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JSAtom.cpp
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/* -*- 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/. */
/*
* JS atom table.
*/
#include "vm/JSAtom-inl.h"
#include "mozilla/ArrayUtils.h"
#include "mozilla/EndianUtils.h"
#include "mozilla/RangedPtr.h"
#include "mozilla/Unused.h"
#include <string.h>
#include "jstypes.h"
#include "gc/GC.h"
#include "gc/Marking.h"
#include "gc/MaybeRooted.h"
#include "js/CharacterEncoding.h"
#include "js/Symbol.h"
#include "util/Text.h"
#include "vm/JSContext.h"
#include "vm/SymbolType.h"
#include "vm/Xdr.h"
#include "gc/AtomMarking-inl.h"
#include "vm/JSContext-inl.h"
#include "vm/JSObject-inl.h"
#include "vm/Realm-inl.h"
#include "vm/StringType-inl.h"
using namespace js;
using mozilla::ArrayEnd;
using mozilla::ArrayLength;
using mozilla::Maybe;
using mozilla::Nothing;
using mozilla::RangedPtr;
template <typename CharT, typename InputCharsT>
extern void InflateUTF8CharsToBufferAndTerminate(const InputCharsT src,
CharT* dst, size_t dstLen,
JS::SmallestEncoding encoding);
template <typename CharT, typename CharsT>
extern bool UTF8OrWTF8EqualsChars(const CharsT utf8, const CharT* chars);
template <typename InputCharsT>
extern bool GetUTF8AtomizationData(JSContext* cx, const InputCharsT utf8,
size_t* outlen,
JS::SmallestEncoding* encoding,
HashNumber* hashNum);
struct js::AtomHasher::Lookup {
union {
const JS::Latin1Char* latin1Chars;
const char16_t* twoByteChars;
LittleEndianChars littleEndianChars;
const char* utf8Bytes;
};
enum { TwoByteChar, LittleEndianTwoByte, Latin1, UTF8, WTF8 } type;
size_t length;
size_t byteLength;
const JSAtom* atom; /* Optional. */
JS::AutoCheckCannotGC nogc;
HashNumber hash;
MOZ_ALWAYS_INLINE Lookup(const char* utf8Bytes, size_t byteLen, size_t length,
HashNumber hash)
: utf8Bytes(utf8Bytes),
type(UTF8),
length(length),
byteLength(byteLen),
atom(nullptr),
hash(hash) {}
MOZ_ALWAYS_INLINE Lookup(const char16_t* chars, size_t length)
: twoByteChars(chars),
type(TwoByteChar),
length(length),
atom(nullptr),
hash(mozilla::HashString(chars, length)) {}
MOZ_ALWAYS_INLINE Lookup(const JS::Latin1Char* chars, size_t length)
: latin1Chars(chars),
type(Latin1),
length(length),
atom(nullptr),
hash(mozilla::HashString(chars, length)) {}
inline explicit Lookup(const JSAtom* atom)
: type(atom->hasLatin1Chars() ? Latin1 : TwoByteChar),
length(atom->length()),
atom(atom),
hash(atom->hash()) {
if (type == Latin1) {
latin1Chars = atom->latin1Chars(nogc);
MOZ_ASSERT(mozilla::HashString(latin1Chars, length) == hash);
} else {
MOZ_ASSERT(type == TwoByteChar);
twoByteChars = atom->twoByteChars(nogc);
MOZ_ASSERT(mozilla::HashString(twoByteChars, length) == hash);
}
}
MOZ_ALWAYS_INLINE Lookup(LittleEndianChars chars, size_t length)
: littleEndianChars(chars),
type(LittleEndianTwoByte),
length(length),
atom(nullptr),
hash(mozilla::HashStringKnownLength(chars, length)) {}
};
inline HashNumber js::AtomHasher::hash(const Lookup& l) { return l.hash; }
MOZ_ALWAYS_INLINE bool js::AtomHasher::match(const AtomStateEntry& entry,
const Lookup& lookup) {
JSAtom* key = entry.asPtrUnbarriered();
if (lookup.atom) {
return lookup.atom == key;
}
if (key->length() != lookup.length || key->hash() != lookup.hash) {
return false;
}
auto EqualsLittleEndianChars = [&lookup](auto keyChars) {
for (size_t i = 0, len = lookup.length; i < len; i++) {
if (keyChars[i] != lookup.littleEndianChars[i]) {
return false;
}
}
return true;
};
if (key->hasLatin1Chars()) {
const Latin1Char* keyChars = key->latin1Chars(lookup.nogc);
switch (lookup.type) {
case Lookup::Latin1:
return mozilla::ArrayEqual(keyChars, lookup.latin1Chars, lookup.length);
case Lookup::TwoByteChar:
return EqualChars(keyChars, lookup.twoByteChars, lookup.length);
case Lookup::LittleEndianTwoByte:
