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/*
* Copyright (C) 2014 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 "DFGStaticExecutionCountEstimationPhase.h"
#if ENABLE(DFG_JIT)
#include "DFGBasicBlockInlines.h"
#include "DFGGraph.h"
#include "DFGPhase.h"
#include "JSCInlines.h"
namespace JSC { namespace DFG {
class StaticExecutionCountEstimationPhase : public Phase {
public:
StaticExecutionCountEstimationPhase(Graph& graph)
: Phase(graph, "static execution count estimation")
{
}
bool run()
{
m_graph.m_naturalLoops.computeIfNecessary(m_graph);
// Estimate basic block execution counts based on loop depth.
for (BlockIndex blockIndex = m_graph.numBlocks(); blockIndex--;) {
BasicBlock* block = m_graph.block(blockIndex);
if (!block)
continue;
block->executionCount = pow(10, m_graph.m_naturalLoops.loopDepth(block));
}
// Estimate branch weights based on execution counts. This isn't quite correct. It'll
// assume that each block's conditional successor only has that block as its
// predecessor.
for (BlockIndex blockIndex = m_graph.numBlocks(); blockIndex--;) {
BasicBlock* block = m_graph.block(blockIndex);
if (!block)
continue;
switch (block->last()->op()) {
case Branch: {
BranchData* data = block->last()->branchData();
applyCounts(data->taken);
applyCounts(data->notTaken);
break;
}
case Switch: {
SwitchData* data = block->last()->switchData();
for (unsigned i = data->cases.size(); i--;)
applyCounts(data->cases[i].target);
applyCounts(data->fallThrough);
break;
}
default:
break;
}
}
return true;
}
private:
void applyCounts(BranchTarget& target)
{
target.count = target.block->executionCount;
}
};
bool performStaticExecutionCountEstimation(Graph& graph)
{
SamplingRegion samplingRegion("DFG Static Execution Count Estimation");
return runPhase<StaticExecutionCountEstimationPhase>(graph);
}
} } // namespace JSC::DFG
#endif // ENABLE(DFG_JIT)
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