Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 905 insertions, 0 deletions

diff --git a/js/src/frontend/ParserAtom.h b/js/src/frontend/ParserAtom.h
new file mode 100644
index 0000000000..86a033af2c
--- /dev/null
+++ b/js/src/frontend/ParserAtom.h
@@ -0,0 +1,905 @@
+/* -*- 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/. */
+
+#ifndef frontend_ParserAtom_h
+#define frontend_ParserAtom_h
+
+#include "mozilla/MemoryReporting.h"  // mozilla::MallocSizeOf
+#include "mozilla/Range.h"            // mozilla::Range
+#include "mozilla/Span.h"             // mozilla::Span
+#include "mozilla/TextUtils.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "jstypes.h"
+#include "NamespaceImports.h"
+
+#include "frontend/TypedIndex.h"  // TypedIndex
+#include "js/HashTable.h"         // HashMap
+#include "js/ProtoKey.h"          // JS_FOR_EACH_PROTOTYPE
+#include "js/Symbol.h"            // JS_FOR_EACH_WELL_KNOWN_SYMBOL
+#include "js/TypeDecls.h"         // Latin1Char
+#include "js/Utility.h"           // UniqueChars
+#include "js/Vector.h"            // Vector
+#include "threading/Mutex.h"      // Mutex
+#include "util/Text.h"            // InflatedChar16Sequence
+#include "vm/CommonPropertyNames.h"
+#include "vm/StaticStrings.h"
+#include "vm/WellKnownAtom.h"  // WellKnownAtomId, WellKnownAtomInfo
+
+struct JS_PUBLIC_API JSContext;
+
+class JSAtom;
+class JSString;
+
+namespace mozilla {
+union Utf8Unit;
+}
+
+namespace js {
+
+class AtomSet;
+class JS_PUBLIC_API GenericPrinter;
+class LifoAlloc;
+class StringBuffer;
+
+namespace frontend {
+
+struct CompilationAtomCache;
+struct CompilationStencil;
+
+template <typename CharT>
+class SpecificParserAtomLookup;
+
+// These types correspond into indices in the StaticStrings arrays.
+enum class Length1StaticParserString : uint8_t;
+enum class Length2StaticParserString : uint16_t;
+enum class Length3StaticParserString : uint8_t;
+
+class ParserAtom;
+using ParserAtomIndex = TypedIndex<ParserAtom>;
+
+// ParserAtomIndex, WellKnownAtomId, Length1StaticParserString,
+// Length2StaticParserString, Length3StaticParserString, or null.
+//
+// 0x0000_0000  Null atom
+//
+// 0x1YYY_YYYY  28-bit ParserAtom
+//
+// 0x2000_YYYY  Well-known atom ID
+// 0x2001_YYYY  Static length-1 atom : whole Latin1 range
+// 0x2002_YYYY  Static length-2 atom : `[A-Za-z0-9$_]{2}`
+// 0x2003_YYYY  Static length-3 atom : decimal "100" to "255"
+class TaggedParserAtomIndex {
+  uint32_t data_;
+
+ public:
+  static constexpr size_t IndexBit = 28;
+  static constexpr size_t IndexMask = BitMask(IndexBit);
+
+  static constexpr size_t TagShift = IndexBit;
+  static constexpr size_t TagBit = 4;
+  static constexpr size_t TagMask = BitMask(TagBit) << TagShift;
+
+  enum class Kind : uint32_t {
+    Null = 0,
+    ParserAtomIndex,
+    WellKnown,
+  };
+
+ private:
+  static constexpr size_t SmallIndexBit = 16;
+  static constexpr size_t SmallIndexMask = BitMask(SmallIndexBit);
+
+  static constexpr size_t SubTagShift = SmallIndexBit;
+  static constexpr size_t SubTagBit = 2;
+  static constexpr size_t SubTagMask = BitMask(SubTagBit) << SubTagShift;
+
+ public:
+  static constexpr uint32_t NullTag = uint32_t(Kind::Null) << TagShift;
+  static constexpr uint32_t ParserAtomIndexTag = uint32_t(Kind::ParserAtomIndex)
+                                                 << TagShift;
+  static constexpr uint32_t WellKnownTag = uint32_t(Kind::WellKnown)
+                                           << TagShift;
+
+ private:
+  static constexpr uint32_t WellKnownSubTag = 0 << SubTagShift;
+  static constexpr uint32_t Length1StaticSubTag = 1 << SubTagShift;
+  static constexpr uint32_t Length2StaticSubTag = 2 << SubTagShift;
+  static constexpr uint32_t Length3StaticSubTag = 3 << SubTagShift;
+
+ public:
+  static constexpr uint32_t IndexLimit = Bit(IndexBit);
+  static constexpr uint32_t SmallIndexLimit = Bit(SmallIndexBit);
+
+  static constexpr size_t Length1StaticLimit = 256U;
+  static constexpr size_t Length2StaticLimit =
+      StaticStrings::NUM_LENGTH2_ENTRIES;
+  static constexpr size_t Length3StaticLimit = 256U;
+
+ private:
+  explicit TaggedParserAtomIndex(uint32_t data) : data_(data) {}
+
+ public:
+  constexpr TaggedParserAtomIndex() : data_(NullTag) {}
+
+  explicit constexpr TaggedParserAtomIndex(ParserAtomIndex index)
+      : data_(index.index | ParserAtomIndexTag) {
+    MOZ_ASSERT(index.index < IndexLimit);
+  }
+  explicit constexpr TaggedParserAtomIndex(WellKnownAtomId index)
+      : data_(uint32_t(index) | WellKnownTag | WellKnownSubTag) {
+    MOZ_ASSERT(uint32_t(index) < SmallIndexLimit);
+
+    // Length1Static/Length2Static string shouldn't use WellKnownAtomId.
