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/*
* Copyright (C) 2008-2021 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.
* 3. Neither the name of Apple Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "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 OR ITS 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 "CodeBlock.h"
#include "JSSymbolTableObject.h"
#include "SymbolTable.h"
WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN
namespace JSC {
class LLIntOffsetsExtractor;
class JSLexicalEnvironment : public JSSymbolTableObject {
friend class JIT;
friend class LLIntOffsetsExtractor;
public:
template<typename CellType, SubspaceAccess>
static CompleteSubspace* subspaceFor(VM& vm)
{
static_assert(CellType::needsDestruction == DoesNotNeedDestruction);
return &vm.variableSizedCellSpace();
}
using Base = JSSymbolTableObject;
static constexpr unsigned StructureFlags = Base::StructureFlags | OverridesGetOwnPropertySlot | OverridesGetOwnSpecialPropertyNames | OverridesPut;
WriteBarrierBase<Unknown>* variables()
{
return std::bit_cast<WriteBarrierBase<Unknown>*>(std::bit_cast<char*>(this) + offsetOfVariables());
}
bool isValidScopeOffset(ScopeOffset offset)
{
return !!offset && offset.offset() < symbolTable()->scopeSize();
}
WriteBarrierBase<Unknown>& variableAt(ScopeOffset offset)
{
ASSERT(isValidScopeOffset(offset));
return variables()[offset.offset()];
}
static size_t offsetOfVariables()
{
return WTF::roundUpToMultipleOf<sizeof(WriteBarrier<Unknown>)>(sizeof(JSLexicalEnvironment));
}
static size_t offsetOfVariable(ScopeOffset offset)
{
Checked<size_t> scopeOffset = offset.offset();
return offsetOfVariables() + scopeOffset * sizeof(WriteBarrier<Unknown>);
}
static size_t allocationSizeForScopeSize(Checked<size_t> scopeSize)
{
return offsetOfVariables() + scopeSize * sizeof(WriteBarrier<Unknown>);
}
static size_t allocationSize(SymbolTable* symbolTable)
{
return allocationSizeForScopeSize(symbolTable->scopeSize());
}
static JSLexicalEnvironment* create(
VM& vm, Structure* structure, JSScope* currentScope, SymbolTable* symbolTable, JSValue initialValue)
{
JSLexicalEnvironment* result =
new (
NotNull,
allocateCell<JSLexicalEnvironment>(vm, allocationSize(symbolTable)))
JSLexicalEnvironment(vm, structure, currentScope, symbolTable, initialValue);
result->finishCreation(vm);
return result;
}
static JSLexicalEnvironment* create(VM& vm, JSGlobalObject* globalObject, JSScope* currentScope, SymbolTable* symbolTable, JSValue initialValue)
{
Structure* structure = globalObject->activationStructure();
return create(vm, structure, currentScope, symbolTable, initialValue);
}
static bool getOwnPropertySlot(JSObject*, JSGlobalObject*, PropertyName, PropertySlot&);
static void getOwnSpecialPropertyNames(JSObject*, JSGlobalObject*, PropertyNameArray&, DontEnumPropertiesMode);
static bool put(JSCell*, JSGlobalObject*, PropertyName, JSValue, PutPropertySlot&);
static bool deleteProperty(JSCell*, JSGlobalObject*, PropertyName, DeletePropertySlot&);
DECLARE_INFO;
inline static Structure* createStructure(VM&, JSGlobalObject*);
protected:
JSLexicalEnvironment(VM&, Structure*, JSScope*, SymbolTable*, JSValue initialValue);
DECLARE_DEFAULT_FINISH_CREATION;
DECLARE_VISIT_CHILDREN;
static void analyzeHeap(JSCell*, HeapAnalyzer&);
};
inline JSLexicalEnvironment::JSLexicalEnvironment(VM& vm, Structure* structure, JSScope* currentScope, SymbolTable* symbolTable, JSValue initialValue)
: Base(vm, structure, currentScope, symbolTable)
{
ASSERT(initialValue == jsUndefined() || initialValue == jsTDZValue());
for (unsigned i = this->symbolTable()->scopeSize(); i--;) {
// Filling this with undefined/TDZEmptyValue is useful because that's what variables start out as.
variableAt(ScopeOffset(i)).setStartingValue(initialValue);
}
}
} // namespace JSC
WTF_ALLOW_UNSAFE_BUFFER_USAGE_END
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