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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.bcel.generic;
/**
* Super class for JSR - Jump to subroutine
*
* @version $Id$
*/
public abstract class JsrInstruction extends BranchInstruction implements UnconditionalBranch,
TypedInstruction, StackProducer {
JsrInstruction(final short opcode, final InstructionHandle target) {
super(opcode, target);
}
/**
* Empty constructor needed for the Class.newInstance() statement in
* Instruction.readInstruction(). Not to be used otherwise.
*/
JsrInstruction() {
}
/** @return return address type
*/
@Override
public Type getType( final ConstantPoolGen cp ) {
return new ReturnaddressType(physicalSuccessor());
}
/**
* Returns an InstructionHandle to the physical successor
* of this JsrInstruction. <B>For this method to work,
* this JsrInstruction object must not be shared between
* multiple InstructionHandle objects!</B>
* Formally, there must not be InstructionHandle objects
* i, j where i != j and i.getInstruction() == this ==
* j.getInstruction().
* @return an InstructionHandle to the "next" instruction that
* will be executed when RETurned from a subroutine.
*/
public InstructionHandle physicalSuccessor() {
InstructionHandle ih = super.getTarget();
// Rewind!
while (ih.getPrev() != null) {
ih = ih.getPrev();
}
// Find the handle for "this" JsrInstruction object.
while (ih.getInstruction() != this) {
ih = ih.getNext();
}
final InstructionHandle toThis = ih;
while (ih != null) {
ih = ih.getNext();
if ((ih != null) && (ih.getInstruction() == this)) {
throw new RuntimeException("physicalSuccessor() called on a shared JsrInstruction.");
}
}
// Return the physical successor
return toThis.getNext();
}
}
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