1 files changed, 864 insertions, 0 deletions
diff --git a/js/src/frontend/ParserAtom.cpp b/js/src/frontend/ParserAtom.cpp
new file mode 100644
index 0000000000..e310549671
--- /dev/null
+++ b/js/src/frontend/ParserAtom.cpp
@@ -0,0 +1,864 @@
+/* -*- 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 "frontend/ParserAtom.h"
+
+#include <memory>  // std::uninitialized_fill_n
+#include <type_traits>
+
+#include "jsnum.h"
+
+#include "frontend/CompilationInfo.h"
+#include "frontend/NameCollections.h"
+#include "frontend/StencilXdr.h"  // CanCopyDataToDisk
+#include "vm/JSContext.h"
+#include "vm/Printer.h"
+#include "vm/Runtime.h"
+#include "vm/StringType.h"
+
+using namespace js;
+using namespace js::frontend;
+
+namespace js {
+
+// Iterates over a sequence of ParserAtoms and yield their sequence of
+// characters in order. This simulates concatenation of atoms. The underlying
+// ParserAtoms may be a mix of Latin1 and char16_t atoms.
+template <>
+class InflatedChar16Sequence<const ParserAtom*> {
+ private:
+  const ParserAtom** cur_ = nullptr;
+  const ParserAtom** lim_ = nullptr;
+  size_t index_ = 0;
+
+  void settle() {
+    // Check if we are out-of-bounds for current ParserAtom.
+    auto outOfBounds = [this]() { return index_ >= (*cur_)->length(); };
+
+    while (hasMore() && outOfBounds()) {
+      // Advance to start of next ParserAtom.
+      cur_++;
+      index_ = 0;
+    }
+  }
+
+ public:
+  explicit InflatedChar16Sequence(
+      const mozilla::Range<const ParserAtom*>& atoms)
+      : cur_(atoms.begin().get()), lim_(atoms.end().get()) {
+    settle();
+  }
+
+  bool hasMore() { return cur_ < lim_; }
+
+  char16_t next() {
+    MOZ_ASSERT(hasMore());
+    char16_t ch = (*cur_)->hasLatin1Chars() ? (*cur_)->latin1Chars()[index_]
+                                            : (*cur_)->twoByteChars()[index_];
+    index_++;
+    settle();
+    return ch;
+  }
+
+  HashNumber computeHash() const {
+    auto copy = *this;
+    HashNumber hash = 0;
+
+    while (copy.hasMore()) {
+      hash = mozilla::AddToHash(hash, copy.next());
+    }
+    return hash;
+  }
+};
+
+}  // namespace js
+
+namespace js {
+
+template <>
+class InflatedChar16Sequence<LittleEndianChars> {
+ private:
+  LittleEndianChars chars_;
+  size_t idx_;
+  size_t len_;
+
+ public:
+  InflatedChar16Sequence(LittleEndianChars chars, size_t length)
+      : chars_(chars), idx_(0), len_(length) {}
+
+  bool hasMore() { return idx_ < len_; }
+
+  char16_t next() {
+    MOZ_ASSERT(hasMore());
+    return chars_[idx_++];
+  }
+
+  HashNumber computeHash() const {
+    auto copy = *this;
+    HashNumber hash = 0;
+    while (copy.hasMore()) {
+      hash = mozilla::AddToHash(hash, copy.next());
+    }
+    return hash;
+  }
+};
+
+}  // namespace js
+
+namespace js {
+namespace frontend {
+
+JSAtom* GetWellKnownAtom(JSContext* cx, WellKnownAtomId atomId) {
