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      1 /*
      2  * Copyright (C) 2014 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef ART_COMPILER_OPTIMIZING_DEAD_CODE_ELIMINATION_H_
     18 #define ART_COMPILER_OPTIMIZING_DEAD_CODE_ELIMINATION_H_
     19 
     20 #include "nodes.h"
     21 #include "optimization.h"
     22 #include "optimizing_compiler_stats.h"
     23 
     24 namespace art {
     25 
     26 /**
     27  * Optimization pass performing dead code elimination (removal of
     28  * unused variables/instructions) on the SSA form.
     29  */
     30 class HDeadCodeElimination : public HOptimization {
     31  public:
     32   HDeadCodeElimination(HGraph* graph,
     33                        OptimizingCompilerStats* stats = nullptr,
     34                        const char* name = kInitialDeadCodeEliminationPassName)
     35       : HOptimization(graph, name, stats) {}
     36 
     37   void Run() OVERRIDE;
     38 
     39   static constexpr const char* kInitialDeadCodeEliminationPassName = "dead_code_elimination";
     40   static constexpr const char* kFinalDeadCodeEliminationPassName = "dead_code_elimination_final";
     41 
     42  private:
     43   void MaybeRecordDeadBlock(HBasicBlock* block);
     44   void RemoveDeadBlocks();
     45   void RemoveDeadInstructions();
     46 
     47   DISALLOW_COPY_AND_ASSIGN(HDeadCodeElimination);
     48 };
     49 
     50 }  // namespace art
     51 
     52 #endif  // ART_COMPILER_OPTIMIZING_DEAD_CODE_ELIMINATION_H_
     53