+#define CHECK_(_, NAME, _2) MOZ_ASSERT(index != WellKnownAtomId::NAME);
+    FOR_EACH_NON_EMPTY_TINY_PROPERTYNAME(CHECK_)
+#undef CHECK_
+  }
+  explicit constexpr TaggedParserAtomIndex(Length1StaticParserString index)
+      : data_(uint32_t(index) | WellKnownTag | Length1StaticSubTag) {}
+  explicit constexpr TaggedParserAtomIndex(Length2StaticParserString index)
+      : data_(uint32_t(index) | WellKnownTag | Length2StaticSubTag) {}
+  explicit constexpr TaggedParserAtomIndex(Length3StaticParserString index)
+      : data_(uint32_t(index) | WellKnownTag | Length3StaticSubTag) {}
+
+  class WellKnown {
+   public:
+#define METHOD_(_, NAME, _2)                             \
+  static constexpr TaggedParserAtomIndex NAME() {        \
+    return TaggedParserAtomIndex(WellKnownAtomId::NAME); \
+  }
+    FOR_EACH_NONTINY_COMMON_PROPERTYNAME(METHOD_)
+#undef METHOD_
+
+#define METHOD_(NAME, _)                                 \
+  static constexpr TaggedParserAtomIndex NAME() {        \
+    return TaggedParserAtomIndex(WellKnownAtomId::NAME); \
+  }
+    JS_FOR_EACH_PROTOTYPE(METHOD_)
+#undef METHOD_
+
+#define METHOD_(NAME)                                    \
+  static constexpr TaggedParserAtomIndex NAME() {        \
+    return TaggedParserAtomIndex(WellKnownAtomId::NAME); \
+  }
+    JS_FOR_EACH_WELL_KNOWN_SYMBOL(METHOD_)
+#undef METHOD_
+
+#define METHOD_(_, NAME, STR)                                          \
+  static constexpr TaggedParserAtomIndex NAME() {                      \
+    return TaggedParserAtomIndex(Length1StaticParserString((STR)[0])); \
+  }
+    FOR_EACH_LENGTH1_PROPERTYNAME(METHOD_)
+#undef METHOD_
+
+#define METHOD_(_, NAME, STR)                                         \
+  static constexpr TaggedParserAtomIndex NAME() {                     \
+    return TaggedParserAtomIndex(Length2StaticParserString(           \
+        (StaticStrings::getLength2IndexStatic((STR)[0], (STR)[1])))); \
+  }
+    FOR_EACH_LENGTH2_PROPERTYNAME(METHOD_)
+#undef METHOD_
+
+    static constexpr TaggedParserAtomIndex empty() {
+      return TaggedParserAtomIndex(WellKnownAtomId::empty);
+    }
+  };
+
+  // The value of rawData() for WellKnown TaggedParserAtomIndex.
+  // For using in switch-case.