return EqualsLittleEndianChars(keyChars);
case Lookup::UTF8: {
JS::UTF8Chars utf8(lookup.utf8Bytes, lookup.byteLength);
return UTF8OrWTF8EqualsChars(utf8, keyChars);
}
case Lookup::WTF8: {
JS::WTF8Chars wtf8(lookup.utf8Bytes, lookup.byteLength);
return UTF8OrWTF8EqualsChars(wtf8, keyChars);
}
}
}
const char16_t* keyChars = key->twoByteChars(lookup.nogc);
switch (lookup.type) {
case Lookup::Latin1:
return EqualChars(lookup.latin1Chars, keyChars, lookup.length);
case Lookup::TwoByteChar:
return mozilla::ArrayEqual(keyChars, lookup.twoByteChars, lookup.length);
case Lookup::LittleEndianTwoByte:
return EqualsLittleEndianChars(keyChars);
case Lookup::UTF8: {
JS::UTF8Chars utf8(lookup.utf8Bytes, lookup.byteLength);
return UTF8OrWTF8EqualsChars(utf8, keyChars);
}
case Lookup::WTF8: {
JS::WTF8Chars wtf8(lookup.utf8Bytes, lookup.byteLength);
return UTF8OrWTF8EqualsChars(wtf8, keyChars);
}
}
MOZ_ASSERT_UNREACHABLE("AtomHasher::match unknown type");
return false;
}
inline JSAtom* js::AtomStateEntry::asPtr(JSContext* cx) const {
JSAtom* atom = asPtrUnbarriered();
if (!cx->isHelperThreadContext()) {
JSString::readBarrier(atom);
}
return atom;
}
UniqueChars js::AtomToPrintableString(JSContext* cx, JSAtom* atom) {
return QuoteString(cx, atom);
}
#define DEFINE_PROTO_STRING(name, clasp) const char js_##name##_str[] = #name;
JS_FOR_EACH_PROTOTYPE(DEFINE_PROTO_STRING)
#undef DEFINE_PROTO_STRING
#define CONST_CHAR_STR(idpart, id, text) const char js_##idpart##_str[] = text;
FOR_EACH_COMMON_PROPERTYNAME(CONST_CHAR_STR)
#undef CONST_CHAR_STR
// Use a low initial capacity for the permanent atoms table to avoid penalizing
// runtimes that create a small number of atoms.
static const uint32_t JS_PERMANENT_ATOM_SIZE = 64;
MOZ_ALWAYS_INLINE AtomSet::Ptr js::FrozenAtomSet::readonlyThreadsafeLookup(
const AtomSet::Lookup& l) const {
return mSet->readonlyThreadsafeLookup(l);
}
struct CommonNameInfo {
const char* str;
size_t length;
};
bool JSRuntime::initializeAtoms(JSContext* cx) {
MOZ_ASSERT(!atoms_);
MOZ_ASSERT(!permanentAtomsDuringInit_);
MOZ_ASSERT(!permanentAtoms_);
if (parentRuntime) {
permanentAtoms_ = parentRuntime->permanentAtoms_;
staticStrings = parentRuntime->staticStrings;
commonNames = parentRuntime->commonNames;
emptyString = parentRuntime->emptyString;
wellKnownSymbols = parentRuntime->wellKnownSymbols;
atoms_ = js_new<AtomsTable>();
if (!atoms_) {
return false;
}
return atoms_->init();
}
permanentAtomsDuringInit_ = js_new<AtomSet>(JS_PERMANENT_ATOM_SIZE);
if (!permanentAtomsDuringInit_) {
return false;
}
staticStrings = js_new<StaticStrings>();
if (!staticStrings || !staticStrings->init(cx)) {
return false;
}
static const CommonNameInfo cachedNames[] = {
#define COMMON_NAME_INFO(idpart, id, text) \
{js_##idpart##_str, sizeof(text) - 1},
FOR_EACH_COMMON_PROPERTYNAME(COMMON_NAME_INFO)
#undef COMMON_NAME_INFO
#define COMMON_NAME_INFO(name, clasp) {js_##name##_str, sizeof(#name) - 1},
JS_FOR_EACH_PROTOTYPE(COMMON_NAME_INFO)
#undef COMMON_NAME_INFO
#define COMMON_NAME_INFO(name) {#name, sizeof(#name) - 1},
JS_FOR_EACH_WELL_KNOWN_SYMBOL(COMMON_NAME_INFO)
#undef COMMON_NAME_INFO
#define COMMON_NAME_INFO(name) {"Symbol." #name, sizeof("Symbol." #name) - 1},
JS_FOR_EACH_WELL_KNOWN_SYMBOL(COMMON_NAME_INFO)
#undef COMMON_NAME_INFO
};
commonNames = js_new<JSAtomState>();
if (!commonNames) {
return false;
}
ImmutablePropertyNamePtr* names =
reinterpret_cast<ImmutablePropertyNamePtr*>(commonNames.ref());
for (size_t i = 0; i < ArrayLength(cachedNames); i++, names++) {
JSAtom* atom =
Atomize(cx, cachedNames[i].str, cachedNames[i].length, PinAtom);
if (!atom) {
return false;
}
names->init(atom->asPropertyName());
}
MOZ_ASSERT(uintptr_t(names) == uintptr_t(commonNames + 1));
emptyString = commonNames->empty;
// Create the well-known symbols.
