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/*
* Copyright (C) 2013 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 "DFGStrengthReductionPhase.h"
#if ENABLE(DFG_JIT)
#include "DFGGraph.h"
#include "DFGInsertionSet.h"
#include "DFGPhase.h"
#include "DFGPredictionPropagationPhase.h"
#include "DFGVariableAccessDataDump.h"
#include "Operations.h"
namespace JSC { namespace DFG {
class StrengthReductionPhase : public Phase {
public:
StrengthReductionPhase(Graph& graph)
: Phase(graph, "strength reduction")
, m_insertionSet(graph)
{
}
bool run()
{
ASSERT(m_graph.m_fixpointState == FixpointNotConverged);
m_changed = false;
for (BlockIndex blockIndex = m_graph.numBlocks(); blockIndex--;) {
m_block = m_graph.block(blockIndex);
if (!m_block)
continue;
for (m_nodeIndex = 0; m_nodeIndex < m_block->size(); ++m_nodeIndex) {
m_node = m_block->at(m_nodeIndex);
handleNode();
}
m_insertionSet.execute(m_block);
}
return m_changed;
}
private:
void handleNode()
{
switch (m_node->op()) {
case BitOr:
if (m_node->child1()->isConstant()) {
JSValue op1 = m_graph.valueOfJSConstant(m_node->child1().node());
if (op1.isInt32() && !op1.asInt32()) {
convertToIdentityOverChild2();
break;
}
}
if (m_node->child2()->isConstant()) {
JSValue op2 = m_graph.valueOfJSConstant(m_node->child2().node());
if (op2.isInt32() && !op2.asInt32()) {
convertToIdentityOverChild1();
break;
}
}
break;
case BitLShift:
case BitRShift:
case BitURShift:
if (m_node->child2()->isConstant()) {
JSValue op2 = m_graph.valueOfJSConstant(m_node->child2().node());
if (op2.isInt32() && !(op2.asInt32() & 0x1f)) {
convertToIdentityOverChild1();
break;
}
}
break;
case UInt32ToNumber:
if (m_node->child1()->op() == BitURShift
&& m_node->child1()->child2()->isConstant()) {
JSValue shiftAmount = m_graph.valueOfJSConstant(
m_node->child1()->child2().node());
if (shiftAmount.isInt32() && (shiftAmount.asInt32() & 0x1f)) {
m_node->convertToIdentity();
m_changed = true;
break;
}
}
break;
case GetArrayLength:
if (JSArrayBufferView* view = m_graph.tryGetFoldableViewForChild1(m_node))
foldTypedArrayPropertyToConstant(view, jsNumber(view->length()));
break;
case GetTypedArrayByteOffset:
if (JSArrayBufferView* view = m_graph.tryGetFoldableView(m_node->child1().node()))
foldTypedArrayPropertyToConstant(view, jsNumber(view->byteOffset()));
break;
case GetIndexedPropertyStorage:
if (JSArrayBufferView* view = m_graph.tryGetFoldableViewForChild1(m_node)) {
if (view->mode() != FastTypedArray) {
prepareToFoldTypedArray(view);
m_node->convertToConstantStoragePointer(view->vector());
m_changed = true;
break;
} else {
// FIXME: It would be awesome to be able to fold the property storage for
// these GC-allocated typed arrays. For now it doesn't matter because the
// most common use-cases for constant typed arrays involve large arrays with
// aliased buffer views.
// https://bugs.webkit.org/show_bug.cgi?id=125425
}
}
break;
default:
break;
}
}
void convertToIdentityOverChild(unsigned childIndex)
{
m_insertionSet.insertNode(
m_nodeIndex, SpecNone, Phantom, m_node->codeOrigin, m_node->children);
m_node->children.removeEdge(childIndex ^ 1);
m_node->convertToIdentity();
m_changed = true;
}
void convertToIdentityOverChild1()
{
convertToIdentityOverChild(0);
}
void convertToIdentityOverChild2()
{
convertToIdentityOverChild(1);
}
void foldTypedArrayPropertyToConstant(JSArrayBufferView* view, JSValue constant)
{
prepareToFoldTypedArray(view);
m_graph.convertToConstant(m_node, constant);
m_changed = true;
}
void prepareToFoldTypedArray(JSArrayBufferView* view)
{
m_insertionSet.insertNode(
m_nodeIndex, SpecNone, TypedArrayWatchpoint, m_node->codeOrigin,
OpInfo(view));
m_insertionSet.insertNode(
m_nodeIndex, SpecNone, Phantom, m_node->codeOrigin, m_node->children);
}
InsertionSet m_insertionSet;
BasicBlock* m_block;
unsigned m_nodeIndex;
Node* m_node;
bool m_changed;
};
bool performStrengthReduction(Graph& graph)
{
SamplingRegion samplingRegion("DFG Strength Reduction Phase");
return runPhase<StrengthReductionPhase>(graph);
}
} } // namespace JSC::DFG
#endif // ENABLE(DFG_JIT)
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