+  class WellKnownRawData {
+   public:
+#define METHOD_(_, NAME, _2)                                                 \
+  static constexpr uint32_t NAME() {                                         \
+    return uint32_t(WellKnownAtomId::NAME) | WellKnownTag | WellKnownSubTag; \
+  }
+    FOR_EACH_NONTINY_COMMON_PROPERTYNAME(METHOD_)
+#undef METHOD_
+
+#define METHOD_(NAME, _)                                                     \
+  static constexpr uint32_t NAME() {                                         \
+    return uint32_t(WellKnownAtomId::NAME) | WellKnownTag | WellKnownSubTag; \
+  }
+    JS_FOR_EACH_PROTOTYPE(METHOD_)
+#undef METHOD_
+
+#define METHOD_(NAME)                                                        \
+  static constexpr uint32_t NAME() {                                         \
+    return uint32_t(WellKnownAtomId::NAME) | WellKnownTag | WellKnownSubTag; \
+  }
+    JS_FOR_EACH_WELL_KNOWN_SYMBOL(METHOD_)
+#undef METHOD_
+
+#define METHOD_(_, NAME, STR)                                       \
+  static constexpr uint32_t NAME() {                                \
+    return uint32_t((STR)[0]) | WellKnownTag | Length1StaticSubTag; \
+  }
+    FOR_EACH_LENGTH1_PROPERTYNAME(METHOD_)
+#undef METHOD_
+
+#define METHOD_(_, NAME, STR)                                              \
+  static constexpr uint32_t NAME() {                                       \
+    return uint32_t(                                                       \
+               StaticStrings::getLength2IndexStatic((STR)[0], (STR)[1])) | \
+           WellKnownTag | Length2StaticSubTag;                             \
+  }
+    FOR_EACH_LENGTH2_PROPERTYNAME(METHOD_)
+#undef METHOD_
+
+    static constexpr uint32_t empty() {
+      return uint32_t(WellKnownAtomId::empty) | WellKnownTag | WellKnownSubTag;
+    }
+  };
+
+  // NOTE: this is not well-known "null".
+  static TaggedParserAtomIndex null() { return TaggedParserAtomIndex(); }
+
+#ifdef DEBUG
+  void validateRaw();
+#endif
+
+  static TaggedParserAtomIndex fromRaw(uint32_t data) {
+    auto result = TaggedParserAtomIndex(data);
+#ifdef DEBUG
+    result.validateRaw();
+#endif
+    return result;
+  }
+
+  bool isParserAtomIndex() const {
+    return (data_ & TagMask) == ParserAtomIndexTag;
+  }
+  bool isWellKnownAtomId() const {
+    return (data_ & (TagMask | SubTagMask)) == (WellKnownTag | WellKnownSubTag);
+  }
+  bool isLength1StaticParserString() const {
+    return (data_ & (TagMask | SubTagMask)) ==
+           (WellKnownTag | Length1StaticSubTag);
+  }
+  bool isLength2StaticParserString() const {
+    return (data_ & (TagMask | SubTagMask)) ==
+           (WellKnownTag | Length2StaticSubTag);
+  }
+  bool isLength3StaticParserString() const {
+    return (data_ & (TagMask | SubTagMask)) ==
+           (WellKnownTag | Length3StaticSubTag);
+  }
+  bool isNull() const {
+    bool result = !data_;
+    MOZ_ASSERT_IF(result, (data_ & TagMask) == NullTag);
+    return result;
+  }
+  HashNumber staticOrWellKnownHash() const;
+
+  ParserAtomIndex toParserAtomIndex() const {
+    MOZ_ASSERT(isParserAtomIndex());
+    return ParserAtomIndex(data_ & IndexMask);
+  }
+  WellKnownAtomId toWellKnownAtomId() const {
+    MOZ_ASSERT(isWellKnownAtomId());
+    return WellKnownAtomId(data_ & SmallIndexMask);
+  }
+  Length1StaticParserString toLength1StaticParserString() const {
+    MOZ_ASSERT(isLength1StaticParserString());
+    return Length1StaticParserString(data_ & SmallIndexMask);
+  }
+  Length2StaticParserString toLength2StaticParserString() const {
+    MOZ_ASSERT(isLength2StaticParserString());
+    return Length2StaticParserString(data_ & SmallIndexMask);
+  }
+  Length3StaticParserString toLength3StaticParserString() const {
+    MOZ_ASSERT(isLength3StaticParserString());
+    return Length3StaticParserString(data_ & SmallIndexMask);
+  }
+
+  uint32_t* rawDataRef() { return &data_; }
+  uint32_t rawData() const { return data_; }
+
+  bool operator==(const TaggedParserAtomIndex& rhs) const {
+    return data_ == rhs.data_;
+  }
+  bool operator!=(const TaggedParserAtomIndex& rhs) const {
+    return data_ != rhs.data_;
+  }
+
+  explicit operator bool() const { return !isNull(); }
+};
+
+// Trivial variant of TaggedParserAtomIndex, to use in collection that requires
+// trivial type.
+// Provides minimal set of methods to use in collection.
