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 * @version $Id: JsrInstruction.java 1812166 2017-10-13 23:48:11Z ggregory $ 024 */ 025public abstract class JsrInstruction extends BranchInstruction implements UnconditionalBranch, 026 TypedInstruction, StackProducer { 027 028 JsrInstruction(final short opcode, final InstructionHandle target) { 029 super(opcode, target); 030 } 031 032 033 /** 034 * Empty constructor needed for Instruction.readInstruction. 035 * Not to be used otherwise. 036 */ 037 JsrInstruction() { 038 } 039 040 041 /** @return return address type 042 */ 043 @Override 044 public Type getType( final ConstantPoolGen cp ) { 045 return new ReturnaddressType(physicalSuccessor()); 046 } 047 048 049 /** 050 * Returns an InstructionHandle to the physical successor 051 * of this JsrInstruction. <B>For this method to work, 052 * this JsrInstruction object must not be shared between 053 * multiple InstructionHandle objects!</B> 054 * Formally, there must not be InstructionHandle objects 055 * i, j where i != j and i.getInstruction() == this == 056 * j.getInstruction(). 057 * @return an InstructionHandle to the "next" instruction that 058 * will be executed when RETurned from a subroutine. 059 */ 060 public InstructionHandle physicalSuccessor() { 061 InstructionHandle ih = super.getTarget(); 062 // Rewind! 063 while (ih.getPrev() != null) { 064 ih = ih.getPrev(); 065 } 066 // Find the handle for "this" JsrInstruction object. 067 while (ih.getInstruction() != this) { 068 ih = ih.getNext(); 069 } 070 final InstructionHandle toThis = ih; 071 while (ih != null) { 072 ih = ih.getNext(); 073 if ((ih != null) && (ih.getInstruction() == this)) { 074 throw new RuntimeException("physicalSuccessor() called on a shared JsrInstruction."); 075 } 076 } 077 // Return the physical successor 078 return toThis.getNext(); 079 } 080}