001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 * 017 */ 018package org.apache.bcel.generic; 019 020/** 021 * Super class for JSR - Jump to subroutine 022 * 023 */ 024public abstract class JsrInstruction extends BranchInstruction implements UnconditionalBranch, TypedInstruction, StackProducer { 025 026 /** 027 * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise. 028 */ 029 JsrInstruction() { 030 } 031 032 JsrInstruction(final short opcode, final InstructionHandle target) { 033 super(opcode, target); 034 } 035 036 /** 037 * @return return address type 038 */ 039 @Override 040 public Type getType(final ConstantPoolGen cp) { 041 return new ReturnaddressType(physicalSuccessor()); 042 } 043 044 /** 045 * Returns an InstructionHandle to the physical successor of this JsrInstruction. <B>For this method to work, this 046 * JsrInstruction object must not be shared between multiple InstructionHandle objects!</B> Formally, there must not be 047 * InstructionHandle objects i, j where i != j and i.getInstruction() == this == j.getInstruction(). 048 * 049 * @return an InstructionHandle to the "next" instruction that will be executed when RETurned from a subroutine. 050 */ 051 public InstructionHandle physicalSuccessor() { 052 InstructionHandle ih = super.getTarget(); 053 // Rewind! 054 while (ih.getPrev() != null) { 055 ih = ih.getPrev(); 056 } 057 // Find the handle for "this" JsrInstruction object. 058 while (ih.getInstruction() != this) { 059 ih = ih.getNext(); 060 } 061 final InstructionHandle toThis = ih; 062 while (ih != null) { 063 ih = ih.getNext(); 064 if (ih != null && ih.getInstruction() == this) { 065 throw new IllegalStateException("physicalSuccessor() called on a shared JsrInstruction."); 066 } 067 } 068 // Return the physical successor 069 return toThis.getNext(); 070 } 071}