+#define ASSERT_OFFSET_(idpart, id, text)       \
+  static_assert(offsetof(JSAtomState, id) ==   \
+                int32_t(WellKnownAtomId::id) * \
+                    sizeof(js::ImmutablePropertyNamePtr));
+  FOR_EACH_COMMON_PROPERTYNAME(ASSERT_OFFSET_);
+#undef ASSERT_OFFSET_
+
+#define ASSERT_OFFSET_(name, clasp)              \
+  static_assert(offsetof(JSAtomState, name) ==   \
+                int32_t(WellKnownAtomId::name) * \
+                    sizeof(js::ImmutablePropertyNamePtr));
+  JS_FOR_EACH_PROTOTYPE(ASSERT_OFFSET_);
+#undef ASSERT_OFFSET_
+
+  static_assert(int32_t(WellKnownAtomId::abort) == 0,
+                "Unexpected order of WellKnownAtom");
+
+  return (&cx->names().abort)[int32_t(atomId)];
+}
+
+#ifdef DEBUG
+void TaggedParserAtomIndex::validateRaw() {
+  if (isParserAtomIndex()) {
+    MOZ_ASSERT(toParserAtomIndex().index < IndexLimit);
+  } else if (isWellKnownAtomId()) {
+    MOZ_ASSERT(uint32_t(toWellKnownAtomId()) <
+               uint32_t(WellKnownAtomId::Limit));
+  } else if (isStaticParserString1()) {
+    MOZ_ASSERT(size_t(toStaticParserString1()) <
+               WellKnownParserAtoms_ROM::ASCII_STATIC_LIMIT);
+  } else if (isStaticParserString2()) {
+    MOZ_ASSERT(size_t(toStaticParserString2()) <
+               WellKnownParserAtoms_ROM::NUM_LENGTH2_ENTRIES);
+  } else {
+    MOZ_ASSERT(isNull());
+  }
+}
+#endif
+
+template <typename CharT, typename SeqCharT>
+/* static */ ParserAtomEntry* ParserAtomEntry::allocate(
+    JSContext* cx, LifoAlloc& alloc, InflatedChar16Sequence<SeqCharT> seq,
+    uint32_t length, HashNumber hash) {
+  constexpr size_t HeaderSize = sizeof(ParserAtomEntry);
+  void* raw = alloc.alloc(HeaderSize + (sizeof(CharT) * length));
+  if (!raw) {
+    js::ReportOutOfMemory(cx);
+    return nullptr;
+  }
+
+  constexpr bool hasTwoByteChars = (sizeof(CharT) == 2);
+  static_assert(sizeof(CharT) == 1 || sizeof(CharT) == 2,
+                "CharT should be 1 or 2 byte type");
+  ParserAtomEntry* entry =
+      new (raw) ParserAtomEntry(length, hash, hasTwoByteChars);
+  CharT* entryBuf = entry->chars<CharT>();
+  drainChar16Seq(entryBuf, seq, length);
+  return entry;
+}
+
+/* static */ ParserAtomEntry* ParserAtomEntry::allocateRaw(
+    JSContext* cx, LifoAlloc& alloc, const uint8_t* srcRaw,
+    size_t totalLength) {
+  void* raw = alloc.alloc(totalLength);
+  if (!raw) {
+    js::ReportOutOfMemory(cx);
+    return nullptr;
+  }
+
+  memcpy(raw, srcRaw, totalLength);
+
+  return static_cast<ParserAtomEntry*>(raw);
+}
+
+bool ParserAtomEntry::equalsJSAtom(JSAtom* other) const {
+  // Compare hashes and lengths first.
+  if (hash_ != other->hash() || length_ != other->length()) {
+    return false;
+  }
+
+  JS::AutoCheckCannotGC nogc;
+
+  if (hasTwoByteChars()) {
+    // Compare heap-allocated 16-bit chars to atom.