+class TrivialTaggedParserAtomIndex {
+  uint32_t data_;
+
+ public:
+  static TrivialTaggedParserAtomIndex from(TaggedParserAtomIndex index) {
+    TrivialTaggedParserAtomIndex result;
+    result.data_ = index.rawData();
+    return result;
+  }
+
+  operator TaggedParserAtomIndex() const {
+    return TaggedParserAtomIndex::fromRaw(data_);
+  }
+
+  static TrivialTaggedParserAtomIndex null() {
+    TrivialTaggedParserAtomIndex result;
+    result.data_ = 0;
+    return result;
+  }
+
+  bool isNull() const {
+    static_assert(TaggedParserAtomIndex::NullTag == 0);
+    return data_ == 0;
+  }
+
+  uint32_t rawData() const { return data_; }
+
+  bool operator==(const TrivialTaggedParserAtomIndex& rhs) const {
+    return data_ == rhs.data_;
+  }
+  bool operator!=(const TrivialTaggedParserAtomIndex& rhs) const {
+    return data_ != rhs.data_;
+  }
+
+  explicit operator bool() const { return !isNull(); }
+};
+
+/**
+ * A ParserAtom is an in-parser representation of an interned atomic
+ * string.  It mostly mirrors the information carried by a JSAtom*.
+ *
+ * The atom contents are stored in one of two locations:
+ *  1. Inline Latin1Char storage (immediately after the ParserAtom memory).
+ *  2. Inline char16_t storage (immediately after the ParserAtom memory).
+ */
+class alignas(alignof(uint32_t)) ParserAtom {
+  friend class ParserAtomsTable;
+  friend class WellKnownParserAtoms;
+
+  static const uint16_t MAX_LATIN1_CHAR = 0xff;
+
+  // Bit flags inside flags_.
+  static constexpr uint32_t HasTwoByteCharsFlag = 1 << 0;
+  static constexpr uint32_t UsedByStencilFlag = 1 << 1;
+  static constexpr uint32_t AtomizeFlag = 1 << 2;
+
+ public:
+  // Whether to atomize the ParserAtom during instantiation.
+  //
+  // If this ParserAtom is used by opcode with JOF_ATOM, or used as a binding
+  // in scope, it needs to be instantiated as JSAtom.
+  // Otherwise, it needs to be instantiated as LinearString, to reduce the
+  // cost of atomization.
+  enum class Atomize : uint32_t {
+    No = 0,
+    Yes = AtomizeFlag,
+  };
+
+ private:
+  // Helper routine to read some sequence of two-byte chars, and write them
+  // into a target buffer of a particular character width.
+  //
+  // The characters in the sequence must have been verified prior
+  template <typename CharT, typename SeqCharT>
+  static void drainChar16Seq(CharT* buf, InflatedChar16Sequence<SeqCharT> seq,
+                             uint32_t length) {
+    static_assert(
+        std::is_same_v<CharT, char16_t> || std::is_same_v<CharT, Latin1Char>,
+        "Invalid target buffer type.");
+    CharT* cur = buf;
+    while (seq.hasMore()) {
+      char16_t ch = seq.next();
+      if constexpr (std::is_same_v<CharT, Latin1Char>) {
+        MOZ_ASSERT(ch <= MAX_LATIN1_CHAR);
+      }
+      MOZ_ASSERT(cur < (buf + length));
+      *cur = ch;
+      cur++;
+    }
+  }
+
+ private:
+  // The JSAtom-compatible hash of the string.
+  HashNumber hash_ = 0;
+
+  // The length of the buffer in chars_.
+  uint32_t length_ = 0;
+
+  uint32_t flags_ = 0;
+
+  // End of fields.
+
+  ParserAtom(uint32_t length, HashNumber hash, bool hasTwoByteChars)
+      : hash_(hash),
+        length_(length),
+        flags_(hasTwoByteChars ? HasTwoByteCharsFlag : 0) {}
+
+ public:
+  // The constexpr constructor is used by XDR
+  constexpr ParserAtom() = default;
+
+  // ParserAtoms may own their content buffers in variant_, and thus
+  // cannot be copy-constructed - as a new chars would need to be allocated.
