package com.sun.org.apache.bcel.internal.generic;

/* ====================================================================
 * The Apache Software License, Version 1.1
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 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
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 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
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 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache BCEL" must not be used to endorse or promote products
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 * <http://www.apache.org/>.
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/** 
 * Super class for JSR - Jump to subroutine
 *
 * @version $Id: JsrInstruction.java,v 1.1.1.1 2001/10/29 20:00:20 jvanzyl Exp $
 * @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();
  }
}