+    return other->hasLatin1Chars()
+               ? EqualChars(twoByteChars(), other->latin1Chars(nogc), length_)
+               : EqualChars(twoByteChars(), other->twoByteChars(nogc), length_);
+  }
+
+  MOZ_ASSERT(hasLatin1Chars());
+  return other->hasLatin1Chars()
+             ? EqualChars(latin1Chars(), other->latin1Chars(nogc), length_)
+             : EqualChars(latin1Chars(), other->twoByteChars(nogc), length_);
+}
+
+template <typename CharT>
+UniqueChars ToPrintableStringImpl(JSContext* cx, mozilla::Range<CharT> str) {
+  Sprinter sprinter(cx);
+  if (!sprinter.init()) {
+    return nullptr;
+  }
+  if (!QuoteString<QuoteTarget::String>(&sprinter, str)) {
+    return nullptr;
+  }
+  return sprinter.release();
+}
+
+UniqueChars ParserAtomToPrintableString(JSContext* cx, const ParserAtom* atom) {
+  size_t length = atom->length();
+
+  return atom->hasLatin1Chars()
+             ? ToPrintableStringImpl(
+                   cx, mozilla::Range(atom->latin1Chars(), length))
+             : ToPrintableStringImpl(
+                   cx, mozilla::Range(atom->twoByteChars(), length));
+}
+
+bool ParserAtomEntry::isIndex(uint32_t* indexp) const {
+  size_t len = length();
+  if (len == 0 || len > UINT32_CHAR_BUFFER_LENGTH) {
+    return false;
+  }
+  if (hasLatin1Chars()) {
+    return mozilla::IsAsciiDigit(*latin1Chars()) &&
+           js::CheckStringIsIndex(latin1Chars(), len, indexp);
+  }
+  return mozilla::IsAsciiDigit(*twoByteChars()) &&
+         js::CheckStringIsIndex(twoByteChars(), len, indexp);
+}
+
+JSAtom* ParserAtomEntry::toJSAtom(JSContext* cx,
+                                  CompilationAtomCache& atomCache) const {
+  if (isParserAtomIndex()) {
+    JSAtom* atom = atomCache.getAtomAt(toParserAtomIndex());
+    if (atom) {
+      return atom;
+    }
+
+    return instantiate(cx, atomCache);
+  }
+
+  if (isWellKnownAtomId()) {
+    return GetWellKnownAtom(cx, toWellKnownAtomId());
+  }
+
+  if (isStaticParserString1()) {
+    char16_t ch = static_cast<char16_t>(toStaticParserString1());
+    return cx->staticStrings().getUnit(ch);
+  }
+
+  MOZ_ASSERT(isStaticParserString2());
+  size_t s = static_cast<size_t>(toStaticParserString2());
+  return cx->staticStrings().getLength2FromIndex(s);
+}
+
+JSAtom* ParserAtomEntry::toExistingJSAtom(
+    JSContext* cx, CompilationAtomCache& atomCache) const {
+  if (isParserAtomIndex()) {
+    JSAtom* atom = atomCache.getExistingAtomAt(toParserAtomIndex());
+    MOZ_ASSERT(atom);
+    return atom;
+  }
+
+  if (isWellKnownAtomId()) {
+    return GetWellKnownAtom(cx, toWellKnownAtomId());
+  }
+
+  if (isStaticParserString1()) {
+    char16_t ch = static_cast<char16_t>(toStaticParserString1());
+    return cx->staticStrings().getUnit(ch);
+  }
+
+  MOZ_ASSERT(isStaticParserString2());
+  size_t s = static_cast<size_t>(toStaticParserString2());
+  return cx->staticStrings().getLength2FromIndex(s);
+}
+
+JSAtom* ParserAtomEntry::instantiate(JSContext* cx,
+                                     CompilationAtomCache& atomCache) const {
+  JSAtom* atom;
+  if (hasLatin1Chars()) {
+    atom = AtomizeChars(cx, hash(), latin1Chars(), length());
+  } else {
+    atom = AtomizeChars(cx, hash(), twoByteChars(), length());
+  }
+  if (!atom) {
+    js::ReportOutOfMemory(cx);
+    return nullptr;
+  }
+  if (!atomCache.setAtomAt(cx, toParserAtomIndex(), atom)) {
+    return nullptr;
+  }
+
+  return atom;
+}
+
+bool ParserAtomEntry::toNumber(JSContext* cx, double* result) const {
+  return hasLatin1Chars() ? CharsToNumber(cx, latin1Chars(), length(), result)
+                          : CharsToNumber(cx, twoByteChars(), length(), result);
+}
+
+#if defined(DEBUG) || defined(JS_JITSPEW)
+void ParserAtomEntry::dump() const {
+  js::Fprinter out(stderr);
+  out.put("\"");
+  dumpCharsNoQuote(out);
+  out.put("\"\n");
+}
+
+void ParserAtomEntry::dumpCharsNoQuote(js::GenericPrinter& out) const {
+  if (hasLatin1Chars()) {
+    JSString::dumpCharsNoQuote<Latin1Char>(latin1Chars(), length(), out);
+  } else {