auto wks = js_new<WellKnownSymbols>();
if (!wks) {
return false;
}
// Prevent GC until we have fully initialized the well known symbols table.
// Faster than zeroing the array and null checking during every GC.
gc::AutoSuppressGC nogc(cx);
ImmutablePropertyNamePtr* descriptions =
commonNames->wellKnownSymbolDescriptions();
ImmutableSymbolPtr* symbols = reinterpret_cast<ImmutableSymbolPtr*>(wks);
for (size_t i = 0; i < JS::WellKnownSymbolLimit; i++) {
HandlePropertyName description = descriptions[i];
JS::Symbol* symbol = JS::Symbol::new_(cx, JS::SymbolCode(i), description);
if (!symbol) {
ReportOutOfMemory(cx);
return false;
}
symbols[i].init(symbol);
}
wellKnownSymbols = wks;
return true;
}
void JSRuntime::finishAtoms() {
js_delete(atoms_.ref());
if (!parentRuntime) {
js_delete(permanentAtomsDuringInit_.ref());
js_delete(permanentAtoms_.ref());
js_delete(staticStrings.ref());
js_delete(commonNames.ref());
js_delete(wellKnownSymbols.ref());
}
atoms_ = nullptr;
permanentAtomsDuringInit_ = nullptr;
permanentAtoms_ = nullptr;
staticStrings = nullptr;
commonNames = nullptr;
wellKnownSymbols = nullptr;
emptyString = nullptr;
}
class AtomsTable::AutoLock {
Mutex* lock = nullptr;
public:
MOZ_ALWAYS_INLINE explicit AutoLock(JSRuntime* rt, Mutex& aLock) {
if (rt->hasHelperThreadZones()) {
lock = &aLock;
lock->lock();
}
}
MOZ_ALWAYS_INLINE ~AutoLock() {
if (lock) {
lock->unlock();
}
}
};
AtomsTable::Partition::Partition(uint32_t index)
: lock(
MutexId{mutexid::AtomsTable.name, mutexid::AtomsTable.order + index}),
atoms(InitialTableSize),
atomsAddedWhileSweeping(nullptr) {}
AtomsTable::Partition::~Partition() { MOZ_ASSERT(!atomsAddedWhileSweeping); }
AtomsTable::~AtomsTable() {
for (size_t i = 0; i < PartitionCount; i++) {
js_delete(partitions[i]);
}
}
bool AtomsTable::init() {
for (size_t i = 0; i < PartitionCount; i++) {
partitions[i] = js_new<Partition>(i);
if (!partitions[i]) {
return false;
}
}
return true;
}
void AtomsTable::lockAll() {
MOZ_ASSERT(!allPartitionsLocked);
for (size_t i = 0; i < PartitionCount; i++) {
partitions[i]->lock.lock();
}
#ifdef DEBUG
allPartitionsLocked = true;
#endif
}
void AtomsTable::unlockAll() {
MOZ_ASSERT(allPartitionsLocked);
for (size_t i = 0; i < PartitionCount; i++) {
partitions[PartitionCount - i - 1]->lock.unlock();
}
#ifdef DEBUG
allPartitionsLocked = false;
#endif
}
MOZ_ALWAYS_INLINE size_t
AtomsTable::getPartitionIndex(const AtomHasher::Lookup& lookup) {
size_t index = lookup.hash >> (32 - PartitionShift);
MOZ_ASSERT(index < PartitionCount);
return index;
}
inline void AtomsTable::tracePinnedAtomsInSet(JSTracer* trc, AtomSet& atoms) {
for (auto r = atoms.all(); !r.empty(); r.popFront()) {
const AtomStateEntry& entry = r.front();
MOZ_ASSERT(entry.isPinned() == entry.asPtrUnbarriered()->isPinned());
MOZ_DIAGNOSTIC_ASSERT(entry.asPtrUnbarriered());
if (entry.isPinned()) {
JSAtom* atom = entry.asPtrUnbarriered();
TraceRoot(trc, &atom, "interned_atom");
MOZ_ASSERT(entry.asPtrUnbarriered() == atom);
}
}
}
void AtomsTable::tracePinnedAtoms(JSTracer* trc,
const AutoAccessAtomsZone& access) {
for (size_t i = 0; i < PartitionCount; i++) {
Partition& part = *partitions[i];
tracePinnedAtomsInSet(trc, part.atoms);
if (part.atomsAddedWhileSweeping) {
tracePinnedAtomsInSet(trc, *part.atomsAddedWhileSweeping);
}
}
}
void js::TraceAtoms(JSTracer* trc, const AutoAccessAtomsZone& access) {
JSRuntime* rt = trc->runtime();
if (rt->permanentAtomsPopulated()) {
rt->atoms().tracePinnedAtoms(trc, access);
}
}
static void TracePermanentAtoms(JSTracer* trc, AtomSet::Range atoms) {
for (; !atoms.empty(); atoms.popFront()) {
const AtomStateEntry& entry = atoms.front();
JSAtom* atom = entry.asPtrUnbarriered();
MOZ_ASSERT(atom->isPinned());
TraceProcessGlobalRoot(trc, atom, "permanent atom");
}
}
void JSRuntime::tracePermanentAtoms(JSTracer* trc) {
// Permanent atoms only need to be traced in the runtime which owns them.
if (parentRuntime) {
return;
}
// Static strings are not included in the permanent atoms table.
if (staticStrings) {
staticStrings->trace(trc);
}
if (permanentAtomsDuringInit_) {
TracePermanentAtoms(trc, permanentAtomsDuringInit_->all());
}
if (permanentAtoms_) {
TracePermanentAtoms(trc, permanentAtoms_->all());
}
}
void js::TraceWellKnownSymbols(JSTracer* trc) {
JSRuntime* rt = trc->runtime();
if (rt->parentRuntime) {
return;
}
if (WellKnownSymbols* wks = rt->wellKnownSymbols) {
for (size_t i = 0; i < JS::WellKnownSymbolLimit; i++) {
TraceProcessGlobalRoot(trc, wks->get(i).get(), "well_known_symbol");
}
}
}
void AtomsTable::traceWeak(JSTracer* trc) {
JSRuntime* rt = trc->runtime();
for (size_t i = 0; i < PartitionCount; i++) {
AutoLock lock(rt, partitions[i]->lock);
AtomSet& atoms = partitions[i]->atoms;
for (AtomSet::Enum e(atoms); !e.empty(); e.popFront()) {
JSAtom* atom = e.front().asPtrUnbarriered();
MOZ_DIAGNOSTIC_ASSERT(atom);
if (!TraceManuallyBarrieredWeakEdge(trc, &atom,
"AtomsTable::partitions::atoms")) {
e.removeFront();
} else {
MOZ_ASSERT(atom == e.front().asPtrUnbarriered());
}
}
}
}
AtomsTable::SweepIterator::SweepIterator(AtomsTable& atoms)
: atoms(atoms), partitionIndex(0) {
startSweepingPartition();
settle();
}
inline void AtomsTable::SweepIterator::startSweepingPartition() {
MOZ_ASSERT(atoms.partitions[partitionIndex]->atomsAddedWhileSweeping);
atomsIter.emplace(atoms.partitions[partitionIndex]->atoms);
}
inline void AtomsTable::SweepIterator::finishSweepingPartition() {
atomsIter.reset();
atoms.mergeAtomsAddedWhileSweeping(*atoms.partitions[partitionIndex]);
}
inline void AtomsTable::SweepIterator::settle() {
MOZ_ASSERT(!empty());
while (atomsIter->empty()) {
finishSweepingPartition();
partitionIndex++;
if (empty()) {
return;
