mirror of
https://github.com/darlinghq/darling-JavaScriptCore.git
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114 lines
3.7 KiB
C++
114 lines
3.7 KiB
C++
/*
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* Copyright (C) 2016-2020 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 "DestructionMode.h"
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#include "EnsureStillAliveHere.h"
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namespace JSC {
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class CellContainer;
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class Heap;
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class PreciseAllocation;
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class MarkedBlock;
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class Subspace;
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class VM;
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struct CellAttributes;
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class HeapCell {
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public:
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enum Kind : int8_t {
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JSCell,
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JSCellWithIndexingHeader,
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Auxiliary
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};
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HeapCell() { }
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// We're intentionally only zapping the bits for the structureID and leaving
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// the rest of the cell header bits intact for crash analysis uses.
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enum ZapReason : int8_t { Unspecified, Destruction, StopAllocating };
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void zap(ZapReason reason)
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{
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uint32_t* cellWords = bitwise_cast<uint32_t*>(this);
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cellWords[0] = 0;
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// Leaving cellWords[1] alone for crash analysis if needed.
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cellWords[2] = reason;
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}
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bool isZapped() const { return !*bitwise_cast<const uint32_t*>(this); }
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bool isLive();
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bool isPreciseAllocation() const;
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CellContainer cellContainer() const;
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MarkedBlock& markedBlock() const;
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PreciseAllocation& preciseAllocation() const;
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// If you want performance and you know that your cell is small, you can do this instead:
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// ASSERT(!cell->isPreciseAllocation());
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// cell->markedBlock().vm()
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// We currently only use this hack for callees to make CallFrame::vm() fast. It's not
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// recommended to use it for too many other things, since the large allocation cutoff is
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// a runtime option and its default value is small (400 bytes).
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Heap* heap() const;
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VM& vm() const;
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size_t cellSize() const;
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CellAttributes cellAttributes() const;
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DestructionMode destructionMode() const;
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Kind cellKind() const;
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Subspace* subspace() const;
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// Call use() after the last point where you need `this` pointer to be kept alive. You usually don't
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// need to use this, but it might be necessary if you're otherwise referring to an object's innards
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// but not the object itself.
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ALWAYS_INLINE void use() const
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{
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ensureStillAliveHere(this);
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}
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};
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inline bool isJSCellKind(HeapCell::Kind kind)
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{
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return kind == HeapCell::JSCell || kind == HeapCell::JSCellWithIndexingHeader;
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}
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inline bool mayHaveIndexingHeader(HeapCell::Kind kind)
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{
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return kind == HeapCell::Auxiliary || kind == HeapCell::JSCellWithIndexingHeader;
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}
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} // namespace JSC
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namespace WTF {
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class PrintStream;
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void printInternal(PrintStream&, JSC::HeapCell::Kind);
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} // namespace WTF
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