Source/JavaScriptCore/bytecode/UnlinkedFunctionExecutable.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 2012-2019 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.
  */

 #include "config.h"
 #include "UnlinkedFunctionExecutable.h"

 #include "BuiltinExecutables.h"
 #include "BytecodeGenerator.h"
 #include "CachedTypes.h"
 #include "ClassInfo.h"
 #include "CodeCache.h"
 #include "Debugger.h"
 #include "ExecutableInfo.h"
 #include "FunctionOverrides.h"
 #include "IsoCellSetInlines.h"
 #include "JSCInlines.h"
 #include "Parser.h"
 #include "SourceProvider.h"
 #include "Structure.h"
 #include "UnlinkedFunctionCodeBlock.h"
 #include <wtf/Optional.h>

 namespace JSC {

 static_assert(sizeof(UnlinkedFunctionExecutable) <= 128, "UnlinkedFunctionExecutable should fit in a 128-byte cell to keep allocated blocks count to only one after initializing JSGlobalObject.");

 const ClassInfo UnlinkedFunctionExecutable::s_info = { "UnlinkedFunctionExecutable", nullptr, nullptr, nullptr, CREATE_METHOD_TABLE(UnlinkedFunctionExecutable) };

 static UnlinkedFunctionCodeBlock* generateUnlinkedFunctionCodeBlock(
     VM& vm, UnlinkedFunctionExecutable* executable, const SourceCode& source,
     CodeSpecializationKind kind, OptionSet<CodeGenerationMode> codeGenerationMode,
     UnlinkedFunctionKind functionKind, ParserError& error, SourceParseMode parseMode)
 {
     JSParserBuiltinMode builtinMode = executable->isBuiltinFunction() ? JSParserBuiltinMode::Builtin : JSParserBuiltinMode::NotBuiltin;
     JSParserStrictMode strictMode = executable->isInStrictContext() ? JSParserStrictMode::Strict : JSParserStrictMode::NotStrict;
     JSParserScriptMode scriptMode = executable->scriptMode();
     ASSERT(isFunctionParseMode(executable->parseMode()));
     std::unique_ptr<FunctionNode> function = parse<FunctionNode>(
         vm, source, executable->name(), builtinMode, strictMode, scriptMode, executable->parseMode(), executable->superBinding(), error, nullptr);

     if (!function) {
         ASSERT(error.isValid());
         return nullptr;
     }

     function->finishParsing(executable->name(), executable->functionMode());
     executable->recordParse(function->features(), function->hasCapturedVariables());

     bool isClassContext = executable->superBinding() == SuperBinding::Needed;

     UnlinkedFunctionCodeBlock* result = UnlinkedFunctionCodeBlock::create(vm, FunctionCode, ExecutableInfo(function->usesEval(), function->isStrictMode(), kind == CodeForConstruct, functionKind == UnlinkedBuiltinFunction, executable->constructorKind(), scriptMode, executable->superBinding(), parseMode, executable->derivedContextType(), false, isClassContext, EvalContextType::FunctionEvalContext), codeGenerationMode);

     VariableEnvironment parentScopeTDZVariables = executable->parentScopeTDZVariables();
     error = BytecodeGenerator::generate(vm, function.get(), source, result, codeGenerationMode, &parentScopeTDZVariables);

     if (error.isValid())
         return nullptr;
     vm.codeCache()->updateCache(executable, source, kind, result);
     return result;
 }

