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
Run()21 void SideEffectsAnalysis::Run() {
22 // Inlining might have created more blocks, so we need to increase the size
23 // if needed.
24 block_effects_.SetSize(graph_->GetBlocks().Size());
25 loop_effects_.SetSize(graph_->GetBlocks().Size());
26
27 if (kIsDebugBuild) {
28 for (HReversePostOrderIterator it(*graph_); !it.Done(); it.Advance()) {
29 HBasicBlock* block = it.Current();
30 SideEffects effects = GetBlockEffects(block);
31 DCHECK(!effects.HasSideEffects() && !effects.HasDependencies());
32 if (block->IsLoopHeader()) {
33 effects = GetLoopEffects(block);
34 DCHECK(!effects.HasSideEffects() && !effects.HasDependencies());
35 }
36 }
37 }
38
39 // Do a post order visit to ensure we visit a loop header after its loop body.
40 for (HPostOrderIterator it(*graph_); !it.Done(); it.Advance()) {
41 HBasicBlock* block = it.Current();
42
43 SideEffects effects = SideEffects::None();
44 // Update `effects` with the side effects of all instructions in this block.
45 for (HInstructionIterator inst_it(block->GetInstructions()); !inst_it.Done();
46 inst_it.Advance()) {
47 HInstruction* instruction = inst_it.Current();
48 effects = effects.Union(instruction->GetSideEffects());
49 if (effects.HasAllSideEffects()) {
50 break;
51 }
52 }
53
54 block_effects_.Put(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
GetLoopEffects(HBasicBlock * block) const74 SideEffects SideEffectsAnalysis::GetLoopEffects(HBasicBlock* block) const {
75 DCHECK(block->IsLoopHeader());
76 return loop_effects_.Get(block->GetBlockId());
77 }
78
GetBlockEffects(HBasicBlock * block) const79 SideEffects SideEffectsAnalysis::GetBlockEffects(HBasicBlock* block) const {
80 return block_effects_.Get(block->GetBlockId());
81 }
82
UpdateLoopEffects(HLoopInformation * info,SideEffects effects)83 void SideEffectsAnalysis::UpdateLoopEffects(HLoopInformation* info, SideEffects effects) {
84 int id = info->GetHeader()->GetBlockId();
85 loop_effects_.Put(id, loop_effects_.Get(id).Union(effects));
86 }
87
88 } // namespace art
89