DFGVariableAccessData.h [plain text]
#ifndef DFGVariableAccessData_h
#define DFGVariableAccessData_h
#include "DFGDoubleFormatState.h"
#include "DFGNodeFlags.h"
#include "Operands.h"
#include "SpeculatedType.h"
#include "VirtualRegister.h"
#include <wtf/Platform.h>
#include <wtf/UnionFind.h>
#include <wtf/Vector.h>
namespace JSC { namespace DFG {
enum DoubleBallot { VoteValue, VoteDouble };
class VariableAccessData : public UnionFind<VariableAccessData> {
public:
VariableAccessData()
: m_local(static_cast<VirtualRegister>(std::numeric_limits<int>::min()))
, m_prediction(SpecNone)
, m_argumentAwarePrediction(SpecNone)
, m_flags(0)
, m_isCaptured(false)
, m_shouldNeverUnbox(false)
, m_isArgumentsAlias(false)
, m_structureCheckHoistingFailed(false)
, m_isProfitableToUnbox(false)
, m_isLoadedFrom(false)
, m_doubleFormatState(EmptyDoubleFormatState)
{
clearVotes();
}
VariableAccessData(VirtualRegister local, bool isCaptured)
: m_local(local)
, m_prediction(SpecNone)
, m_argumentAwarePrediction(SpecNone)
, m_flags(0)
, m_isCaptured(isCaptured)
, m_shouldNeverUnbox(isCaptured)
, m_isArgumentsAlias(false)
, m_structureCheckHoistingFailed(false)
, m_isProfitableToUnbox(false)
, m_doubleFormatState(EmptyDoubleFormatState)
{
clearVotes();
}
VirtualRegister local()
{
ASSERT(m_local == find()->m_local);
return m_local;
}
int operand()
{
return static_cast<int>(local());
}
bool mergeIsCaptured(bool isCaptured)
{
return checkAndSet(m_shouldNeverUnbox, m_shouldNeverUnbox | isCaptured)
| checkAndSet(m_isCaptured, m_isCaptured | isCaptured);
}
bool isCaptured()
{
return m_isCaptured;
}
bool mergeIsProfitableToUnbox(bool isProfitableToUnbox)
{
return checkAndSet(m_isProfitableToUnbox, m_isProfitableToUnbox | isProfitableToUnbox);
}
bool isProfitableToUnbox()
{
return m_isProfitableToUnbox;
}
bool mergeShouldNeverUnbox(bool shouldNeverUnbox)
{
bool newShouldNeverUnbox = m_shouldNeverUnbox | shouldNeverUnbox;
if (newShouldNeverUnbox == m_shouldNeverUnbox)
return false;
m_shouldNeverUnbox = newShouldNeverUnbox;
return true;
}
bool shouldNeverUnbox()
{
ASSERT(!(m_isCaptured && !m_shouldNeverUnbox));
return m_shouldNeverUnbox;
}
bool shouldUnboxIfPossible()
{
return !shouldNeverUnbox() && isProfitableToUnbox();
}
bool mergeStructureCheckHoistingFailed(bool failed)
{
return checkAndSet(m_structureCheckHoistingFailed, m_structureCheckHoistingFailed | failed);
}
bool structureCheckHoistingFailed()
{
return m_structureCheckHoistingFailed;
}
bool mergeIsArgumentsAlias(bool isArgumentsAlias)
{
return checkAndSet(m_isArgumentsAlias, m_isArgumentsAlias | isArgumentsAlias);
}
bool isArgumentsAlias()
{
return m_isArgumentsAlias;
}
bool mergeIsLoadedFrom(bool isLoadedFrom)
{
return checkAndSet(m_isLoadedFrom, m_isLoadedFrom | isLoadedFrom);
}
void setIsLoadedFrom(bool isLoadedFrom)
{
m_isLoadedFrom = isLoadedFrom;
}
bool isLoadedFrom()
{
return m_isLoadedFrom;
}
bool predict(SpeculatedType prediction)
{
VariableAccessData* self = find();
bool result = mergeSpeculation(self->m_prediction, prediction);
if (result)
mergeSpeculation(m_argumentAwarePrediction, m_prediction);
return result;
}
SpeculatedType nonUnifiedPrediction()
{
return m_prediction;
}
SpeculatedType prediction()
{
return find()->m_prediction;
}
SpeculatedType argumentAwarePrediction()
{
return find()->m_argumentAwarePrediction;
}
bool mergeArgumentAwarePrediction(SpeculatedType prediction)
{
return mergeSpeculation(find()->m_argumentAwarePrediction, prediction);
}
void clearVotes()
{
ASSERT(find() == this);
m_votes[0] = 0;
m_votes[1] = 0;
}
void vote(unsigned ballot)
{
ASSERT(ballot < 2);
m_votes[ballot]++;
}
double voteRatio()
{
ASSERT(find() == this);
return static_cast<double>(m_votes[1]) / m_votes[0];
}
bool shouldUseDoubleFormatAccordingToVote()
{
if (operandIsArgument(operand()))
return false;
if (!isNumberSpeculation(prediction())) {
return false;
}
if (isDoubleSpeculation(prediction()))
return true;
if (flags() & NodeUsedAsInt)
return false;
if (voteRatio() >= Options::doubleVoteRatioForDoubleFormat())
return true;
return false;
}
DoubleFormatState doubleFormatState()
{
return find()->m_doubleFormatState;
}
bool shouldUseDoubleFormat()
{
ASSERT(isRoot());
bool doubleState = m_doubleFormatState == UsingDoubleFormat;
ASSERT(!(doubleState && shouldNeverUnbox()));
ASSERT(!(doubleState && isCaptured()));
return doubleState && isProfitableToUnbox();
}
bool tallyVotesForShouldUseDoubleFormat()
{
ASSERT(isRoot());
if (operandIsArgument(local()) || shouldNeverUnbox())
return DFG::mergeDoubleFormatState(m_doubleFormatState, NotUsingDoubleFormat);
if (m_doubleFormatState == CantUseDoubleFormat)
return false;
bool newValueOfShouldUseDoubleFormat = shouldUseDoubleFormatAccordingToVote();
if (!newValueOfShouldUseDoubleFormat) {
return false;
}
if (m_doubleFormatState == UsingDoubleFormat)
return false;
return DFG::mergeDoubleFormatState(m_doubleFormatState, UsingDoubleFormat);
}
bool mergeDoubleFormatState(DoubleFormatState doubleFormatState)
{
return DFG::mergeDoubleFormatState(find()->m_doubleFormatState, doubleFormatState);
}
bool makePredictionForDoubleFormat()
{
ASSERT(isRoot());
if (m_doubleFormatState != UsingDoubleFormat)
return false;
return mergeSpeculation(m_prediction, SpecDouble);
}
NodeFlags flags() const { return m_flags; }
bool mergeFlags(NodeFlags newFlags)
{
return checkAndSet(m_flags, m_flags | newFlags);
}
private:
VirtualRegister m_local;
SpeculatedType m_prediction;
SpeculatedType m_argumentAwarePrediction;
NodeFlags m_flags;
bool m_isCaptured;
bool m_shouldNeverUnbox;
bool m_isArgumentsAlias;
bool m_structureCheckHoistingFailed;
bool m_isProfitableToUnbox;
bool m_isLoadedFrom;
float m_votes[2]; DoubleFormatState m_doubleFormatState;
};
} }
#endif // DFGVariableAccessData_h