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	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 RegisterFile_h
	30	#define RegisterFile_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	namespace JSC {
	39
	40	class ConservativeRoots;
	41	class DFGCodeBlocks;
	42	class LLIntOffsetsExtractor;
	43
	44	class RegisterFile {
	45	WTF_MAKE_NONCOPYABLE(RegisterFile);
	46	public:
	47	enum CallFrameHeaderEntry {
	48	CallFrameHeaderSize = 6,
	49
	50	ArgumentCount = -6,
	51	CallerFrame = -5,
	52	Callee = -4,
	53	ScopeChain = -3,
	54	ReturnPC = -2, // This is either an Instruction* or a pointer into JIT generated code stored as an Instruction*.
	55	CodeBlock = -1,
	56	};
	57
	58	static const size_t defaultCapacity = 512 * 1024;
	59	static const size_t commitSize = 16 * 1024;
	60	// Allow 8k of excess registers before we start trying to reap the registerfile
	61	static const ptrdiff_t maxExcessCapacity = 8 * 1024;
	62
	63	RegisterFile(size_t capacity = defaultCapacity);
	64	~RegisterFile();
	65
	66	void gatherConservativeRoots(ConservativeRoots&);
	67	void gatherConservativeRoots(ConservativeRoots&, DFGCodeBlocks&);
	68
	69	Register* begin() const { return static_cast<Register*>(m_reservation.base()); }
	70	Register* end() const { return m_end; }
	71	size_t size() const { return end() - begin(); }
	72
	73	bool grow(Register*);
	74	void shrink(Register*);
	75
	76	static size_t committedByteCount();
	77	static void initializeThreading();
	78
	79	Register* const * addressOfEnd() const
	80	{
	81	return &m_end;
	82	}
	83
	84	private:
	85	friend class LLIntOffsetsExtractor;
	86
	87	bool growSlowCase(Register*);
	88	void releaseExcessCapacity();
	89	void addToCommittedByteCount(long);
	90	Register* m_end;
	91	Register* m_commitEnd;
	92	PageReservation m_reservation;
	93	};
	94
	95	inline RegisterFile::RegisterFile(size_t capacity)
	96	: m_end(0)
	97	{
	98	ASSERT(capacity && isPageAligned(capacity));
	99
	100	m_reservation = PageReservation::reserve(roundUpAllocationSize(capacity * sizeof(Register), commitSize), OSAllocator::JSVMStackPages);
	101	m_end = static_cast<Register*>(m_reservation.base());
	102	m_commitEnd = static_cast<Register*>(m_reservation.base());
	103	}
	104
	105	inline void RegisterFile::shrink(Register* newEnd)
	106	{
	107	if (newEnd >= m_end)
	108	return;
	109	m_end = newEnd;
	110	if (m_end == m_reservation.base() && (m_commitEnd - begin()) >= maxExcessCapacity)
	111	releaseExcessCapacity();
	112	}
	113
	114	inline bool RegisterFile::grow(Register* newEnd)
	115	{
	116	if (newEnd <= m_end)
	117	return true;
	118	return growSlowCase(newEnd);
	119	}
	120
	121	} // namespace JSC
	122
	123	#endif // RegisterFile_h