Source/JavaScriptCore/dfg/DFGGenerationInfo.h - platform/external/webkit - Git at Google

 /*
  * Copyright (C) 2011 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.
  */

 #ifndef DFGGenerationInfo_h
 #define DFGGenerationInfo_h

 #if ENABLE(DFG_JIT)

 #include <dfg/DFGJITCompiler.h>

 namespace JSC { namespace DFG {

 // === DataFormat ===
 //
 // This enum tracks the current representation in which a value is being held.
 // Values may be unboxed primitives (int32, double, or cell), or boxed as a JSValue.
 // For boxed values, we may know the type of boxing that has taken place.
 // (May also need bool, array, object, string types!)
 enum DataFormat {
     DataFormatNone = 0,
     DataFormatInteger = 1,
     DataFormatDouble = 2,
     DataFormatCell = 3,
     DataFormatJS = 8,
     DataFormatJSInteger = DataFormatJS | DataFormatInteger,
     DataFormatJSDouble = DataFormatJS | DataFormatDouble,
     DataFormatJSCell = DataFormatJS | DataFormatCell,
 };

 // === GenerationInfo ===
 //
 // This class is used to track the current status of a live values during code generation.
 // Can provide information as to whether a value is in machine registers, and if so which,
 // whether a value has been spilled to the RegsiterFile, and if so may be able to provide
 // details of the format in memory (all values are spilled in a boxed form, but we may be
 // able to track the type of box), and tracks how many outstanding uses of a value remain,
 // so that we know when the value is dead and the machine registers associated with it
 // may be released.
 class GenerationInfo {
 public:
     GenerationInfo()
         : m_nodeIndex(NoNode)
         , m_useCount(0)
         , m_registerFormat(DataFormatNone)
         , m_spillFormat(DataFormatNone)
         , m_canFill(false)
     {
     }

     void initConstant(NodeIndex nodeIndex, uint32_t useCount)
     {
         m_nodeIndex = nodeIndex;
         m_useCount = useCount;
         m_registerFormat = DataFormatNone;
         m_spillFormat = DataFormatNone;
         m_canFill = true;
     }
     void initInteger(NodeIndex nodeIndex, uint32_t useCount, GPRReg gpr)
     {
         m_nodeIndex = nodeIndex;
         m_useCount = useCount;
         m_registerFormat = DataFormatInteger;
         m_spillFormat = DataFormatNone;
         m_canFill = false;
         u.gpr = gpr;
     }
     void initJSValue(NodeIndex nodeIndex, uint32_t useCount, GPRReg gpr, DataFormat format = DataFormatJS)
     {
         ASSERT(format & DataFormatJS);

         m_nodeIndex = nodeIndex;
         m_useCount = useCount;
         m_registerFormat = format;
         m_spillFormat = DataFormatNone;
         m_canFill = false;
         u.gpr = gpr;
     }
     void initCell(NodeIndex nodeIndex, uint32_t useCount, GPRReg gpr)
     {
         m_nodeIndex = nodeIndex;
         m_useCount = useCount;
         m_registerFormat = DataFormatCell;
         m_spillFormat = DataFormatNone;
         m_canFill = false;
         u.gpr = gpr;
     }
     void initDouble(NodeIndex nodeIndex, uint32_t useCount, FPRReg fpr)
     {
         m_nodeIndex = nodeIndex;
         m_useCount = useCount;
         m_registerFormat = DataFormatDouble;
         m_spillFormat = DataFormatNone;
         m_canFill = false;
         u.fpr = fpr;
     }
     void initNone(NodeIndex nodeIndex, uint32_t useCount)
     {
         m_nodeIndex = nodeIndex;
         m_useCount = useCount;
         m_registerFormat = DataFormatNone;
         m_spillFormat = DataFormatNone;
         m_canFill = false;
     }

     // Get the index of the node that produced this value.
     NodeIndex nodeIndex() { return m_nodeIndex; }

     // Mark the value as having been used (decrement the useCount).
     // Returns true if this was the last use of the value, and any
     // associated machine registers may be freed.
     bool use()
     {
         return !--m_useCount;
     }

     // Used to check the operands of operations to see if they are on
     // their last use; in some cases it may be safe to reuse the same
     // machine register for the result of the operation.
     bool canReuse()
     {
         ASSERT(m_useCount);
         return m_useCount == 1;
     }

     // Get the format of the value in machine registers (or 'none').
     DataFormat registerFormat() { return m_registerFormat; }
     // Get the format of the value as it is spilled in the RegisterFile (or 'none').
     DataFormat spillFormat() { return m_spillFormat; }

     // Get the machine resister currently holding the value.
     GPRReg gpr() { ASSERT(m_registerFormat && m_registerFormat != DataFormatDouble); return u.gpr; }
     FPRReg fpr() { ASSERT(m_registerFormat == DataFormatDouble); return u.fpr; }

