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/*
* Copyright (C) 2013-2021 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include "BrandedStructure.h"
#include "JSArrayBufferView.h"
#include "JSCJSValueInlines.h"
#include "JSGlobalObject.h"
#include "PropertyTable.h"
#include "Structure.h"
#include "StructureChain.h"
#include "StructureRareDataInlines.h"
#include <wtf/Threading.h>
namespace JSC {
class DeferredStructureTransitionWatchpointFire final : public DeferredWatchpointFire {
WTF_MAKE_NONCOPYABLE(DeferredStructureTransitionWatchpointFire);
public:
JS_EXPORT_PRIVATE DeferredStructureTransitionWatchpointFire(VM&, Structure*);
JS_EXPORT_PRIVATE ~DeferredStructureTransitionWatchpointFire() final;
void dump(PrintStream&) const final;
const Structure* structure() const { return m_structure; }
private:
const Structure* m_structure;
};
inline Structure* Structure::create(VM& vm, JSGlobalObject* globalObject, JSValue prototype, const TypeInfo& typeInfo, const ClassInfo* classInfo, IndexingType indexingModeIncludingHistory, unsigned inlineCapacity)
{
ASSERT(vm.structureStructure);
ASSERT(classInfo);
if (auto* object = prototype.getObject()) {
ASSERT(!object->anyObjectInChainMayInterceptIndexedAccesses(vm) || hasSlowPutArrayStorage(indexingModeIncludingHistory) || !hasIndexedProperties(indexingModeIncludingHistory));
object->didBecomePrototype();
}
Structure* structure = new (NotNull, allocateCell<Structure>(vm)) Structure(vm, globalObject, prototype, typeInfo, classInfo, indexingModeIncludingHistory, inlineCapacity);
structure->finishCreation(vm);
ASSERT(structure->type() == StructureType);
return structure;
}
inline Structure* Structure::createStructure(VM& vm)
{
ASSERT(!vm.structureStructure);
Structure* structure = new (NotNull, allocateCell<Structure>(vm)) Structure(vm, CreatingEarlyCell);
structure->finishCreation(vm, CreatingEarlyCell);
return structure;
}
inline Structure* Structure::create(VM& vm, Structure* previous, DeferredStructureTransitionWatchpointFire* deferred)
{
ASSERT(vm.structureStructure);
Structure* newStructure;
if (previous->isBrandedStructure())
newStructure = new (NotNull, allocateCell<BrandedStructure>(vm)) BrandedStructure(vm, jsCast<BrandedStructure*>(previous), deferred);
else
newStructure = new (NotNull, allocateCell<Structure>(vm)) Structure(vm, previous, deferred);
newStructure->finishCreation(vm, previous);
return newStructure;
}
inline bool Structure::mayInterceptIndexedAccesses() const
{
if (indexingModeIncludingHistory() & MayHaveIndexedAccessors)
return true;
// Consider a scenario where object O (of global G1)'s prototype is set to A
// (of global G2), and G2 is already having a bad time. If an object B with
// indexed accessors is then set as the prototype of A:
// O -> A -> B
// Then, O should be converted to SlowPutArrayStorage (because it now has an
// object with indexed accessors in its prototype chain). But it won't be
// converted because this conversion is done by JSGlobalObject::haveAbadTime(),
// but G2 is already having a bad time. We solve this by conservatively
// treating A as potentially having indexed accessors if its global is already
// having a bad time. Hence, when A is set as O's prototype, O will be
// converted to SlowPutArrayStorage.