+    JSString::dumpCharsNoQuote<char16_t>(twoByteChars(), length(), out);
+  }
+}
+#endif
+
+ParserAtomsTable::ParserAtomsTable(JSRuntime* rt, LifoAlloc& alloc)
+    : wellKnownTable_(*rt->commonParserNames), alloc_(alloc) {}
+
+const ParserAtom* ParserAtomsTable::addEntry(JSContext* cx,
+                                             EntrySet::AddPtr& addPtr,
+                                             ParserAtomEntry* entry) {
+  MOZ_ASSERT(!addPtr);
+  ParserAtomIndex index = ParserAtomIndex(entries_.length());
+  if (size_t(index) >= TaggedParserAtomIndex::IndexLimit) {
+    ReportAllocationOverflow(cx);
+    return nullptr;
+  }
+  if (!entries_.append(entry)) {
+    js::ReportOutOfMemory(cx);
+    return nullptr;
+  }
+  entry->setParserAtomIndex(index);
+  if (!entrySet_.add(addPtr, entry)) {
+    js::ReportOutOfMemory(cx);
+    return nullptr;
+  }
+  return entry->asAtom();
+}
+
+template <typename AtomCharT, typename SeqCharT>
+const ParserAtom* ParserAtomsTable::internChar16Seq(
+    JSContext* cx, EntrySet::AddPtr& addPtr, HashNumber hash,
+    InflatedChar16Sequence<SeqCharT> seq, uint32_t length) {
+  MOZ_ASSERT(!addPtr);
+
+  ParserAtomEntry* entry =
+      ParserAtomEntry::allocate<AtomCharT>(cx, alloc_, seq, length, hash);
+  if (!entry) {
+    return nullptr;
+  }
+  return addEntry(cx, addPtr, entry);
+}
+
+static const uint16_t MAX_LATIN1_CHAR = 0xff;
+
+const ParserAtom* ParserAtomsTable::internAscii(JSContext* cx,
+                                                const char* asciiPtr,
+                                                uint32_t length) {
+  // ASCII strings are strict subsets of Latin1 strings.
+  const Latin1Char* latin1Ptr = reinterpret_cast<const Latin1Char*>(asciiPtr);
+  return internLatin1(cx, latin1Ptr, length);
+}
+
+const ParserAtom* ParserAtomsTable::internLatin1(JSContext* cx,
+                                                 const Latin1Char* latin1Ptr,
+                                                 uint32_t length) {
+  // Check for tiny strings which are abundant in minified code.
+  if (const ParserAtom* tiny = wellKnownTable_.lookupTiny(latin1Ptr, length)) {
+    return tiny;
+  }
+
+  // Check for well-known atom.
+  InflatedChar16Sequence<Latin1Char> seq(latin1Ptr, length);
+  SpecificParserAtomLookup<Latin1Char> lookup(seq);
+  if (const ParserAtom* wk = wellKnownTable_.lookupChar16Seq(lookup)) {
+    return wk;
+  }
+
+  // Check for existing atom.
+  auto addPtr = entrySet_.lookupForAdd(lookup);
+  if (addPtr) {
+    return (*addPtr)->asAtom();
+  }
+
+  return internChar16Seq<Latin1Char>(cx, addPtr, lookup.hash(), seq, length);
+}
+
+ParserAtomSpanBuilder::ParserAtomSpanBuilder(JSRuntime* rt,
+                                             ParserAtomSpan& entries)
+    : wellKnownTable_(*rt->commonParserNames), entries_(entries) {}
+
+bool ParserAtomSpanBuilder::allocate(JSContext* cx, LifoAlloc& alloc,
+                                     size_t count) {
+  if (count >= TaggedParserAtomIndex::IndexLimit) {
+    ReportAllocationOverflow(cx);
+    return false;
+  }
+
+  auto* p = alloc.newArrayUninitialized<ParserAtomEntry*>(count);
+  if (!p) {
+    js::ReportOutOfMemory(cx);
+    return false;
+  }
+  std::uninitialized_fill_n(p, count, nullptr);
+
+  entries_ = mozilla::Span(p, count);
+  return true;
+}
+
+const ParserAtom* ParserAtomsTable::internUtf8(JSContext* cx,
+                                               const mozilla::Utf8Unit* utf8Ptr,
+                                               uint32_t nbyte) {
+  // Check for tiny strings which are abundant in minified code.
+  // NOTE: The tiny atoms are all ASCII-only so we can directly look at the
+  //        UTF-8 data without worrying about surrogates.
+  if (const ParserAtom* tiny = wellKnownTable_.lookupTiny(
+          reinterpret_cast<const Latin1Char*>(utf8Ptr), nbyte)) {
+    return tiny;
+  }
+
+  // If source text is ASCII, then the length of the target char buffer
+  // is the same as the length of the UTF8 input.  Convert it to a Latin1
+  // encoded string on the heap.