+  ParserAtom(const ParserAtom&) = delete;
+  ParserAtom(ParserAtom&& other) = delete;
+
+  template <typename CharT, typename SeqCharT>
+  static ParserAtom* allocate(FrontendContext* fc, LifoAlloc& alloc,
+                              InflatedChar16Sequence<SeqCharT> seq,
+                              uint32_t length, HashNumber hash);
+
+  bool hasLatin1Chars() const { return !(flags_ & HasTwoByteCharsFlag); }
+  bool hasTwoByteChars() const { return flags_ & HasTwoByteCharsFlag; }
+
+  bool isAscii() const {
+    if (hasTwoByteChars()) {
+      return false;
+    }
+    for (Latin1Char ch : latin1Range()) {
+      if (!mozilla::IsAscii(ch)) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  bool isPrivateName() const {
+    if (length() < 2) {
+      return false;
+    }
+
+    return charAt(0) == '#';
+  }
+
+  HashNumber hash() const { return hash_; }
+  uint32_t length() const { return length_; }
+
+  bool isUsedByStencil() const { return flags_ & UsedByStencilFlag; }
+
+ private:
+  bool isMarkedAtomize() const { return flags_ & AtomizeFlag; }
+
+  static constexpr uint32_t MinimumLengthForNonAtom = 8;
+
+ public:
+  bool isInstantiatedAsJSAtom() const;
+
+  template <typename CharT>
+  bool equalsSeq(HashNumber hash, InflatedChar16Sequence<CharT> seq) const;
+
+  // Convert NotInstantiated and usedByStencil entry to a js-atom.
+  JSString* instantiateString(JSContext* cx, FrontendContext* fc,
+                              ParserAtomIndex index,
+                              CompilationAtomCache& atomCache) const;
+  JSAtom* instantiateAtom(JSContext* cx, FrontendContext* fc,
+                          ParserAtomIndex index,
+                          CompilationAtomCache& atomCache) const;
+  JSAtom* instantiatePermanentAtom(JSContext* cx, FrontendContext* fc,
+                                   AtomSet& atomSet, ParserAtomIndex index,
+                                   CompilationAtomCache& atomCache) const;
+
+ private:
+  void markUsedByStencil(Atomize atomize) {
+    flags_ |= UsedByStencilFlag | uint32_t(atomize);
+  }
+  void markAtomize(Atomize atomize) { flags_ |= uint32_t(atomize); }
+
+  template <typename CharT>
+  const CharT* chars() const {
+    MOZ_ASSERT(sizeof(CharT) == (hasTwoByteChars() ? 2 : 1));
+    return reinterpret_cast<const CharT*>(this + 1);
+  }
+
+  template <typename CharT>
+  CharT* chars() {
+    MOZ_ASSERT(sizeof(CharT) == (hasTwoByteChars() ? 2 : 1));
+    return reinterpret_cast<CharT*>(this + 1);
+  }
+
+  const Latin1Char* latin1Chars() const { return chars<Latin1Char>(); }
+  const char16_t* twoByteChars() const { return chars<char16_t>(); }
+  mozilla::Range<const Latin1Char> latin1Range() const {
+    return mozilla::Range(latin1Chars(), length_);
+  }
+  mozilla::Range<const char16_t> twoByteRange() const {
+    return mozilla::Range(twoByteChars(), length_);
+  }
+
+  // Returns index-th char.
+  // Boundary check isn't performed.
+  char16_t charAt(size_t index) const {
+    MOZ_ASSERT(index < length());
+    if (hasLatin1Chars()) {
+      return latin1Chars()[index];
+    }
+    return twoByteChars()[index];
+  }
+
+ public:
+#if defined(DEBUG) || defined(JS_JITSPEW)
+  void dump() const;
+  void dumpCharsNoQuote(js::GenericPrinter& out) const;
+#endif
+};
+
+/**
+ * A lookup structure that allows for querying ParserAtoms in
+ * a hashtable using a flexible input type that supports string
+ * representations of various forms.
+ */
+class ParserAtomLookup {
+ protected:
+  HashNumber hash_;
+
+  ParserAtomLookup(HashNumber hash) : hash_(hash) {}
+
+ public:
+  HashNumber hash() const { return hash_; }
+
+  virtual bool equalsEntry(const ParserAtom* entry) const = 0;
+  virtual bool equalsEntry(const WellKnownAtomInfo* info) const = 0;
+};
+
+struct ParserAtomLookupHasher {
+  using Lookup = ParserAtomLookup;
+
+  static inline HashNumber hash(const Lookup& l) { return l.hash(); }
+  static inline bool match(const ParserAtom* entry, const Lookup& l) {
+    return l.equalsEntry(entry);
+  }
+};
+
+struct WellKnownAtomInfoHasher {
+  using Lookup = ParserAtomLookup;
+
+  static inline HashNumber hash(const Lookup& l) { return l.hash(); }
+  static inline bool match(const WellKnownAtomInfo* info, const Lookup& l) {
+    return l.equalsEntry(info);
+  }
+};
+
+using ParserAtomVector = Vector<ParserAtom*, 0, js::SystemAllocPolicy>;
+using ParserAtomSpan = mozilla::Span<ParserAtom*>;
+
+/**
+ * WellKnownParserAtoms allows the parser to lookup up specific atoms in
+ * constant time.
