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90 lines
3.3 KiB
90 lines
3.3 KiB
/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "side_effects_analysis.h"
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namespace art {
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bool SideEffectsAnalysis::Run() {
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// Inlining might have created more blocks, so we need to increase the size
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// if needed.
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block_effects_.resize(graph_->GetBlocks().size());
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loop_effects_.resize(graph_->GetBlocks().size());
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// In DEBUG mode, ensure side effects are properly initialized to empty.
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if (kIsDebugBuild) {
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for (HBasicBlock* block : graph_->GetReversePostOrder()) {
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SideEffects effects = GetBlockEffects(block);
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DCHECK(effects.DoesNothing());
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if (block->IsLoopHeader()) {
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effects = GetLoopEffects(block);
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DCHECK(effects.DoesNothing());
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}
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}
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}
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// Do a post order visit to ensure we visit a loop header after its loop body.
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for (HBasicBlock* block : graph_->GetPostOrder()) {
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SideEffects effects = SideEffects::None();
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// Update `effects` with the side effects of all instructions in this block.
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for (HInstructionIterator inst_it(block->GetInstructions()); !inst_it.Done();
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inst_it.Advance()) {
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HInstruction* instruction = inst_it.Current();
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effects = effects.Union(instruction->GetSideEffects());
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// If all side effects are represented, scanning further will not add any
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// more information to side-effects of this block.
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if (effects.DoesAll()) {
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break;
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}
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}
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block_effects_[block->GetBlockId()] = effects;
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if (block->IsLoopHeader()) {
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// The side effects of the loop header are part of the loop.
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UpdateLoopEffects(block->GetLoopInformation(), effects);
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HBasicBlock* pre_header = block->GetLoopInformation()->GetPreHeader();
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if (pre_header->IsInLoop()) {
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// Update the side effects of the outer loop with the side effects of the inner loop.
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// Note that this works because we know all the blocks of the inner loop are visited
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// before the loop header of the outer loop.
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UpdateLoopEffects(pre_header->GetLoopInformation(), GetLoopEffects(block));
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}
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} else if (block->IsInLoop()) {
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// Update the side effects of the loop with the side effects of this block.
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UpdateLoopEffects(block->GetLoopInformation(), effects);
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}
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}
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has_run_ = true;
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return true;
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}
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SideEffects SideEffectsAnalysis::GetLoopEffects(HBasicBlock* block) const {
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DCHECK(block->IsLoopHeader());
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return loop_effects_[block->GetBlockId()];
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}
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SideEffects SideEffectsAnalysis::GetBlockEffects(HBasicBlock* block) const {
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return block_effects_[block->GetBlockId()];
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}
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void SideEffectsAnalysis::UpdateLoopEffects(HLoopInformation* info, SideEffects effects) {
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uint32_t id = info->GetHeader()->GetBlockId();
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loop_effects_[id] = loop_effects_[id].Union(effects);
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}
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} // namespace art
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