+  JS::UTF8Chars utf8(utf8Ptr, nbyte);
+  JS::SmallestEncoding minEncoding = FindSmallestEncoding(utf8);
+  if (minEncoding == JS::SmallestEncoding::ASCII) {
+    // As ascii strings are a subset of Latin1 strings, and each encoding
+    // unit is the same size, we can reliably cast this `Utf8Unit*`
+    // to a `Latin1Char*`.
+    const Latin1Char* latin1Ptr = reinterpret_cast<const Latin1Char*>(utf8Ptr);
+    return internLatin1(cx, latin1Ptr, nbyte);
+  }
+
+  // Check for existing.
+  // NOTE: Well-known are all ASCII so have been handled above.
+  InflatedChar16Sequence<mozilla::Utf8Unit> seq(utf8Ptr, nbyte);
+  SpecificParserAtomLookup<mozilla::Utf8Unit> lookup(seq);
+  MOZ_ASSERT(wellKnownTable_.lookupChar16Seq(lookup) == nullptr);
+  EntrySet::AddPtr addPtr = entrySet_.lookupForAdd(lookup);
+  if (addPtr) {
+    return (*addPtr)->asAtom();
+  }
+
+  // Compute length in code-points.
+  uint32_t length = 0;
+  InflatedChar16Sequence<mozilla::Utf8Unit> seqCopy = seq;
+  while (seqCopy.hasMore()) {
+    mozilla::Unused << seqCopy.next();
+    length += 1;
+  }
+
+  // Otherwise, add new entry.
+  bool wide = (minEncoding == JS::SmallestEncoding::UTF16);
+  return wide
+             ? internChar16Seq<char16_t>(cx, addPtr, lookup.hash(), seq, length)
+             : internChar16Seq<Latin1Char>(cx, addPtr, lookup.hash(), seq,
+                                           length);
+}
+
+const ParserAtom* ParserAtomsTable::internChar16(JSContext* cx,
+                                                 const char16_t* char16Ptr,
+                                                 uint32_t length) {
+  // Check for tiny strings which are abundant in minified code.
+  if (const ParserAtom* tiny = wellKnownTable_.lookupTiny(char16Ptr, length)) {
+    return tiny;
+  }
+
+  // Check against well-known.
+  InflatedChar16Sequence<char16_t> seq(char16Ptr, length);
+  SpecificParserAtomLookup<char16_t> lookup(seq);
+  if (const ParserAtom* wk = wellKnownTable_.lookupChar16Seq(lookup)) {
+    return wk;
+  }
+
+  // Check for existing atom.
+  EntrySet::AddPtr addPtr = entrySet_.lookupForAdd(lookup);
+  if (addPtr) {
+    return (*addPtr)->asAtom();
+  }
+
+  // Compute the target encoding.
+  // NOTE: Length in code-points will be same, even if we deflate to Latin1.
+  bool wide = false;
+  InflatedChar16Sequence<char16_t> seqCopy = seq;
+  while (seqCopy.hasMore()) {
+    char16_t ch = seqCopy.next();
+    if (ch > MAX_LATIN1_CHAR) {
+      wide = true;
+      break;
+    }
+  }
+
+  // Otherwise, add new entry.
+  return wide
+             ? internChar16Seq<char16_t>(cx, addPtr, lookup.hash(), seq, length)
+             : internChar16Seq<Latin1Char>(cx, addPtr, lookup.hash(), seq,
+                                           length);
+}
+
+const ParserAtom* ParserAtomsTable::internJSAtom(JSContext* cx,
+                                                 CompilationStencil& stencil,
+                                                 JSAtom* atom) {
+  const ParserAtom* parserAtom;
+  {
+    JS::AutoCheckCannotGC nogc;
+
+    parserAtom =
+        atom->hasLatin1Chars()
+            ? internLatin1(cx, atom->latin1Chars(nogc), atom->length())
+            : internChar16(cx, atom->twoByteChars(nogc), atom->length());
+    if (!parserAtom) {
+      return nullptr;
+    }
+  }
+
+  if (parserAtom->isParserAtomIndex()) {
+    ParserAtomIndex index = parserAtom->toParserAtomIndex();
+    auto& atomCache = stencil.input.atomCache;
+
+    if (!atomCache.hasAtomAt(index)) {
+      if (!atomCache.setAtomAt(cx, index, atom)) {
+        return nullptr;
+      }
+    }
+  }
+
+  // We should (infallibly) map back to the same JSAtom.