+ */
+class WellKnownParserAtoms {
+  static WellKnownParserAtoms singleton_;
+
+  // Common property and prototype names are tracked in a hash table. This table
+  // does not key for any items already in a direct-indexing tiny atom table.
+  using EntryMap = HashMap<const WellKnownAtomInfo*, TaggedParserAtomIndex,
+                           WellKnownAtomInfoHasher, js::SystemAllocPolicy>;
+  EntryMap wellKnownMap_;
+
+  bool initSingle(const WellKnownAtomInfo& info, TaggedParserAtomIndex index);
+
+  bool init();
+  void free();
+
+ public:
+  static bool initSingleton();
+  static void freeSingleton();
+
+  static WellKnownParserAtoms& getSingleton() {
+    MOZ_ASSERT(!singleton_.wellKnownMap_.empty());
+    return singleton_;
+  }
+
+  // Maximum length of any well known atoms. This can be increased if needed.
+  static constexpr size_t MaxWellKnownLength = 32;
+
+  template <typename CharT>
+  TaggedParserAtomIndex lookupChar16Seq(
+      const SpecificParserAtomLookup<CharT>& lookup) const;
+
+  template <typename CharsT>
+  TaggedParserAtomIndex lookupTinyIndex(CharsT chars, size_t length) const {
+    static_assert(std::is_same_v<CharsT, const Latin1Char*> ||
+                      std::is_same_v<CharsT, const char16_t*> ||
+                      std::is_same_v<CharsT, const char*> ||
+                      std::is_same_v<CharsT, char16_t*>,
+                  "This assert mostly explicitly documents the calling types, "
+                  "and forces that to be updated if new types show up.");
+    switch (length) {
+      case 0:
+        return TaggedParserAtomIndex::WellKnown::empty();
+
+      case 1: {
+        if (char16_t(chars[0]) < TaggedParserAtomIndex::Length1StaticLimit) {
+          return TaggedParserAtomIndex(Length1StaticParserString(chars[0]));
+        }
+        break;
+      }
+
+      case 2:
+        if (StaticStrings::fitsInSmallChar(chars[0]) &&
+            StaticStrings::fitsInSmallChar(chars[1])) {
+          return TaggedParserAtomIndex(Length2StaticParserString(
+              StaticStrings::getLength2Index(chars[0], chars[1])));
+        }
+        break;
+
+      case 3: {
+        int i;
+        if (StaticStrings::fitsInLength3Static(chars[0], chars[1], chars[2],
+                                               &i)) {
+          return TaggedParserAtomIndex(Length3StaticParserString(i));
+        }
+        break;
+      }
+    }
+
+    // No match on tiny Atoms
+    return TaggedParserAtomIndex::null();
+  }
+
+  TaggedParserAtomIndex lookupTinyIndexUTF8(const mozilla::Utf8Unit* utf8Ptr,
+                                            size_t nbyte) const;
+
+  size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
+    return wellKnownMap_.shallowSizeOfExcludingThis(mallocSizeOf);
+  }
+};
+
+bool InstantiateMarkedAtoms(JSContext* cx, FrontendContext* fc,
+                            const ParserAtomSpan& entries,
+                            CompilationAtomCache& atomCache);
+
+bool InstantiateMarkedAtomsAsPermanent(JSContext* cx, FrontendContext* fc,
+                                       AtomSet& atomSet,
+                                       const ParserAtomSpan& entries,
+                                       CompilationAtomCache& atomCache);
+
+/**
+ * A ParserAtomsTable owns and manages the vector of ParserAtom entries
+ * associated with a given compile session.
+ */
+class ParserAtomsTable {
+  friend struct CompilationStencil;
+
+ private:
+  LifoAlloc* alloc_;
+
+  // The ParserAtom are owned by the LifoAlloc.
+  using EntryMap = HashMap<const ParserAtom*, TaggedParserAtomIndex,
+                           ParserAtomLookupHasher, js::SystemAllocPolicy>;
+  EntryMap entryMap_;
+  ParserAtomVector entries_;
+
+ public:
+  explicit ParserAtomsTable(LifoAlloc& alloc);
+  ParserAtomsTable(ParserAtomsTable&&) = default;
+  ParserAtomsTable& operator=(ParserAtomsTable&& other) noexcept {
+    entryMap_ = std::move(other.entryMap_);
+    entries_ = std::move(other.entries_);
+    return *this;
+  }
+
+  void fixupAlloc(LifoAlloc& alloc) { alloc_ = &alloc; }
+
+  size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
+    return entryMap_.shallowSizeOfExcludingThis(mallocSizeOf) +
+           entries_.sizeOfExcludingThis(mallocSizeOf);
+  }
+  size_t sizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
+    return mallocSizeOf(this) + sizeOfExcludingThis(mallocSizeOf);
+  }
+
+ private:
+  // Internal APIs for interning to the table after well-known atoms cases have
+  // been tested.
