| // Copyright (c) 2018, the R8 project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| package com.android.tools.r8.ir.code; |
| |
| import com.android.tools.r8.graph.AppInfoWithSubtyping; |
| import com.android.tools.r8.graph.AppView; |
| import com.android.tools.r8.graph.DexType; |
| import com.android.tools.r8.utils.InternalOptions; |
| import java.util.ListIterator; |
| import java.util.Set; |
| |
| public class LinearFlowInstructionListIterator implements InstructionListIterator { |
| |
| private final IRCode code; |
| |
| private BasicBlock currentBlock; |
| private InstructionListIterator currentBlockIterator; |
| |
| public LinearFlowInstructionListIterator(IRCode code, BasicBlock block) { |
| this(code, block, 0); |
| } |
| |
| public LinearFlowInstructionListIterator(IRCode code, BasicBlock block, int index) { |
| this.code = code; |
| this.currentBlock = block; |
| this.currentBlockIterator = block.listIterator(code, index); |
| // If index is pointing after the last instruction, and it is a goto with a linear edge, |
| // we have to move the pointer. This is achieved by calling previous and next. |
| if (index > 0) { |
| this.previous(); |
| this.next(); |
| } |
| } |
| |
| @Override |
| public void replaceCurrentInstruction(Instruction newInstruction) { |
| currentBlockIterator.replaceCurrentInstruction(newInstruction); |
| } |
| |
| @Override |
| public Value insertConstNullInstruction(IRCode code, InternalOptions options) { |
| return currentBlockIterator.insertConstNullInstruction(code, options); |
| } |
| |
| @Override |
| public Value insertConstIntInstruction(IRCode code, InternalOptions options, int value) { |
| return currentBlockIterator.insertConstIntInstruction(code, options, value); |
| } |
| |
| @Override |
| public void replaceCurrentInstructionWithThrowNull( |
| AppView<? extends AppInfoWithSubtyping> appView, |
| IRCode code, |
| ListIterator<BasicBlock> blockIterator, |
| Set<BasicBlock> blocksToRemove, |
| Set<Value> affectedValues) { |
| currentBlockIterator.replaceCurrentInstructionWithThrowNull( |
| appView, code, blockIterator, blocksToRemove, affectedValues); |
| } |
| |
| @Override |
| public BasicBlock split(IRCode code, ListIterator<BasicBlock> blockIterator) { |
| return currentBlockIterator.split(code, blockIterator); |
| } |
| |
| @Override |
| public BasicBlock split(IRCode code, int instructions, ListIterator<BasicBlock> blockIterator) { |
| return currentBlockIterator.split(code, instructions, blockIterator); |
| } |
| |
| @Override |
| public BasicBlock inlineInvoke( |
| AppView<?> appView, |
| IRCode code, |
| IRCode inlinee, |
| ListIterator<BasicBlock> blockIterator, |
| Set<BasicBlock> blocksToRemove, |
| DexType downcast) { |
| return currentBlockIterator.inlineInvoke( |
| appView, code, inlinee, blockIterator, blocksToRemove, downcast); |
| } |
| |
| @Override |
| public void add(Instruction instruction) { |
| currentBlockIterator.add(instruction); |
| } |
| |
| @Override |
| public void removeOrReplaceByDebugLocalRead() { |
| currentBlockIterator.removeOrReplaceByDebugLocalRead(); |
| } |
| |
| private boolean isLinearEdge(BasicBlock pred, BasicBlock succ) { |
| assert pred.getSuccessors().contains(succ); |
| assert succ.getPredecessors().contains(pred); |
| Goto exit = pred.exit().asGoto(); |
| return exit != null && exit.getTarget() == succ && succ.getPredecessors().size() == 1; |
| } |
| |
| @Override |
| public boolean hasNext() { |
| return currentBlockIterator.hasNext(); |
| } |
| |
| @Override |
| public Instruction next() { |
| Instruction current = currentBlockIterator.next(); |
| if (!current.isGoto()) { |
| return current; |
| } |
| BasicBlock target = current.asGoto().getTarget(); |
| if (!isLinearEdge(currentBlock, target)) { |
| return current; |
| } |
| while (target.isTrivialGoto()) { |
| BasicBlock candidate = target.exit().asGoto().getTarget(); |
| if (!isLinearEdge(target, candidate)) { |
| break; |
| } |
| target = candidate; |
| } |
| currentBlock = target; |
| currentBlockIterator = currentBlock.listIterator(code); |
| return currentBlockIterator.next(); |
| } |
| |
| private BasicBlock getBeginningOfTrivialLinearGotoChain(BasicBlock block) { |
| if (block.getPredecessors().size() != 1 |
| || !isLinearEdge(block.getPredecessors().get(0), block)) { |
| return null; |
| } |
| BasicBlock target = block.getPredecessors().get(0); |
| while (target.getPredecessors().size() == 1 |
| && isLinearEdge(target.getPredecessors().get(0), target) |
| && target.isTrivialGoto()) { |
| target = target.getPredecessors().get(0); |
| } |
| return target.isTrivialGoto() ? null : target; |
| } |
| |
| @Override |
| public boolean hasPrevious() { |
| if (currentBlockIterator.hasPrevious()) { |
| return true; |
| } |
| return getBeginningOfTrivialLinearGotoChain(currentBlock) != null; |
| } |
| |
| @Override |
| public Instruction previous() { |
| if (currentBlockIterator.hasPrevious()) { |
| return currentBlockIterator.previous(); |
| } |
| BasicBlock target = getBeginningOfTrivialLinearGotoChain(currentBlock); |
| if (target == null) { |
| // No existing linear predecessor. Force an error by calling previous. |
| return currentBlockIterator.previous(); |
| } |
| currentBlock = target; |
| currentBlockIterator = currentBlock.listIterator(code, currentBlock.getInstructions().size()); |
| // Iterate over the jump. |
| currentBlockIterator.previous(); |
| return currentBlockIterator.previous(); |
| } |
| |
| @Override |
| public int nextIndex() { |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public int previousIndex() { |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public void remove() { |
| currentBlockIterator.remove(); |
| } |
| |
| @Override |
| public void set(Instruction instruction) { |
| currentBlockIterator.set(instruction); |
| } |
| } |