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 quicken_index_for_dex_pc_(std::less<uint32_t>(), arena_->Adapter()) {} 42 43 // Creates basic blocks in `graph_` at branch target dex_pc positions of the 44 // `code_item_`. Blocks are connected but left unpopulated with instructions. 45 // TryBoundary blocks are inserted at positions where control-flow enters/ 46 // exits a try block. 47 bool Build(); 48 GetNumberOfBranches()49 size_t GetNumberOfBranches() const { return number_of_branches_; } GetBlockAt(uint32_t dex_pc)50 HBasicBlock* GetBlockAt(uint32_t dex_pc) const { return branch_targets_[dex_pc]; } 51 52 size_t GetQuickenIndex(uint32_t dex_pc) const; 53 54 private: 55 // Creates a basic block starting at given `dex_pc`. 56 HBasicBlock* MaybeCreateBlockAt(uint32_t dex_pc); 57 58 // Creates a basic block for bytecode instructions at `semantic_dex_pc` and 59 // stores it under the `store_dex_pc` key. This is used when multiple blocks 60 // share the same semantic dex_pc, e.g. when building switch decision trees. 61 HBasicBlock* MaybeCreateBlockAt(uint32_t semantic_dex_pc, uint32_t store_dex_pc); 62 63 bool CreateBranchTargets(); 64 void ConnectBasicBlocks(); 65 void InsertTryBoundaryBlocks(); 66 67 // Helper method which decides whether `catch_block` may have live normal 68 // predecessors and thus whether a synthetic catch block needs to be created 69 // to avoid mixing normal and exceptional predecessors. 70 // Should only be called during InsertTryBoundaryBlocks on blocks at catch 71 // handler dex_pcs. 72 bool MightHaveLiveNormalPredecessors(HBasicBlock* catch_block); 73 74 ArenaAllocator* const arena_; 75 HGraph* const graph_; 76 77 const DexFile* const dex_file_; 78 const DexFile::CodeItem& code_item_; 79 80 ArenaVector<HBasicBlock*> branch_targets_; 81 ArenaVector<HBasicBlock*> throwing_blocks_; 82 size_t number_of_branches_; 83 84 // A table to quickly find the quicken index for the first instruction of a basic block. 85 ArenaSafeMap<uint32_t, uint32_t> quicken_index_for_dex_pc_; 86 87 static constexpr size_t kDefaultNumberOfThrowingBlocks = 2u; 88 89 DISALLOW_COPY_AND_ASSIGN(HBasicBlockBuilder); 90 }; 91 92 } // namespace art 93 94 #endif // ART_COMPILER_OPTIMIZING_BLOCK_BUILDER_H_ 95