProperty property) {
+  switch (property) {
+    case UCHAR_BASIC_EMOJI:
+    case UCHAR_EMOJI_KEYCAP_SEQUENCE:
+    case UCHAR_RGI_EMOJI_MODIFIER_SEQUENCE:
+    case UCHAR_RGI_EMOJI_FLAG_SEQUENCE:
+    case UCHAR_RGI_EMOJI_TAG_SEQUENCE:
+    case UCHAR_RGI_EMOJI_ZWJ_SEQUENCE:
+    case UCHAR_RGI_EMOJI:
+      return true;
+    default:
+      break;
+  }
+  return false;
+}
+
+bool IsUnicodePropertyValueCharacter(char c) {
+  // https://tc39.github.io/proposal-regexp-unicode-property-escapes/
+  //
+  // Note that using this to validate each parsed char is quite conservative.
+  // A possible alternative solution would be to only ensure the parsed
+  // property name/value candidate string does not contain '\0' characters and
+  // let ICU lookups trigger the final failure.
+  if ('a' <= c && c <= 'z') return true;
+  if ('A' <= c && c <= 'Z') return true;
+  if ('0' <= c && c <= '9') return true;
+  return (c == '_');
+}
+
+}  // namespace
+
+template <class CharT>
+bool RegExpParserImpl<CharT>::ParsePropertyClassName(ZoneVector<char>* name_1,
+                                                     ZoneVector<char>* name_2) {
+  DCHECK(name_1->empty());
+  DCHECK(name_2->empty());
+  // Parse the property class as follows:
+  // - In \p{name}, 'name' is interpreted
+  //   - either as a general category property value name.
+  //   - or as a binary property name.
+  // - In \p{name=value}, 'name' is interpreted as an enumerated property name,
+  //   and 'value' is interpreted as one of the available property value names.
+  // - Aliases in PropertyAlias.txt and PropertyValueAlias.txt can be used.
+  // - Loose matching is not applied.
+  if (current() == '{') {
+    // Parse \p{[PropertyName=]PropertyNameValue}
+    for (Advance(); current() != '}' && current() != '='; Advance()) {
+      if (!IsUnicodePropertyValueCharacter(current())) return false;
+      if (!has_next()) return false;
+      name_1->push_back(static_cast<char>(current()));
+    }
+    if (current() == '=') {
+      for (Advance(); current() != '}'; Advance()) {
+        if (!IsUnicodePropertyValueCharacter(current())) return false;
+        if (!has_next()) return false;
+        name_2->push_back(static_cast<char>(current()));
+      }
+      name_2->push_back(0);  // null-terminate string.
+    }
+  } else {
+    return false;
+  }
+  Advance();
+  name_1->push_back(0);  // null-terminate string.
+
+  DCHECK(name_1->size() - 1 == std::strlen(name_1->data()));
+  DCHECK(name_2->empty() || name_2->size() - 1 == std::strlen(name_2->data()));
+  return true;
+}
+
+template <class CharT>
+bool RegExpParserImpl<CharT>::AddPropertyClassRange(
+    ZoneList<CharacterRange>* add_to_ranges,
+    CharacterClassStrings* add_to_strings, bool negate,
+    const ZoneVector<char>& name_1, const ZoneVector<char>& name_2) {
+  if (name_2.empty()) {
+    // First attempt to interpret as general category property value name.
+    const char* name = name_1.data();
+    if (LookupPropertyValueName(UCHAR_GENERAL_CATEGORY_MASK, name, negate,
+                                add_to_ranges, add_to_strings, flags(),
+                                zone())) {
+      return true;
+    }
+    // Interpret "Any", "ASCII", and "Assigned".
+    if (LookupSpecialPropertyValueName(name, add_to_ranges, negate, flags(),
+                                       zone())) {
+      return true;
+    }
+    // Then attempt to interpret as binary property name with value name 'Y'.
+    UProperty property = u_getPropertyEnum(name);
+    if (!IsSupportedBinaryProperty(property, unicode_sets())) return false;
+    if (!IsExactPropertyAlias(name, property)) return false;
+    // Negation of properties with strings is not allowed.
+    // TODO(v8:11935): Change permalink once proposal is in stage 4.
+    // See
+    // https://arai-a.github.io/ecma262-compare/snapshot.html?pr=2418#sec-static-semantics-maycontainstrings
+    if (negate && IsBinaryPropertyOfStrings(property)) return false;
+    return LookupPropertyValueName(property, negate ? "N" : "Y", false,
+                                   add_to_ranges, add_to_strings, flags(),
+                                   zone());
+  } else {
+    // Both property name and value name are specified. Attempt to interpret
+    // the property name as enumerated property.
+    const char* property_name = name_1.data();
+    const char* value_name = name_2.data();
+    UProperty property = u_getPropertyEnum(property_name);
+    if (!IsExactPropertyAlias(property_name, property)) return false;
+    if (property == UCHAR_GENERAL_CATEGORY) {
+      // We want to allow aggregate value names such as "Letter".
+      property = UCHAR_GENERAL_CATEGORY_MASK;
+    } else if (property != UCHAR_SCRIPT &&
+               property != UCHAR_SCRIPT_EXTENSIONS) {
+      return false;
+    }
+    return LookupPropertyValueName(property, value_name, negate, add_to_ranges,
+                                   add_to_strings, flags(), zone());
+  }
+}
+
+#else  // V8_INTL_SUPPORT
+
+template <class CharT>
+bool RegExpParserImpl<CharT>::ParsePropertyClassName(ZoneVector<char>* name_1,
+                                                     ZoneVector<char>* name_2) {
+  return false;
+}
+
+template <class CharT>
+bool RegExpParserImpl<CharT>::AddPropertyClassRange(
+    ZoneList<CharacterRange>* add_to_ranges,
+    CharacterClassStrings* add_to_strings, bool negate,
+    const ZoneVector<char>& name_1, const ZoneVector<char>& name_2) {
+  return false;
+}
+
+#endif  // V8_INTL_SUPPORT
+
+template <class CharT>
+bool RegExpParserImpl<CharT>::ParseUnlimitedLengthHexNumber(int max_value,
+                                                            base::uc32* value) {
+  base::uc32 x = 0;
+  int d = base::HexValue(current());
+  if (d < 0) {
+    return false;
+  }
+  while (d >= 0) {
+    x = x * 16 + d;
+    if (x > static_cast<base::uc32>(max_value)) {
+      return false;
+    }
+    Advance();
+    d = base::HexValue(current());
+  }
+  *value = x;
+  return true;
+}
+
+// https://tc39.es/ecma262/#prod-CharacterEscape
+template <class CharT>
+base::uc32 RegExpParserImpl<CharT>::ParseCharacterEscape(
+    InClassEscapeState in_class_escape_state,
+    bool* is_escaped_unicode_character) {
+  DCHECK_EQ('\\', current());
+  DCHECK(has_next());
+
+  Advance();
+
+  const base::uc32 c = current();
+  switch (c) {
+    // CharacterEscape ::
+    //   ControlEscape :: one of
+    //     f n r t v
+    case 'f':
+      Advance();
+      return '\f';
+    case 'n':
+      Advance();
+      return '\n';
+    case 'r':
+      Advance();
+      return '\r';
+    case 't':
+      Advance();
+      return '\t';
+    case 'v':
+      Advance();
+      return '\v';
+    // CharacterEscape ::
+    //   c ControlLetter
+    case 'c': {
+      base::uc32 controlLetter = Next();
+      base::uc32 letter = controlLetter & ~('A' ^ 'a');
+      if (letter >= 'A' && letter <= 'Z') {
+        Advance(2);
+        // Control letters mapped to ASCII control characters in the range
+        // 0x00-0x1F.
+        return controlLetter & 0x1F;
+      }
+      if (IsUnicodeMode()) {
+        // With /u and /v, invalid escapes are not treated as identity escapes.
+        ReportError(RegExpError::kInvalidUnicodeEscape);
+        return 0;
+      }
+      if (in_class_escape_state == InClassEscapeState::kInClass) {
+        // Inside a character class, we also accept digits and underscore as
+        // control characters, unless with /u or /v. See Annex B:
+        // ES#prod-annexB-ClassControlLetter
+        if ((controlLetter >= '0' && controlLetter <= '9') ||
+            controlLetter == '_') {
+          Advance(2);
+          return controlLetter & 0x1F;
+        }
+      }
+      // We match JSC in reading the backslash as a literal
+      // character instead of as starting an escape.
+      return '\\';
+    }
+    // CharacterEscape ::
+    //   0 [lookahead ∉ DecimalDigit]
+    //   [~UnicodeMode] LegacyOctalEscapeSequence
+    case '0':
+      // \0 is interpreted as NUL if not followed by another digit.
+      if (Next() < '0' || Next() > '9') {
+        Advance();
+        return 0;
+      }
+      V8_FALLTHROUGH;
+    case '1':
+    case '2':
+    case '3':
+    case '4':
+    case '5':
+    case '6':
+    case '7':
+      // For compatibility, we interpret a decimal escape that isn't
+      // a back reference (and therefore either \0 or not valid according
+      // to the specification) as a 1..3 digit octal character code.
+      // ES#prod-annexB-LegacyOctalEscapeSequence
+      if (IsUnicodeMode()) {
+        // With /u or /v, decimal escape is not interpreted as octal character
+        // code.
