/*
|
* 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_
|
