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/*
* Copyright (C) 2013-2017 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 "DFGLivenessAnalysisPhase.h"
#if ENABLE(DFG_JIT)
#include "DFGBlockMapInlines.h"
#include "DFGFlowIndexing.h"
#include "DFGGraph.h"
#include "DFGPhase.h"
#include "JSCJSValueInlines.h"
#include <wtf/BitVector.h>
#include <wtf/IndexSparseSet.h>
namespace JSC { namespace DFG {
namespace {
// Uncomment this to log hashtable operations.
// static const char templateString[] = "unsigned, DefaultHash<unsigned>, WTF::UnsignedWithZeroKeyHashTraits<unsigned>";
// typedef LoggingHashSet<templateString, unsigned, DefaultHash<unsigned>, WTF::UnsignedWithZeroKeyHashTraits<unsigned>> LiveSet;
typedef UncheckedKeyHashSet<unsigned, DefaultHash<unsigned>, WTF::UnsignedWithZeroKeyHashTraits<unsigned>> LiveSet;
typedef IndexSparseSet<unsigned, DefaultIndexSparseSetTraits<unsigned>, UnsafeVectorOverflow> Workset;
class LivenessAnalysisPhase : public Phase {
public:
LivenessAnalysisPhase(Graph& graph)
: Phase(graph, "liveness analysis"_s)
, m_dirtyBlocks(m_graph.numBlocks())
, m_indexing(*m_graph.m_indexingCache)
, m_liveAtHead(m_graph)
, m_liveAtTail(m_graph)
{
m_graph.m_indexingCache->recompute();
m_workset = makeUnique<Workset>(m_graph.m_indexingCache->numIndices());
}
bool run()
{
// Start with all valid block dirty.
BlockIndex numBlock = m_graph.numBlocks();
m_dirtyBlocks.ensureSize(numBlock);
for (BlockIndex blockIndex = 0; blockIndex < numBlock; ++blockIndex) {
if (m_graph.block(blockIndex))
m_dirtyBlocks.quickSet(blockIndex);
}
// Fixpoint until we do not add any new live values at tail.
bool changed;
do {
changed = false;
for (BlockIndex blockIndex = numBlock; blockIndex--;) {
if (!m_dirtyBlocks.quickClear(blockIndex))
continue;
changed |= processBlock(blockIndex);
}
} while (changed);
// Update the per-block node list for live and tail.
for (BlockIndex blockIndex = numBlock; blockIndex--;) {
BasicBlock* block = m_graph.block(blockIndex);
if (!block)
continue;
{
block->ssa->liveAtHead = m_liveAtHead[blockIndex].map([this](auto index) {
return m_indexing.nodeProjection(index);
});
}
{
block->ssa->liveAtTail = WTF::map(m_liveAtTail[blockIndex], [this](auto index) {
return m_indexing.nodeProjection(index);
});
}
}
return true;
}
private:
bool processBlock(BlockIndex blockIndex)
{
BasicBlock* block = m_graph.block(blockIndex);
ASSERT_WITH_MESSAGE(block, "Only dirty blocks needs updates. A null block should never be dirty.");
m_workset->clear();
for (unsigned index : m_liveAtTail[blockIndex])
m_workset->add(index);
for (unsigned nodeIndex = block->size(); nodeIndex--;) {
Node* node = block->at(nodeIndex);
auto handleEdge = [&] (Edge& edge) {
bool newEntry = m_workset->add(m_indexing.index(edge.node()));
edge.setKillStatus(newEntry ? DoesKill : DoesNotKill);
};
switch (node->op()) {
case Upsilon: {
ASSERT_WITH_MESSAGE(!m_workset->contains(node->index()), "Upsilon should not be used as defs by other nodes.");
Node* phi = node->phi();
m_workset->remove(m_indexing.shadowIndex(phi));
handleEdge(node->child1());
break;
}
case Phi: {
m_workset->remove(m_indexing.index(node));
m_workset->add(m_indexing.shadowIndex(node));
break;
}
default:
m_workset->remove(m_indexing.index(node));
m_graph.doToChildren(node, handleEdge);
break;
}
}
// Update live at head.
Vector<unsigned, 0, UnsafeVectorOverflow, 1>& liveAtHead = m_liveAtHead[blockIndex];
if (m_workset->size() == liveAtHead.size())
return false;
for (unsigned liveIndexAtHead : liveAtHead)
m_workset->remove(liveIndexAtHead);
ASSERT(!m_workset->isEmpty());
liveAtHead.appendRange(m_workset->begin(), m_workset->end());
bool changedPredecessor = false;
for (BasicBlock* predecessor : block->predecessors) {
LiveSet& liveAtTail = m_liveAtTail[predecessor];
for (unsigned newValue : *m_workset) {
if (liveAtTail.add(newValue)) {
if (!m_dirtyBlocks.quickSet(predecessor->index))
changedPredecessor = true;
}
}
}
return changedPredecessor;
}
// Blocks with new live values at tail.
BitVector m_dirtyBlocks;
FlowIndexing& m_indexing;
// Live values per block edge.
BlockMap<Vector<unsigned, 0, UnsafeVectorOverflow, 1>> m_liveAtHead;
BlockMap<LiveSet> m_liveAtTail;
// Single sparse set allocated once and used by every basic block.
std::unique_ptr<Workset> m_workset;
};
} // anonymous namespace
bool performGraphPackingAndLivenessAnalysis(Graph& graph)
{
graph.packNodeIndices();
#ifndef NDEBUG
graph.clearAbstractValues();
#endif
return runPhase<LivenessAnalysisPhase>(graph);
}
} } // namespace JSC::DFG
#endif // ENABLE(DFG_JIT)
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