/* * Copyright (C) 2016-2017 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. */ #pragma once #include "DestructionMode.h" namespace JSC { class CellContainer; class Heap; class LargeAllocation; class MarkedBlock; class VM; struct AllocatorAttributes; class HeapCell { public: enum Kind : int8_t { JSCell, Auxiliary }; HeapCell() { } void zap() { *reinterpret_cast_ptr<uintptr_t**>(this) = 0; } bool isZapped() const { return !*reinterpret_cast_ptr<uintptr_t* const*>(this); } bool isLive(); bool isLargeAllocation() const; CellContainer cellContainer() const; MarkedBlock& markedBlock() const; LargeAllocation& largeAllocation() const; // If you want performance and you know that your cell is small, you can do this instead: // ASSERT(!cell->isLargeAllocation()); // cell->markedBlock().vm() // We currently only use this hack for callees to make ExecState::vm() fast. It's not // recommended to use it for too many other things, since the large allocation cutoff is // a runtime option and its default value is small (400 bytes). Heap* heap() const; VM* vm() const; size_t cellSize() const; AllocatorAttributes allocatorAttributes() const; DestructionMode destructionMode() const; Kind cellKind() const; // Call use() after the last point where you need `this` pointer to be kept alive. You usually don't // need to use this, but it might be necessary if you're otherwise referring to an object's innards // but not the object itself. #if COMPILER(GCC_OR_CLANG) void use() const { asm volatile ("" : : "r"(this) : "memory"); } #else void use() const; #endif }; } // namespace JSC namespace WTF { class PrintStream; void printInternal(PrintStream&, JSC::HeapCell::Kind); } // namespace WTF