+  TaggedParserAtomIndex addEntry(FrontendContext* fc, EntryMap::AddPtr& addPtr,
+                                 ParserAtom* entry);
+  template <typename AtomCharT, typename SeqCharT>
+  TaggedParserAtomIndex internChar16Seq(FrontendContext* fc,
+                                        EntryMap::AddPtr& addPtr,
+                                        HashNumber hash,
+                                        InflatedChar16Sequence<SeqCharT> seq,
+                                        uint32_t length);
+
+  template <typename AtomCharT>
+  TaggedParserAtomIndex internExternalParserAtomImpl(FrontendContext* fc,
+                                                     const ParserAtom* atom);
+
+ public:
+  TaggedParserAtomIndex internAscii(FrontendContext* fc, const char* asciiPtr,
+                                    uint32_t length);
+
+  TaggedParserAtomIndex internLatin1(FrontendContext* fc,
+                                     const JS::Latin1Char* latin1Ptr,
+                                     uint32_t length);
+
+  TaggedParserAtomIndex internUtf8(FrontendContext* fc,
+                                   const mozilla::Utf8Unit* utf8Ptr,
+                                   uint32_t nbyte);
+
+  TaggedParserAtomIndex internChar16(FrontendContext* fc,
+                                     const char16_t* char16Ptr,
+                                     uint32_t length);
+
+  TaggedParserAtomIndex internJSAtom(FrontendContext* fc,
+                                     CompilationAtomCache& atomCache,
+                                     JSAtom* atom);
+
+  // Intern ParserAtom data from other ParserAtomTable.
+  // This copies flags as well.
+  TaggedParserAtomIndex internExternalParserAtom(FrontendContext* fc,
+                                                 const ParserAtom* atom);
+
+  // The atomIndex given as argument is in relation with the context Stencil.
+  // The atomIndex might be a well-known or static, in which case this function
+  // is a no-op.
+  TaggedParserAtomIndex internExternalParserAtomIndex(
+      FrontendContext* fc, const CompilationStencil& context,
+      TaggedParserAtomIndex atomIndex);
+
+  // Compare an internal atom index with an external atom index coming from the
+  // stencil given as argument.
+  bool isEqualToExternalParserAtomIndex(TaggedParserAtomIndex internal,
+                                        const CompilationStencil& context,
+                                        TaggedParserAtomIndex external) const;
+
+  bool addPlaceholder(FrontendContext* fc);
+
+ private:
+  const ParserAtom* getWellKnown(WellKnownAtomId atomId) const;
+  ParserAtom* getParserAtom(ParserAtomIndex index) const;
+
+ public:
+  const ParserAtomVector& entries() const { return entries_; }
+
+  // Accessors for querying atom properties.
+  bool isIdentifier(TaggedParserAtomIndex index) const;
+  bool isPrivateName(TaggedParserAtomIndex index) const;
+  bool isExtendedUnclonedSelfHostedFunctionName(
+      TaggedParserAtomIndex index) const;
+  bool isModuleExportName(TaggedParserAtomIndex index) const;
+  bool isIndex(TaggedParserAtomIndex index, uint32_t* indexp) const;
+  bool isInstantiatedAsJSAtom(TaggedParserAtomIndex index) const;
+  uint32_t length(TaggedParserAtomIndex index) const;
+  HashNumber hash(TaggedParserAtomIndex index) const;
+
+  // Methods for atom.
