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_PHI_ELIMINATION_H_ 18 #define ART_COMPILER_OPTIMIZING_SSA_PHI_ELIMINATION_H_ 19 20 #include "nodes.h" 21 22 namespace art { 23 24 /** 25 * Optimization phase that removes dead phis from the graph. Dead phis are unused 26 * phis, or phis only used by other phis. 27 */ 28 class SsaDeadPhiElimination : public ValueObject { 29 public: SsaDeadPhiElimination(HGraph * graph)30 explicit SsaDeadPhiElimination(HGraph* graph) 31 : graph_(graph), worklist_(graph->GetArena(), kDefaultWorklistSize) {} 32 33 void Run(); 34 35 private: 36 HGraph* const graph_; 37 GrowableArray<HPhi*> worklist_; 38 39 static constexpr size_t kDefaultWorklistSize = 8; 40 41 DISALLOW_COPY_AND_ASSIGN(SsaDeadPhiElimination); 42 }; 43 44 /** 45 * Removes redundant phis that may have been introduced when doing SSA conversion. 46 * For example, when entering a loop, we create phis for all live registers. These 47 * registers might be updated with the same value, or not updated at all. We can just 48 * replace the phi with the value when entering the loop. 49 */ 50 class SsaRedundantPhiElimination : public ValueObject { 51 public: SsaRedundantPhiElimination(HGraph * graph)52 explicit SsaRedundantPhiElimination(HGraph* graph) 53 : graph_(graph), worklist_(graph->GetArena(), kDefaultWorklistSize) {} 54 55 void Run(); 56 57 private: 58 HGraph* const graph_; 59 GrowableArray<HPhi*> worklist_; 60 61 static constexpr size_t kDefaultWorklistSize = 8; 62 63 DISALLOW_COPY_AND_ASSIGN(SsaRedundantPhiElimination); 64 }; 65 66 } // namespace art 67 68 #endif // ART_COMPILER_OPTIMIZING_SSA_PHI_ELIMINATION_H_ 69