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/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_COMPILER_OPTIMIZING_SSA_PHI_ELIMINATION_H_
#define ART_COMPILER_OPTIMIZING_SSA_PHI_ELIMINATION_H_
#include "base/macros.h"
#include "nodes.h"
#include "optimization.h"
namespace art HIDDEN {
/**
* Optimization phase that removes dead phis from the graph. Dead phis are unused
* phis, or phis only used by other phis.
*/
class SsaDeadPhiElimination : public HOptimization {
public:
explicit SsaDeadPhiElimination(HGraph* graph)
: HOptimization(graph, kSsaDeadPhiEliminationPassName) {}
bool Run() override;
void MarkDeadPhis();
void EliminateDeadPhis();
static constexpr const char* kSsaDeadPhiEliminationPassName = "dead_phi_elimination";
private:
DISALLOW_COPY_AND_ASSIGN(SsaDeadPhiElimination);
};
/**
* Removes redundant phis that may have been introduced when doing SSA conversion.
* For example, when entering a loop, we create phis for all live registers. These
* registers might be updated with the same value, or not updated at all. We can just
* replace the phi with the value when entering the loop.
*/
class SsaRedundantPhiElimination : public HOptimization {
public:
explicit SsaRedundantPhiElimination(HGraph* graph)
: HOptimization(graph, kSsaRedundantPhiEliminationPassName) {}
bool Run() override;
static constexpr const char* kSsaRedundantPhiEliminationPassName = "redundant_phi_elimination";
private:
DISALLOW_COPY_AND_ASSIGN(SsaRedundantPhiElimination);
};
} // namespace art
#endif // ART_COMPILER_OPTIMIZING_SSA_PHI_ELIMINATION_H_
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