     // Check whether a value needs spilling in order to free up any associated machine registers.
     bool needsSpill()
     {
         // This should only be called on values that are currently in a register.
         ASSERT(m_registerFormat != DataFormatNone);
         // Constants do not need spilling, nor do values that have already been
         // spilled to the RegisterFile.
         return !m_canFill;
     }

     // Called when a VirtualRegister is being spilled to the RegisterFile for the first time.
     void spill(DataFormat spillFormat)
     {
         // We shouldn't be spill values that don't need spilling.
         ASSERT(!m_canFill);
         ASSERT(m_spillFormat == DataFormatNone);
         // We should only be spilling values that are currently in machine registers.
         ASSERT(m_registerFormat != DataFormatNone);
         // We only spill values that have been boxed as a JSValue; otherwise the GC
         // would need a way to distinguish cell pointers from numeric primitives.
         ASSERT(spillFormat & DataFormatJS);

         m_registerFormat = DataFormatNone;
         m_spillFormat = spillFormat;
         m_canFill = true;
     }

     // Called on values that don't need spilling (constants and values that have
     // already been spilled), to mark them as no longer being in machine registers.
     void setSpilled()
     {
         // Should only be called on values that don't need spilling, and are currently in registers.
         ASSERT(m_canFill && m_registerFormat != DataFormatNone);
         m_registerFormat = DataFormatNone;
     }

     // Record that this value is filled into machine registers,
     // tracking which registers, and what format the value has.
     void fillJSValue(GPRReg gpr, DataFormat format = DataFormatJS)
     {
         ASSERT(format & DataFormatJS);
         m_registerFormat = format;
         u.gpr = gpr;
     }
     void fillInteger(GPRReg gpr)
     {
         m_registerFormat = DataFormatInteger;
         u.gpr = gpr;
     }
     void fillDouble(FPRReg fpr)
     {
         m_registerFormat = DataFormatDouble;
         u.fpr = fpr;
     }

 #ifndef NDEBUG
     bool alive()
     {
         return m_useCount;
     }
 #endif

 private:
     // The index of the node whose result is stored in this virtual register.
     // FIXME: Can we remove this? - this is currently only used when collecting
     // snapshots of the RegisterBank for SpeculationCheck/EntryLocation. Could
     // investigate storing NodeIndex as the name in RegsiterBank, instead of
     // VirtualRegister.
     NodeIndex m_nodeIndex;
     uint32_t m_useCount;
     DataFormat m_registerFormat;
     DataFormat m_spillFormat;
     bool m_canFill;
     union {
         GPRReg gpr;
         FPRReg fpr;
     } u;
 };

 } } // namespace JSC::DFG

 #endif
 #endif
	/*
	* Copyright (C) 2011 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.
	*/

	#ifndef DFGGenerationInfo_h
	#define DFGGenerationInfo_h

	#if ENABLE(DFG_JIT)

	#include <dfg/DFGJITCompiler.h>

	namespace JSC { namespace DFG {

	// === DataFormat ===
	//
	// This enum tracks the current representation in which a value is being held.
	// Values may be unboxed primitives (int32, double, or cell), or boxed as a JSValue.
	// For boxed values, we may know the type of boxing that has taken place.
	// (May also need bool, array, object, string types!)
	enum DataFormat {
	DataFormatNone = 0,
	DataFormatInteger = 1,
	DataFormatDouble = 2,
	DataFormatCell = 3,
	DataFormatJS = 8,
	DataFormatJSInteger = DataFormatJS \| DataFormatInteger,
	DataFormatJSDouble = DataFormatJS \| DataFormatDouble,
	DataFormatJSCell = DataFormatJS \| DataFormatCell,
	};

	// === GenerationInfo ===
	//
	// This class is used to track the current status of a live values during code generation.
	// Can provide information as to whether a value is in machine registers, and if so which,
	// whether a value has been spilled to the RegsiterFile, and if so may be able to provide
	// details of the format in memory (all values are spilled in a boxed form, but we may be
	// able to track the type of box), and tracks how many outstanding uses of a value remain,
	// so that we know when the value is dead and the machine registers associated with it
	// may be released.
	class GenerationInfo {
	public:
	GenerationInfo()
	: m_nodeIndex(NoNode)
	, m_useCount(0)
	, m_registerFormat(DataFormatNone)
	, m_spillFormat(DataFormatNone)
	, m_canFill(false)
	{
	}

	void initConstant(NodeIndex nodeIndex, uint32_t useCount)
	{
	m_nodeIndex = nodeIndex;
	m_useCount = useCount;
	m_registerFormat = DataFormatNone;
	m_spillFormat = DataFormatNone;
	m_canFill = true;
	}
	void initInteger(NodeIndex nodeIndex, uint32_t useCount, GPRReg gpr)
	{
	m_nodeIndex = nodeIndex;
	m_useCount = useCount;
	m_registerFormat = DataFormatInteger;
	m_spillFormat = DataFormatNone;
	m_canFill = false;
	u.gpr = gpr;
	}
	void initJSValue(NodeIndex nodeIndex, uint32_t useCount, GPRReg gpr, DataFormat format = DataFormatJS)
	{
	ASSERT(format & DataFormatJS);

