1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 */ 18 package org.apache.bcel.generic; 19 20 /** 21 * Super class for JSR - Jump to subroutine 22 * 23 * @version $Id$ 24 */ 25 public abstract class JsrInstruction extends BranchInstruction implements UnconditionalBranch, 26 TypedInstruction, StackProducer { 27 JsrInstruction(final short opcode, final InstructionHandle target)28 JsrInstruction(final short opcode, final InstructionHandle target) { 29 super(opcode, target); 30 } 31 32 33 /** 34 * