1 /* 2 * Copyright (C) 2016 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_BLOCK_BUILDER_H_ 18 #define ART_COMPILER_OPTIMIZING_BLOCK_BUILDER_H_ 19 20 #include "base/arena_containers.h" 21 #include "base/arena_object.h" 22 #include "dex_file.h" 23 #include "nodes.h" 24 25 namespace art { 26 27 class HBasicBlockBuilder : public ValueObject { 28 public: HBasicBlockBuilder(HGraph * graph,const DexFile * const dex_file,const DexFile::CodeItem & code_item)29 HBasicBlockBuilder(HGraph* graph, 30 const DexFile* const dex_file, 31 const DexFile::CodeItem& code_item) 32 : arena_(graph->GetArena()), 33 graph_(graph), 34 dex_file_(dex_file), 35 code_item_(code_item), 36 branch_targets_(code_item.insns_size_in_code_units_, 37 nullptr, 38 arena_->Adapter(kArenaAllocGraphBuilder)), 39 throwing_blocks_(kDefaultNumberOfThrowingBlocks, arena_->Adapter(kArenaAllocGraphBuilder)), 40 number_of_branches_(0u) {} 41 42 // Creates basic blocks in `graph_` at branch target dex_pc positions of the 43 // `code_item_`. Blocks are connected but left unpopulated with instructions. 44 // TryBoundary blocks are inserted at positions where control-flow enters/ 45 // exits a try block. 46 bool Build(); 47 GetNumberOfBranches()48 size_t GetNumberOfBranches() const { return number_of_branches_; } GetBlockAt(uint32_t dex_pc)49 HBasicBlock* GetBlockAt(uint32_t dex_pc) const { return branch_targets_[dex_pc]; } 50 51 private: 52 // Creates a basic block starting at given `dex_pc`. 53 HBasicBlock* MaybeCreateBlockAt(uint32_t dex_pc); 54 55 // Creates a basic block for bytecode instructions at `semantic_dex_pc` and 56 // stores it under the `store_dex_pc` key. This is used when multiple blocks 57 // share the same semantic dex_pc, e.g. when building switch decision trees. 58 HBasicBlock* MaybeCreateBlockAt(uint32_t semantic_dex_pc, uint32_t store_dex_pc); 59 60 bool CreateBranchTargets(); 61 void ConnectBasicBlocks(); 62 void InsertTryBoundaryBlocks(); 63 64 // Helper method which decides whether `catch_block` may have live normal 65 // predecessors and thus whether a synthetic catch block needs to be created 66 // to avoid mixing normal and exceptional predecessors. 67 // Should only be called during InsertTryBoundaryBlocks on blocks at catch 68 // handler dex_pcs. 69 bool MightHaveLiveNormalPredecessors(HBasicBlock* catch_block); 70 71 ArenaAllocator* const arena_; 72 HGraph* const graph_; 73 74 const DexFile* const dex_file_; 75 const DexFile::CodeItem& code_item_; 76 77 ArenaVector<HBasicBlock*> branch_targets_; 78 ArenaVector<HBasicBlock*> throwing_blocks_; 79 size_t number_of_branches_; 80 81 static constexpr size_t kDefaultNumberOfThrowingBlocks = 2u; 82 83 DISALLOW_COPY_AND_ASSIGN(HBasicBlockBuilder); 84 }; 85 86 } // namespace art 87 88 #endif // ART_COMPILER_OPTIMIZING_BLOCK_BUILDER_H_ 89