 UnlinkedFunctionExecutable::UnlinkedFunctionExecutable(VM& vm, Structure* structure, const SourceCode& parentSource, FunctionMetadataNode* node, UnlinkedFunctionKind kind, ConstructAbility constructAbility, JSParserScriptMode scriptMode, Optional<CompactVariableMap::Handle> parentScopeTDZVariables, DerivedContextType derivedContextType, bool isBuiltinDefaultClassConstructor)
     : Base(vm, structure)
     , m_firstLineOffset(node->firstLine() - parentSource.firstLine().oneBasedInt())
     , m_isInStrictContext(node->isInStrictContext())
     , m_lineCount(node->lastLine() - node->firstLine())
     , m_hasCapturedVariables(false)
     , m_unlinkedFunctionNameStart(node->functionNameStart() - parentSource.startOffset())
     , m_isBuiltinFunction(kind == UnlinkedBuiltinFunction)
     , m_unlinkedBodyStartColumn(node->startColumn())
     , m_isBuiltinDefaultClassConstructor(isBuiltinDefaultClassConstructor)
     , m_unlinkedBodyEndColumn(m_lineCount ? node->endColumn() : node->endColumn() - node->startColumn())
     , m_constructAbility(static_cast<unsigned>(constructAbility))
     , m_startOffset(node->source().startOffset() - parentSource.startOffset())
     , m_scriptMode(static_cast<unsigned>(scriptMode))
     , m_sourceLength(node->source().length())
     , m_superBinding(static_cast<unsigned>(node->superBinding()))
     , m_parametersStartOffset(node->parametersStart())
     , m_isCached(false)
     , m_typeProfilingStartOffset(node->functionKeywordStart())
     , m_typeProfilingEndOffset(node->startStartOffset() + node->source().length() - 1)
     , m_parameterCount(node->parameterCount())
     , m_features(0)
     , m_sourceParseMode(node->parseMode())
     , m_constructorKind(static_cast<unsigned>(node->constructorKind()))
     , m_functionMode(static_cast<unsigned>(node->functionMode()))
     , m_derivedContextType(static_cast<unsigned>(derivedContextType))
     , m_isGeneratedFromCache(false)
     , m_unlinkedCodeBlockForCall()
     , m_unlinkedCodeBlockForConstruct()
     , m_name(node->ident())
     , m_ecmaName(node->ecmaName())
 {
     // Make sure these bitfields are adequately wide.
     ASSERT(m_constructAbility == static_cast<unsigned>(constructAbility));
     ASSERT(m_constructorKind == static_cast<unsigned>(node->constructorKind()));
     ASSERT(m_functionMode == static_cast<unsigned>(node->functionMode()));
     ASSERT(m_scriptMode == static_cast<unsigned>(scriptMode));
     ASSERT(m_superBinding == static_cast<unsigned>(node->superBinding()));
     ASSERT(m_derivedContextType == static_cast<unsigned>(derivedContextType));
     ASSERT(!(m_isBuiltinDefaultClassConstructor && constructorKind() == ConstructorKind::None));
     if (!node->classSource().isNull())
         setClassSource(node->classSource());
     if (parentScopeTDZVariables)
         ensureRareData().m_parentScopeTDZVariables = WTFMove(*parentScopeTDZVariables);
 }

 UnlinkedFunctionExecutable::~UnlinkedFunctionExecutable()
 {
     if (m_isCached)
         m_decoder.~RefPtr();
 }

 void UnlinkedFunctionExecutable::destroy(JSCell* cell)
 {
     static_cast<UnlinkedFunctionExecutable*>(cell)->~UnlinkedFunctionExecutable();
 }

 void UnlinkedFunctionExecutable::visitChildren(JSCell* cell, SlotVisitor& visitor)
 {
     UnlinkedFunctionExecutable* thisObject = jsCast<UnlinkedFunctionExecutable*>(cell);
     ASSERT_GC_OBJECT_INHERITS(thisObject, info());
     Base::visitChildren(thisObject, visitor);

     if (thisObject->codeBlockEdgeMayBeWeak()) {
         auto markIfProfitable = [&] (WriteBarrier<UnlinkedFunctionCodeBlock>& unlinkedCodeBlock) {
             if (!unlinkedCodeBlock)
                 return;
             if (unlinkedCodeBlock->didOptimize() == TrueTriState)
                 visitor.append(unlinkedCodeBlock);
             else if (unlinkedCodeBlock->age() < UnlinkedCodeBlock::maxAge)
                 visitor.append(unlinkedCodeBlock);
         };
         markIfProfitable(thisObject->m_unlinkedCodeBlockForCall);
         markIfProfitable(thisObject->m_unlinkedCodeBlockForConstruct);
     } else if (!thisObject->m_isCached) {
         visitor.append(thisObject->m_unlinkedCodeBlockForCall);
         visitor.append(thisObject->m_unlinkedCodeBlockForConstruct);
     }
 }