}
startSweepingPartition();
}
}
inline bool AtomsTable::SweepIterator::empty() const {
return partitionIndex == PartitionCount;
}
inline JSAtom* AtomsTable::SweepIterator::front() const {
MOZ_ASSERT(!empty());
return atomsIter->front().asPtrUnbarriered();
}
inline void AtomsTable::SweepIterator::removeFront() {
MOZ_ASSERT(!empty());
return atomsIter->removeFront();
}
inline void AtomsTable::SweepIterator::popFront() {
MOZ_ASSERT(!empty());
atomsIter->popFront();
settle();
}
bool AtomsTable::startIncrementalSweep() {
MOZ_ASSERT(JS::RuntimeHeapIsCollecting());
bool ok = true;
for (size_t i = 0; i < PartitionCount; i++) {
auto& part = *partitions[i];
auto newAtoms = js_new<AtomSet>();
if (!newAtoms) {
ok = false;
break;
}
MOZ_ASSERT(!part.atomsAddedWhileSweeping);
part.atomsAddedWhileSweeping = newAtoms;
}
if (!ok) {
for (size_t i = 0; i < PartitionCount; i++) {
auto& part = *partitions[i];
js_delete(part.atomsAddedWhileSweeping);
part.atomsAddedWhileSweeping = nullptr;
}
}
return ok;
}
void AtomsTable::mergeAtomsAddedWhileSweeping(Partition& part) {
// Add atoms that were added to the secondary table while we were sweeping
// the main table.
AutoEnterOOMUnsafeRegion oomUnsafe;
auto newAtoms = part.atomsAddedWhileSweeping;
part.atomsAddedWhileSweeping = nullptr;
for (auto r = newAtoms->all(); !r.empty(); r.popFront()) {
if (!part.atoms.putNew(AtomHasher::Lookup(r.front().asPtrUnbarriered()),
r.front())) {
oomUnsafe.crash("Adding atom from secondary table after sweep");
}
}
js_delete(newAtoms);
}
bool AtomsTable::sweepIncrementally(SweepIterator& atomsToSweep,
SliceBudget& budget) {
// Sweep the table incrementally until we run out of work or budget.
while (!atomsToSweep.empty()) {
budget.step();
if (budget.isOverBudget()) {
return false;
}
JSAtom* atom = atomsToSweep.front();
MOZ_DIAGNOSTIC_ASSERT(atom);
// TODO: Bug 1574981 - investigate talos regression in
// AtomsTable::sweepIncrementally
if (IsAboutToBeFinalizedUnbarriered(&atom)) {
MOZ_ASSERT(!atom->isPinned());
atomsToSweep.removeFront();
} else {
MOZ_ASSERT(atom == atomsToSweep.front());
}
atomsToSweep.popFront();
}
for (size_t i = 0; i < PartitionCount; i++) {
MOZ_ASSERT(!partitions[i]->atomsAddedWhileSweeping);
}
return true;
}
size_t AtomsTable::sizeOfIncludingThis(
mozilla::MallocSizeOf mallocSizeOf) const {
size_t size = sizeof(AtomsTable);
for (size_t i = 0; i < PartitionCount; i++) {
size += sizeof(Partition);
size += partitions[i]->atoms.shallowSizeOfExcludingThis(mallocSizeOf);
}
return size;
}
bool JSRuntime::initMainAtomsTables(JSContext* cx) {
MOZ_ASSERT(!parentRuntime);
MOZ_ASSERT(!permanentAtomsPopulated());
// The permanent atoms table has now been populated.
permanentAtoms_ =
js_new<FrozenAtomSet>(permanentAtomsDuringInit_); // Takes ownership.
permanentAtomsDuringInit_ = nullptr;
// Initialize the main atoms table.
