Commit e5b69658 authored by bmeurer@chromium.org's avatar bmeurer@chromium.org

Turn redundant phi elimination into proper HPhase.

R=dslomov@chromium.org

Review URL: https://codereview.chromium.org/18549004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15533 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
parent 6c4594b7
// Copyright 2013 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * 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.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "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 THE COPYRIGHT
// OWNER 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 "hydrogen-redundant-phi.h"
namespace v8 {
namespace internal {
void HRedundantPhiEliminationPhase::Run() {
// We do a simple fixed point iteration without any work list, because
// machine-generated JavaScript can lead to a very dense Hydrogen graph with
// an enormous work list and will consequently result in OOM. Experiments
// showed that this simple algorithm is good enough, and even e.g. tracking
// the set or range of blocks to consider is not a real improvement.
bool need_another_iteration;
const ZoneList<HBasicBlock*>* blocks(graph()->blocks());
ZoneList<HPhi*> redundant_phis(blocks->length(), zone());
do {
need_another_iteration = false;
for (int i = 0; i < blocks->length(); ++i) {
HBasicBlock* block = blocks->at(i);
for (int j = 0; j < block->phis()->length(); j++) {
HPhi* phi = block->phis()->at(j);
HValue* replacement = phi->GetRedundantReplacement();
if (replacement != NULL) {
// Remember phi to avoid concurrent modification of the block's phis.
redundant_phis.Add(phi, zone());
for (HUseIterator it(phi->uses()); !it.Done(); it.Advance()) {
HValue* value = it.value();
value->SetOperandAt(it.index(), replacement);
need_another_iteration |= value->IsPhi();
}
}
}
for (int i = 0; i < redundant_phis.length(); i++) {
block->RemovePhi(redundant_phis[i]);
}
redundant_phis.Clear();
}
} while (need_another_iteration);
#if DEBUG
// Make sure that we *really* removed all redundant phis.
for (int i = 0; i < blocks->length(); ++i) {
for (int j = 0; j < blocks->at(i)->phis()->length(); j++) {
ASSERT(blocks->at(i)->phis()->at(j)->GetRedundantReplacement() == NULL);
}
}
#endif
}
} } // namespace v8::internal
// Copyright 2013 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * 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.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "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 THE COPYRIGHT
// OWNER 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.
#ifndef V8_HYDROGEN_REDUNDANT_PHI_H_
#define V8_HYDROGEN_REDUNDANT_PHI_H_
#include "hydrogen.h"
namespace v8 {
namespace internal {
// Replace all phis consisting of a single non-loop operand plus any number of
// loop operands by that single non-loop operand.
class HRedundantPhiEliminationPhase : public HPhase {
public:
explicit HRedundantPhiEliminationPhase(HGraph* graph)
: HPhase("H_Redundant phi elimination", graph) { }
void Run();
private:
DISALLOW_COPY_AND_ASSIGN(HRedundantPhiEliminationPhase);
};
} } // namespace v8::internal
#endif // V8_HYDROGEN_REDUNDANT_PHI_H_
......@@ -40,6 +40,7 @@
#include "hydrogen-gvn.h"
#include "hydrogen-osr.h"
#include "hydrogen-range-analysis.h"
#include "hydrogen-redundant-phi.h"
#include "hydrogen-sce.h"
#include "hydrogen-uint32-analysis.h"
#include "lithium-allocator.h"
......@@ -2523,53 +2524,6 @@ void HGraph::NullifyUnreachableInstructions() {
}
// Replace all phis consisting of a single non-loop operand plus any number of
// loop operands by that single non-loop operand.
void HGraph::EliminateRedundantPhis() {
HPhase phase("H_Redundant phi elimination", this);
// We do a simple fixed point iteration without any work list, because
// machine-generated JavaScript can lead to a very dense Hydrogen graph with
// an enormous work list and will consequently result in OOM. Experiments
// showed that this simple algorithm is good enough, and even e.g. tracking
// the set or range of blocks to consider is not a real improvement.
bool need_another_iteration;
ZoneList<HPhi*> redundant_phis(blocks_.length(), zone());
do {
need_another_iteration = false;
for (int i = 0; i < blocks_.length(); ++i) {
HBasicBlock* block = blocks_[i];
for (int j = 0; j < block->phis()->length(); j++) {
HPhi* phi = block->phis()->at(j);
HValue* replacement = phi->GetRedundantReplacement();
if (replacement != NULL) {
// Remember phi to avoid concurrent modification of the block's phis.
redundant_phis.Add(phi, zone());
for (HUseIterator it(phi->uses()); !it.Done(); it.Advance()) {
HValue* value = it.value();
value->SetOperandAt(it.index(), replacement);
need_another_iteration |= value->IsPhi();
}
}
}
for (int i = 0; i < redundant_phis.length(); i++) {
block->RemovePhi(redundant_phis[i]);
}
redundant_phis.Clear();
}
} while (need_another_iteration);
#if DEBUG
// Make sure that we *really* removed all redundant phis.
for (int i = 0; i < blocks_.length(); ++i) {
for (int j = 0; j < blocks_[i]->phis()->length(); j++) {
ASSERT(blocks_[i]->phis()->at(j)->GetRedundantReplacement() == NULL);
}
}
#endif
}
bool HGraph::CheckArgumentsPhiUses() {
int block_count = blocks_.length();
for (int i = 0; i < block_count; ++i) {
......@@ -3417,7 +3371,7 @@ bool HGraph::Optimize(SmartArrayPointer<char>* bailout_reason) {
"Unsupported phi use of const variable"));
return false;
}
EliminateRedundantPhis();
Run<HRedundantPhiEliminationPhase>();
if (!CheckArgumentsPhiUses()) {
*bailout_reason = SmartArrayPointer<char>(StrDup(
"Unsupported phi use of arguments"));
......
......@@ -298,7 +298,6 @@ class HGraph: public ZoneObject {
void MarkDeoptimizeOnUndefined();
void ComputeMinusZeroChecks();
bool ProcessArgumentsObject();
void EliminateRedundantPhis();
void Canonicalize();
void OrderBlocks();
void AssignDominators();
......
......@@ -351,6 +351,8 @@
'../../src/hydrogen-infer-representation.h',
'../../src/hydrogen-range-analysis.cc',
'../../src/hydrogen-range-analysis.h',
'../../src/hydrogen-redundant-phi.cc',
'../../src/hydrogen-redundant-phi.h',
'../../src/hydrogen-sce.cc',
'../../src/hydrogen-sce.h',
'../../src/hydrogen-uint32-analysis.cc',
......
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