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/*
* Copyright (C) 2017 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 "B3EnsureLoopPreHeaders.h"
#if ENABLE(B3_JIT)
#include "B3BasicBlockInlines.h"
#include "B3BlockInsertionSet.h"
#include "B3NaturalLoops.h"
#include "B3ValueInlines.h"
namespace JSC { namespace B3 {
bool ensureLoopPreHeaders(Procedure& proc)
{
NaturalLoops& loops = proc.naturalLoops();
BlockInsertionSet insertionSet(proc);
for (unsigned loopIndex = loops.numLoops(); loopIndex--;) {
const NaturalLoop& loop = loops.loop(loopIndex);
Vector<BasicBlock*, 4> outOfBodyPredecessors;
double totalFrequency = 0;
for (BasicBlock* predecessor : loop.header()->predecessors()) {
if (loops.belongsTo(predecessor, loop))
continue;
outOfBodyPredecessors.append(predecessor);
totalFrequency += predecessor->frequency();
}
if (outOfBodyPredecessors.size() <= 1)
continue;
BasicBlock* preHeader = insertionSet.insertBefore(loop.header(), totalFrequency);
preHeader->appendNew<Value>(proc, Jump, loop.header()->at(0)->origin());
preHeader->setSuccessors(FrequentedBlock(loop.header()));
for (BasicBlock* predecessor : outOfBodyPredecessors) {
predecessor->replaceSuccessor(loop.header(), preHeader);
preHeader->addPredecessor(predecessor);
loop.header()->removePredecessor(predecessor);
}
loop.header()->addPredecessor(preHeader);
}
if (insertionSet.execute()) {
proc.invalidateCFG();
return true;
}
return false;
}
} } // namespace JSC::B3
#endif // ENABLE(B3_JIT)
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