instruction_simplifier.cc revision fa93b504b324784dd9a96e28e6e8f3f1b1ac456a
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 "instruction_simplifier.h" 18 19namespace art { 20 21class InstructionSimplifierVisitor : public HGraphVisitor { 22 public: 23 explicit InstructionSimplifierVisitor(HGraph* graph) : HGraphVisitor(graph) {} 24 25 private: 26 void VisitSuspendCheck(HSuspendCheck* check) OVERRIDE; 27 void VisitEqual(HEqual* equal) OVERRIDE; 28 void VisitArraySet(HArraySet* equal) OVERRIDE; 29 void VisitTypeConversion(HTypeConversion* instruction) OVERRIDE; 30}; 31 32void InstructionSimplifier::Run() { 33 InstructionSimplifierVisitor visitor(graph_); 34 visitor.VisitInsertionOrder(); 35} 36 37void InstructionSimplifierVisitor::VisitSuspendCheck(HSuspendCheck* check) { 38 HBasicBlock* block = check->GetBlock(); 39 // Currently always keep the suspend check at entry. 40 if (block->IsEntryBlock()) return; 41 42 // Currently always keep suspend checks at loop entry. 43 if (block->IsLoopHeader() && block->GetFirstInstruction() == check) { 44 DCHECK(block->GetLoopInformation()->GetSuspendCheck() == check); 45 return; 46 } 47 48 // Remove the suspend check that was added at build time for the baseline 49 // compiler. 50 block->RemoveInstruction(check); 51} 52 53void InstructionSimplifierVisitor::VisitEqual(HEqual* equal) { 54 HInstruction* input1 = equal->InputAt(0); 55 HInstruction* input2 = equal->InputAt(1); 56 if (input1->GetType() == Primitive::kPrimBoolean && input2->IsIntConstant()) { 57 if (input2->AsIntConstant()->GetValue() == 1) { 58 // Replace (bool_value == 1) with bool_value 59 equal->ReplaceWith(equal->InputAt(0)); 60 equal->GetBlock()->RemoveInstruction(equal); 61 } else { 62 // We should replace (bool_value == 0) with !bool_value, but we unfortunately 63 // do not have such instruction. 64 DCHECK_EQ(input2->AsIntConstant()->GetValue(), 0); 65 } 66 } 67} 68 69void InstructionSimplifierVisitor::VisitArraySet(HArraySet* instruction) { 70 HInstruction* value = instruction->GetValue(); 71 if (value->GetType() != Primitive::kPrimNot) return; 72 73 if (value->IsArrayGet()) { 74 if (value->AsArrayGet()->GetArray() == instruction->GetArray()) { 75 // If the code is just swapping elements in the array, no need for a type check. 76 instruction->ClearNeedsTypeCheck(); 77 } 78 } 79} 80 81void InstructionSimplifierVisitor::VisitTypeConversion(HTypeConversion* instruction) { 82 if (instruction->GetResultType() == instruction->GetInputType()) { 83 // Remove the instruction if it's converting to the same type. 84 instruction->ReplaceWith(instruction->GetInput()); 85 instruction->GetBlock()->RemoveInstruction(instruction); 86 } 87} 88 89} // namespace art 90