Nicolas Geoffray | 804d093 | 2014-05-02 08:46:00 +0100 | [diff] [blame] | 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 | #ifndef ART_COMPILER_OPTIMIZING_SSA_LIVENESS_ANALYSIS_H_ |
| 18 | #define ART_COMPILER_OPTIMIZING_SSA_LIVENESS_ANALYSIS_H_ |
| 19 | |
| 20 | #include "nodes.h" |
| 21 | |
| 22 | namespace art { |
| 23 | |
| 24 | class BlockInfo : public ArenaObject { |
| 25 | public: |
| 26 | BlockInfo(ArenaAllocator* allocator, const HBasicBlock& block, size_t number_of_ssa_values) |
| 27 | : block_(block), |
| 28 | live_in_(allocator, number_of_ssa_values, false), |
| 29 | live_out_(allocator, number_of_ssa_values, false), |
| 30 | kill_(allocator, number_of_ssa_values, false) { |
| 31 | live_in_.ClearAllBits(); |
| 32 | live_out_.ClearAllBits(); |
| 33 | kill_.ClearAllBits(); |
| 34 | } |
| 35 | |
| 36 | private: |
| 37 | const HBasicBlock& block_; |
| 38 | ArenaBitVector live_in_; |
| 39 | ArenaBitVector live_out_; |
| 40 | ArenaBitVector kill_; |
| 41 | |
| 42 | friend class SsaLivenessAnalysis; |
| 43 | |
| 44 | DISALLOW_COPY_AND_ASSIGN(BlockInfo); |
| 45 | }; |
| 46 | |
| 47 | class SsaLivenessAnalysis : public ValueObject { |
| 48 | public: |
| 49 | explicit SsaLivenessAnalysis(const HGraph& graph) |
| 50 | : graph_(graph), |
| 51 | block_infos_(graph.GetArena(), graph.GetBlocks().Size()), |
| 52 | number_of_ssa_values_(0) { |
| 53 | block_infos_.SetSize(graph.GetBlocks().Size()); |
| 54 | } |
| 55 | |
| 56 | void Analyze(); |
| 57 | |
| 58 | BitVector* GetLiveInSet(const HBasicBlock& block) const { |
| 59 | return &block_infos_.Get(block.GetBlockId())->live_in_; |
| 60 | } |
| 61 | |
| 62 | BitVector* GetLiveOutSet(const HBasicBlock& block) const { |
| 63 | return &block_infos_.Get(block.GetBlockId())->live_out_; |
| 64 | } |
| 65 | |
| 66 | BitVector* GetKillSet(const HBasicBlock& block) const { |
| 67 | return &block_infos_.Get(block.GetBlockId())->kill_; |
| 68 | } |
| 69 | |
| 70 | private: |
| 71 | // Give an SSA number to each instruction that defines a value used by another instruction. |
| 72 | void NumberInstructions(); |
| 73 | |
| 74 | // Compute live_in, live_out and kill sets. |
| 75 | void ComputeSets(); |
| 76 | |
| 77 | // Compute the initial live_in, live_out and kill sets, without analyzing |
| 78 | // backward branches. |
| 79 | void ComputeInitialSets(); |
| 80 | |
| 81 | // After computing the initial sets, this method does a fixed point |
| 82 | // calculation over the live_in and live_out set to take into account |
| 83 | // backwards branches. |
| 84 | void ComputeLiveInAndLiveOutSets(); |
| 85 | |
| 86 | // Update the live_in set of the block and returns whether it has changed. |
| 87 | bool UpdateLiveIn(const HBasicBlock& block); |
| 88 | |
| 89 | // Update the live_out set of the block and returns whether it has changed. |
| 90 | bool UpdateLiveOut(const HBasicBlock& block); |
| 91 | |
| 92 | const HGraph& graph_; |
| 93 | GrowableArray<BlockInfo*> block_infos_; |
| 94 | size_t number_of_ssa_values_; |
| 95 | |
| 96 | DISALLOW_COPY_AND_ASSIGN(SsaLivenessAnalysis); |
| 97 | }; |
| 98 | |
| 99 | } // namespace art |
| 100 | |
| 101 | #endif // ART_COMPILER_OPTIMIZING_SSA_LIVENESS_ANALYSIS_H_ |