+  MOZ_ASSERT(parserAtom->toJSAtom(cx, stencil.input.atomCache) == atom);
+
+  return parserAtom;
+}
+
+const ParserAtom* ParserAtomsTable::concatAtoms(
+    JSContext* cx, mozilla::Range<const ParserAtom*> atoms) {
+  MOZ_ASSERT(atoms.length() >= 2,
+             "concatAtoms should only be used for multiple inputs");
+
+  // Compute final length and encoding.
+  bool catLatin1 = true;
+  uint32_t catLen = 0;
+  for (const ParserAtom* atom : atoms) {
+    if (atom->hasTwoByteChars()) {
+      catLatin1 = false;
+    }
+    // Overflow check here, length
+    if (atom->length() >= (ParserAtomEntry::MAX_LENGTH - catLen)) {
+      js::ReportOutOfMemory(cx);
+      return nullptr;
+    }
+    catLen += atom->length();
+  }
+
+  // Short Latin1 strings must check for both Tiny and WellKnown atoms so simple
+  // concatenate onto stack and use `internLatin1`.
+  if (catLatin1 && (catLen <= WellKnownParserAtoms::MaxWellKnownLength)) {
+    Latin1Char buf[WellKnownParserAtoms::MaxWellKnownLength];
+    size_t offset = 0;
+    for (const ParserAtom* atom : atoms) {
+      mozilla::PodCopy(buf + offset, atom->latin1Chars(), atom->length());
+      offset += atom->length();
+    }
+    return internLatin1(cx, buf, catLen);
+  }
+
+  // NOTE: We have ruled out Tiny and WellKnown atoms and can ignore below.
+
+  InflatedChar16Sequence<const ParserAtom*> seq(atoms);
+  SpecificParserAtomLookup<const ParserAtom*> lookup(seq);
+
+  // Check for existing atom.
+  auto addPtr = entrySet_.lookupForAdd(lookup);
+  if (addPtr) {
+    return (*addPtr)->asAtom();
+  }
+
+  // Otherwise, add new entry.
+  return catLatin1 ? internChar16Seq<Latin1Char>(cx, addPtr, lookup.hash(), seq,
+                                                 catLen)
+                   : internChar16Seq<char16_t>(cx, addPtr, lookup.hash(), seq,
+                                               catLen);
+}
+
+const ParserAtom* WellKnownParserAtoms::getWellKnown(
+    WellKnownAtomId atomId) const {
+#define ASSERT_OFFSET_(idpart, id, text)              \
+  static_assert(offsetof(WellKnownParserAtoms, id) == \
+                int32_t(WellKnownAtomId::id) * sizeof(ParserAtom*));
+  FOR_EACH_COMMON_PROPERTYNAME(ASSERT_OFFSET_);
+#undef ASSERT_OFFSET_
+
+#define ASSERT_OFFSET_(name, clasp)                     \
+  static_assert(offsetof(WellKnownParserAtoms, name) == \
+                int32_t(WellKnownAtomId::name) * sizeof(ParserAtom*));
+  JS_FOR_EACH_PROTOTYPE(ASSERT_OFFSET_);
+#undef ASSERT_OFFSET_
+
+  static_assert(int32_t(WellKnownAtomId::abort) == 0,
+                "Unexpected order of WellKnownAtom");
+
+  return (&abort)[int32_t(atomId)];
+}
+
+/* static */
+const ParserAtom* WellKnownParserAtoms::getStatic1(StaticParserString1 s) {
+  return WellKnownParserAtoms::rom_.length1Table[size_t(s)].asAtom();
+}
+
+/* static */
+const ParserAtom* WellKnownParserAtoms::getStatic2(StaticParserString2 s) {
+  return WellKnownParserAtoms::rom_.length2Table[size_t(s)].asAtom();
+}
+
+const ParserAtom* ParserAtomSpanBuilder::getWellKnown(
+    WellKnownAtomId atomId) const {
+  return wellKnownTable_.getWellKnown(atomId);
+}
+
+const ParserAtom* ParserAtomSpanBuilder::getStatic1(
+    StaticParserString1 s) const {
+  return WellKnownParserAtoms::getStatic1(s);
+}
+
