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// Copyright (c) 2017, 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.optimize;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import com.android.tools.r8.ir.code.Argument;
import com.android.tools.r8.ir.code.BasicBlock;
import com.android.tools.r8.ir.code.ConstNumber;
import com.android.tools.r8.ir.code.Goto;
import com.android.tools.r8.ir.code.IRCode;
import com.android.tools.r8.ir.code.If;
import com.android.tools.r8.ir.code.If.Type;
import com.android.tools.r8.ir.code.Instruction;
import com.android.tools.r8.ir.code.Position;
import com.android.tools.r8.ir.code.Return;
import com.android.tools.r8.ir.code.Throw;
import com.android.tools.r8.ir.code.Value;
import com.android.tools.r8.ir.code.ValueNumberGenerator;
import com.android.tools.r8.ir.code.ValueType;
import com.google.common.collect.ImmutableList;
import java.util.LinkedList;
import org.junit.Test;
public class TrivialGotoEliminationTest {
@Test
public void trivialGotoInEntryBlock() {
// Setup silly block structure:
//
// block0:
// goto block2
// block1:
// v0 = const-number 0
// throw v0
// block2:
// return
BasicBlock block2 = new BasicBlock();
block2.setNumber(2);
BasicBlock block0 = BasicBlock.createGotoBlock(0, block2);
block0.setFilledForTesting();
block2.getPredecessors().add(block0);
Instruction ret = new Return();
ret.setPosition(Position.none());
block2.add(ret);
block2.setFilledForTesting();
BasicBlock block1 = new BasicBlock();
block1.setNumber(1);
Value value = new Value(0, ValueType.INT, null);
Instruction number = new ConstNumber(value, 0);
number.setPosition(Position.none());
block1.add(number);
Instruction throwing = new Throw(value);
throwing.setPosition(Position.none());
block1.add(throwing);
block1.setFilledForTesting();
LinkedList<BasicBlock> blocks = new LinkedList<>();
blocks.add(block0);
blocks.add(block1);
blocks.add(block2);
// Check that the goto in block0 remains. There was a bug in the trivial goto elimination
// that ended up removing that goto changing the code to start with the unreachable
// throw.
IRCode code = new IRCode(null, null, blocks, new ValueNumberGenerator(), false);
CodeRewriter.collapsTrivialGotos(null, code);
assertTrue(code.blocks.get(0).isTrivialGoto());
assertTrue(blocks.contains(block0));
assertTrue(blocks.contains(block1));
assertTrue(blocks.contains(block2));
}
@Test
public void trivialGotoLoopAsFallthrough() {
// Setup block structure:
// block0:
// v0 <- argument
// if ne v0 block2
//
// block1:
// goto block3
//
// block2:
// return
//
// block3:
// goto block3
BasicBlock block2 = new BasicBlock();
block2.setNumber(2);
Instruction ret = new Return();
ret.setPosition(Position.none());
block2.add(ret);
block2.setFilledForTesting();
BasicBlock block3 = new BasicBlock();
block3.setNumber(3);
Instruction instruction = new Goto();
instruction.setPosition(Position.none());
block3.add(instruction);
block3.setFilledForTesting();
block3.getSuccessors().add(block3);
BasicBlock block1 = BasicBlock.createGotoBlock(1);
block1.getSuccessors().add(block3);
block1.setFilledForTesting();
BasicBlock block0 = new BasicBlock();
block0.setNumber(0);
Value value = new Value(0, ValueType.OBJECT, null);
instruction = new Argument(value);
instruction.setPosition(Position.none());
block0.add(instruction);
instruction = new If(Type.EQ, value);
instruction.setPosition(Position.none());
block0.add(instruction);
block0.getSuccessors().add(block2);
block0.getSuccessors().add(block1);
block0.setFilledForTesting();
block1.getPredecessors().add(block0);
block2.getPredecessors().add(block0);
block3.getPredecessors().add(block1);
block3.getPredecessors().add(block3);
LinkedList<BasicBlock> blocks = new LinkedList<>();
blocks.add(block0);
blocks.add(block1);
blocks.add(block2);
blocks.add(block3);
// Check that the goto in block0 remains. There was a bug in the trivial goto elimination
// that ended up removing that goto changing the code to start with the unreachable
// throw.
IRCode code = new IRCode(null, null, blocks, new ValueNumberGenerator(), false);
CodeRewriter.collapsTrivialGotos(null, code);
assertTrue(block0.getInstructions().get(1).isIf());
assertEquals(block1, block0.getInstructions().get(1).asIf().fallthroughBlock());
assertTrue(blocks.containsAll(ImmutableList.of(block0, block1, block2, block3)));
}
}