net.bytebuddy.utility.visitor.LocalVariableAwareMethodVisitor Maven / Gradle / Ivy
/*
* Copyright 2014 - Present Rafael Winterhalter
*
* 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 net.bytebuddy.utility.visitor;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import net.bytebuddy.description.method.MethodDescription;
import net.bytebuddy.utility.OpenedClassReader;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
/**
* A method visitor that traces the amount of used local variable slots.
*/
public class LocalVariableAwareMethodVisitor extends MethodVisitor {
/**
* The first offset that was observed to not be used.
*/
private int freeOffset;
/**
* Creates a local variable aware method visitor.
*
* @param methodVisitor The method visitor to delegate to.
* @param methodDescription The method being visited.
*/
public LocalVariableAwareMethodVisitor(MethodVisitor methodVisitor, MethodDescription methodDescription) {
super(OpenedClassReader.ASM_API, methodVisitor);
freeOffset = methodDescription.getStackSize();
}
@Override
@SuppressFBWarnings(value = "SF_SWITCH_NO_DEFAULT", justification = "No action required on default option.")
public void visitVarInsn(int opcode, int offset) {
switch (opcode) {
case Opcodes.ISTORE:
case Opcodes.FSTORE:
case Opcodes.ASTORE:
freeOffset = Math.max(freeOffset, offset + 1);
break;
case Opcodes.LSTORE:
case Opcodes.DSTORE:
freeOffset = Math.max(freeOffset, offset + 2);
break;
}
super.visitVarInsn(opcode, offset);
}
/**
* Returns the first offset that was observed to be free.
*
* @return The first offset that was observed to be free.
*/
public int getFreeOffset() {
return freeOffset;
}
}