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 #include "side_effects_analysis.h" 18 19 namespace art { 20 21 void SideEffectsAnalysis::Run() { 22 // Inlining might have created more blocks, so we need to increase the size 23 // if needed. 24 block_effects_.resize(graph_->GetBlocks().size()); 25 loop_effects_.resize(graph_->GetBlocks().size()); 26 27 // In DEBUG mode, ensure side effects are properly initialized to empty. 28 if (kIsDebugBuild) { 29 for (HReversePostOrderIterator it(*graph_); !it.Done(); it.Advance()) { 30 HBasicBlock* block = it.Current(); 31 SideEffects effects = GetBlockEffects(block); 32 DCHECK(effects.DoesNothing()); 33 if (block->IsLoopHeader()) { 34 effects = GetLoopEffects(block); 35 DCHECK(effects.DoesNothing()); 36 } 37 } 38 } 39 40 // Do a post order visit to ensure we visit a loop header after its loop body. 41 for (HPostOrderIterator it(*graph_); !it.Done(); it.Advance()) { 42 HBasicBlock* block = it.Current(); 43 44 SideEffects effects = SideEffects::None(); 45 // Update `effects` with the side effects of all instructions in this block. 46 for (HInstructionIterator inst_it(block->GetInstructions()); !inst_it.Done(); 47 inst_it.Advance()) { 48 HInstruction* instruction = inst_it.Current(); 49 effects = effects.Union(instruction->GetSideEffects()); 50 // If all side effects are represented, scanning further will not add any 51 // more information to side-effects of this block. 52 if (effects.DoesAll()) { 53 break; 54 } 55 } 56 57 block_effects_[block->GetBlockId()] = effects; 58 59 if (block->IsLoopHeader()) { 60 // The side effects of the loop header are part of the loop. 61 UpdateLoopEffects(block->GetLoopInformation(), effects); 62 HBasicBlock* pre_header = block->GetLoopInformation()->GetPreHeader(); 63 if (pre_header->IsInLoop()) { 64 // Update the side effects of the outer loop with the side effects of the inner loop. 65 // Note that this works because we know all the blocks of the inner loop are visited 66 // before the loop header of the outer loop. 67 UpdateLoopEffects(pre_header->GetLoopInformation(), GetLoopEffects(block)); 68 } 69 } else if (block->IsInLoop()) { 70 // Update the side effects of the loop with the side effects of this block. 71 UpdateLoopEffects(block->GetLoopInformation(), effects); 72 } 73 } 74 has_run_ = true; 75 } 76 77 SideEffects SideEffectsAnalysis::GetLoopEffects(HBasicBlock* block) const { 78 DCHECK(block->IsLoopHeader()); 79 return loop_effects_[block->GetBlockId()]; 80 } 81 82 SideEffects SideEffectsAnalysis::GetBlockEffects(HBasicBlock* block) const { 83 return block_effects_[block->GetBlockId()]; 84 } 85 86 void SideEffectsAnalysis::UpdateLoopEffects(HLoopInformation* info, SideEffects effects) { 87 uint32_t id = info->GetHeader()->GetBlockId(); 88 loop_effects_[id] = loop_effects_[id].Union(effects); 89 } 90 91 } // namespace art 92