+        ReportError(RegExpError::kInvalidClassEscape);
+        return 0;
+      }
+      return ParseOctalLiteral();
+    // CharacterEscape ::
+    //   HexEscapeSequence
+    case 'x': {
+      Advance();
+      base::uc32 value;
+      if (ParseHexEscape(2, &value)) return value;
+      if (IsUnicodeMode()) {
+        // With /u or /v, invalid escapes are not treated as identity escapes.
+        ReportError(RegExpError::kInvalidEscape);
+        return 0;
+      }
+      // If \x is not followed by a two-digit hexadecimal, treat it
+      // as an identity escape.
+      return 'x';
+    }
+    // CharacterEscape ::
+    //   RegExpUnicodeEscapeSequence [?UnicodeMode]
+    case 'u': {
+      Advance();
+      base::uc32 value;
+      if (ParseUnicodeEscape(&value)) {
+        *is_escaped_unicode_character = true;
+        return value;
+      }
+      if (IsUnicodeMode()) {
+        // With /u or /v, invalid escapes are not treated as identity escapes.
+        ReportError(RegExpError::kInvalidUnicodeEscape);
+        return 0;
+      }
+      // If \u is not followed by a two-digit hexadecimal, treat it
+      // as an identity escape.
+      return 'u';
+    }
+    default:
+      break;
+  }
+
+  // CharacterEscape ::
+  //   IdentityEscape[?UnicodeMode, ?N]
+  //
+  // * With /u, no identity escapes except for syntax characters are
+  //   allowed.
+  // * With /v, no identity escapes except for syntax characters and
+  //   ClassSetReservedPunctuators (if within a class) are allowed.
+  // * Without /u or /v:
+  //   * '\c' is not an IdentityEscape.
+  //   * '\k' is not an IdentityEscape when named captures exist.
+  //   * Otherwise, all identity escapes are allowed.
+  if (unicode_sets() && in_class_escape_state == InClassEscapeState::kInClass) {
+    if (IsClassSetReservedPunctuator(c)) {
+      Advance();
+      return c;
+    }
+  }
+  if (IsUnicodeMode()) {
+    if (!IsSyntaxCharacterOrSlash(c)) {
+      ReportError(RegExpError::kInvalidEscape);
+      return 0;
+    }
+    Advance();
+    return c;
+  }
+  DCHECK(!IsUnicodeMode());
+  if (c == 'c') {
+    ReportError(RegExpError::kInvalidEscape);
+    return 0;
+  }
+  Advance();
+  // Note: It's important to Advance before the HasNamedCaptures call s.t. we
+  // don't start scanning in the middle of an escape.
+  if (c == 'k' && HasNamedCaptures(in_class_escape_state)) {
+    ReportError(RegExpError::kInvalidEscape);
+    return 0;
+  }
+  return c;
+}
+
+// TODO(v8:11935): Change permalink once proposal is in stage 4.
+// https://arai-a.github.io/ecma262-compare/snapshot.html?pr=2418#prod-ClassRanges
+template <class CharT>
+RegExpTree* RegExpParserImpl<CharT>::ParseClassRanges(
+    ZoneList<CharacterRange>* ranges, bool add_unicode_case_equivalents) {
+  base::uc32 char_1, char_2;
+  bool is_class_1, is_class_2;
+  while (has_more() && current() != ']') {
+    ParseClassEscape(ranges, zone(), add_unicode_case_equivalents, &char_1,
+                     &is_class_1 CHECK_FAILED);
+    // ClassAtom
+    if (current() == '-') {
+      Advance();
+      if (!has_more()) {
+        // If we reach the end we break out of the loop and let the
+        // following code report an error.
+        break;
+      } else if (current() == ']') {
+        if (!is_class_1) ranges->Add(CharacterRange::Singleton(char_1), zone());
+        ranges->Add(CharacterRange::Singleton('-'), zone());
+        break;
+      }
+      ParseClassEscape(ranges, zone(), add_unicode_case_equivalents, &char_2,
+                       &is_class_2 CHECK_FAILED);
+      if (is_class_1 || is_class_2) {
+        // Either end is an escaped character class. Treat the '-' verbatim.
+        if (IsUnicodeMode()) {
+          // ES2015 21.2.2.15.1 step 1.
+          return ReportError(RegExpError::kInvalidCharacterClass);
+        }
+        if (!is_class_1) ranges->Add(CharacterRange::Singleton(char_1), zone());
+        ranges->Add(CharacterRange::Singleton('-'), zone());
+        if (!is_class_2) ranges->Add(CharacterRange::Singleton(char_2), zone());
+        continue;
+      }
+      // ES2015 21.2.2.15.1 step 6.
+      if (char_1 > char_2) {
+        return ReportError(RegExpError::kOutOfOrderCharacterClass);
+      }
+      ranges->Add(CharacterRange::Range(char_1, char_2), zone());
+    } else {
+      if (!is_class_1) ranges->Add(CharacterRange::Singleton(char_1), zone());
+    }
+  }
+  return nullptr;
+}
+
+// https://tc39.es/ecma262/#prod-ClassEscape
+template <class CharT>
+void RegExpParserImpl<CharT>::ParseClassEscape(
+    ZoneList<CharacterRange>* ranges, Zone* zone,
+    bool add_unicode_case_equivalents, base::uc32* char_out,
+    bool* is_class_escape) {
+  *is_class_escape = false;
+
+  if (current() != '\\') {
+    // Not a ClassEscape.
+    *char_out = current();
+    Advance();
+    return;
+  }
+
+  const base::uc32 next = Next();
+  switch (next) {
+    case 'b':
+      *char_out = '\b';
+      Advance(2);
+      return;
+    case '-':
+      if (IsUnicodeMode()) {
+        *char_out = next;
+        Advance(2);
+        return;
+      }
+      break;
+    case kEndMarker:
+      ReportError(RegExpError::kEscapeAtEndOfPattern);
+      return;
+    default:
+      break;
+  }
+
+  static constexpr InClassEscapeState kInClassEscape =
+      InClassEscapeState::kInClass;
+  *is_class_escape =
+      TryParseCharacterClassEscape(next, kInClassEscape, ranges, nullptr, zone,
+                                   add_unicode_case_equivalents);
+  if (*is_class_escape) return;
+
+  bool dummy = false;  // Unused.
+  *char_out = ParseCharacterEscape(kInClassEscape, &dummy);
+}
+
+// https://tc39.es/ecma262/#prod-CharacterClassEscape
+template <class CharT>
+bool RegExpParserImpl<CharT>::TryParseCharacterClassEscape(
+    base::uc32 next, InClassEscapeState in_class_escape_state,
+    ZoneList<CharacterRange>* ranges, CharacterClassStrings* strings,
+    Zone* zone, bool add_unicode_case_equivalents) {
+  DCHECK_EQ(current(), '\\');
+  DCHECK_EQ(Next(), next);
+
+  switch (next) {
+    case 'd':
+    case 'D':
+    case 's':
+    case 'S':
+    case 'w':
+    case 'W':
+      CharacterRange::AddClassEscape(static_cast<StandardCharacterSet>(next),
+                                     ranges, add_unicode_case_equivalents,
+                                     zone);
+      Advance(2);
+      return true;
+    case 'p':
+    case 'P': {
+      if (!IsUnicodeMode()) return false;
+      bool negate = next == 'P';
+      Advance(2);
+      ZoneVector<char> name_1(zone);
+      ZoneVector<char> name_2(zone);
+      if (!ParsePropertyClassName(&name_1, &name_2) ||
+          !AddPropertyClassRange(ranges, strings, negate, name_1, name_2)) {
+        ReportError(in_class_escape_state == InClassEscapeState::kInClass
+                        ? RegExpError::kInvalidClassPropertyName
+                        : RegExpError::kInvalidPropertyName);
+      }
+      return true;
+    }
+    default:
+      return false;
+  }
+}
+
+namespace {
+
+// Add |string| to |ranges| if length of |string| == 1, otherwise add |string|
+// to |strings|.
+void AddClassString(ZoneList<base::uc32>* normalized_string,
+                    RegExpTree* regexp_string, ZoneList<CharacterRange>* ranges,
+                    CharacterClassStrings* strings, Zone* zone) {
+  if (normalized_string->length() == 1) {
+    ranges->Add(CharacterRange::Singleton(normalized_string->at(0)), zone);
+  } else {
+    strings->emplace(normalized_string->ToVector(), regexp_string);
+  }
+}
+
+}  // namespace
+
+// TODO(v8:11935): Change permalink once proposal is in stage 4.
+// https://arai-a.github.io/ecma262-compare/snapshot.html?pr=2418#prod-ClassStringDisjunction
+template <class CharT>
+RegExpTree* RegExpParserImpl<CharT>::ParseClassStringDisjunction(
+    ZoneList<CharacterRange>* ranges, CharacterClassStrings* strings) {
+  DCHECK(unicode_sets());
+  DCHECK_EQ(current(), '\\');
+  DCHECK_EQ(Next(), 'q');
+  Advance(2);
+  if (current() != '{') {
+    // Identity escape of 'q' is not allowed in unicode mode.
+    return ReportError(RegExpError::kInvalidEscape);
+  }
+  Advance();
+
+  ZoneList<base::uc32>* string =
+      zone()->template New<ZoneList<base::uc32>>(4, zone());
+  RegExpTextBuilder::SmallRegExpTreeVector string_storage(
+      ZoneAllocator<RegExpTree*>{zone()});
+  RegExpTextBuilder string_builder(zone(), &string_storage, flags());
+
+  while (has_more() && current() != '}') {
+    if (current() == '|') {
+      AddClassString(string, string_builder.ToRegExp(), ranges, strings,
+                     zone());
+      string = zone()->template New<ZoneList<base::uc32>>(4, zone());
+      string_storage.clear();
+      Advance();
+    } else {
+      base::uc32 c = ParseClassSetCharacter(CHECK_FAILED);
+      if (ignore_case()) {
+#ifdef V8_INTL_SUPPORT
+        c = u_foldCase(c, U_FOLD_CASE_DEFAULT);
+#else
+        c = AsciiAlphaToLower(c);
+#endif
+      }
+      string->Add(c, zone());
+      string_builder.AddUnicodeCharacter(c);
+    }
+  }
+
+  AddClassString(string, string_builder.ToRegExp(), ranges, strings, zone());
+  CharacterRange::Canonicalize(ranges);
+
+  // We don't need to handle missing closing '}' here.
+  // If the character class is correctly closed, ParseClassSetCharacter will
+  // report an error.
+  Advance();
+  return nullptr;
+}
+
+// TODO(v8:11935): Change permalink once proposal is in stage 4.
+// https://arai-a.github.io/ecma262-compare/snapshot.html?pr=2418#prod-ClassSetOperand
+// Tree returned based on type_out:
+//  * kNestedClass: RegExpClassSetExpression
+//  * For all other types: RegExpClassSetOperand
+template <class CharT>
+RegExpTree* RegExpParserImpl<CharT>::ParseClassSetOperand(
+    const RegExpBuilder* builder, ClassSetOperandType* type_out) {
+  ZoneList<CharacterRange>* ranges =
+      zone()->template New<ZoneList<CharacterRange>>(1, zone());
+  CharacterClassStrings* strings =
+      zone()->template New<CharacterClassStrings>(zone());
+  RegExpTree* tree =
+      ParseClassSetOperand(builder, type_out, ranges, strings CHECK_FAILED);
+  DCHECK_IMPLIES(*type_out != ClassSetOperandType::kNestedClass,
+                 tree == nullptr);
+  DCHECK_IMPLIES(*type_out == ClassSetOperandType::kClassSetCharacter,
+                 ranges->length() == 1);
+  DCHECK_IMPLIES(*type_out == ClassSetOperandType::kClassSetCharacter,
+                 strings->empty());
+  DCHECK_IMPLIES(*type_out == ClassSetOperandType::kNestedClass,
+                 ranges->is_empty());
+  DCHECK_IMPLIES(*type_out == ClassSetOperandType::kNestedClass,
+                 strings->empty());
+  DCHECK_IMPLIES(*type_out == ClassSetOperandType::kNestedClass,
+                 tree->IsClassSetExpression());
+  // ClassSetRange is only used within ClassSetUnion().
+  DCHECK_NE(*type_out, ClassSetOperandType::kClassSetRange);
+  // There are no restrictions for kCharacterClassEscape.
+  // CharacterClassEscape includes \p{}, which can contain ranges, strings or
+  // both and \P{}, which could contain nothing (i.e. \P{Any}).
+  if (tree == nullptr) {
+    tree = zone()->template New<RegExpClassSetOperand>(ranges, strings);
+  }
+  return tree;
+}
+
+// TODO(v8:11935): Change permalink once proposal is in stage 4.
+// https://arai-a.github.io/ecma262-compare/snapshot.html?pr=2418#prod-ClassSetOperand
+// Based on |type_out| either a tree is returned or ranges/strings modified.
+// If a tree is returned, ranges/strings are not modified.
+// If |type_out| is kNestedClass, a tree of type RegExpClassSetExpression is
+// returned. For all other types, ranges is modified and nullptr is returned.
+template <class CharT>
+RegExpTree* RegExpParserImpl<CharT>::ParseClassSetOperand(
+    const RegExpBuilder* builder, ClassSetOperandType* type_out,
+    ZoneList<CharacterRange>* ranges, CharacterClassStrings* strings) {
+  DCHECK(unicode_sets());
+  base::uc32 c = current();
+  if (c == '\\') {
+    const base::uc32 next = Next();
+    if (next == 'q') {
+      *type_out = ClassSetOperandType::kClassStringDisjunction;
+      ParseClassStringDisjunction(ranges, strings CHECK_FAILED);
+      return nullptr;
+    }
+    static constexpr InClassEscapeState kInClassEscape =
+        InClassEscapeState::kInClass;
+    const bool add_unicode_case_equivalents = ignore_case();
+    if (TryParseCharacterClassEscape(next, kInClassEscape, ranges, strings,
+                                     zone(), add_unicode_case_equivalents)) {
+      *type_out = ClassSetOperandType::kCharacterClassEscape;
+      return nullptr;
+    }
+  }
+
+  if (c == '[') {
+    *type_out = ClassSetOperandType::kNestedClass;
+    return ParseCharacterClass(builder);
+  }
+
+  *type_out = ClassSetOperandType::kClassSetCharacter;
+  c = ParseClassSetCharacter(CHECK_FAILED);
+  ranges->Add(CharacterRange::Singleton(c), zone());
+  return nullptr;
+}
+
+template <class CharT>
+base::uc32 RegExpParserImpl<CharT>::ParseClassSetCharacter() {
+  DCHECK(unicode_sets());
+  const base::uc32 c = current();
+  if (c == '\\') {
+    const base::uc32 next = Next();
+    switch (next) {
+      case 'b':
+        Advance(2);
+        return '\b';
+      case kEndMarker:
+        ReportError(RegExpError::kEscapeAtEndOfPattern);
+        return 0;
+    }
+    static constexpr InClassEscapeState kInClassEscape =
+        InClassEscapeState::kInClass;
+
+    bool dummy = false;  // Unused.
+    return ParseCharacterEscape(kInClassEscape, &dummy);
+  }
+  if (IsClassSetSyntaxCharacter(c)) {
+    ReportError(RegExpError::kInvalidCharacterInClass);
+    return 0;
+  }
+  if (IsClassSetReservedDoublePunctuator(c)) {
+    ReportError(RegExpError::kInvalidClassSetOperation);
+    return 0;
+  }
+  Advance();
+  return c;
+}
+
+namespace {
+
+bool MayContainStrings(ClassSetOperandType type, RegExpTree* operand) {
+  switch (type) {
+    case ClassSetOperandType::kClassSetCharacter:
+    case ClassSetOperandType::kClassSetRange:
+      return false;
+    case ClassSetOperandType::kCharacterClassEscape:
+    case ClassSetOperandType::kClassStringDisjunction:
+      return operand->AsClassSetOperand()->has_strings();
+    case ClassSetOperandType::kNestedClass:
+      if (operand->IsClassRanges()) return false;
+      return operand->AsClassSetExpression()->may_contain_strings();
+  }
+}
+
+}  // namespace
+
+// TODO(v8:11935): Change permalink once proposal is in stage 4.
+// https://arai-a.github.io/ecma262-compare/snapshot.html?pr=2418#prod-ClassUnion
+template <class CharT>
+RegExpTree* RegExpParserImpl<CharT>::ParseClassUnion(
+    const RegExpBuilder* builder, bool is_negated, RegExpTree* first_operand,
+    ClassSetOperandType first_operand_type, ZoneList<CharacterRange>* ranges,
+    CharacterClassStrings* strings) {
+  DCHECK(unicode_sets());
+  ZoneList<RegExpTree*>* operands =
+      zone()->template New<ZoneList<RegExpTree*>>(2, zone());
+  bool may_contain_strings = false;
+  // Add the lhs to operands if necessary.
+  // Either the lhs values were added to |ranges|/|strings| (in which case
+  // |first_operand| is nullptr), or the lhs was evaluated to a tree and passed
+  // as |first_operand| (in which case |ranges| and |strings| are empty).
+  if (first_operand != nullptr) {
+    may_contain_strings = MayContainStrings(first_operand_type, first_operand);
+    operands->Add(first_operand, zone());
+  }
+  ClassSetOperandType last_type = first_operand_type;
+  const bool needs_case_folding = ignore_case();
+  while (has_more() && current() != ']') {
+    if (current() == '-') {
+      // Mix of ClassSetRange and ClassSubtraction is not allowed.
+      if (Next() == '-') {
+        return ReportError(RegExpError::kInvalidClassSetOperation);
+      }
+      Advance();
+      if (!has_more()) {
+        // If we reach the end we break out of the loop and let the
+        // following code report an error.
+        break;
+      }
+      // If the lhs and rhs around '-' are both ClassSetCharacters, they
+      // represent a character range.
+      // In case one of them is not a ClassSetCharacter, it is a syntax error,
+      // as '-' can not be used unescaped within a class with /v.
+      // TODO(v8:11935): Change permalink once proposal is in stage 4.
+      // See
+      // https://arai-a.github.io/ecma262-compare/snapshot.html?pr=2418#prod-ClassSetRange
+      if (last_type != ClassSetOperandType::kClassSetCharacter) {
+        return ReportError(RegExpError::kInvalidCharacterClass);
+      }
+      ParseClassSetOperand(builder, &last_type, ranges, strings CHECK_FAILED);
+      if (last_type != ClassSetOperandType::kClassSetCharacter) {
+        return ReportError(RegExpError::kInvalidCharacterClass);
+      }
+      // Remove the last two singleton characters added to ranges, and combine
+      // them into a range.
+      auto rhs_ranges = ranges->RemoveLast();
+      auto lhs_ranges = ranges->RemoveLast();
+      DCHECK(lhs_ranges.IsSingleton());
+      DCHECK(rhs_ranges.IsSingleton());
+      base::uc32 from = lhs_ranges.from();
+      base::uc32 to = rhs_ranges.from();
+      if (from > to) {
+        return ReportError(RegExpError::kOutOfOrderCharacterClass);
+      }
+      ranges->Add(CharacterRange::Range(from, to), zone());
+      last_type = ClassSetOperandType::kClassSetRange;
+    } else {
+      DCHECK_NE(current(), '-');
+      RegExpTree* operand = ParseClassSetOperand(builder, &last_type, ranges,
+                                                 strings CHECK_FAILED);
+      if (operand != nullptr) {
+        may_contain_strings |= MayContainStrings(last_type, operand);
+        // Add the range we started building as operand and reset the current
+        // range.
+        if (!ranges->is_empty() || !strings->empty()) {
+          if (needs_case_folding) {
+            CharacterRange::Canonicalize(ranges);
+            CharacterRange::AddUnicodeCaseEquivalents(ranges, zone());
+          }
+          may_contain_strings |= !strings->empty();
+          operands->Add(
+              zone()->template New<RegExpClassSetOperand>(ranges, strings),
+              zone());
+          ranges = zone()->template New<ZoneList<CharacterRange>>(2, zone());
+          strings = zone()->template New<CharacterClassStrings>(zone());
+        }
+        operands->Add(operand, zone());
+      }
+    }
+  }
+
+  if (!has_more()) {
+    return ReportError(RegExpError::kUnterminatedCharacterClass);
+  }
+
+  // Add the range we started building as operand.
+  if (!ranges->is_empty() || !strings->empty()) {
+    if (needs_case_folding) {
+      CharacterRange::Canonicalize(ranges);
+      CharacterRange::AddUnicodeCaseEquivalents(ranges, zone());
+    }
+    may_contain_strings |= !strings->empty();
+    operands->Add(zone()->template New<RegExpClassSetOperand>(ranges, strings),
+                  zone());
+  }
+
+  DCHECK_EQ(current(), ']');
+  Advance();
+
+  if (is_negated && may_contain_strings) {
+    return ReportError(RegExpError::kNegatedCharacterClassWithStrings);
+  }
+
+  if (operands->is_empty()) {
+    // Return empty expression if no operands were added (e.g. [\P{Any}]
+    // produces an empty range).
+    DCHECK(ranges->is_empty());
+    DCHECK(strings->empty());
+    return RegExpClassSetExpression::Empty(zone(), is_negated);
+  }
+
+  return zone()->template New<RegExpClassSetExpression>(
+      RegExpClassSetExpression::OperationType::kUnion, is_negated,
+      may_contain_strings, operands);
+}
+
+// TODO(v8:11935): Change permalink once proposal is in stage 4.
+// https://arai-a.github.io/ecma262-compare/snapshot.html?pr=2418#prod-ClassIntersection
+template <class CharT>
+RegExpTree* RegExpParserImpl<CharT>::ParseClassIntersection(
+    const RegExpBuilder* builder, bool is_negated, RegExpTree* first_operand,
+    ClassSetOperandType first_operand_type) {
+  DCHECK(unicode_sets());
+  DCHECK(current() == '&' && Next() == '&');
+  bool may_contain_strings =
+      MayContainStrings(first_operand_type, first_operand);
+  ZoneList<RegExpTree*>* operands =
+      zone()->template New<ZoneList<RegExpTree*>>(2, zone());
+  operands->Add(first_operand, zone());
+  while (has_more() && current() != ']') {
+    if (current() != '&' || Next() != '&') {
+      return ReportError(RegExpError::kInvalidClassSetOperation);
+    }
+    Advance(2);
+    // [lookahead ≠ &]
+    if (current() == '&') {
+      return ReportError(RegExpError::kInvalidCharacterInClass);
+    }
+
+    ClassSetOperandType operand_type;
+    RegExpTree* operand =
+        ParseClassSetOperand(builder, &operand_type CHECK_FAILED);
+    may_contain_strings &= MayContainStrings(operand_type, operand);
+    operands->Add(operand, zone());
+  }
+  if (!has_more()) {
+    return ReportError(RegExpError::kUnterminatedCharacterClass);
+  }
+  if (is_negated && may_contain_strings) {
+    return ReportError(RegExpError::kNegatedCharacterClassWithStrings);
+  }
+  DCHECK_EQ(current(), ']');
+  Advance();
+  return zone()->template New<RegExpClassSetExpression>(
+      RegExpClassSetExpression::OperationType::kIntersection, is_negated,
+      may_contain_strings, operands);
+}
+
+// TODO(v8:11935): Change permalink once proposal is in stage 4.
+// https://arai-a.github.io/ecma262-compare/snapshot.html?pr=2418#prod-ClassSubtraction
+template <class CharT>
+RegExpTree* RegExpParserImpl<CharT>::ParseClassSubtraction(
+    const RegExpBuilder* builder, bool is_negated, RegExpTree* first_operand,
+    ClassSetOperandType first_operand_type) {
+  DCHECK(unicode_sets());
+  DCHECK(current() == '-' && Next() == '-');
+  const bool may_contain_strings =
+      MayContainStrings(first_operand_type, first_operand);
+  if (is_negated && may_contain_strings) {
+    return ReportError(RegExpError::kNegatedCharacterClassWithStrings);
+  }
+  ZoneList<RegExpTree*>* operands =
+      zone()->template New<ZoneList<RegExpTree*>>(2, zone());
+  operands->Add(first_operand, zone());
+  while (has_more() && current() != ']') {
+    if (current() != '-' || Next() != '-') {
+      return ReportError(RegExpError::kInvalidClassSetOperation);
+    }
+    Advance(2);
+    ClassSetOperandType dummy;  // unused
+    RegExpTree* operand = ParseClassSetOperand(builder, &dummy CHECK_FAILED);
+    operands->Add(operand, zone());
+  }
+  if (!has_more()) {
+    return ReportError(RegExpError::kUnterminatedCharacterClass);
+  }
+  DCHECK_EQ(current(), ']');
+  Advance();
+  return zone()->template New<RegExpClassSetExpression>(
+      RegExpClassSetExpression::OperationType::kSubtraction, is_negated,
+      may_contain_strings, operands);
+}
+
+// https://tc39.es/ecma262/#prod-CharacterClass
+template <class CharT>
+RegExpTree* RegExpParserImpl<CharT>::ParseCharacterClass(
+    const RegExpBuilder* builder) {
+  DCHECK_EQ(current(), '[');
+  Advance();
+  bool is_negated = false;
+  if (current() == '^') {
+    is_negated = true;
+    Advance();
+  }
+  ZoneList<CharacterRange>* ranges =
+      zone()->template New<ZoneList<CharacterRange>>(2, zone());
+  if (current() == ']') {
+    Advance();
+    if (unicode_sets()) {
+      return RegExpClassSetExpression::Empty(zone(), is_negated);
+    } else {
+      RegExpClassRanges::ClassRangesFlags class_ranges_flags;
+      if (is_negated) class_ranges_flags = RegExpClassRanges::NEGATED;
+      return zone()->template New<RegExpClassRanges>(zone(), ranges,
+                                                     class_ranges_flags);
+    }
+  }
+
+  if (!unicode_sets()) {
+    bool add_unicode_case_equivalents = IsUnicodeMode() && ignore_case();
+    ParseClassRanges(ranges, add_unicode_case_equivalents CHECK_FAILED);
+    if (!has_more()) {
+      return ReportError(RegExpError::kUnterminatedCharacterClass);
+    }
+    DCHECK_EQ(current(), ']');
+    Advance();
+    RegExpClassRanges::ClassRangesFlags character_class_flags;
+    if (is_negated) character_class_flags = RegExpClassRanges::NEGATED;
+    return zone()->template New<RegExpClassRanges>(zone(), ranges,
+                                                   character_class_flags);
+  } else {
+    ClassSetOperandType operand_type;
+    CharacterClassStrings* strings =
+        zone()->template New<CharacterClassStrings>(zone());
+    RegExpTree* operand = ParseClassSetOperand(builder, &operand_type, ranges,
+                                               strings CHECK_FAILED);
+    switch (current()) {
+      case '-':
+        if (Next() == '-') {
+          if (operand == nullptr) {
+            operand =
+                zone()->template New<RegExpClassSetOperand>(ranges, strings);
+          }
+          return ParseClassSubtraction(builder, is_negated, operand,
+                                       operand_type);
+        }
+        // ClassSetRange is handled in ParseClassUnion().
+        break;
+      case '&':
+        if (Next() == '&') {
+          if (operand == nullptr) {
+            operand =
+                zone()->template New<RegExpClassSetOperand>(ranges, strings);
+          }
+          return ParseClassIntersection(builder, is_negated, operand,
+                                        operand_type);
+        }
+    }
+    return ParseClassUnion(builder, is_negated, operand, operand_type, ranges,
+                           strings);
+  }
+}
+
+#undef CHECK_FAILED
+
+template <class CharT>
+bool RegExpParserImpl<CharT>::Parse(RegExpCompileData* result) {
+  DCHECK_NOT_NULL(result);
+  RegExpTree* tree = ParsePattern();
+
+  if (failed()) {
+    DCHECK_NULL(tree);
+    DCHECK_NE(error_, RegExpError::kNone);
+    result->error = error_;
+    result->error_pos = error_pos_;
+    return false;
+  }
+
+  DCHECK_NOT_NULL(tree);
+  DCHECK_EQ(error_, RegExpError::kNone);
+  if (v8_flags.trace_regexp_parser) {
+    StdoutStream os;
+    tree->Print(os, zone());
+    os << "\n";
+  }
+
+  result->tree = tree;
+  const int capture_count = captures_started();
+  result->simple = tree->IsAtom() && simple() && capture_count == 0;
+  result->contains_anchor = contains_anchor();
+  result->capture_count = capture_count;
+  result->named_captures = GetNamedCaptures();
+  return true;
+}
+
+void RegExpBuilder::FlushText() { text_builder().FlushText(); }
+
+void RegExpBuilder::AddCharacter(base::uc16 c) {
+  pending_empty_ = false;
+  text_builder().AddCharacter(c);
+}
+
+void RegExpBuilder::AddUnicodeCharacter(base::uc32 c) {
+  pending_empty_ = false;
+  text_builder().AddUnicodeCharacter(c);
+}
+
+void RegExpBuilder::AddEscapedUnicodeCharacter(base::uc32 character) {
+  pending_empty_ = false;
+  text_builder().AddEscapedUnicodeCharacter(character);
+}
+
+void RegExpBuilder::AddEmpty() {
+  text_builder().FlushPendingSurrogate();
+  pending_empty_ = true;
+}
+
+void RegExpBuilder::AddClassRanges(RegExpClassRanges* cc) {
+  pending_empty_ = false;
+  text_builder().AddClassRanges(cc);
+}
+
+void RegExpBuilder::AddAtom(RegExpTree* term) {
+  if (term->IsEmpty()) {
+    AddEmpty();
+    return;
+  }
+  pending_empty_ = false;
+  if (term->IsTextElement()) {
+    text_builder().AddAtom(term);
+  } else {
+    FlushText();
+    terms_.emplace_back(term);
+  }
+}
+
+void RegExpBuilder::AddTerm(RegExpTree* term) {
+  DCHECK(!term->IsEmpty());
+  pending_empty_ = false;
+  if (term->IsTextElement()) {
+    text_builder().AddTerm(term);
+  } else {
+    FlushText();
+    terms_.emplace_back(term);
+  }
+}
+
+void RegExpBuilder::AddAssertion(RegExpTree* assert) {
+  FlushText();
+  pending_empty_ = false;
+  terms_.emplace_back(assert);
+}
+
+void RegExpBuilder::NewAlternative() { FlushTerms(); }
+
+void RegExpBuilder::FlushTerms() {
+  FlushText();
+  size_t num_terms = terms_.size();
+  RegExpTree* alternative;
+  if (num_terms == 0) {
+    alternative = zone()->New<RegExpEmpty>();
+  } else if (num_terms == 1) {
+    alternative = terms_.back();
+  } else {
+    alternative =
+        zone()->New<RegExpAlternative>(zone()->New<ZoneList<RegExpTree*>>(
+            base::VectorOf(terms_.begin(), terms_.size()), zone()));
+  }
+  alternatives_.emplace_back(alternative);
+  terms_.clear();
+}
+
+RegExpTree* RegExpBuilder::ToRegExp() {
+  FlushTerms();
+  size_t num_alternatives = alternatives_.size();
+  if (num_alternatives == 0) return zone()->New<RegExpEmpty>();
+  if (num_alternatives == 1) return alternatives_.back();
+  return zone()->New<RegExpDisjunction>(zone()->New<ZoneList<RegExpTree*>>(
+      base::VectorOf(alternatives_.begin(), alternatives_.size()), zone()));
+}
+
+bool RegExpBuilder::AddQuantifierToAtom(
+    int min, int max, RegExpQuantifier::QuantifierType quantifier_type) {
+  if (pending_empty_) {
+    pending_empty_ = false;
+    return true;
+  }
+  RegExpTree* atom = text_builder().PopLastAtom();
+  if (atom != nullptr) {
+    FlushText();
+  } else if (terms_.size() > 0) {
+    atom = terms_.back();
+    terms_.pop_back();
+    if (atom->IsLookaround()) {
+      // With /u or /v, lookarounds are not quantifiable.
+      if (IsUnicodeMode()) return false;
+      // Lookbehinds are not quantifiable.
+      if (atom->AsLookaround()->type() == RegExpLookaround::LOOKBEHIND) {
+        return false;
+      }
+    }
+    if (atom->max_match() == 0) {
+      // Guaranteed to only match an empty string.
+      if (min == 0) {
+        return true;
+      }
+      terms_.emplace_back(atom);
+      return true;
+    }
+  } else {
+    // Only call immediately after adding an atom or character!
+    UNREACHABLE();
+  }
+  terms_.emplace_back(
+      zone()->New<RegExpQuantifier>(min, max, quantifier_type, atom));
+  return true;
+}
+
+template class RegExpParserImpl<uint8_t>;
+template class RegExpParserImpl<base::uc16>;
+
+}  // namespace
+
+// static
+bool RegExpParser::ParseRegExpFromHeapString(Isolate* isolate, Zone* zone,
+                                             Handle<String> input,
+                                             RegExpFlags flags,
+                                             RegExpCompileData* result) {
+  DisallowGarbageCollection no_gc;
+  uintptr_t stack_limit = isolate->stack_guard()->real_climit();
+  String::FlatContent content = input->GetFlatContent(no_gc);
+  if (content.IsOneByte()) {
+    base::Vector<const uint8_t> v = content.ToOneByteVector();
+    return RegExpParserImpl<uint8_t>{v.begin(),   v.length(), flags,
+                                     stack_limit, zone,       no_gc}
+        .Parse(result);
+  } else {
+    base::Vector<const base::uc16> v = content.ToUC16Vector();
+    return RegExpParserImpl<base::uc16>{v.begin(),   v.length(), flags,
+                                        stack_limit, zone,       no_gc}
+        .Parse(result);
+  }
+}
+
+// static
+template <class CharT>
+bool RegExpParser::VerifyRegExpSyntax(Zone* zone, uintptr_t stack_limit,
+                                      const CharT* input, int input_length,
+                                      RegExpFlags flags,
+                                      RegExpCompileData* result,
+                                      const DisallowGarbageCollection& no_gc) {
+  return RegExpParserImpl<CharT>{input,       input_length, flags,
+                                 stack_limit, zone,         no_gc}
+      .Parse(result);
+}
+
+template bool RegExpParser::VerifyRegExpSyntax<uint8_t>(
+    Zone*, uintptr_t, const uint8_t*, int, RegExpFlags, RegExpCompileData*,
+    const DisallowGarbageCollection&);
+template bool RegExpParser::VerifyRegExpSyntax<base::uc16>(
+    Zone*, uintptr_t, const base::uc16*, int, RegExpFlags, RegExpCompileData*,
+    const DisallowGarbageCollection&);
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/irregexp/imported/regexp-parser.h b/js/src/irregexp/imported/regexp-parser.h
new file mode 100644
index 0000000000..1e45d97532
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-parser.h
@@ -0,0 +1,34 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_PARSER_H_
+#define V8_REGEXP_REGEXP_PARSER_H_
+
+#include "irregexp/RegExpShim.h"
+
+namespace v8 {
+namespace internal {
+
+class String;
+class Zone;
+
+struct RegExpCompileData;
+
+class V8_EXPORT_PRIVATE RegExpParser : public AllStatic {
+ public:
+  static bool ParseRegExpFromHeapString(Isolate* isolate, Zone* zone,
+                                        Handle<String> input, RegExpFlags flags,
+                                        RegExpCompileData* result);
+
+  template <class CharT>
+  static bool VerifyRegExpSyntax(Zone* zone, uintptr_t stack_limit,
+                                 const CharT* input, int input_length,
+                                 RegExpFlags flags, RegExpCompileData* result,
+                                 const DisallowGarbageCollection& no_gc);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_PARSER_H_
diff --git a/js/src/irregexp/imported/regexp-stack.cc b/js/src/irregexp/imported/regexp-stack.cc
new file mode 100644
index 0000000000..ad0aedc67a
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-stack.cc
@@ -0,0 +1,96 @@
+// Copyright 2009 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "irregexp/imported/regexp-stack.h"
+
+
+namespace v8 {
+namespace internal {
+
+RegExpStackScope::RegExpStackScope(Isolate* isolate)
+    : regexp_stack_(isolate->regexp_stack()),
+      old_sp_top_delta_(regexp_stack_->sp_top_delta()) {
+  DCHECK(regexp_stack_->IsValid());
+}
+
+RegExpStackScope::~RegExpStackScope() {
+  CHECK_EQ(old_sp_top_delta_, regexp_stack_->sp_top_delta());
+  regexp_stack_->ResetIfEmpty();
+}
+
+RegExpStack::RegExpStack() : thread_local_(this) {}
+
+RegExpStack::~RegExpStack() { thread_local_.FreeAndInvalidate(); }
+
+char* RegExpStack::ArchiveStack(char* to) {
+  if (!thread_local_.owns_memory_) {
+    // Force dynamic stacks prior to archiving. Any growth will do. A dynamic
+    // stack is needed because stack archival & restoration rely on `memory_`
+    // pointing at a fixed-location backing store, whereas the static stack is
+    // tied to a RegExpStack instance.
+    EnsureCapacity(thread_local_.memory_size_ + 1);
+    DCHECK(thread_local_.owns_memory_);
+  }
+
+  MemCopy(reinterpret_cast<void*>(to), &thread_local_, kThreadLocalSize);
+  thread_local_ = ThreadLocal(this);
+  return to + kThreadLocalSize;
+}
+
+
+char* RegExpStack::RestoreStack(char* from) {
+  MemCopy(&thread_local_, reinterpret_cast<void*>(from), kThreadLocalSize);
+  return from + kThreadLocalSize;
+}
+
+void RegExpStack::ThreadLocal::ResetToStaticStack(RegExpStack* regexp_stack) {
+  if (owns_memory_) DeleteArray(memory_);
+
+  memory_ = regexp_stack->static_stack_;
+  memory_top_ = regexp_stack->static_stack_ + kStaticStackSize;
+  memory_size_ = kStaticStackSize;
+  stack_pointer_ = memory_top_;
+  limit_ = reinterpret_cast<Address>(regexp_stack->static_stack_) +
+           kStackLimitSlack * kSystemPointerSize;
+  owns_memory_ = false;
+}
+
+void RegExpStack::ThreadLocal::FreeAndInvalidate() {
+  if (owns_memory_) DeleteArray(memory_);
+
+  // This stack may not be used after being freed. Just reset to invalid values
+  // to ensure we don't accidentally use old memory areas.
+  memory_ = nullptr;
+  memory_top_ = nullptr;
+  memory_size_ = 0;
+  stack_pointer_ = nullptr;
+  limit_ = kMemoryTop;
+}
+
+Address RegExpStack::EnsureCapacity(size_t size) {
+  if (size > kMaximumStackSize) return kNullAddress;
+  if (thread_local_.memory_size_ < size) {
+    if (size < kMinimumDynamicStackSize) size = kMinimumDynamicStackSize;
+    byte* new_memory = NewArray<byte>(size);
+    if (thread_local_.memory_size_ > 0) {
+      // Copy original memory into top of new memory.
+      MemCopy(new_memory + size - thread_local_.memory_size_,
+              thread_local_.memory_, thread_local_.memory_size_);
+      if (thread_local_.owns_memory_) DeleteArray(thread_local_.memory_);
+    }
+    ptrdiff_t delta = sp_top_delta();
+    thread_local_.memory_ = new_memory;
+    thread_local_.memory_top_ = new_memory + size;
+    thread_local_.memory_size_ = size;
+    thread_local_.stack_pointer_ = thread_local_.memory_top_ + delta;
+    thread_local_.limit_ = reinterpret_cast<Address>(new_memory) +
+                           kStackLimitSlack * kSystemPointerSize;
+    thread_local_.owns_memory_ = true;
+  }
+  return reinterpret_cast<Address>(thread_local_.memory_top_);
+}
+
+
+}  // namespace internal
+}  // namespace v8
diff --git a/js/src/irregexp/imported/regexp-stack.h b/js/src/irregexp/imported/regexp-stack.h
new file mode 100644
index 0000000000..f03898bb00
--- /dev/null
+++ b/js/src/irregexp/imported/regexp-stack.h
@@ -0,0 +1,159 @@
+// Copyright 2009 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_STACK_H_
+#define V8_REGEXP_REGEXP_STACK_H_
+
+#include "irregexp/RegExpShim.h"
+
+namespace v8 {
+namespace internal {
+
+class RegExpStack;
+
+// Maintains a per-v8thread stack area that can be used by irregexp
+// implementation for its backtracking stack.
+class V8_NODISCARD RegExpStackScope final {
+ public:
+  // Create and delete an instance to control the life-time of a growing stack.
+
+  // Initializes the stack memory area if necessary.
+  explicit RegExpStackScope(Isolate* isolate);
+  ~RegExpStackScope();  // Releases the stack if it has grown.
+  RegExpStackScope(const RegExpStackScope&) = delete;
+  RegExpStackScope& operator=(const RegExpStackScope&) = delete;
+
+  RegExpStack* stack() const { return regexp_stack_; }
+
+ private:
+  RegExpStack* const regexp_stack_;
+  const ptrdiff_t old_sp_top_delta_;
+};
+
+class RegExpStack final {
+ public:
+  RegExpStack();
+  ~RegExpStack();
+  RegExpStack(const RegExpStack&) = delete;
+  RegExpStack& operator=(const RegExpStack&) = delete;
+
+  // Number of allocated locations on the stack below the limit. No sequence of
+  // pushes must be longer than this without doing a stack-limit check.
+  static constexpr int kStackLimitSlack = 32;
+
+  Address memory_top() const {
+    DCHECK_NE(0, thread_local_.memory_size_);
+    DCHECK_EQ(thread_local_.memory_top_,
+              thread_local_.memory_ + thread_local_.memory_size_);
+    return reinterpret_cast<Address>(thread_local_.memory_top_);
+  }
+
+  Address stack_pointer() const {
+    return reinterpret_cast<Address>(thread_local_.stack_pointer_);
+  }
+
+  size_t memory_size() const { return thread_local_.memory_size_; }
+
+  // If the stack pointer gets below the limit, we should react and
+  // either grow the stack or report an out-of-stack exception.
+  // There is only a limited number of locations below the stack limit,
+  // so users of the stack should check the stack limit during any
+  // sequence of pushes longer that this.
+  Address* limit_address_address() { return &thread_local_.limit_; }
+
+  // Ensures that there is a memory area with at least the specified size.
+  // If passing zero, the default/minimum size buffer is allocated.
+  Address EnsureCapacity(size_t size);
+
+  // Thread local archiving.
+  static constexpr int ArchiveSpacePerThread() {
+    return static_cast<int>(kThreadLocalSize);
+  }
+  char* ArchiveStack(char* to);
+  char* RestoreStack(char* from);
+  void FreeThreadResources() { thread_local_.ResetToStaticStack(this); }
+
+  // Maximal size of allocated stack area.
+  static constexpr size_t kMaximumStackSize = 64 * MB;
+
+ private:
+  // Artificial limit used when the thread-local state has been destroyed.
+  static const Address kMemoryTop =
+      static_cast<Address>(static_cast<uintptr_t>(-1));
+
+  // Minimal size of dynamically-allocated stack area.
+  static constexpr size_t kMinimumDynamicStackSize = 1 * KB;
+
+  // In addition to dynamically-allocated, variable-sized stacks, we also have
+  // a statically allocated and sized area that is used whenever no dynamic
+  // stack is allocated. This guarantees that a stack is always available and
+  // we can skip availability-checks later on.
+  // It's double the slack size to ensure that we have a bit of breathing room
+  // before NativeRegExpMacroAssembler::GrowStack must be called.
+  static constexpr size_t kStaticStackSize =
+      2 * kStackLimitSlack * kSystemPointerSize;
+  byte static_stack_[kStaticStackSize] = {0};
+
+  static_assert(kStaticStackSize <= kMaximumStackSize);
+
+  // Structure holding the allocated memory, size and limit. Thread switching
+  // archives and restores this struct.
+  struct ThreadLocal {
+    explicit ThreadLocal(RegExpStack* regexp_stack) {
+      ResetToStaticStack(regexp_stack);
+    }
+
+    // If memory_size_ > 0 then
+    //  - memory_, memory_top_, stack_pointer_ must be non-nullptr
+    //  - memory_top_ = memory_ + memory_size_
+    //  - memory_ <= stack_pointer_ <= memory_top_
+    byte* memory_ = nullptr;
+    byte* memory_top_ = nullptr;
+    size_t memory_size_ = 0;
+    byte* stack_pointer_ = nullptr;
+    Address limit_ = kNullAddress;
+    bool owns_memory_ = false;  // Whether memory_ is owned and must be freed.
+
+    void ResetToStaticStack(RegExpStack* regexp_stack);
+    void ResetToStaticStackIfEmpty(RegExpStack* regexp_stack) {
+      if (stack_pointer_ == memory_top_) ResetToStaticStack(regexp_stack);
+    }
+    void FreeAndInvalidate();
+  };
+  static constexpr size_t kThreadLocalSize = sizeof(ThreadLocal);
+
+  Address memory_top_address_address() {
+    return reinterpret_cast<Address>(&thread_local_.memory_top_);
+  }
+
+  Address stack_pointer_address() {
+    return reinterpret_cast<Address>(&thread_local_.stack_pointer_);
+  }
+
+  // A position-independent representation of the stack pointer.
+  ptrdiff_t sp_top_delta() const {
+    ptrdiff_t result =
+        reinterpret_cast<intptr_t>(thread_local_.stack_pointer_) -
+        reinterpret_cast<intptr_t>(thread_local_.memory_top_);
+    DCHECK_LE(result, 0);
+    return result;
+  }
+
+  // Resets the buffer if it has grown beyond the default/minimum size and is
+  // empty.
+  void ResetIfEmpty() { thread_local_.ResetToStaticStackIfEmpty(this); }
+
+  // Whether the ThreadLocal storage has been invalidated.
+  bool IsValid() const { return thread_local_.memory_ != nullptr; }
+
+  ThreadLocal thread_local_;
+
+  friend class ExternalReference;
+  friend class RegExpStackScope;
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_STACK_H_
diff --git a/js/src/irregexp/imported/regexp.h b/js/src/irregexp/imported/regexp.h
new file mode 100644
index 0000000000..50269a4b71
--- /dev/null
+++ b/js/src/irregexp/imported/regexp.h
@@ -0,0 +1,236 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_REGEXP_H_
+#define V8_REGEXP_REGEXP_H_
+
+#include "irregexp/imported/regexp-error.h"
+#include "irregexp/RegExpShim.h"
+
+namespace v8 {
+namespace internal {
+
+class JSRegExp;
+class RegExpCapture;
+class RegExpMatchInfo;
+class RegExpNode;
+class RegExpTree;
+
+enum class RegExpCompilationTarget : int { kBytecode, kNative };
+
+// TODO(jgruber): Do not expose in regexp.h.
