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/*
* Copyright (C) 2011 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 "DFGDominators.h"
#if ENABLE(DFG_JIT)
#include "DFGGraph.h"
namespace JSC { namespace DFG {
Dominators::Dominators()
: m_valid(false)
{
}
Dominators::~Dominators()
{
}
void Dominators::compute(Graph& graph)
{
// This implements a naive dominator solver.
ASSERT(graph.m_blocks[0]->m_predecessors.isEmpty());
unsigned numBlocks = graph.m_blocks.size();
if (numBlocks > m_results.size()) {
m_results.grow(numBlocks);
for (unsigned i = numBlocks; i--;)
m_results[i].resize(numBlocks);
m_scratch.resize(numBlocks);
}
m_results[0].clearAll();
m_results[0].set(0);
m_scratch.clearAll();
for (unsigned i = numBlocks; i--;) {
if (!graph.m_blocks[i])
continue;
m_scratch.set(i);
}
for (unsigned i = numBlocks; i-- > 1;) {
if (!graph.m_blocks[i] || graph.m_blocks[i]->m_predecessors.isEmpty())
m_results[i].clearAll();
else
m_results[i].set(m_scratch);
}
bool changed;
do {
changed = false;
for (unsigned i = 1; i < numBlocks; ++i)
changed |= iterateForBlock(graph, i);
if (!changed)
break;
changed = false;
for (unsigned i = numBlocks; i-- > 1;)
changed |= iterateForBlock(graph, i);
} while (changed);
m_valid = true;
}
bool Dominators::iterateForBlock(Graph& graph, BlockIndex i)
{
BasicBlock* block = graph.m_blocks[i].get();
if (!block)
return false;
if (block->m_predecessors.isEmpty())
return false;
m_scratch.set(m_results[block->m_predecessors[0]]);
for (unsigned j = block->m_predecessors.size(); j-- > 1;)
m_scratch.filter(m_results[block->m_predecessors[j]]);
m_scratch.set(i);
return m_results[i].setAndCheck(m_scratch);
}
} } // namespace JSC::DFG
#endif // ENABLE(DFG_JIT)
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