+  void markUsedByStencil(TaggedParserAtomIndex index,
+                         ParserAtom::Atomize atomize) const;
+  void markAtomize(TaggedParserAtomIndex index,
+                   ParserAtom::Atomize atomize) const;
+  double toNumber(TaggedParserAtomIndex index) const;
+  UniqueChars toNewUTF8CharsZ(FrontendContext* fc,
+                              TaggedParserAtomIndex index) const;
+  UniqueChars toPrintableString(TaggedParserAtomIndex index) const;
+  UniqueChars toQuotedString(TaggedParserAtomIndex index) const;
+  JSAtom* toJSAtom(JSContext* cx, FrontendContext* fc,
+                   TaggedParserAtomIndex index,
+                   CompilationAtomCache& atomCache) const;
+
+ private:
+  JSAtom* toWellKnownJSAtom(JSContext* cx, TaggedParserAtomIndex index) const;
+
+ public:
+  bool appendTo(StringBuffer& buffer, TaggedParserAtomIndex index) const;
+
+ public:
+#if defined(DEBUG) || defined(JS_JITSPEW)
+  void dump(TaggedParserAtomIndex index) const;
+  void dumpCharsNoQuote(js::GenericPrinter& out,
+                        TaggedParserAtomIndex index) const;
+
+  static void dumpCharsNoQuote(js::GenericPrinter& out, WellKnownAtomId id);
+  static void dumpCharsNoQuote(js::GenericPrinter& out,
+                               Length1StaticParserString index);
+  static void dumpCharsNoQuote(js::GenericPrinter& out,
+                               Length2StaticParserString index);
+  static void dumpCharsNoQuote(js::GenericPrinter& out,
+                               Length3StaticParserString index);
+#endif
+
+  static void getLength1Content(Length1StaticParserString s,
+                                Latin1Char contents[1]) {
+    contents[0] = Latin1Char(s);
+  }
+
+  static void getLength2Content(Length2StaticParserString s, char contents[2]) {
+    contents[0] = StaticStrings::firstCharOfLength2(size_t(s));
+    contents[1] = StaticStrings::secondCharOfLength2(size_t(s));
+  }
+
+  static void getLength3Content(Length3StaticParserString s, char contents[3]) {
+    contents[0] = StaticStrings::firstCharOfLength3(int32_t(s));
+    contents[1] = StaticStrings::secondCharOfLength3(int32_t(s));
+    contents[2] = StaticStrings::thirdCharOfLength3(int32_t(s));
+  }
+};
+
+// Lightweight version of ParserAtomsTable.
+// This doesn't support deduplication.
+// Used while decoding XDR.
+class ParserAtomSpanBuilder {
+  ParserAtomSpan& entries_;
+
+ public:
+  explicit ParserAtomSpanBuilder(ParserAtomSpan& entries) : entries_(entries) {}
+
+  bool allocate(FrontendContext* fc, LifoAlloc& alloc, size_t count);
+
+  void set(ParserAtomIndex index, const ParserAtom* atom) {
+    entries_[index] = const_cast<ParserAtom*>(atom);
+  }
+};
+
+template <typename CharT>
+class SpecificParserAtomLookup : public ParserAtomLookup {
+  // The sequence of characters to look up.
+  InflatedChar16Sequence<CharT> seq_;
+
+ public:
+  explicit SpecificParserAtomLookup(const InflatedChar16Sequence<CharT>& seq)
+      : SpecificParserAtomLookup(seq, seq.computeHash()) {}
+
+  SpecificParserAtomLookup(const InflatedChar16Sequence<CharT>& seq,
+                           HashNumber hash)
+      : ParserAtomLookup(hash), seq_(seq) {
+    MOZ_ASSERT(seq_.computeHash() == hash);
+  }
+
+  virtual bool equalsEntry(const ParserAtom* entry) const override {
+    return entry->equalsSeq<CharT>(hash_, seq_);
+  }
+
+  virtual bool equalsEntry(const WellKnownAtomInfo* info) const override {
+    // Compare hashes first.
+    if (info->hash != hash_) {
+      return false;
+    }
+
+    InflatedChar16Sequence<CharT> seq = seq_;
+    for (uint32_t i = 0; i < info->length; i++) {
+      if (!seq.hasMore() || char16_t(info->content[i]) != seq.next()) {
+        return false;
+      }
+    }
+    return !seq.hasMore();
+  }
+};
+
+template <typename CharT>
+inline bool ParserAtom::equalsSeq(HashNumber hash,
+                                  InflatedChar16Sequence<CharT> seq) const {
+  // Compare hashes first.
+  if (hash_ != hash) {
+    return false;
+  }
+
+  if (hasTwoByteChars()) {
+    const char16_t* chars = twoByteChars();
+    for (uint32_t i = 0; i < length_; i++) {
+      if (!seq.hasMore() || chars[i] != seq.next()) {
+        return false;
+      }
+    }
+  } else {
+    const Latin1Char* chars = latin1Chars();
+    for (uint32_t i = 0; i < length_; i++) {
+      if (!seq.hasMore() || char16_t(chars[i]) != seq.next()) {
+        return false;
+      }
+    }
+  }
+  return !seq.hasMore();
+}
+
+JSAtom* GetWellKnownAtom(JSContext* cx, WellKnownAtomId atomId);
+
+} /* namespace frontend */
+} /* namespace js */
+
+#endif  // frontend_ParserAtom_h