+// TODO(jgruber): Consider splitting between ParseData and CompileData.
+struct RegExpCompileData {
+  // The parsed AST as produced by the RegExpParser.
+  RegExpTree* tree = nullptr;
+
+  // The compiled Node graph as produced by RegExpTree::ToNode methods.
+  RegExpNode* node = nullptr;
+
+  // Either the generated code as produced by the compiler or a trampoline
+  // to the interpreter.
+  Handle<Object> code;
+
+  // True, iff the pattern is a 'simple' atom with zero captures. In other
+  // words, the pattern consists of a string with no metacharacters and special
+  // regexp features, and can be implemented as a standard string search.
+  bool simple = true;
+
+  // True, iff the pattern is anchored at the start of the string with '^'.
+  bool contains_anchor = false;
+
+  // Only set if the pattern contains named captures.
+  // Note: the lifetime equals that of the parse/compile zone.
+  ZoneVector<RegExpCapture*>* named_captures = nullptr;
+
+  // The error message. Only used if an error occurred during parsing or
+  // compilation.
+  RegExpError error = RegExpError::kNone;
+
+  // The position at which the error was detected. Only used if an
+  // error occurred.
+  int error_pos = 0;
+
+  // The number of capture groups, without the global capture \0.
+  int capture_count = 0;
+
+  // The number of registers used by the generated code.
+  int register_count = 0;
+
+  // The compilation target (bytecode or native code).
+  RegExpCompilationTarget compilation_target;
+};
+
+class RegExp final : public AllStatic {
+ public:
+  // Whether the irregexp engine generates interpreter bytecode.
+  static bool CanGenerateBytecode();
+
+  // Verify that the given flags combination is valid.
+  V8_EXPORT_PRIVATE static bool VerifyFlags(RegExpFlags flags);
+
+  // Verify the given pattern, i.e. check that parsing succeeds. If
+  // verification fails, `regexp_error_out` is set.
+  template <class CharT>
+  static bool VerifySyntax(Zone* zone, uintptr_t stack_limit,
+                           const CharT* input, int input_length,
+                           RegExpFlags flags, RegExpError* regexp_error_out,
+                           const DisallowGarbageCollection& no_gc);
+
+  // Parses the RegExp pattern and prepares the JSRegExp object with
+  // generic data and choice of implementation - as well as what
+  // the implementation wants to store in the data field.
+  // Returns false if compilation fails.
+  V8_WARN_UNUSED_RESULT static MaybeHandle<Object> Compile(
+      Isolate* isolate, Handle<JSRegExp> re, Handle<String> pattern,
+      RegExpFlags flags, uint32_t backtrack_limit);
+
+  // Ensures that a regexp is fully compiled and ready to be executed on a
+  // subject string.  Returns true on success. Return false on failure, and
+  // then an exception will be pending.
+  V8_WARN_UNUSED_RESULT static bool EnsureFullyCompiled(Isolate* isolate,
+                                                        Handle<JSRegExp> re,
+                                                        Handle<String> subject);
+
+  enum CallOrigin : int {
+    kFromRuntime = 0,
+    kFromJs = 1,
+  };
+
+  enum class ExecQuirks {
+    kNone,
+    // Used to work around an issue in the RegExpPrototypeSplit fast path,
+    // which diverges from the spec by not creating a sticky copy of the RegExp
+    // instance and calling `exec` in a loop. If called in this context, we
+    // must not update the last_match_info on a successful match at the subject
+    // string end. See crbug.com/1075514 for more information.
+    kTreatMatchAtEndAsFailure,
+  };
+
+  // See ECMA-262 section 15.10.6.2.
+  // This function calls the garbage collector if necessary.
+  V8_EXPORT_PRIVATE V8_WARN_UNUSED_RESULT static MaybeHandle<Object> Exec(
+      Isolate* isolate, Handle<JSRegExp> regexp, Handle<String> subject,
+      int index, Handle<RegExpMatchInfo> last_match_info,
+      ExecQuirks exec_quirks = ExecQuirks::kNone);
+
+  V8_EXPORT_PRIVATE V8_WARN_UNUSED_RESULT static MaybeHandle<Object>
+  ExperimentalOneshotExec(Isolate* isolate, Handle<JSRegExp> regexp,
+                          Handle<String> subject, int index,
+                          Handle<RegExpMatchInfo> last_match_info,
+                          ExecQuirks exec_quirks = ExecQuirks::kNone);
+
+  // Integral return values used throughout regexp code layers.
+  static constexpr int kInternalRegExpFailure = 0;
+  static constexpr int kInternalRegExpSuccess = 1;
+  static constexpr int kInternalRegExpException = -1;
+  static constexpr int kInternalRegExpRetry = -2;
+  static constexpr int kInternalRegExpFallbackToExperimental = -3;
+  static constexpr int kInternalRegExpSmallestResult = -3;
+
+  enum IrregexpResult : int32_t {
+    RE_FAILURE = kInternalRegExpFailure,
+    RE_SUCCESS = kInternalRegExpSuccess,
+    RE_EXCEPTION = kInternalRegExpException,
+    RE_RETRY = kInternalRegExpRetry,
+    RE_FALLBACK_TO_EXPERIMENTAL = kInternalRegExpFallbackToExperimental,
+  };
+
+  // Set last match info.  If match is nullptr, then setting captures is
+  // omitted.
+  static Handle<RegExpMatchInfo> SetLastMatchInfo(
+      Isolate* isolate, Handle<RegExpMatchInfo> last_match_info,
+      Handle<String> subject, int capture_count, int32_t* match);
+
+  V8_EXPORT_PRIVATE static bool CompileForTesting(
+      Isolate* isolate, Zone* zone, RegExpCompileData* input, RegExpFlags flags,
+      Handle<String> pattern, Handle<String> sample_subject, bool is_one_byte);
+
+  V8_EXPORT_PRIVATE static void DotPrintForTesting(const char* label,
+                                                   RegExpNode* node);
+
+  static const int kRegExpTooLargeToOptimize = 20 * KB;
+
+  V8_WARN_UNUSED_RESULT
+  static MaybeHandle<Object> ThrowRegExpException(Isolate* isolate,
+                                                  Handle<JSRegExp> re,
+                                                  RegExpFlags flags,
+                                                  Handle<String> pattern,
+                                                  RegExpError error);
+  static void ThrowRegExpException(Isolate* isolate, Handle<JSRegExp> re,
+                                   RegExpError error_text);
+
+  static bool IsUnmodifiedRegExp(Isolate* isolate, Handle<JSRegExp> regexp);
+
+  static Handle<FixedArray> CreateCaptureNameMap(
+      Isolate* isolate, ZoneVector<RegExpCapture*>* named_captures);
+};
+
+// Uses a special global mode of irregexp-generated code to perform a global
+// search and return multiple results at once. As such, this is essentially an
+// iterator over multiple results (retrieved batch-wise in advance).
+class RegExpGlobalCache final {
+ public:
+  RegExpGlobalCache(Handle<JSRegExp> regexp, Handle<String> subject,
+                    Isolate* isolate);
+
+  ~RegExpGlobalCache();
+
+  // Fetch the next entry in the cache for global regexp match results.
+  // This does not set the last match info.  Upon failure, nullptr is
+  // returned. The cause can be checked with Result().  The previous result is
+  // still in available in memory when a failure happens.
+  int32_t* FetchNext();
+
+  int32_t* LastSuccessfulMatch();
+
+  bool HasException() { return num_matches_ < 0; }
+
+ private:
+  int AdvanceZeroLength(int last_index);
+
+  int num_matches_;
+  int max_matches_;
+  int current_match_index_;
+  int registers_per_match_;
+  // Pointer to the last set of captures.
+  int32_t* register_array_;
+  int register_array_size_;
+  Handle<JSRegExp> regexp_;
+  Handle<String> subject_;
+  Isolate* isolate_;
+};
+
+// Caches results for specific regexp queries on the isolate. At the time of
+// writing, this is used during global calls to RegExp.prototype.exec and
+// @@split.
+class RegExpResultsCache final : public AllStatic {
+ public:
+  enum ResultsCacheType { REGEXP_MULTIPLE_INDICES, STRING_SPLIT_SUBSTRINGS };
+
+  // Attempt to retrieve a cached result.  On failure, 0 is returned as a Smi.
+  // On success, the returned result is guaranteed to be a COW-array.
+  static Object Lookup(Heap* heap, String key_string, Object key_pattern,
+                       FixedArray* last_match_out, ResultsCacheType type);
+  // Attempt to add value_array to the cache specified by type.  On success,
+  // value_array is turned into a COW-array.
+  static void Enter(Isolate* isolate, Handle<String> key_string,
+                    Handle<Object> key_pattern, Handle<FixedArray> value_array,
+                    Handle<FixedArray> last_match_cache, ResultsCacheType type);
+  static void Clear(FixedArray cache);
+
+  static constexpr int kRegExpResultsCacheSize = 0x100;
+
+ private:
+  static constexpr int kStringOffset = 0;
+  static constexpr int kPatternOffset = 1;
+  static constexpr int kArrayOffset = 2;
+  static constexpr int kLastMatchOffset = 3;
+  static constexpr int kArrayEntriesPerCacheEntry = 4;
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_REGEXP_REGEXP_H_
diff --git a/js/src/irregexp/imported/special-case.cc b/js/src/irregexp/imported/special-case.cc
new file mode 100644
index 0000000000..f5a9928b3a
--- /dev/null
+++ b/js/src/irregexp/imported/special-case.cc
@@ -0,0 +1,111 @@
+// Copyright 2020 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that
+// can be found in the LICENSE file.
