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