JSGlobalObject* globalObject = this->globalObject();
if (!globalObject)
return false;
return globalObject->isHavingABadTime();
}
inline JSObject* Structure::storedPrototypeObject() const
{
ASSERT(hasMonoProto());
JSValue value = m_prototype.get();
if (value.isNull())
return nullptr;
return asObject(value);
}
inline Structure* Structure::storedPrototypeStructure() const
{
ASSERT(hasMonoProto());
JSObject* object = storedPrototypeObject();
if (!object)
return nullptr;
return object->structure();
}
ALWAYS_INLINE JSValue Structure::storedPrototype(const JSObject* object) const
{
ASSERT(isCompilationThread() || Thread::mayBeGCThread() || object->structure() == this);
if (hasMonoProto())
return storedPrototype();
return object->getDirect(knownPolyProtoOffset);
}
ALWAYS_INLINE JSObject* Structure::storedPrototypeObject(const JSObject* object) const
{
ASSERT(isCompilationThread() || Thread::mayBeGCThread() || object->structure() == this);
if (hasMonoProto())
return storedPrototypeObject();
JSValue proto = object->getDirect(knownPolyProtoOffset);
if (proto.isNull())
return nullptr;
return asObject(proto);
}
ALWAYS_INLINE Structure* Structure::storedPrototypeStructure(const JSObject* object) const
{
if (JSObject* proto = storedPrototypeObject(object))
return proto->structure();
return nullptr;
}
ALWAYS_INLINE PropertyOffset Structure::get(VM& vm, PropertyName propertyName)
{
unsigned attributes;
return get(vm, propertyName, attributes);
}
ALWAYS_INLINE PropertyOffset Structure::get(VM& vm, PropertyName propertyName, unsigned& attributes)
{
ASSERT(!isCompilationThread());
ASSERT(structure(vm)->classInfo() == info());
if (m_seenProperties.ruleOut(bitwise_cast<uintptr_t>(propertyName.uid())))
return invalidOffset;
PropertyTable* propertyTable = ensurePropertyTableIfNotEmpty(vm);
if (!propertyTable)
return invalidOffset;
PropertyMapEntry* entry = propertyTable->get(propertyName.uid());
if (!entry)
return invalidOffset;
attributes = entry->attributes;
return entry->offset;
}
template<typename Functor>
void Structure::forEachPropertyConcurrently(const Functor& functor)
{
Vector<Structure*, 8> structures;
Structure* tableStructure;
PropertyTable* table;
bool didFindStructure = findStructuresAndMapForMaterialization(structures, tableStructure, table);
HashSet<UniquedStringImpl*> seenProperties;
for (auto* structure : structures) {
if (!structure->m_transitionPropertyName || seenProperties.contains(structure->m_transitionPropertyName.get()))
continue;
seenProperties.add(structure->m_transitionPropertyName.get());
switch (structure->transitionKind()) {
case TransitionKind::PropertyAddition:
case TransitionKind::PropertyAttributeChange:
break;
case TransitionKind::PropertyDeletion:
case TransitionKind::SetBrand:
continue;
default:
ASSERT_NOT_REACHED();
break;
}
if (!functor(PropertyMapEntry(structure->m_transitionPropertyName.get(), structure->transitionOffset(), structure->transitionPropertyAttributes()))) {
if (didFindStructure) {
assertIsHeld(tableStructure->m_lock); // Sadly Clang needs some help here.
tableStructure->m_lock.unlock();
}
return;
}
}
if (didFindStructure) {
assertIsHeld(tableStructure->m_lock); // Sadly Clang needs some help here.
for (auto& entry : *table) {
if (seenProperties.contains(entry.key))
continue;
if (!functor(entry)) {
tableStructure->m_lock.unlock();
return;
}
}
tableStructure->m_lock.unlock();
}
}
template<typename Functor>
void Structure::forEachProperty(VM& vm, const Functor& functor)
{
if (PropertyTable* table = ensurePropertyTableIfNotEmpty(vm)) {
for (auto& entry : *table) {
if (!functor(entry))
return;
}
ensureStillAliveHere(table);
}
}
inline PropertyOffset Structure::getConcurrently(UniquedStringImpl* uid)
{
unsigned attributesIgnored;
return getConcurrently(uid, attributesIgnored);
}
inline bool Structure::hasIndexingHeader(const JSCell* cell) const
{
if (hasIndexedProperties(indexingType()))
return true;
if (!isTypedView(typedArrayTypeForType(m_blob.type())))
return false;
return jsCast<const JSArrayBufferView*>(cell)->mode() == WastefulTypedArray;
}
inline bool Structure::masqueradesAsUndefined(JSGlobalObject* lexicalGlobalObject)
{
return typeInfo().masqueradesAsUndefined() && globalObject() == lexicalGlobalObject;
