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/*
* 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)
{
}
// Used to set the generation info according the the result
// of various operations.
void initArgument(NodeIndex nodeIndex, uint32_t useCount)
{
m_nodeIndex = nodeIndex;
m_useCount = useCount;
m_registerFormat = DataFormatNone;
m_spillFormat = DataFormatNone;
m_canFill = true;
}
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 and arguments 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 †o 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, arguments,
// 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
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