MOZ_ASSERT(!atoms_);
atoms_ = js_new<AtomsTable>();
return atoms_ && atoms_->init();
}
template <typename Chars>
static MOZ_ALWAYS_INLINE JSAtom* AtomizeAndCopyCharsFromLookup(
JSContext* cx, Chars chars, size_t length, const AtomHasher::Lookup& lookup,
PinningBehavior pin, const Maybe<uint32_t>& indexValue);
template <typename CharT, typename = std::enable_if_t<!std::is_const_v<CharT>>>
static MOZ_ALWAYS_INLINE JSAtom* AtomizeAndCopyCharsFromLookup(
JSContext* cx, CharT* chars, size_t length,
const AtomHasher::Lookup& lookup, PinningBehavior pin,
const Maybe<uint32_t>& indexValue) {
return AtomizeAndCopyCharsFromLookup(cx, const_cast<const CharT*>(chars),
length, lookup, pin, indexValue);
}
template <typename Chars>
static MOZ_NEVER_INLINE JSAtom* PermanentlyAtomizeAndCopyChars(
JSContext* cx, Maybe<AtomSet::AddPtr>& zonePtr, Chars chars, size_t length,
const Maybe<uint32_t>& indexValue, const AtomHasher::Lookup& lookup);
template <typename CharT, typename = std::enable_if_t<!std::is_const_v<CharT>>>
static JSAtom* PermanentlyAtomizeAndCopyChars(
JSContext* cx, Maybe<AtomSet::AddPtr>& zonePtr, CharT* chars, size_t length,
const Maybe<uint32_t>& indexValue, const AtomHasher::Lookup& lookup) {
return PermanentlyAtomizeAndCopyChars(
cx, zonePtr, const_cast<const CharT*>(chars), length, indexValue, lookup);
}
template <typename Chars>
static MOZ_ALWAYS_INLINE JSAtom* AtomizeAndCopyCharsFromLookup(
JSContext* cx, Chars chars, size_t length, const AtomHasher::Lookup& lookup,
PinningBehavior pin, const Maybe<uint32_t>& indexValue) {
// Try the per-Zone cache first. If we find the atom there we can avoid the
// atoms lock, the markAtom call, and the multiple HashSet lookups below.
// We don't use the per-Zone cache if we want a pinned atom: handling that
// is more complicated and pinning atoms is relatively uncommon.
Zone* zone = cx->zone();
Maybe<AtomSet::AddPtr> zonePtr;
if (MOZ_LIKELY(zone && pin == DoNotPinAtom)) {
zonePtr.emplace(zone->atomCache().lookupForAdd(lookup));
if (zonePtr.ref()) {
// The cache is purged on GC so if we're in the middle of an
// incremental GC we should have barriered the atom when we put
// it in the cache.
JSAtom* atom = zonePtr.ref()->asPtrUnbarriered();
MOZ_ASSERT(AtomIsMarked(zone, atom));
return atom;
}
}
// This function can be called during initialization, while the permanent
// atoms table is being created. In this case all atoms created are added to
// the permanent atoms table.
if (!cx->permanentAtomsPopulated()) {
return PermanentlyAtomizeAndCopyChars(cx, zonePtr, chars, length,
indexValue, lookup);
}
AtomSet::Ptr pp = cx->permanentAtoms().readonlyThreadsafeLookup(lookup);
if (pp) {
JSAtom* atom = pp->asPtr(cx);
if (zonePtr && MOZ_UNLIKELY(!zone->atomCache().add(
*zonePtr, AtomStateEntry(atom, false)))) {
ReportOutOfMemory(cx);
return nullptr;
}
return atom;
}
// Validate the length before taking an atoms partition lock, as throwing an
// exception here may reenter this code.
if (MOZ_UNLIKELY(!JSString::validateLength(cx, length))) {
return nullptr;
}
JSAtom* atom = cx->atoms().atomizeAndCopyChars(cx, chars, length, pin,
indexValue, lookup);
if (!atom) {
return nullptr;
}
if (MOZ_UNLIKELY(!cx->atomMarking().inlinedMarkAtomFallible(cx, atom))) {
ReportOutOfMemory(cx);
return nullptr;
}
if (zonePtr && MOZ_UNLIKELY(!zone->atomCache().add(
*zonePtr, AtomStateEntry(atom, false)))) {
ReportOutOfMemory(cx);
return nullptr;
}
return atom;
}
template <typename Chars>
static MOZ_ALWAYS_INLINE JSAtom* AllocateNewAtom(
JSContext* cx, Chars chars, size_t length, PinningBehavior pin,
const Maybe<uint32_t>& indexValue, const AtomHasher::Lookup& lookup);
template <typename CharT, typename = std::enable_if_t<!std::is_const_v<CharT>>>
static MOZ_ALWAYS_INLINE JSAtom* AllocateNewAtom(
JSContext* cx, CharT* chars, size_t length, PinningBehavior pin,
const Maybe<uint32_t>& indexValue, const AtomHasher::Lookup& lookup) {
return AllocateNewAtom(cx, const_cast<const CharT*>(chars), length, pin,
indexValue, lookup);
}
template <typename Chars>
MOZ_ALWAYS_INLINE JSAtom* AtomsTable::atomizeAndCopyChars(
JSContext* cx, Chars chars, size_t length, PinningBehavior pin,
const Maybe<uint32_t>& indexValue, const AtomHasher::Lookup& lookup) {
Partition& part = *partitions[getPartitionIndex(lookup)];
AutoLock lock(cx->runtime(), part.lock);
AtomSet& atoms = part.atoms;
AtomSet* atomsAddedWhileSweeping = part.atomsAddedWhileSweeping;
AtomSet::AddPtr p;
if (!atomsAddedWhileSweeping) {
p = atoms.lookupForAdd(lookup);
} else {
// We're currently sweeping the main atoms table and all new atoms will
// be added to a secondary table. Check this first.
