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 * DO NOT REMOVE OR ALTER!
 */
/*
 * 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,
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package com.sun.org.apache.bcel.internal.generic;


/**
 * Super class for JSR - Jump to subroutine
 *
 * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
 */
public abstract class JsrInstruction extends BranchInstruction
  implements UnconditionalBranch, TypedInstruction, StackProducer
{
  JsrInstruction(short opcode, 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
   */
  public Type getType(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 = this.target;

    // Rewind!
    while(ih.getPrev() != null)
      ih = ih.getPrev();

    // Find the handle for "this" JsrInstruction object.
    while(ih.getInstruction() != this)
      ih = ih.getNext();

    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();
  }
}