 SourceCode UnlinkedFunctionExecutable::linkedSourceCode(const SourceCode& passedParentSource) const
 {
     const SourceCode& parentSource = !m_isBuiltinDefaultClassConstructor ? passedParentSource : BuiltinExecutables::defaultConstructorSourceCode(constructorKind());
     unsigned startColumn = linkedStartColumn(parentSource.startColumn().oneBasedInt());
     unsigned startOffset = parentSource.startOffset() + m_startOffset;
     unsigned firstLine = parentSource.firstLine().oneBasedInt() + m_firstLineOffset;
     return SourceCode(parentSource.provider(), startOffset, startOffset + m_sourceLength, firstLine, startColumn);
 }

 FunctionExecutable* UnlinkedFunctionExecutable::link(VM& vm, ScriptExecutable* topLevelExecutable, const SourceCode& passedParentSource, Optional<int> overrideLineNumber, Intrinsic intrinsic)
 {
     SourceCode source = linkedSourceCode(passedParentSource);
     FunctionOverrides::OverrideInfo overrideInfo;
     bool hasFunctionOverride = false;
     if (UNLIKELY(Options::functionOverrides()))
         hasFunctionOverride = FunctionOverrides::initializeOverrideFor(source, overrideInfo);

     FunctionExecutable* result = FunctionExecutable::create(vm, topLevelExecutable, source, this, intrinsic);
     if (overrideLineNumber)
         result->setOverrideLineNumber(*overrideLineNumber);

     if (UNLIKELY(hasFunctionOverride))
         result->overrideInfo(overrideInfo);

     return result;
 }

 UnlinkedFunctionExecutable* UnlinkedFunctionExecutable::fromGlobalCode(
     const Identifier& name, ExecState& exec, const SourceCode& source,
     JSObject*& exception, int overrideLineNumber, Optional<int> functionConstructorParametersEndPosition)
 {
     ParserError error;
     VM& vm = exec.vm();
     auto& globalObject = *exec.lexicalGlobalObject();
     CodeCache* codeCache = vm.codeCache();
     OptionSet<CodeGenerationMode> codeGenerationMode = globalObject.defaultCodeGenerationMode();
     UnlinkedFunctionExecutable* executable = codeCache->getUnlinkedGlobalFunctionExecutable(vm, name, source, codeGenerationMode, functionConstructorParametersEndPosition, error);

     if (globalObject.hasDebugger())
         globalObject.debugger()->sourceParsed(&exec, source.provider(), error.line(), error.message());

     if (error.isValid()) {
         exception = error.toErrorObject(&globalObject, source, overrideLineNumber);
         return nullptr;
     }

     return executable;
 }

 UnlinkedFunctionCodeBlock* UnlinkedFunctionExecutable::unlinkedCodeBlockFor(
     VM& vm, const SourceCode& source, CodeSpecializationKind specializationKind,
     OptionSet<CodeGenerationMode> codeGenerationMode, ParserError& error, SourceParseMode parseMode)
 {
     if (m_isCached)
         decodeCachedCodeBlocks(vm);
     switch (specializationKind) {
     case CodeForCall:
         if (UnlinkedFunctionCodeBlock* codeBlock = m_unlinkedCodeBlockForCall.get())
             return codeBlock;
         break;
     case CodeForConstruct:
         if (UnlinkedFunctionCodeBlock* codeBlock = m_unlinkedCodeBlockForConstruct.get())
             return codeBlock;
         break;
     }

     UnlinkedFunctionCodeBlock* result = generateUnlinkedFunctionCodeBlock(
         vm, this, source, specializationKind, codeGenerationMode,
         isBuiltinFunction() ? UnlinkedBuiltinFunction : UnlinkedNormalFunction,
         error, parseMode);

     if (error.isValid())
         return nullptr;

     switch (specializationKind) {
     case CodeForCall:
         m_unlinkedCodeBlockForCall.set(vm, this, result);
         break;
     case CodeForConstruct:
         m_unlinkedCodeBlockForConstruct.set(vm, this, result);
         break;
     }
     vm.unlinkedFunctionExecutableSpace.set.add(this);
     return result;
 }

 void UnlinkedFunctionExecutable::decodeCachedCodeBlocks(VM& vm)
 {
     ASSERT(m_isCached);
     ASSERT(m_decoder);
     ASSERT(m_cachedCodeBlockForCallOffset || m_cachedCodeBlockForConstructOffset);

     RefPtr<Decoder> decoder = WTFMove(m_decoder);
     int32_t cachedCodeBlockForCallOffset = m_cachedCodeBlockForCallOffset;
     int32_t cachedCodeBlockForConstructOffset = m_cachedCodeBlockForConstructOffset;