}
inline bool Structure::transitivelyTransitionedFrom(Structure* structureToFind)
{
for (Structure* current = this; current; current = current->previousID()) {
if (current == structureToFind)
return true;
}
return false;
}
inline void Structure::setCachedPropertyNames(VM& vm, CachedPropertyNamesKind kind, JSImmutableButterfly* cached)
{
ensureRareData(vm)->setCachedPropertyNames(vm, kind, cached);
}
inline JSImmutableButterfly* Structure::cachedPropertyNames(CachedPropertyNamesKind kind) const
{
if (!hasRareData())
return nullptr;
return rareData()->cachedPropertyNames(kind);
}
inline JSImmutableButterfly* Structure::cachedPropertyNamesIgnoringSentinel(CachedPropertyNamesKind kind) const
{
if (!hasRareData())
return nullptr;
return rareData()->cachedPropertyNamesIgnoringSentinel(kind);
}
inline bool Structure::canCacheOwnPropertyNames() const
{
if (isDictionary())
return false;
if (hasIndexedProperties(indexingType()))
return false;
if (typeInfo().overridesAnyFormOfGetOwnPropertyNames())
return false;
return true;
}
ALWAYS_INLINE JSValue prototypeForLookupPrimitiveImpl(JSGlobalObject* globalObject, const Structure* structure)
{
ASSERT(!structure->isObject());
if (structure->typeInfo().type() == StringType)
return globalObject->stringPrototype();
if (structure->typeInfo().type() == HeapBigIntType)
return globalObject->bigIntPrototype();
ASSERT(structure->typeInfo().type() == SymbolType);
return globalObject->symbolPrototype();
}
inline JSValue Structure::prototypeForLookup(JSGlobalObject* globalObject) const
{
ASSERT(hasMonoProto());
if (isObject())
return storedPrototype();
return prototypeForLookupPrimitiveImpl(globalObject, this);
}
inline JSValue Structure::prototypeForLookup(JSGlobalObject* globalObject, JSCell* base) const
{
ASSERT(base->structure() == this);
if (isObject())
return storedPrototype(asObject(base));
return prototypeForLookupPrimitiveImpl(globalObject, this);
}
inline StructureChain* Structure::prototypeChain(VM& vm, JSGlobalObject* globalObject, JSObject* base) const
{
ASSERT(base->structure(vm) == this);
// We cache our prototype chain so our clients can share it.
if (!isValid(globalObject, m_cachedPrototypeChain.get(), base)) {
JSValue prototype = prototypeForLookup(globalObject, base);
const_cast<Structure*>(this)->clearCachedPrototypeChain();
m_cachedPrototypeChain.set(vm, this, StructureChain::create(vm, prototype.isNull() ? nullptr : asObject(prototype)));
}
return m_cachedPrototypeChain.get();
}
inline bool Structure::isValid(JSGlobalObject* globalObject, StructureChain* cachedPrototypeChain, JSObject* base) const
{
if (!cachedPrototypeChain)
return false;
VM& vm = globalObject->vm();
JSValue prototype = prototypeForLookup(globalObject, base);
StructureID* cachedStructure = cachedPrototypeChain->head();
while (*cachedStructure && !prototype.isNull()) {
if (asObject(prototype)->structureID() != *cachedStructure)
return false;
++cachedStructure;
prototype = asObject(prototype)->getPrototypeDirect(vm);
}
return prototype.isNull() && !*cachedStructure;
}
inline void Structure::didReplaceProperty(PropertyOffset offset)
{
if (LIKELY(!hasRareData()))
return;
auto* rareData = this->rareData();
if (LIKELY(rareData->m_replacementWatchpointSets.isNullStorage()))
return;
WatchpointSet* set = rareData->m_replacementWatchpointSets.get(offset);
if (LIKELY(!set))
return;
set->fireAll(vm(), "Property did get replaced");
}
inline WatchpointSet* Structure::propertyReplacementWatchpointSet(PropertyOffset offset)
{
ConcurrentJSLocker locker(m_lock);
StructureRareData* rareData = tryRareData();
if (!rareData)
return nullptr;
if (!rareData->m_replacementWatchpointSets.isNullStorage())
return rareData->m_replacementWatchpointSets.get(offset);
return nullptr;
}
template<typename DetailsFunc>
ALWAYS_INLINE bool Structure::checkOffsetConsistency(PropertyTable* propertyTable, const DetailsFunc& detailsFunc) const
{
// We cannot reliably assert things about the property table in the concurrent
// compilation thread. It is possible for the table to be stolen and then have
// things added to it, which leads to the offsets being all messed up. We could
// get around this by grabbing a lock here, but I think that would be overkill.
