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/*
* Copyright (C) 2014, 2015 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.
*/
#include "config.h"
#include "DFGVariableAccessData.h"
#if ENABLE(DFG_JIT)
namespace JSC { namespace DFG {
VariableAccessData::VariableAccessData()
: m_local(static_cast<VirtualRegister>(std::numeric_limits<int>::min()))
, m_prediction(SpecNone)
, m_argumentAwarePrediction(SpecNone)
, m_flags(0)
, m_shouldNeverUnbox(false)
, m_structureCheckHoistingFailed(false)
, m_checkArrayHoistingFailed(false)
, m_isProfitableToUnbox(false)
, m_isLoadedFrom(false)
, m_doubleFormatState(EmptyDoubleFormatState)
{
clearVotes();
}
VariableAccessData::VariableAccessData(VirtualRegister local)
: m_local(local)
, m_prediction(SpecNone)
, m_argumentAwarePrediction(SpecNone)
, m_flags(0)
, m_shouldNeverUnbox(false)
, m_structureCheckHoistingFailed(false)
, m_checkArrayHoistingFailed(false)
, m_isProfitableToUnbox(false)
, m_isLoadedFrom(false)
, m_doubleFormatState(EmptyDoubleFormatState)
{
clearVotes();
}
bool VariableAccessData::mergeShouldNeverUnbox(bool shouldNeverUnbox)
{
bool newShouldNeverUnbox = m_shouldNeverUnbox | shouldNeverUnbox;
if (newShouldNeverUnbox == m_shouldNeverUnbox)
return false;
m_shouldNeverUnbox = newShouldNeverUnbox;
return true;
}
bool VariableAccessData::predict(SpeculatedType prediction)
{
VariableAccessData* self = find();
bool result = mergeSpeculation(self->m_prediction, prediction);
if (result)
mergeSpeculation(m_argumentAwarePrediction, m_prediction);
return result;
}
bool VariableAccessData::mergeArgumentAwarePrediction(SpeculatedType prediction)
{
return mergeSpeculation(find()->m_argumentAwarePrediction, prediction);
}
bool VariableAccessData::shouldUseDoubleFormatAccordingToVote()
{
// We don't support this facility for arguments, yet.
// FIXME: make this work for arguments.
if (local().isArgument())
return false;
// If the variable is not a number prediction, then this doesn't
// make any sense.
if (!isFullNumberSpeculation(prediction())) {
// FIXME: we may end up forcing a local in inlined argument position to be a double even
// if it is sometimes not even numeric, since this never signals the fact that it doesn't
// want doubles. https://bugs.webkit.org/show_bug.cgi?id=109511
return false;
}
// If the variable is predicted to hold only doubles, then it's a
// no-brainer: it should be formatted as a double.
if (isDoubleSpeculation(prediction()))
return true;
// If the variable is known to be used as an integer, then be safe -
// don't force it to be a double.
if (flags() & NodeBytecodeUsesAsInt)
return false;
// If the variable has been voted to become a double, then make it a
// double.
if (voteRatio() >= Options::doubleVoteRatioForDoubleFormat())
return true;
return false;
}
bool VariableAccessData::tallyVotesForShouldUseDoubleFormat()
{
ASSERT(isRoot());
if (local().isArgument() || shouldNeverUnbox()
|| (flags() & NodeBytecodeUsesAsArrayIndex))
return DFG::mergeDoubleFormatState(m_doubleFormatState, NotUsingDoubleFormat);
if (m_doubleFormatState == CantUseDoubleFormat)
return false;
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_doubleFormatState == UsingDoubleFormat)
return false;
return DFG::mergeDoubleFormatState(m_doubleFormatState, UsingDoubleFormat);
}
bool VariableAccessData::mergeDoubleFormatState(DoubleFormatState doubleFormatState)
{
return DFG::mergeDoubleFormatState(find()->m_doubleFormatState, doubleFormatState);
}
bool VariableAccessData::makePredictionForDoubleFormat()
{
ASSERT(isRoot());
if (m_doubleFormatState != UsingDoubleFormat)
return false;
SpeculatedType type = m_prediction;
if (type & ~SpecBytecodeNumber)
type |= SpecDoublePureNaN;
if (type & SpecAnyInt)
type |= SpecAnyIntAsDouble;
return checkAndSet(m_prediction, type);
}
bool VariableAccessData::couldRepresentInt52()
{
if (shouldNeverUnbox())
return false;
return couldRepresentInt52Impl();
}
bool VariableAccessData::couldRepresentInt52Impl()
{
// The hardware has to support it.
if (!enableInt52())
return false;
// We punt for machine arguments.
if (m_local.isArgument())
return false;
// The argument-aware prediction -- which merges all of an (inlined or machine)
// argument's variable access datas' predictions -- must possibly be AnyInt.
return !(argumentAwarePrediction() & ~SpecAnyInt);
}
FlushFormat VariableAccessData::flushFormat()
{
ASSERT(find() == this);
if (!shouldUnboxIfPossible())
return FlushedJSValue;
if (shouldUseDoubleFormat())
return FlushedDouble;
SpeculatedType prediction = argumentAwarePrediction();
// This guard is here to protect the call to couldRepresentInt52(), which will return
// true for !prediction.
if (!prediction)
return FlushedJSValue;
if (isInt32Speculation(prediction))
return FlushedInt32;
if (couldRepresentInt52Impl())
return FlushedInt52;
if (isCellSpeculation(prediction))
return FlushedCell;
if (isBooleanSpeculation(prediction))
return FlushedBoolean;
return FlushedJSValue;
}
} } // namespace JSC::DFG
#endif // ENABLE(DFG_JIT)