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/*
* Copyright (C) 2016 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.
*/
/*
* This optimization recognizes the common diamond selection pattern and
* replaces it with an instance of the HSelect instruction.
*
* Recognized patterns:
*
* If [ Condition ]
* / \
* false branch true branch
* \ /
* Phi [FalseValue, TrueValue]
*
* and
*
* If [ Condition ]
* / \
* false branch true branch
* return FalseValue return TrueValue
*
* The pattern will be simplified if `true_branch` and `false_branch` each
* contain at most one instruction without any side effects.
*
* Blocks are merged into one and Select replaces the If and the Phi.
*
* For the first pattern it simplifies to:
*
* true branch
* false branch
* Select [FalseValue, TrueValue, Condition]
*
* For the second pattern it simplifies to:
*
* true branch
* false branch
* return Select [FalseValue, TrueValue, Condition]
*
* Note: In order to recognize no side-effect blocks, this optimization must be
* run after the instruction simplifier has removed redundant suspend checks.
*/
#ifndef ART_COMPILER_OPTIMIZING_SELECT_GENERATOR_H_
#define ART_COMPILER_OPTIMIZING_SELECT_GENERATOR_H_
#include "optimization.h"
namespace art {
class HSelectGenerator : public HOptimization {
public:
HSelectGenerator(HGraph* graph,
VariableSizedHandleScope* handles,
OptimizingCompilerStats* stats,
const char* name = kSelectGeneratorPassName);
bool Run() OVERRIDE;
static constexpr const char* kSelectGeneratorPassName = "select_generator";
private:
VariableSizedHandleScope* handle_scope_;
DISALLOW_COPY_AND_ASSIGN(HSelectGenerator);
};
} // namespace art
#endif // ART_COMPILER_OPTIMIZING_SELECT_GENERATOR_H_