if (isCompilationThread())
return true;
unsigned totalSize = propertyTable->propertyStorageSize();
unsigned inlineOverflowAccordingToTotalSize = totalSize < m_inlineCapacity ? 0 : totalSize - m_inlineCapacity;
auto fail = [&] (const char* description) {
dataLog("Detected offset inconsistency: ", description, "!\n");
dataLog("this = ", RawPointer(this), "\n");
dataLog("transitionOffset = ", transitionOffset(), "\n");
dataLog("maxOffset = ", maxOffset(), "\n");
dataLog("m_inlineCapacity = ", m_inlineCapacity, "\n");
dataLog("propertyTable = ", RawPointer(propertyTable), "\n");
dataLog("numberOfSlotsForMaxOffset = ", numberOfSlotsForMaxOffset(maxOffset(), m_inlineCapacity), "\n");
dataLog("totalSize = ", totalSize, "\n");
dataLog("inlineOverflowAccordingToTotalSize = ", inlineOverflowAccordingToTotalSize, "\n");
dataLog("numberOfOutOfLineSlotsForMaxOffset = ", numberOfOutOfLineSlotsForMaxOffset(maxOffset()), "\n");
detailsFunc();
UNREACHABLE_FOR_PLATFORM();
};
if (numberOfSlotsForMaxOffset(maxOffset(), m_inlineCapacity) != totalSize)
fail("numberOfSlotsForMaxOffset doesn't match totalSize");
if (inlineOverflowAccordingToTotalSize != numberOfOutOfLineSlotsForMaxOffset(maxOffset()))
fail("inlineOverflowAccordingToTotalSize doesn't match numberOfOutOfLineSlotsForMaxOffset");
return true;
}
ALWAYS_INLINE bool Structure::checkOffsetConsistency() const
{
PropertyTable* propertyTable = propertyTableOrNull();
if (!propertyTable) {
ASSERT(!isPinnedPropertyTable());
return true;
}
// We cannot reliably assert things about the property table in the concurrent
// compilation thread. It is possible for the table to be stolen and then have
// things added to it, which leads to the offsets being all messed up. We could
// get around this by grabbing a lock here, but I think that would be overkill.
if (isCompilationThread())
return true;
return checkOffsetConsistency(propertyTable, [] () { });
}
inline void Structure::checkConsistency()
{
checkOffsetConsistency();
}
inline size_t nextOutOfLineStorageCapacity(size_t currentCapacity)
{
if (!currentCapacity)
return initialOutOfLineCapacity;
return currentCapacity * outOfLineGrowthFactor;
}
inline void Structure::cacheSpecialProperty(JSGlobalObject* globalObject, VM& vm, JSValue value, CachedSpecialPropertyKey key, const PropertySlot& slot)
{
if (!hasRareData())
allocateRareData(vm);
rareData()->cacheSpecialProperty(globalObject, vm, this, value, key, slot);
}
template<Structure::ShouldPin shouldPin, typename Func>
inline PropertyOffset Structure::add(VM& vm, PropertyName propertyName, unsigned attributes, const Func& func)
{
PropertyTable* table = ensurePropertyTable(vm);
GCSafeConcurrentJSLocker locker(m_lock, vm);
switch (shouldPin) {
case ShouldPin::Yes:
pin(locker, vm, table);
break;
case ShouldPin::No:
setPropertyTable(vm, table);
break;
}
ASSERT(!JSC::isValidOffset(get(vm, propertyName)));
checkConsistency();
if (attributes & PropertyAttribute::DontEnum || propertyName.isSymbol())
setIsQuickPropertyAccessAllowedForEnumeration(false);
if (propertyName == vm.propertyNames->underscoreProto)
setHasUnderscoreProtoPropertyExcludingOriginalProto(true);
auto rep = propertyName.uid();
PropertyOffset newOffset = table->nextOffset(m_inlineCapacity);
m_propertyHash = m_propertyHash ^ rep->existingSymbolAwareHash();
m_seenProperties.add(bitwise_cast<uintptr_t>(rep));
auto result = table->add(vm, PropertyMapEntry(rep, newOffset, attributes));
ASSERT_UNUSED(result, result.second);
ASSERT_UNUSED(result, result.first.first->offset == newOffset);
auto newMaxOffset = std::max(newOffset, maxOffset());
func(locker, newOffset, newMaxOffset);
ASSERT(maxOffset() == newMaxOffset);
checkConsistency();
return newOffset;
}