     DeferGC deferGC(vm.heap);

     // No need to clear m_unlinkedCodeBlockForCall here, since we moved the decoder out of the same slot
     if (cachedCodeBlockForCallOffset)
         decodeFunctionCodeBlock(*decoder, cachedCodeBlockForCallOffset, m_unlinkedCodeBlockForCall, this);
     if (cachedCodeBlockForConstructOffset)
         decodeFunctionCodeBlock(*decoder, cachedCodeBlockForConstructOffset, m_unlinkedCodeBlockForConstruct, this);
     else
         m_unlinkedCodeBlockForConstruct.clear();

     WTF::storeStoreFence();
     m_isCached = false;
     vm.heap.writeBarrier(this);
 }

 UnlinkedFunctionExecutable::RareData& UnlinkedFunctionExecutable::ensureRareDataSlow()
 {
     ASSERT(!m_rareData);
     m_rareData = makeUnique<RareData>();
     return *m_rareData;
 }

 void UnlinkedFunctionExecutable::setInvalidTypeProfilingOffsets()
 {
     m_typeProfilingStartOffset = std::numeric_limits<unsigned>::max();
     m_typeProfilingEndOffset = std::numeric_limits<unsigned>::max();
 }

 void UnlinkedFunctionExecutable::finalizeUnconditionally(VM& vm)
 {
     if (codeBlockEdgeMayBeWeak()) {
         bool isCleared = false;
         bool isStillValid = false;
         auto clearIfDead = [&] (WriteBarrier<UnlinkedFunctionCodeBlock>& unlinkedCodeBlock) {
             if (!unlinkedCodeBlock)
                 return;
             if (!vm.heap.isMarked(unlinkedCodeBlock.get())) {
                 unlinkedCodeBlock.clear();
                 isCleared = true;
             } else
                 isStillValid = true;
         };
         clearIfDead(m_unlinkedCodeBlockForCall);
         clearIfDead(m_unlinkedCodeBlockForConstruct);
         if (isCleared && !isStillValid)
             vm.unlinkedFunctionExecutableSpace.set.remove(this);
     }
 }

 } // namespace JSC
	/*
	* Copyright (C) 2012-2019 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.
	*/

	#include "config.h"
	#include "UnlinkedFunctionExecutable.h"

	#include "BuiltinExecutables.h"
	#include "BytecodeGenerator.h"
	#include "CachedTypes.h"
	#include "ClassInfo.h"
	#include "CodeCache.h"
	#include "Debugger.h"
	#include "ExecutableInfo.h"
	#include "FunctionOverrides.h"
	#include "IsoCellSetInlines.h"
	#include "JSCInlines.h"
	#include "Parser.h"
	#include "SourceProvider.h"
	#include "Structure.h"
	#include "UnlinkedFunctionCodeBlock.h"
	#include <wtf/Optional.h>

	namespace JSC {

	static_assert(sizeof(UnlinkedFunctionExecutable) <= 128, "UnlinkedFunctionExecutable should fit in a 128-byte cell to keep allocated blocks count to only one after initializing JSGlobalObject.");

	const ClassInfo UnlinkedFunctionExecutable::s_info = { "UnlinkedFunctionExecutable", nullptr, nullptr, nullptr, CREATE_METHOD_TABLE(UnlinkedFunctionExecutable) };

	static UnlinkedFunctionCodeBlock* generateUnlinkedFunctionCodeBlock(
	VM& vm, UnlinkedFunctionExecutable* executable, const SourceCode& source,
	CodeSpecializationKind kind, OptionSet<CodeGenerationMode> codeGenerationMode,
	UnlinkedFunctionKind functionKind, ParserError& error, SourceParseMode parseMode)
	{
	JSParserBuiltinMode builtinMode = executable->isBuiltinFunction() ? JSParserBuiltinMode::Builtin : JSParserBuiltinMode::NotBuiltin;
	JSParserStrictMode strictMode = executable->isInStrictContext() ? JSParserStrictMode::Strict : JSParserStrictMode::NotStrict;
	JSParserScriptMode scriptMode = executable->scriptMode();
	ASSERT(isFunctionParseMode(executable->parseMode()));
	std::unique_ptr<FunctionNode> function = parse<FunctionNode>(
	vm, source, executable->name(), builtinMode, strictMode, scriptMode, executable->parseMode(), executable->superBinding(), error, nullptr);

	if (!function) {
	ASSERT(error.isValid());
	return nullptr;
	}

	function->finishParsing(executable->name(), executable->functionMode());
	executable->recordParse(function->features(), function->hasCapturedVariables());

	bool isClassContext = executable->superBinding() == SuperBinding::Needed;

