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:
HDeadCodeElimination(HGraph * graph,OptimizingCompilerStats * stats,const char * name)32   HDeadCodeElimination(HGraph* graph, OptimizingCompilerStats* stats, const char* name)
33       : HOptimization(graph, name, stats) {}
34 
35   bool Run() override;
36 
37   static constexpr const char* kDeadCodeEliminationPassName = "dead_code_elimination";
38 
39  private:
40   void MaybeRecordDeadBlock(HBasicBlock* block);
41   void MaybeRecordSimplifyIf();
42   bool RemoveDeadBlocks();
43   void RemoveDeadInstructions();
44   bool SimplifyAlwaysThrows();
45   bool SimplifyIfs();
46   void ConnectSuccessiveBlocks();
47 
48   DISALLOW_COPY_AND_ASSIGN(HDeadCodeElimination);
49 };
50 
51 }  // namespace art
52 
53 #endif  // ART_COMPILER_OPTIMIZING_DEAD_CODE_ELIMINATION_H_
54