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Commit	Line	Data
	1	/*
	2	* Copyright (C) 2008, 2009 Apple Inc. All rights reserved.
	3	*
	4	* Redistribution and use in source and binary forms, with or without
	5	* modification, are permitted provided that the following conditions
	6	* are met:
	7	*
	8	* 1. Redistributions of source code must retain the above copyright
	9	* notice, this list of conditions and the following disclaimer.
	10	* 2. Redistributions in binary form must reproduce the above copyright
	11	* notice, this list of conditions and the following disclaimer in the
	12	* documentation and/or other materials provided with the distribution.
	13	* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
	14	* its contributors may be used to endorse or promote products derived
	15	* from this software without specific prior written permission.
	16	*
	17	* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
	18	* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
	19	* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	20	* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
	21	* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
	22	* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	23	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
	24	* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	27	*/
	28
	29	#ifndef JSStack_h
	30	#define JSStack_h
	31
	32	#include "ExecutableAllocator.h"
	33	#include "Register.h"
	34	#include <wtf/Noncopyable.h>
	35	#include <wtf/PageReservation.h>
	36	#include <wtf/VMTags.h>
	37
	38	#if !defined(NDEBUG) && !defined(ENABLE_DEBUG_JSSTACK)
	39	#define ENABLE_DEBUG_JSSTACK 1
	40	#endif
	41
	42	namespace JSC {
	43
	44	class ConservativeRoots;
	45	class DFGCodeBlocks;
	46	class ExecState;
	47	class JITStubRoutineSet;
	48	class VM;
	49	class LLIntOffsetsExtractor;
	50
	51	class JSStack {
	52	WTF_MAKE_NONCOPYABLE(JSStack);
	53	public:
	54	enum CallFrameHeaderEntry {
	55	CallFrameHeaderSize = 6,
	56
	57	ArgumentCount = -6,
	58	CallerFrame = -5,
	59	Callee = -4,
	60	ScopeChain = -3,
	61	ReturnPC = -2, // This is either an Instruction* or a pointer into JIT generated code stored as an Instruction*.
	62	CodeBlock = -1,
	63	};
	64
	65	static const size_t defaultCapacity = 512 * 1024;
	66	static const size_t commitSize = 16 * 1024;
	67	// Allow 8k of excess registers before we start trying to reap the stack
	68	static const ptrdiff_t maxExcessCapacity = 8 * 1024;
	69
	70	JSStack(VM&, size_t capacity = defaultCapacity);
	71	~JSStack();
	72
	73	void gatherConservativeRoots(ConservativeRoots&);
	74	void gatherConservativeRoots(ConservativeRoots&, JITStubRoutineSet&, DFGCodeBlocks&);
	75
	76	Register* begin() const { return static_cast<Register*>(m_reservation.base()); }
	77	Register* end() const { return m_end; }
	78	size_t size() const { return end() - begin(); }
	79
	80	bool grow(Register*);
	81
	82	static size_t committedByteCount();
	83	static void initializeThreading();
	84
	85	Register* const * addressOfEnd() const
	86	{
	87	return &m_end;
	88	}
	89
	90	Register* getTopOfFrame(CallFrame*);
	91	Register* getStartOfFrame(CallFrame*);
	92	Register* getTopOfStack();
	93
	94	CallFrame* pushFrame(CallFrame* callerFrame, class CodeBlock*,
	95	JSScope, int argsCount, JSObject callee);
	96
	97	void popFrame(CallFrame*);
	98
	99	void enableErrorStackReserve();
	100	void disableErrorStackReserve();
	101
	102	#if ENABLE(DEBUG_JSSTACK)
	103	void installFence(CallFrame, const char function = "", int lineNo = 0);
	104	void validateFence(CallFrame, const char function = "", int lineNo = 0);
	105	static const int FenceSize = 4;
	106	#else // !ENABLE(DEBUG_JSSTACK)
	107	void installFence(CallFrame, const char = "", int = 0) { }
	108	void validateFence(CallFrame, const char = "", int = 0) { }
	109	#endif // !ENABLE(DEBUG_JSSTACK)
	110
	111	private:
	112	Register* reservationEnd() const
	113	{
	114	char* base = static_cast<char*>(m_reservation.base());
	115	char* reservationEnd = base + m_reservation.size();
	116	return reinterpret_cast_ptr<Register*>(reservationEnd);
	117	}
	118
	119	#if ENABLE(DEBUG_JSSTACK)
	120	static JSValue generateFenceValue(size_t argIndex);
	121	void installTrapsAfterFrame(CallFrame*);
	122	#else
	123	void installTrapsAfterFrame(CallFrame*) { }
	124	#endif
	125
	126	bool growSlowCase(Register*);
	127	void shrink(Register*);
	128	void releaseExcessCapacity();
	129	void addToCommittedByteCount(long);
	130
	131	Register* m_end;
	132	Register* m_commitEnd;
	133	Register* m_useableEnd;
	134	PageReservation m_reservation;
	135	CallFrame*& m_topCallFrame;
	136
	137	friend class LLIntOffsetsExtractor;
	138	};
	139
	140	inline void JSStack::shrink(Register* newEnd)
	141	{
	142	if (newEnd >= m_end)
	143	return;
	144	m_end = newEnd;
	145	if (m_end == m_reservation.base() && (m_commitEnd - begin()) >= maxExcessCapacity)
	146	releaseExcessCapacity();
	147	}
	148
	149	inline bool JSStack::grow(Register* newEnd)
	150	{
	151	if (newEnd <= m_end)
	152	return true;
	153	return growSlowCase(newEnd);
	154	}
	155
	156	} // namespace JSC
	157
	158	#endif // JSStack_h