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_SSA_BUILDER_H_
18 #define ART_COMPILER_OPTIMIZING_SSA_BUILDER_H_
19 
20 #include "nodes.h"
21 
22 namespace art {
23 
24 static constexpr int kDefaultNumberOfLoops = 2;
25 
26 class SsaBuilder : public HGraphVisitor {
27  public:
SsaBuilder(HGraph * graph)28   explicit SsaBuilder(HGraph* graph)
29       : HGraphVisitor(graph),
30         current_locals_(nullptr),
31         loop_headers_(graph->GetArena(), kDefaultNumberOfLoops),
32         locals_for_(graph->GetArena(), graph->GetBlocks().Size()) {
33     locals_for_.SetSize(graph->GetBlocks().Size());
34   }
35 
36   void BuildSsa();
37 
GetLocalsFor(HBasicBlock * block)38   GrowableArray<HInstruction*>* GetLocalsFor(HBasicBlock* block) {
39     HEnvironment* env = locals_for_.Get(block->GetBlockId());
40     if (env == nullptr) {
41       env = new (GetGraph()->GetArena()) HEnvironment(
42           GetGraph()->GetArena(), GetGraph()->GetNumberOfVRegs());
43       locals_for_.Put(block->GetBlockId(), env);
44     }
45     return env->GetVRegs();
46   }
47 
48   HInstruction* ValueOfLocal(HBasicBlock* block, size_t local);
49 
50   void VisitBasicBlock(HBasicBlock* block);
51   void VisitLoadLocal(HLoadLocal* load);
52   void VisitStoreLocal(HStoreLocal* store);
53   void VisitInstruction(HInstruction* instruction);
54 
55  private:
56   // Locals for the current block being visited.
57   GrowableArray<HInstruction*>* current_locals_;
58 
59   // Keep track of loop headers found. The last phase of the analysis iterates
60   // over these blocks to set the inputs of their phis.
61   GrowableArray<HBasicBlock*> loop_headers_;
62 
63   // HEnvironment for each block.
64   GrowableArray<HEnvironment*> locals_for_;
65 
66   DISALLOW_COPY_AND_ASSIGN(SsaBuilder);
67 };
68 
69 }  // namespace art
70 
71 #endif  // ART_COMPILER_OPTIMIZING_SSA_BUILDER_H_
72