/*
* Copyright 2014 Alexey Andreev.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.teavm.optimization;
import java.util.ArrayList;
import java.util.List;
import org.teavm.model.*;
import org.teavm.model.instructions.EmptyInstruction;
import org.teavm.model.instructions.UnwrapArrayInstruction;
import org.teavm.model.util.DefinitionExtractor;
/**
*
* @author Alexey Andreev
*/
public class ArrayUnwrapMotion implements MethodOptimization {
@Override
public void optimize(MethodReader method, Program program) {
for (int i = 0; i < program.basicBlockCount(); ++i) {
optimize(program.basicBlockAt(i));
}
}
private void optimize(BasicBlock block) {
List<Instruction> newInstructions = new ArrayList<>();
List<Instruction> instructions = block.getInstructions();
for (int i = 0; i < instructions.size(); ++i) {
Instruction insn = instructions.get(i);
if (insn instanceof UnwrapArrayInstruction) {
UnwrapArrayInstruction unwrap = (UnwrapArrayInstruction)insn;
instructions.set(i, new EmptyInstruction());
int def = whereDefined(instructions, i, unwrap.getArray());
if (def < 0) {
newInstructions.add(unwrap);
} else {
instructions.add(def + 1, unwrap);
++i;
}
}
}
if (!newInstructions.isEmpty()) {
instructions.addAll(0, newInstructions);
}
}
private int whereDefined(List<Instruction> instructions, int index, Variable var) {
DefinitionExtractor def = new DefinitionExtractor();
while (index >= 0) {
Instruction insn = instructions.get(index);
insn.acceptVisitor(def);
for (Variable defVar : def.getDefinedVariables()) {
if (defVar == var) {
return index;
}
}
--index;
}
return index;
}
}