p = atomsAddedWhileSweeping->lookupForAdd(lookup);
// If that fails check the main table but check if any atom found there
// is dead.
if (!p) {
if (AtomSet::AddPtr p2 = atoms.lookupForAdd(lookup)) {
JSAtom* atom = p2->asPtrUnbarriered();
if (!IsAboutToBeFinalizedUnbarriered(&atom)) {
p = p2;
}
}
}
}
if (p) {
JSAtom* atom = p->asPtr(cx);
if (pin && !atom->isPinned()) {
atom->setPinned();
p->setPinned(true);
}
return atom;
}
JSAtom* atom = AllocateNewAtom(cx, chars, length, pin, indexValue, lookup);
if (!atom) {
return nullptr;
}
// We have held the lock since looking up p, and the operations we've done
// since then can't GC; therefore the atoms table has not been modified and
// p is still valid.
AtomSet* addSet =
part.atomsAddedWhileSweeping ? part.atomsAddedWhileSweeping : &atoms;
if (MOZ_UNLIKELY(!addSet->add(p, AtomStateEntry(atom, bool(pin))))) {
ReportOutOfMemory(cx); /* SystemAllocPolicy does not report OOM. */
return nullptr;
}
return atom;
}
/* |chars| must not point into an inline or short string. */
template <typename CharT>
static MOZ_ALWAYS_INLINE JSAtom* AtomizeAndCopyChars(
JSContext* cx, const CharT* chars, size_t length, PinningBehavior pin,
const Maybe<uint32_t>& indexValue) {
if (JSAtom* s = cx->staticStrings().lookup(chars, length)) {
return s;
}
AtomHasher::Lookup lookup(chars, length);
return AtomizeAndCopyCharsFromLookup(cx, chars, length, lookup, pin,
indexValue);
}
template <typename Chars>
static MOZ_NEVER_INLINE JSAtom* PermanentlyAtomizeAndCopyChars(
JSContext* cx, Maybe<AtomSet::AddPtr>& zonePtr, Chars chars, size_t length,
const Maybe<uint32_t>& indexValue, const AtomHasher::Lookup& lookup) {
MOZ_ASSERT(!cx->permanentAtomsPopulated());
MOZ_ASSERT(CurrentThreadCanAccessRuntime(cx->runtime()));
JSRuntime* rt = cx->runtime();
AtomSet& atoms = *rt->permanentAtomsDuringInit();
AtomSet::AddPtr p = atoms.lookupForAdd(lookup);
if (p) {
return p->asPtr(cx);
}
JSAtom* atom =
AllocateNewAtom(cx, chars, length, DoNotPinAtom, indexValue, lookup);
if (!atom) {
return nullptr;
}
atom->morphIntoPermanentAtom();
// We are single threaded at this point, and the operations we've done since
// then can't GC; therefore the atoms table has not been modified and p is
// still valid.
if (!atoms.add(p, AtomStateEntry(atom, true))) {
ReportOutOfMemory(cx); /* SystemAllocPolicy does not report OOM. */
return nullptr;
}
if (zonePtr && MOZ_UNLIKELY(!cx->zone()->atomCache().add(
*zonePtr, AtomStateEntry(atom, false)))) {
ReportOutOfMemory(cx);
return nullptr;
}
return atom;
}
template <typename CharsT>
struct AtomizeUTF8OrWTF8CharsWrapper {
CharsT utf8;
JS::SmallestEncoding encoding;
AtomizeUTF8OrWTF8CharsWrapper(const CharsT& chars,
JS::SmallestEncoding minEncode)
: utf8(chars), encoding(minEncode) {}
};
// MakeLinearStringForAtomization has 4 variants.