template<Structure::ShouldPin shouldPin, typename Func>
inline PropertyOffset Structure::remove(VM& vm, PropertyName propertyName, const Func& func)
{
PropertyTable* table = ensurePropertyTable(vm);
GCSafeConcurrentJSLocker locker(m_lock, vm);
switch (shouldPin) {
case ShouldPin::Yes:
pin(locker, vm, table);
break;
case ShouldPin::No:
setPropertyTable(vm, table);
break;
}
ASSERT(JSC::isValidOffset(get(vm, propertyName)));
checkConsistency();
auto rep = propertyName.uid();
PropertyTable::find_iterator position = table->find(rep);
if (!position.first)
return invalidOffset;
setIsQuickPropertyAccessAllowedForEnumeration(false);
PropertyOffset offset = position.first->offset;
table->remove(vm, position);
table->addDeletedOffset(offset);
PropertyOffset newMaxOffset = maxOffset();
func(locker, offset, newMaxOffset);
ASSERT(maxOffset() == newMaxOffset);
ASSERT(!JSC::isValidOffset(get(vm, propertyName)));
checkConsistency();
return offset;
}
template<Structure::ShouldPin shouldPin, typename Func>
inline PropertyOffset Structure::attributeChange(VM& vm, PropertyName propertyName, unsigned attributes, const Func& func)
{
PropertyTable* table = ensurePropertyTable(vm);
GCSafeConcurrentJSLocker locker(m_lock, vm);
switch (shouldPin) {
case ShouldPin::Yes:
pin(locker, vm, table);
break;
case ShouldPin::No:
setPropertyTable(vm, table);
break;
}
ASSERT(JSC::isValidOffset(get(vm, propertyName)));
checkConsistency();
PropertyMapEntry* entry = table->get(propertyName.uid());
if (!entry)
return invalidOffset;
PropertyOffset offset = entry->offset;
if (attributes & PropertyAttribute::DontEnum)
setIsQuickPropertyAccessAllowedForEnumeration(false);
if (attributes & PropertyAttribute::ReadOnly)
setContainsReadOnlyProperties();
entry->attributes = attributes;
PropertyOffset newMaxOffset = maxOffset();
func(locker, offset, newMaxOffset);
ASSERT(maxOffset() == newMaxOffset);
ASSERT(JSC::isValidOffset(get(vm, propertyName)));
checkConsistency();
return offset;
}
template<typename Func>
inline PropertyOffset Structure::addPropertyWithoutTransition(VM& vm, PropertyName propertyName, unsigned attributes, const Func& func)
{
return add<ShouldPin::Yes>(vm, propertyName, attributes, func);
}
template<typename Func>
inline PropertyOffset Structure::removePropertyWithoutTransition(VM& vm, PropertyName propertyName, const Func& func)
{
ASSERT(isUncacheableDictionary());
ASSERT(isPinnedPropertyTable());
ASSERT(propertyTableOrNull());
return remove<ShouldPin::Yes>(vm, propertyName, func);
}
template<typename Func>
inline PropertyOffset Structure::attributeChangeWithoutTransition(VM& vm, PropertyName propertyName, unsigned attributes, const Func& func)
{
return attributeChange<ShouldPin::Yes>(vm, propertyName, attributes, func);
}
ALWAYS_INLINE void Structure::setPrototypeWithoutTransition(VM& vm, JSValue prototype)
{
ASSERT(isValidPrototype(prototype));
m_prototype.set(vm, this, prototype);
}
ALWAYS_INLINE void Structure::setGlobalObject(VM& vm, JSGlobalObject* globalObject)
{
m_globalObject.set(vm, this, globalObject);
}
ALWAYS_INLINE void Structure::setPropertyTable(VM& vm, PropertyTable* table)
{
m_propertyTableUnsafe.setMayBeNull(vm, this, table);
}
ALWAYS_INLINE void Structure::setPreviousID(VM& vm, Structure* structure)
{
if (hasRareData())
rareData()->setPreviousID(vm, structure);
else
m_previousOrRareData.set(vm, this, structure);
}
ALWAYS_INLINE bool Structure::shouldConvertToPolyProto(const Structure* a, const Structure* b)
{
if (!a || !b)
return false;
if (a == b)
return false;
if (a->propertyHash() != b->propertyHash())
return false;
// We only care about objects created via a constructor's to_this. These
// all have Structures with rare data and a sharedPolyProtoWatchpoint.
