mirror of
https://github.com/darlinghq/darling-JavaScriptCore.git
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102 lines
3.8 KiB
C++
102 lines
3.8 KiB
C++
/*
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* Copyright (C) 2015-2020 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include "JSCast.h"
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#include "ScopeOffset.h"
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#include "VM.h"
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#include <wtf/Assertions.h>
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#include <wtf/CagedUniquePtr.h>
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namespace JSC {
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// This class's only job is to hold onto the list of ScopeOffsets for each argument that a
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// function has. Most of the time, the BytecodeGenerator will create one of these and it will
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// never be modified subsequently. There is a rare case where a ScopedArguments object is created
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// and aliases one of these and then decides to modify it; in that case we do copy-on-write. This
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// makes sense because such modifications are so uncommon. You'd have to do something crazy like
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// "delete arguments[i]" or some variant of defineOwnProperty.
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class ScopedArgumentsTable final : public JSCell {
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friend class CachedScopedArgumentsTable;
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public:
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using Base = JSCell;
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static constexpr unsigned StructureFlags = Base::StructureFlags | StructureIsImmortal;
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static constexpr bool needsDestruction = true;
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template<typename CellType, SubspaceAccess mode>
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static IsoSubspace* subspaceFor(VM& vm)
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{
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return vm.scopedArgumentsTableSpace<mode>();
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}
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private:
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ScopedArgumentsTable(VM&);
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~ScopedArgumentsTable();
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public:
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static ScopedArgumentsTable* create(VM&);
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static ScopedArgumentsTable* tryCreate(VM&, uint32_t length);
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static void destroy(JSCell*);
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uint32_t length() const { return m_length; }
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ScopedArgumentsTable* trySetLength(VM&, uint32_t newLength);
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ScopeOffset get(uint32_t i) const { return at(i); }
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void lock()
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{
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m_locked = true;
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}
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ScopedArgumentsTable* trySet(VM&, uint32_t index, ScopeOffset);
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DECLARE_INFO;
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static Structure* createStructure(VM&, JSGlobalObject*, JSValue prototype);
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static ptrdiff_t offsetOfLength() { return OBJECT_OFFSETOF(ScopedArgumentsTable, m_length); }
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static ptrdiff_t offsetOfArguments() { return OBJECT_OFFSETOF(ScopedArgumentsTable, m_arguments); }
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typedef CagedUniquePtr<Gigacage::Primitive, ScopeOffset> ArgumentsPtr;
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private:
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ScopedArgumentsTable* tryClone(VM&);
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ScopeOffset& at(uint32_t i) const
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{
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ASSERT_WITH_SECURITY_IMPLICATION(i < m_length);
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return m_arguments.get(length())[i];
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}
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uint32_t m_length;
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bool m_locked; // Being locked means that there are multiple references to this object and none of them expect to see the others' modifications. This means that modifications need to make a copy first.
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ArgumentsPtr m_arguments;
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};
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} // namespace JSC
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