+const ParserAtom* ParserAtomSpanBuilder::getStatic2(
+    StaticParserString2 s) const {
+  return WellKnownParserAtoms::getStatic2(s);
+}
+
+const ParserAtom* ParserAtomSpanBuilder::getParserAtom(
+    ParserAtomIndex index) const {
+  return entries_[index]->asAtom();
+}
+
+template <class T>
+const ParserAtom* GetParserAtom(T self, TaggedParserAtomIndex index) {
+  if (index.isParserAtomIndex()) {
+    return self->getParserAtom(index.toParserAtomIndex());
+  }
+
+  if (index.isWellKnownAtomId()) {
+    return self->getWellKnown(index.toWellKnownAtomId());
+  }
+
+  if (index.isStaticParserString1()) {
+    return self->getStatic1(index.toStaticParserString1());
+  }
+
+  if (index.isStaticParserString2()) {
+    return self->getStatic2(index.toStaticParserString2());
+  }
+
+  MOZ_ASSERT(index.isNull());
+  return nullptr;
+}
+
+const ParserAtom* ParserAtomSpanBuilder::getParserAtom(
+    TaggedParserAtomIndex index) const {
+  return GetParserAtom(this, index);
+}
+
+const ParserAtom* ParserAtomsTable::getWellKnown(WellKnownAtomId atomId) const {
+  return wellKnownTable_.getWellKnown(atomId);
+}
+
+const ParserAtom* ParserAtomsTable::getStatic1(StaticParserString1 s) const {
+  return WellKnownParserAtoms::getStatic1(s);
+}
+
+const ParserAtom* ParserAtomsTable::getStatic2(StaticParserString2 s) const {
+  return WellKnownParserAtoms::getStatic2(s);
+}
+
+const ParserAtom* ParserAtomsTable::getParserAtom(ParserAtomIndex index) const {
+  return entries_[index]->asAtom();
+}
+
+const ParserAtom* ParserAtomsTable::getParserAtom(
+    TaggedParserAtomIndex index) const {
+  return GetParserAtom(this, index);
+}
+
+bool InstantiateMarkedAtoms(JSContext* cx, const ParserAtomSpan& entries,
+                            CompilationAtomCache& atomCache) {
+  for (const auto& entry : entries) {
+    if (!entry) {
+      continue;
+    }
+    if (entry->isUsedByStencil() && entry->isParserAtomIndex() &&
+        !atomCache.hasAtomAt(entry->toParserAtomIndex())) {
+      if (!entry->instantiate(cx, atomCache)) {
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
+template <typename CharT>
+const ParserAtom* WellKnownParserAtoms::lookupChar16Seq(
+    const SpecificParserAtomLookup<CharT>& lookup) const {
+  EntrySet::Ptr get = wellKnownSet_.readonlyThreadsafeLookup(lookup);
+  if (get) {
+    return (*get)->asAtom();
+  }
+  return nullptr;
+}
+
+bool WellKnownParserAtoms::initSingle(JSContext* cx, const ParserName** name,
+                                      const ParserAtomEntry& romEntry) {
+  MOZ_ASSERT(name != nullptr);
+
+  unsigned int len = romEntry.length();
+  const Latin1Char* str = romEntry.latin1Chars();
+
+  // Well-known atoms are all currently ASCII with length <= MaxWellKnownLength.
+  MOZ_ASSERT(len <= MaxWellKnownLength);
+  MOZ_ASSERT(romEntry.isAscii());
+
+  // Strings matched by lookupTiny are stored in static table and aliases should
+  // only be added using initTinyStringAlias.
+  MOZ_ASSERT(lookupTiny(str, len) == nullptr,
+             "Well-known atom matches a tiny StaticString. Did you add it to "
+             "the wrong CommonPropertyNames.h list?");
+
+  InflatedChar16Sequence<Latin1Char> seq(str, len);
+  SpecificParserAtomLookup<Latin1Char> lookup(seq, romEntry.hash());
+
+  // Save name for returning after moving entry into set.
