mirror of
https://github.com/darlinghq/darling-JavaScriptCore.git
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114 lines
4.1 KiB
C++
114 lines
4.1 KiB
C++
/*
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* Copyright (C) 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 "JSCJSValue.h"
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namespace WTF {
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class PrintStream;
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class UniquedStringImpl;
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} // namespace WTF
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using WTF::PrintStream;
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using WTF::UniquedStringImpl;
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namespace JSC {
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class CodeBlock;
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class Identifier;
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class JSCell;
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class SlotVisitor;
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class CacheableIdentifier {
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public:
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CacheableIdentifier() = default;
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static inline CacheableIdentifier createFromCell(JSCell* identifier);
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static inline CacheableIdentifier createFromIdentifierOwnedByCodeBlock(CodeBlock*, const Identifier&);
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static inline CacheableIdentifier createFromIdentifierOwnedByCodeBlock(CodeBlock*, UniquedStringImpl*);
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static inline CacheableIdentifier createFromImmortalIdentifier(UniquedStringImpl*);
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static constexpr CacheableIdentifier createFromRawBits(uintptr_t rawBits) { return CacheableIdentifier(rawBits); }
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CacheableIdentifier(const CacheableIdentifier&) = default;
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CacheableIdentifier(CacheableIdentifier&&) = default;
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CacheableIdentifier(std::nullptr_t)
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: m_bits(0)
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{ }
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bool isUid() const { return m_bits & s_uidTag; }
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bool isCell() const { return !isUid(); }
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inline bool isSymbolCell() const;
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inline bool isStringCell() const;
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bool isSymbol() const { return m_bits && uid()->isSymbol(); }
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inline JSCell* cell() const;
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UniquedStringImpl* uid() const;
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explicit operator bool() const { return m_bits; }
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unsigned hash() const { return uid()->symbolAwareHash(); }
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CacheableIdentifier& operator=(const CacheableIdentifier&) = default;
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CacheableIdentifier& operator=(CacheableIdentifier&&) = default;
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bool operator==(const CacheableIdentifier& other) const;
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bool operator!=(const CacheableIdentifier& other) const;
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bool operator==(const Identifier& other) const;
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static inline bool isCacheableIdentifierCell(JSCell*);
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static inline bool isCacheableIdentifierCell(JSValue);
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uintptr_t rawBits() const { return m_bits; }
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inline void visitAggregate(SlotVisitor&) const;
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JS_EXPORT_PRIVATE void dump(PrintStream&) const;
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private:
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explicit inline CacheableIdentifier(UniquedStringImpl*);
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explicit inline CacheableIdentifier(JSCell* identifier);
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explicit constexpr CacheableIdentifier(uintptr_t rawBits)
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: m_bits(rawBits)
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{ }
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inline void setCellBits(JSCell*);
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inline void setUidBits(UniquedStringImpl*);
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// CacheableIdentifier can either hold a cell pointer or a uid. To discern which
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// it is holding, we tag the low bit if we have a uid. We choose to tag the uid
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// instead of the cell because this keeps the bits of the cell pointer form
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// unpolluted, and therefore, it can be scanned by our conservative GC to keep the
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// cell alive when the CacheableIdentifier is on the stack.
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static constexpr uintptr_t s_uidTag = 1;
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uintptr_t m_bits { 0 };
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};
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} // namespace JSC
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