if (!a->hasRareData() || !b->hasRareData())
return false;
// We only care about Structure's generated from functions that share
// the same executable.
const Box<InlineWatchpointSet>& aInlineWatchpointSet = a->rareData()->sharedPolyProtoWatchpoint();
const Box<InlineWatchpointSet>& bInlineWatchpointSet = b->rareData()->sharedPolyProtoWatchpoint();
if (aInlineWatchpointSet.get() != bInlineWatchpointSet.get() || !aInlineWatchpointSet)
return false;
ASSERT(aInlineWatchpointSet && bInlineWatchpointSet && aInlineWatchpointSet.get() == bInlineWatchpointSet.get());
if (a->hasPolyProto() || b->hasPolyProto())
return false;
if (a->storedPrototype() == b->storedPrototype())
return false;
VM& vm = a->vm();
JSObject* aObj = a->storedPrototypeObject();
JSObject* bObj = b->storedPrototypeObject();
while (aObj && bObj) {
a = aObj->structure(vm);
b = bObj->structure(vm);
if (a->propertyHash() != b->propertyHash())
return false;
aObj = a->storedPrototypeObject(aObj);
bObj = b->storedPrototypeObject(bObj);
}
return !aObj && !bObj;
}
inline Structure* Structure::nonPropertyTransition(VM& vm, Structure* structure, TransitionKind transitionKind)
{
IndexingType indexingModeIncludingHistory = newIndexingType(structure->indexingModeIncludingHistory(), transitionKind);
if (changesIndexingType(transitionKind)) {
if (JSGlobalObject* globalObject = structure->m_globalObject.get()) {
if (globalObject->isOriginalArrayStructure(structure)) {
Structure* result = globalObject->originalArrayStructureForIndexingType(indexingModeIncludingHistory);
if (result->indexingModeIncludingHistory() == indexingModeIncludingHistory) {
structure->didTransitionFromThisStructure();
return result;
}
}
}
}
return nonPropertyTransitionSlow(vm, structure, transitionKind);
}
inline Structure* Structure::addPropertyTransitionToExistingStructureImpl(Structure* structure, UniquedStringImpl* uid, unsigned attributes, PropertyOffset& offset)
{
ASSERT(!structure->isDictionary());
ASSERT(structure->isObject());
offset = invalidOffset;
if (structure->hasBeenDictionary())
return nullptr;
if (Structure* existingTransition = structure->m_transitionTable.get(uid, attributes, TransitionKind::PropertyAddition)) {
validateOffset(existingTransition->transitionOffset(), existingTransition->inlineCapacity());
offset = existingTransition->transitionOffset();
return existingTransition;
}
return nullptr;
}
ALWAYS_INLINE Structure* Structure::addPropertyTransitionToExistingStructure(Structure* structure, PropertyName propertyName, unsigned attributes, PropertyOffset& offset)
{
ASSERT(!isCompilationThread());
return addPropertyTransitionToExistingStructureImpl(structure, propertyName.uid(), attributes, offset);
}
ALWAYS_INLINE Structure* Structure::addPropertyTransitionToExistingStructureConcurrently(Structure* structure, UniquedStringImpl* uid, unsigned attributes, PropertyOffset& offset)
{
ConcurrentJSLocker locker(structure->m_lock);
return addPropertyTransitionToExistingStructureImpl(structure, uid, attributes, offset);
}
inline Structure* StructureTransitionTable::singleTransition() const
{
ASSERT(isUsingSingleSlot());
if (WeakImpl* impl = this->weakImpl()) {
if (impl->state() == WeakImpl::Live)
return jsCast<Structure*>(impl->jsValue().asCell());
}
return nullptr;
}
inline Structure* StructureTransitionTable::get(UniquedStringImpl* rep, unsigned attributes, TransitionKind transitionKind) const
{
if (isUsingSingleSlot()) {
Structure* transition = singleTransition();
return (transition && transition->m_transitionPropertyName == rep && transition->transitionPropertyAttributes() == attributes && transition->transitionKind() == transitionKind) ? transition : nullptr;
}
return map()->get(StructureTransitionTable::Hash::Key(rep, attributes, transitionKind));
}
inline void Structure::clearCachedPrototypeChain()
{
m_cachedPrototypeChain.clear();
if (!hasRareData())
return;
rareData()->clearCachedPropertyNameEnumerator();
}
} // namespace JSC