+  if (!wellKnownSet_.putNew(lookup, &romEntry)) {
+    js::ReportOutOfMemory(cx);
+    return false;
+  }
+
+  *name = romEntry.asName();
+  return true;
+}
+
+bool WellKnownParserAtoms::initTinyStringAlias(JSContext* cx,
+                                               const ParserName** name,
+                                               const char* str) {
+  MOZ_ASSERT(name != nullptr);
+
+  unsigned int len = strlen(str);
+
+  // Well-known atoms are all currently ASCII with length <= MaxWellKnownLength.
+  MOZ_ASSERT(len <= MaxWellKnownLength);
+  MOZ_ASSERT(FindSmallestEncoding(JS::UTF8Chars(str, len)) ==
+             JS::SmallestEncoding::ASCII);
+
+  // NOTE: If this assert fails, you may need to change which list is it belongs
+  //       to in CommonPropertyNames.h.
+  const ParserAtom* tiny = lookupTiny(str, len);
+  MOZ_ASSERT(tiny, "Tiny common name was not found");
+
+  // Set alias to existing atom.
+  *name = tiny->asName();
+  return true;
+}
+
+bool WellKnownParserAtoms::init(JSContext* cx) {
+  // Tiny strings with a common name need a named alias to an entry in the
+  // WellKnownParserAtoms_ROM.
+#define COMMON_NAME_INIT_(_, name, text)         \
+  if (!initTinyStringAlias(cx, &(name), text)) { \
+    return false;                                \
+  }
+  FOR_EACH_TINY_PROPERTYNAME(COMMON_NAME_INIT_)
+#undef COMMON_NAME_INIT_
+
+  // Initialize the named fields to point to entries in the ROM. This also adds
+  // the atom to the lookup HashSet. The HashSet is used for dynamic lookups
+  // later and does not change once this init method is complete.
+#define COMMON_NAME_INIT_(_, name, _2)       \
+  if (!initSingle(cx, &(name), rom_.name)) { \
+    return false;                            \
+  }
+  FOR_EACH_NONTINY_COMMON_PROPERTYNAME(COMMON_NAME_INIT_)
+#undef COMMON_NAME_INIT_
+#define COMMON_NAME_INIT_(name, _)           \
+  if (!initSingle(cx, &(name), rom_.name)) { \
+    return false;                            \
+  }
+  JS_FOR_EACH_PROTOTYPE(COMMON_NAME_INIT_)
+#undef COMMON_NAME_INIT_
+
+  return true;
+}
+
+} /* namespace frontend */
+} /* namespace js */
+
+// XDR code.
+namespace js {
+
+template <XDRMode mode>
+XDRResult XDRParserAtomEntry(XDRState<mode>* xdr, ParserAtomEntry** entryp) {
+  static_assert(CanCopyDataToDisk<ParserAtomEntry>::value,
+                "ParserAtomEntry cannot be bulk-copied to disk.");
+
+  MOZ_TRY(xdr->align32());
+
+  const ParserAtomEntry* header;
+  if (mode == XDR_ENCODE) {
+    header = *entryp;
+  } else {
+    MOZ_TRY(xdr->peekData(&header));
+  }
+
+  const uint32_t CharSize =
+      header->hasLatin1Chars() ? sizeof(JS::Latin1Char) : sizeof(char16_t);
+  uint32_t totalLength =
+      sizeof(ParserAtomEntry) + (CharSize * header->length());
+
+  MOZ_TRY(xdr->borrowedData(entryp, totalLength));
+
+  return Ok();
+}
+
+template XDRResult XDRParserAtomEntry(XDRState<XDR_ENCODE>* xdr,
+                                      ParserAtomEntry** atomp);
+template XDRResult XDRParserAtomEntry(XDRState<XDR_DECODE>* xdr,
+                                      ParserAtomEntry** atomp);
+
+} /* namespace js */
+
+bool JSRuntime::initializeParserAtoms(JSContext* cx) {
+  MOZ_ASSERT(!commonParserNames);
+
+  if (parentRuntime) {
+    commonParserNames = parentRuntime->commonParserNames;
+    return true;
+  }
+
+  UniquePtr<js::frontend::WellKnownParserAtoms> names(
+      js_new<js::frontend::WellKnownParserAtoms>());
+  if (!names || !names->init(cx)) {
+    return false;
+  }
+
+  commonParserNames = names.release();
+  return true;
+}
+
+void JSRuntime::finishParserAtoms() {
+  if (!parentRuntime) {
+    js_delete(commonParserNames.ref());
+  }
+}