	UnlinkedFunctionCodeBlock* result = UnlinkedFunctionCodeBlock::create(vm, FunctionCode, ExecutableInfo(function->usesEval(), function->isStrictMode(), kind == CodeForConstruct, functionKind == UnlinkedBuiltinFunction, executable->constructorKind(), scriptMode, executable->superBinding(), parseMode, executable->derivedContextType(), false, isClassContext, EvalContextType::FunctionEvalContext), codeGenerationMode);

	VariableEnvironment parentScopeTDZVariables = executable->parentScopeTDZVariables();
	error = BytecodeGenerator::generate(vm, function.get(), source, result, codeGenerationMode, &parentScopeTDZVariables);

	if (error.isValid())
	return nullptr;
	vm.codeCache()->updateCache(executable, source, kind, result);
	return result;
	}

	UnlinkedFunctionExecutable::UnlinkedFunctionExecutable(VM& vm, Structure* structure, const SourceCode& parentSource, FunctionMetadataNode* node, UnlinkedFunctionKind kind, ConstructAbility constructAbility, JSParserScriptMode scriptMode, Optional<CompactVariableMap::Handle> parentScopeTDZVariables, DerivedContextType derivedContextType, bool isBuiltinDefaultClassConstructor)
	: Base(vm, structure)
	, m_firstLineOffset(node->firstLine() - parentSource.firstLine().oneBasedInt())
	, m_isInStrictContext(node->isInStrictContext())
	, m_lineCount(node->lastLine() - node->firstLine())
	, m_hasCapturedVariables(false)
	, m_unlinkedFunctionNameStart(node->functionNameStart() - parentSource.startOffset())
	, m_isBuiltinFunction(kind == UnlinkedBuiltinFunction)
	, m_unlinkedBodyStartColumn(node->startColumn())
	, m_isBuiltinDefaultClassConstructor(isBuiltinDefaultClassConstructor)
	, m_unlinkedBodyEndColumn(m_lineCount ? node->endColumn() : node->endColumn() - node->startColumn())
	, m_constructAbility(static_cast<unsigned>(constructAbility))
	, m_startOffset(node->source().startOffset() - parentSource.startOffset())
	, m_scriptMode(static_cast<unsigned>(scriptMode))
	, m_sourceLength(node->source().length())
	, m_superBinding(static_cast<unsigned>(node->superBinding()))
	, m_parametersStartOffset(node->parametersStart())
	, m_isCached(false)
	, m_typeProfilingStartOffset(node->functionKeywordStart())
	, m_typeProfilingEndOffset(node->startStartOffset() + node->source().length() - 1)
	, m_parameterCount(node->parameterCount())
	, m_features(0)
	, m_sourceParseMode(node->parseMode())
	, m_constructorKind(static_cast<unsigned>(node->constructorKind()))
	, m_functionMode(static_cast<unsigned>(node->functionMode()))
	, m_derivedContextType(static_cast<unsigned>(derivedContextType))
	, m_isGeneratedFromCache(false)
	, m_unlinkedCodeBlockForCall()
	, m_unlinkedCodeBlockForConstruct()
	, m_name(node->ident())
	, m_ecmaName(node->ecmaName())
	{
	// Make sure these bitfields are adequately wide.
	ASSERT(m_constructAbility == static_cast<unsigned>(constructAbility));
	ASSERT(m_constructorKind == static_cast<unsigned>(node->constructorKind()));
	ASSERT(m_functionMode == static_cast<unsigned>(node->functionMode()));
	ASSERT(m_scriptMode == static_cast<unsigned>(scriptMode));
	ASSERT(m_superBinding == static_cast<unsigned>(node->superBinding()));
	ASSERT(m_derivedContextType == static_cast<unsigned>(derivedContextType));
	ASSERT(!(m_isBuiltinDefaultClassConstructor && constructorKind() == ConstructorKind::None));
	if (!node->classSource().isNull())
	setClassSource(node->classSource());
	if (parentScopeTDZVariables)
	ensureRareData().m_parentScopeTDZVariables = WTFMove(*parentScopeTDZVariables);
	}