	m_nodeIndex = nodeIndex;
	m_useCount = useCount;
	m_registerFormat = format;
	m_spillFormat = DataFormatNone;
	m_canFill = false;
	u.gpr = gpr;
	}
	void initCell(NodeIndex nodeIndex, uint32_t useCount, GPRReg gpr)
	{
	m_nodeIndex = nodeIndex;
	m_useCount = useCount;
	m_registerFormat = DataFormatCell;
	m_spillFormat = DataFormatNone;
	m_canFill = false;
	u.gpr = gpr;
	}
	void initDouble(NodeIndex nodeIndex, uint32_t useCount, FPRReg fpr)
	{
	m_nodeIndex = nodeIndex;
	m_useCount = useCount;
	m_registerFormat = DataFormatDouble;
	m_spillFormat = DataFormatNone;
	m_canFill = false;
	u.fpr = fpr;
	}
	void initNone(NodeIndex nodeIndex, uint32_t useCount)
	{
	m_nodeIndex = nodeIndex;
	m_useCount = useCount;
	m_registerFormat = DataFormatNone;
	m_spillFormat = DataFormatNone;
	m_canFill = false;
	}

	// Get the index of the node that produced this value.
	NodeIndex nodeIndex() { return m_nodeIndex; }

	// Mark the value as having been used (decrement the useCount).
	// Returns true if this was the last use of the value, and any
	// associated machine registers may be freed.
	bool use()
	{
	return !--m_useCount;
	}

	// Used to check the operands of operations to see if they are on
	// their last use; in some cases it may be safe to reuse the same
	// machine register for the result of the operation.
	bool canReuse()
	{
	ASSERT(m_useCount);
	return m_useCount == 1;
	}

	// Get the format of the value in machine registers (or 'none').
	DataFormat registerFormat() { return m_registerFormat; }
	// Get the format of the value as it is spilled in the RegisterFile (or 'none').
	DataFormat spillFormat() { return m_spillFormat; }

	// Get the machine resister currently holding the value.
	GPRReg gpr() { ASSERT(m_registerFormat && m_registerFormat != DataFormatDouble); return u.gpr; }
	FPRReg fpr() { ASSERT(m_registerFormat == DataFormatDouble); return u.fpr; }

	// Check whether a value needs spilling in order to free up any associated machine registers.
	bool needsSpill()
	{
	// This should only be called on values that are currently in a register.
	ASSERT(m_registerFormat != DataFormatNone);
	// Constants do not need spilling, nor do values that have already been
	// spilled to the RegisterFile.
	return !m_canFill;
	}

	// Called when a VirtualRegister is being spilled to the RegisterFile for the first time.
	void spill(DataFormat spillFormat)
	{
	// We shouldn't be spill values that don't need spilling.
	ASSERT(!m_canFill);
	ASSERT(m_spillFormat == DataFormatNone);
	// We should only be spilling values that are currently in machine registers.
	ASSERT(m_registerFormat != DataFormatNone);
	// We only spill values that have been boxed as a JSValue; otherwise the GC
	// would need a way to distinguish cell pointers from numeric primitives.
	ASSERT(spillFormat & DataFormatJS);

	m_registerFormat = DataFormatNone;
	m_spillFormat = spillFormat;
	m_canFill = true;
	}

	// Called on values that don't need spilling (constants and values that have
	// already been spilled), to mark them as no longer being in machine registers.
	void setSpilled()
	{
	// Should only be called on values that don't need spilling, and are currently in registers.
	ASSERT(m_canFill && m_registerFormat != DataFormatNone);
	m_registerFormat = DataFormatNone;
	}

	// Record that this value is filled into machine registers,
	// tracking which registers, and what format the value has.
	void fillJSValue(GPRReg gpr, DataFormat format = DataFormatJS)
	{
	ASSERT(format & DataFormatJS);
	m_registerFormat = format;
	u.gpr = gpr;
	}
	void fillInteger(GPRReg gpr)
	{
	m_registerFormat = DataFormatInteger;
	u.gpr = gpr;
	}
	void fillDouble(FPRReg fpr)
	{
	m_registerFormat = DataFormatDouble;
	u.fpr = fpr;
	}

	#ifndef NDEBUG
	bool alive()
	{
	return m_useCount;
	}
	#endif

	private:
	// The index of the node whose result is stored in this virtual register.
	// FIXME: Can we remove this? - this is currently only used when collecting
	// snapshots of the RegisterBank for SpeculationCheck/EntryLocation. Could
	// investigate storing NodeIndex as the name in RegsiterBank, instead of
	// VirtualRegister.
	NodeIndex m_nodeIndex;
	uint32_t m_useCount;
	DataFormat m_registerFormat;
	DataFormat m_spillFormat;
	bool m_canFill;
	union {
	GPRReg gpr;
	FPRReg fpr;
	} u;
	};

	} } // namespace JSC::DFG

	#endif
	#endif