// This is used by Latin1Char and char16_t.
template <typename CharT>
static MOZ_ALWAYS_INLINE JSLinearString* MakeLinearStringForAtomization(
JSContext* cx, const CharT* chars, size_t length) {
return NewStringCopyN<NoGC>(cx, chars, length, gc::TenuredHeap);
}
// MakeLinearStringForAtomization has one further variant -- a non-template
// overload accepting LittleEndianChars.
static MOZ_ALWAYS_INLINE JSLinearString* MakeLinearStringForAtomization(
JSContext* cx, LittleEndianChars chars, size_t length) {
return NewStringFromLittleEndianNoGC(cx, chars, length, gc::TenuredHeap);
}
template <typename CharT, typename WrapperT>
static MOZ_ALWAYS_INLINE JSLinearString* MakeUTF8AtomHelper(
JSContext* cx, const WrapperT* chars, size_t length) {
if (JSInlineString::lengthFits<CharT>(length)) {
CharT* storage;
JSInlineString* str =
AllocateInlineString<NoGC>(cx, length, &storage, gc::TenuredHeap);
if (!str) {
return nullptr;
}
InflateUTF8CharsToBufferAndTerminate(chars->utf8, storage, length,
chars->encoding);
return str;
}
// MakeAtomUTF8Helper is called from deep in the Atomization path, which
// expects functions to fail gracefully with nullptr on OOM, without throwing.
//
// Flat strings are null-terminated. Leave room with length + 1
UniquePtr<CharT[], JS::FreePolicy> newStr(
js_pod_arena_malloc<CharT>(js::StringBufferArena, length + 1));
if (!newStr) {
return nullptr;
}
InflateUTF8CharsToBufferAndTerminate(chars->utf8, newStr.get(), length,
chars->encoding);
return JSLinearString::new_<NoGC>(cx, std::move(newStr), length,
gc::TenuredHeap);
}
// Another 2 variants of MakeLinearStringForAtomization.
// This is used by AtomizeUTF8OrWTF8CharsWrapper with UTF8Chars or WTF8Chars.
template <typename InputCharsT>
/* static */ MOZ_ALWAYS_INLINE JSLinearString* MakeLinearStringForAtomization(
JSContext* cx, const AtomizeUTF8OrWTF8CharsWrapper<InputCharsT>* chars,
size_t length) {
if (length == 0) {
return cx->emptyString();
}
if (chars->encoding == JS::SmallestEncoding::UTF16) {
return MakeUTF8AtomHelper<char16_t>(cx, chars, length);
}
return MakeUTF8AtomHelper<JS::Latin1Char>(cx, chars, length);
}
template <typename Chars>
static MOZ_ALWAYS_INLINE JSAtom* AllocateNewAtom(
JSContext* cx, Chars chars, size_t length, PinningBehavior pin,
const Maybe<uint32_t>& indexValue, const AtomHasher::Lookup& lookup) {
AutoAllocInAtomsZone ac(cx);
JSLinearString* linear = MakeLinearStringForAtomization(cx, chars, length);
if (!linear) {
// Grudgingly forgo last-ditch GC. The alternative would be to release
// the lock, manually GC here, and retry from the top.
ReportOutOfMemory(cx);
return nullptr;
}
JSAtom* atom = linear->morphAtomizedStringIntoAtom(lookup.hash);
MOZ_ASSERT(atom->hash() == lookup.hash);
if (pin) {
atom->setPinned();
}
if (indexValue) {
atom->maybeInitializeIndex(*indexValue, true);
}
return atom;
}
JSAtom* js::AtomizeString(JSContext* cx, JSString* str,
js::PinningBehavior pin /* = js::DoNotPinAtom */) {
if (str->isAtom()) {
JSAtom& atom = str->asAtom();
/* N.B. static atoms are effectively always interned. */
if (pin == PinAtom && !atom.isPinned()) {
cx->runtime()->atoms().pinExistingAtom(cx, &atom);
}
return &atom;
}
JSLinearString* linear = str->ensureLinear(cx);
if (!linear) {
return nullptr;
}
Maybe<uint32_t> indexValue;
if (str->hasIndexValue()) {
indexValue.emplace(str->getIndexValue());
}
JS::AutoCheckCannotGC nogc;
return linear->hasLatin1Chars()
? AtomizeAndCopyChars(cx, linear->latin1Chars(nogc),
linear->length(), pin, indexValue)
: AtomizeAndCopyChars(cx, linear->twoByteChars(nogc),
linear->length(), pin, indexValue);
}
void AtomsTable::pinExistingAtom(JSContext* cx, JSAtom* atom) {
MOZ_ASSERT(atom);
MOZ_ASSERT(!atom->isPinned());
AtomHasher::Lookup lookup(atom);