org.jetbrains.kotlin.codegen.optimization.RedundantGotoMethodTransformer.kt Maven / Gradle / Ivy
/*
* Copyright 2010-2015 JetBrains s.r.o.
*
* 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.jetbrains.kotlin.codegen.optimization
import org.jetbrains.kotlin.codegen.optimization.transformer.MethodTransformer
import org.jetbrains.org.objectweb.asm.tree.MethodNode
import org.jetbrains.org.objectweb.asm.tree.AbstractInsnNode
import org.jetbrains.org.objectweb.asm.tree.LabelNode
import org.jetbrains.org.objectweb.asm.Opcodes
import org.jetbrains.org.objectweb.asm.tree.JumpInsnNode
import org.jetbrains.kotlin.codegen.optimization.common.isMeaningful
public class RedundantGotoMethodTransformer : MethodTransformer() {
/**
* Removes redundant GOTO's, i.e. to subsequent labels
*/
override fun transform(internalClassName: String, methodNode: MethodNode) {
val insns = methodNode.instructions.toArray()
val insnsToRemove = arrayListOf()
val currentLabels = hashSetOf()
for (insn in insns.reverse()) {
if (insn.isMeaningful) {
if (insn.getOpcode() == Opcodes.GOTO && (insn as JumpInsnNode).label in currentLabels) {
insnsToRemove.add(insn)
}
else {
currentLabels.clear()
}
continue
}
if (insn is LabelNode) {
currentLabels.add(insn)
}
}
for (insnToRemove in insnsToRemove) {
methodNode.instructions.remove(insnToRemove)
}
}
}