	UnlinkedFunctionExecutable::~UnlinkedFunctionExecutable()
	{
	if (m_isCached)
	m_decoder.~RefPtr();
	}

	void UnlinkedFunctionExecutable::destroy(JSCell* cell)
	{
	static_cast<UnlinkedFunctionExecutable*>(cell)->~UnlinkedFunctionExecutable();
	}

	void UnlinkedFunctionExecutable::visitChildren(JSCell* cell, SlotVisitor& visitor)
	{
	UnlinkedFunctionExecutable* thisObject = jsCast<UnlinkedFunctionExecutable*>(cell);
	ASSERT_GC_OBJECT_INHERITS(thisObject, info());
	Base::visitChildren(thisObject, visitor);

	if (thisObject->codeBlockEdgeMayBeWeak()) {
	auto markIfProfitable = [&] (WriteBarrier<UnlinkedFunctionCodeBlock>& unlinkedCodeBlock) {
	if (!unlinkedCodeBlock)
	return;
	if (unlinkedCodeBlock->didOptimize() == TrueTriState)
	visitor.append(unlinkedCodeBlock);
	else if (unlinkedCodeBlock->age() < UnlinkedCodeBlock::maxAge)
	visitor.append(unlinkedCodeBlock);
	};
	markIfProfitable(thisObject->m_unlinkedCodeBlockForCall);
	markIfProfitable(thisObject->m_unlinkedCodeBlockForConstruct);
	} else if (!thisObject->m_isCached) {
	visitor.append(thisObject->m_unlinkedCodeBlockForCall);
	visitor.append(thisObject->m_unlinkedCodeBlockForConstruct);
	}
	}

	SourceCode UnlinkedFunctionExecutable::linkedSourceCode(const SourceCode& passedParentSource) const
	{
	const SourceCode& parentSource = !m_isBuiltinDefaultClassConstructor ? passedParentSource : BuiltinExecutables::defaultConstructorSourceCode(constructorKind());
	unsigned startColumn = linkedStartColumn(parentSource.startColumn().oneBasedInt());
	unsigned startOffset = parentSource.startOffset() + m_startOffset;
	unsigned firstLine = parentSource.firstLine().oneBasedInt() + m_firstLineOffset;
	return SourceCode(parentSource.provider(), startOffset, startOffset + m_sourceLength, firstLine, startColumn);
	}

	FunctionExecutable* UnlinkedFunctionExecutable::link(VM& vm, ScriptExecutable* topLevelExecutable, const SourceCode& passedParentSource, Optional<int> overrideLineNumber, Intrinsic intrinsic)
	{
	SourceCode source = linkedSourceCode(passedParentSource);
	FunctionOverrides::OverrideInfo overrideInfo;
	bool hasFunctionOverride = false;
	if (UNLIKELY(Options::functionOverrides()))
	hasFunctionOverride = FunctionOverrides::initializeOverrideFor(source, overrideInfo);

	FunctionExecutable* result = FunctionExecutable::create(vm, topLevelExecutable, source, this, intrinsic);
	if (overrideLineNumber)
	result->setOverrideLineNumber(*overrideLineNumber);

	if (UNLIKELY(hasFunctionOverride))
	result->overrideInfo(overrideInfo);

	return result;
	}

	UnlinkedFunctionExecutable* UnlinkedFunctionExecutable::fromGlobalCode(
	const Identifier& name, ExecState& exec, const SourceCode& source,
	JSObject*& exception, int overrideLineNumber, Optional<int> functionConstructorParametersEndPosition)
	{
	ParserError error;
	VM& vm = exec.vm();
	auto& globalObject = *exec.lexicalGlobalObject();
	CodeCache* codeCache = vm.codeCache();
	OptionSet<CodeGenerationMode> codeGenerationMode = globalObject.defaultCodeGenerationMode();
	UnlinkedFunctionExecutable* executable = codeCache->getUnlinkedGlobalFunctionExecutable(vm, name, source, codeGenerationMode, functionConstructorParametersEndPosition, error);

	if (globalObject.hasDebugger())
	globalObject.debugger()->sourceParsed(&exec, source.provider(), error.line(), error.message());

