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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 DFGVariableAccessData_h
#define DFGVariableAccessData_h
#include "DFGOperands.h"
#include "PredictedType.h"
#include "VirtualRegister.h"
#include <wtf/Platform.h>
#include <wtf/UnionFind.h>
namespace JSC { namespace DFG {
class VariableAccessData : public UnionFind<VariableAccessData> {
public:
enum Ballot { VoteValue, VoteDouble };
VariableAccessData()
: m_local(static_cast<VirtualRegister>(std::numeric_limits<int>::min()))
, m_prediction(PredictNone)
, m_shouldUseDoubleFormat(false)
{
clearVotes();
}
VariableAccessData(VirtualRegister local)
: m_local(local)
, m_prediction(PredictNone)
, m_shouldUseDoubleFormat(false)
{
clearVotes();
}
VirtualRegister local()
{
ASSERT(m_local == find()->m_local);
return m_local;
}
int operand()
{
return static_cast<int>(local());
}
bool predict(PredictedType prediction)
{
return mergePrediction(find()->m_prediction, prediction);
}
PredictedType prediction()
{
return find()->m_prediction;
}
void clearVotes()
{
ASSERT(find() == this);
m_votes[VoteValue] = 0;
m_votes[VoteDouble] = 0;
}
void vote(Ballot ballot)
{
ASSERT(static_cast<unsigned>(ballot) < 2);
m_votes[ballot]++;
}
double doubleVoteRatio()
{
ASSERT(find() == this);
return static_cast<double>(m_votes[VoteDouble]) / m_votes[VoteValue];
}
bool shouldUseDoubleFormatAccordingToVote()
{
// FIXME: make this work for arguments.
return !operandIsArgument(operand()) && ((isNumberPrediction(prediction()) && doubleVoteRatio() >= Options::doubleVoteRatioForDoubleFormat) || isDoublePrediction(prediction()));
}
bool shouldUseDoubleFormat()
{
ASSERT(find() == this);
return m_shouldUseDoubleFormat;
}
bool tallyVotesForShouldUseDoubleFormat()
{
ASSERT(find() == this);
bool newValueOfShouldUseDoubleFormat = shouldUseDoubleFormatAccordingToVote();
if (!newValueOfShouldUseDoubleFormat) {
// We monotonically convert to double. Hence, if the fixpoint leads us to conclude that we should
// switch back to int, we instead ignore this and stick with double.
return false;
}
if (m_shouldUseDoubleFormat)
return false;
m_shouldUseDoubleFormat = true;
mergePrediction(m_prediction, PredictDouble);
return true;
}
private:
// This is slightly space-inefficient, since anything we're unified with
// will have the same operand and should have the same prediction. But
// putting them here simplifies the code, and we don't expect DFG space
// usage for variable access nodes do be significant.
VirtualRegister m_local;
PredictedType m_prediction;
float m_votes[2];
bool m_shouldUseDoubleFormat;
};
} } // namespace JSC::DFG
#endif // DFGVariableAccessData_h
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