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/*
* Copyright (C) 2012 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 "DFGConstantFoldingPhase.h"
#if ENABLE(DFG_JIT)
#include "DFGAbstractState.h"
#include "DFGBasicBlock.h"
#include "DFGGraph.h"
#include "DFGInsertionSet.h"
#include "DFGPhase.h"
namespace JSC { namespace DFG {
class ConstantFoldingPhase : public Phase {
public:
ConstantFoldingPhase(Graph& graph)
: Phase(graph, "constant folding")
{
}
bool run()
{
bool changed = false;
AbstractState state(m_graph);
InsertionSet<NodeIndex> insertionSet;
for (BlockIndex blockIndex = 0; blockIndex < m_graph.m_blocks.size(); ++blockIndex) {
BasicBlock* block = m_graph.m_blocks[blockIndex].get();
if (!block)
continue;
if (!block->cfaFoundConstants)
continue;
state.beginBasicBlock(block);
for (unsigned indexInBlock = 0; indexInBlock < block->size(); ++indexInBlock) {
if (!state.isValid())
break;
state.execute(indexInBlock);
NodeIndex nodeIndex = block->at(indexInBlock);
Node& node = m_graph[nodeIndex];
if (!node.shouldGenerate()
|| m_graph.clobbersWorld(node)
|| node.hasConstant())
continue;
JSValue value = state.forNode(nodeIndex).value();
if (!value)
continue;
Node phantom(Phantom, node.codeOrigin);
if (node.op() == GetLocal) {
ASSERT(m_graph[node.child1()].op() == Phi);
ASSERT(!m_graph[node.child1()].hasResult());
ASSERT(block->variablesAtHead.operand(node.local()) == nodeIndex);
ASSERT(block->isInPhis(node.child1().index()));
block->variablesAtHead.operand(node.local()) = node.child1().index();
NodeIndex tailNodeIndex = block->variablesAtTail.operand(node.local());
if (tailNodeIndex == nodeIndex)
block->variablesAtTail.operand(node.local()) = node.child1().index();
else {
ASSERT(m_graph[tailNodeIndex].op() == Flush
|| m_graph[tailNodeIndex].op() == SetLocal);
}
}
phantom.children = node.children;
phantom.ref();
m_graph.convertToConstant(nodeIndex, value);
NodeIndex phantomNodeIndex = m_graph.size();
m_graph.append(phantom);
insertionSet.append(indexInBlock, phantomNodeIndex);
changed = true;
}
insertionSet.execute(*block);
state.reset();
}
return changed;
}
};
bool performConstantFolding(Graph& graph)
{
return runPhase<ConstantFoldingPhase>(graph);
}
} } // namespace JSC::DFG
#endif // ENABLE(DFG_JIT)
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