	if (error.isValid()) {
	exception = error.toErrorObject(&globalObject, source, overrideLineNumber);
	return nullptr;
	}

	return executable;
	}

	UnlinkedFunctionCodeBlock* UnlinkedFunctionExecutable::unlinkedCodeBlockFor(
	VM& vm, const SourceCode& source, CodeSpecializationKind specializationKind,
	OptionSet<CodeGenerationMode> codeGenerationMode, ParserError& error, SourceParseMode parseMode)
	{
	if (m_isCached)
	decodeCachedCodeBlocks(vm);
	switch (specializationKind) {
	case CodeForCall:
	if (UnlinkedFunctionCodeBlock* codeBlock = m_unlinkedCodeBlockForCall.get())
	return codeBlock;
	break;
	case CodeForConstruct:
	if (UnlinkedFunctionCodeBlock* codeBlock = m_unlinkedCodeBlockForConstruct.get())
	return codeBlock;
	break;
	}

	UnlinkedFunctionCodeBlock* result = generateUnlinkedFunctionCodeBlock(
	vm, this, source, specializationKind, codeGenerationMode,
	isBuiltinFunction() ? UnlinkedBuiltinFunction : UnlinkedNormalFunction,
	error, parseMode);

	if (error.isValid())
	return nullptr;

	switch (specializationKind) {
	case CodeForCall:
	m_unlinkedCodeBlockForCall.set(vm, this, result);
	break;
	case CodeForConstruct:
	m_unlinkedCodeBlockForConstruct.set(vm, this, result);
	break;
	}
	vm.unlinkedFunctionExecutableSpace.set.add(this);
	return result;
	}

	void UnlinkedFunctionExecutable::decodeCachedCodeBlocks(VM& vm)
	{
	ASSERT(m_isCached);
	ASSERT(m_decoder);
	ASSERT(m_cachedCodeBlockForCallOffset \|\| m_cachedCodeBlockForConstructOffset);

	RefPtr<Decoder> decoder = WTFMove(m_decoder);
	int32_t cachedCodeBlockForCallOffset = m_cachedCodeBlockForCallOffset;
	int32_t cachedCodeBlockForConstructOffset = m_cachedCodeBlockForConstructOffset;

	DeferGC deferGC(vm.heap);

	// No need to clear m_unlinkedCodeBlockForCall here, since we moved the decoder out of the same slot
	if (cachedCodeBlockForCallOffset)
	decodeFunctionCodeBlock(*decoder, cachedCodeBlockForCallOffset, m_unlinkedCodeBlockForCall, this);
	if (cachedCodeBlockForConstructOffset)
	decodeFunctionCodeBlock(*decoder, cachedCodeBlockForConstructOffset, m_unlinkedCodeBlockForConstruct, this);
	else
	m_unlinkedCodeBlockForConstruct.clear();

	WTF::storeStoreFence();
	m_isCached = false;
	vm.heap.writeBarrier(this);
	}

	UnlinkedFunctionExecutable::RareData& UnlinkedFunctionExecutable::ensureRareDataSlow()
	{
	ASSERT(!m_rareData);
	m_rareData = makeUnique<RareData>();
	return *m_rareData;
	}

	void UnlinkedFunctionExecutable::setInvalidTypeProfilingOffsets()
	{
	m_typeProfilingStartOffset = std::numeric_limits<unsigned>::max();
	m_typeProfilingEndOffset = std::numeric_limits<unsigned>::max();
	}

	void UnlinkedFunctionExecutable::finalizeUnconditionally(VM& vm)
	{
	if (codeBlockEdgeMayBeWeak()) {
	bool isCleared = false;
	bool isStillValid = false;
	auto clearIfDead = [&] (WriteBarrier<UnlinkedFunctionCodeBlock>& unlinkedCodeBlock) {
	if (!unlinkedCodeBlock)
	return;
	if (!vm.heap.isMarked(unlinkedCodeBlock.get())) {
	unlinkedCodeBlock.clear();
	isCleared = true;
	} else
	isStillValid = true;
	};
	clearIfDead(m_unlinkedCodeBlockForCall);
	clearIfDead(m_unlinkedCodeBlockForConstruct);
	if (isCleared && !isStillValid)
	vm.unlinkedFunctionExecutableSpace.set.remove(this);
	}
	}

	} // namespace JSC