+
+// Automatically generated by regexp/gen-regexp-special-case.cc
+
+// The following functions are used to build UnicodeSets
+// for special cases where the case-folding algorithm used by
+// UnicodeSet::closeOver(USET_CASE_INSENSITIVE) does not match
+// the algorithm defined in ECMAScript 2020 21.2.2.8.2 (Runtime
+// Semantics: Canonicalize) step 3.
+
+#ifdef V8_INTL_SUPPORT
+#include "irregexp/imported/special-case.h"
+
+#include "unicode/uniset.h"
+namespace v8 {
+namespace internal {
+
+icu::UnicodeSet BuildIgnoreSet() {
+  icu::UnicodeSet set;
+  set.add(0xdf);
+  set.add(0x17f);
+  set.add(0x390);
+  set.add(0x3b0);
+  set.add(0x3f4);
+  set.add(0x1e9e);
+  set.add(0x1f80, 0x1faf);
+  set.add(0x1fb3);
+  set.add(0x1fbc);
+  set.add(0x1fc3);
+  set.add(0x1fcc);
+  set.add(0x1fd3);
+  set.add(0x1fe3);
+  set.add(0x1ff3);
+  set.add(0x1ffc);
+  set.add(0x2126);
+  set.add(0x212a, 0x212b);
+  set.add(0xfb05, 0xfb06);
+  set.freeze();
+  return set;
+}
+
+struct IgnoreSetData {
+  IgnoreSetData() : set(BuildIgnoreSet()) {}
+  const icu::UnicodeSet set;
+};
+
+//static
+const icu::UnicodeSet& RegExpCaseFolding::IgnoreSet() {
+  static base::LazyInstance<IgnoreSetData>::type set =
+      LAZY_INSTANCE_INITIALIZER;
+  return set.Pointer()->set;
+}
+
+icu::UnicodeSet BuildSpecialAddSet() {
+  icu::UnicodeSet set;
+  set.add(0x4b);
+  set.add(0x53);
+  set.add(0x6b);
+  set.add(0x73);
+  set.add(0xc5);
+  set.add(0xe5);
+  set.add(0x398);
+  set.add(0x3a9);
+  set.add(0x3b8);
+  set.add(0x3c9);
+  set.add(0x3d1);
+  set.freeze();
+  return set;
+}
+
+struct SpecialAddSetData {
+  SpecialAddSetData() : set(BuildSpecialAddSet()) {}
+  const icu::UnicodeSet set;
+};
+
+//static
+const icu::UnicodeSet& RegExpCaseFolding::SpecialAddSet() {
+  static base::LazyInstance<SpecialAddSetData>::type set =
+      LAZY_INSTANCE_INITIALIZER;
+  return set.Pointer()->set;
+}
+
+icu::UnicodeSet BuildUnicodeNonSimpleCloseOverSet() {
+  icu::UnicodeSet set;
+  set.add(0x390);
+  set.add(0x3b0);
+  set.add(0x1fd3);
+  set.add(0x1fe3);
+  set.add(0xfb05, 0xfb06);
+  set.freeze();
+  return set;
+}
+
+struct UnicodeNonSimpleCloseOverSetData {
+  UnicodeNonSimpleCloseOverSetData() : set(BuildUnicodeNonSimpleCloseOverSet()) {}
+  const icu::UnicodeSet set;
+};
+
+//static
+const icu::UnicodeSet& RegExpCaseFolding::UnicodeNonSimpleCloseOverSet() {
+  static base::LazyInstance<UnicodeNonSimpleCloseOverSetData>::type set =
+      LAZY_INSTANCE_INITIALIZER;
+  return set.Pointer()->set;
+}
+
+
+}  // namespace internal
+}  // namespace v8
+#endif  // V8_INTL_SUPPORT
diff --git a/js/src/irregexp/imported/special-case.h b/js/src/irregexp/imported/special-case.h
new file mode 100644
index 0000000000..ea511af5a4
--- /dev/null
+++ b/js/src/irregexp/imported/special-case.h
@@ -0,0 +1,127 @@
+// Copyright 2019 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_REGEXP_SPECIAL_CASE_H_
+#define V8_REGEXP_SPECIAL_CASE_H_
+
+#ifdef V8_INTL_SUPPORT
+#include "irregexp/RegExpShim.h"
+
+#include "unicode/uchar.h"
+#include "unicode/uniset.h"
+#include "unicode/unistr.h"
+
+namespace v8 {
+namespace internal {
+
+// Sets of Unicode characters that need special handling under "i" mode
+
+// For non-unicode ignoreCase matches (aka "i", not "iu"), ECMA 262
+// defines slightly different case-folding rules than Unicode. An
+// input character should match a pattern character if the result of
+// the Canonicalize algorithm is the same for both characters.
+//
+// Roughly speaking, for "i" regexps, Canonicalize(c) is the same as
+// c.toUpperCase(), unless a) c.toUpperCase() is a multi-character
+// string, or b) c is non-ASCII, and c.toUpperCase() is ASCII. See
+// https://tc39.es/ecma262/#sec-runtime-semantics-canonicalize-ch for
+// the precise definition.
+//
+// While compiling such regular expressions, we need to compute the
+// set of characters that should match a given input character. (See
+// GetCaseIndependentLetters and CharacterRange::AddCaseEquivalents.)
+// For almost all characters, this can be efficiently computed using
+// UnicodeSet::closeOver(USET_CASE_INSENSITIVE). These sets represent
+// the remaining special cases.
+//
+// For a character c, the rules are as follows:
+//
+// 1. If c is in neither IgnoreSet nor SpecialAddSet, then calling
+//    UnicodeSet::closeOver(USET_CASE_INSENSITIVE) on a UnicodeSet
+//    containing c will produce the set of characters that should
+//    match /c/i (or /[c]/i), and only those characters.
+//
+// 2. If c is in IgnoreSet, then the only character it should match is
+//    itself. However, closeOver will add additional incorrect
+//    matches. For example, consider SHARP S: 'ß' (U+00DF) and 'ẞ'
+//    (U+1E9E). Although closeOver('ß') = "ßẞ", uppercase('ß') is
+//    "SS".  Step 3.e therefore requires that 'ß' canonicalizes to
+//    itself, and should not match 'ẞ'. In these cases, we can skip
+//    the closeOver entirely, because it will never add an equivalent
+//    character.
+//
+// 3. If c is in SpecialAddSet, then it should match at least one
+//    character other than itself. However, closeOver will add at
+//    least one additional incorrect match. For example, consider the
+//    letter 'k'. Closing over 'k' gives "kKK" (lowercase k, uppercase
+//    K, U+212A KELVIN SIGN). However, because of step 3.g, KELVIN
+//    SIGN should not match either of the other two characters. As a
+//    result, "k" and "K" are in SpecialAddSet (and KELVIN SIGN is in
+//    IgnoreSet). To find the correct matches for characters in
+//    SpecialAddSet, we closeOver the original character, but filter
+//    out the results that do not have the same canonical value.
+//
+// The contents of these sets are calculated at build time by
+// src/regexp/gen-regexp-special-case.cc, which generates
+// gen/src/regexp/special-case.cc. This is done by iterating over the
+// result of closeOver for each BMP character, and finding sets for
+// which at least one character has a different canonical value than
+// another character. Characters that match no other characters in
+// their equivalence class are added to IgnoreSet. Characters that
+// match at least one other character are added to SpecialAddSet.
+//
+// For unicode ignoreCase ("iu" and "iv"),
+// UnicodeSet::closeOver(USET_CASE_INSENSITIVE) adds all characters that are in
+// the same equivalence class. This includes characaters that are in the same
+// equivalence class using full case folding. According to the spec, only
+// simple case folding shall be considered. We therefore create
+// UnicodeNonSimpleCloseOverSet containing all characters for which
+// UnicodeSet::closeOver adds characters that are not simple case folds. This
+// set should be used similar to IgnoreSet described above.
+
+class RegExpCaseFolding final : public AllStatic {
+ public:
+  static const icu::UnicodeSet& IgnoreSet();
+  static const icu::UnicodeSet& SpecialAddSet();
+  static const icu::UnicodeSet& UnicodeNonSimpleCloseOverSet();
+
+  // This implements ECMAScript 2020 21.2.2.8.2 (Runtime Semantics:
+  // Canonicalize) step 3, which is used to determine whether
+  // characters match when ignoreCase is true and unicode is false.
+  static UChar32 Canonicalize(UChar32 ch) {
+    // a. Assert: ch is a UTF-16 code unit.
+    CHECK_LE(ch, 0xffff);
+
+    // b. Let s be the String value consisting of the single code unit ch.
+    icu::UnicodeString s(ch);
+
+    // c. Let u be the same result produced as if by performing the algorithm
+    // for String.prototype.toUpperCase using s as the this value.
+    // d. Assert: Type(u) is String.
+    icu::UnicodeString& u = s.toUpper();
+
+    // e. If u does not consist of a single code unit, return ch.
+    if (u.length() != 1) {
+      return ch;
+    }
+
+    // f. Let cu be u's single code unit element.
+    UChar32 cu = u.char32At(0);
+
+    // g. If the value of ch >= 128 and the value of cu < 128, return ch.
+    if (ch >= 128 && cu < 128) {
+      return ch;
+    }
+
+    // h. Return cu.
+    return cu;
+  }
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_INTL_SUPPORT
+
+#endif  // V8_REGEXP_SPECIAL_CASE_H_