/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

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();

  }

}