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 (HBasicBlock* block : graph_->GetReversePostOrder()) { 30 SideEffects effects = GetBlockEffects(block); 31 DCHECK(effects.DoesNothing()); 32 if (block->IsLoopHeader()) { 33 effects = GetLoopEffects(block); 34 DCHECK(effects.DoesNothing()); 35 } 36 } 37 } 38 39 // Do a post order visit to ensure we visit a loop header after its loop body. 40 for (HBasicBlock* block : graph_->GetPostOrder()) { 41 SideEffects effects = SideEffects::None(); 42 // Update `effects` with the side effects of all instructions in this block. 43 for (HInstructionIterator inst_it(block->GetInstructions()); !inst_it.Done(); 44 inst_it.Advance()) { 45 HInstruction* instruction = inst_it.Current(); 46 effects = effects.Union(instruction->GetSideEffects()); 47 // If all side effects are represented, scanning further will not add any 48 // more information to side-effects of this block. 49 if (effects.DoesAll()) { 50 break; 51 } 52 } 53 54 block_effects_[block->GetBlockId()] = effects; 55 56 if (block->IsLoopHeader()) { 57 // The side effects of the loop header are part of the loop. 58 UpdateLoopEffects(block->GetLoopInformation(), effects); 59 HBasicBlock* pre_header = block->GetLoopInformation()->GetPreHeader(); 60 if (pre_header->IsInLoop()) { 61 // Update the side effects of the outer loop with the side effects of the inner loop. 62 // Note that this works because we know all the blocks of the inner loop are visited 63 // before the loop header of the outer loop. 64 UpdateLoopEffects(pre_header->GetLoopInformation(), GetLoopEffects(block)); 65 } 66 } else if (block->IsInLoop()) { 67 // Update the side effects of the loop with the side effects of this block. 68 UpdateLoopEffects(block->GetLoopInformation(), effects); 69 } 70 } 71 has_run_ = true; 72 } 73 74 SideEffects SideEffectsAnalysis::GetLoopEffects(HBasicBlock* block) const { 75 DCHECK(block->IsLoopHeader()); 76 return loop_effects_[block->GetBlockId()]; 77 } 78 79 SideEffects SideEffectsAnalysis::GetBlockEffects(HBasicBlock* block) const { 80 return block_effects_[block->GetBlockId()]; 81 } 82 83 void SideEffectsAnalysis::UpdateLoopEffects(HLoopInformation* info, SideEffects effects) { 84 uint32_t id = info->GetHeader()->GetBlockId(); 85 loop_effects_[id] = loop_effects_[id].Union(effects); 86 } 87 88 } // namespace art 89
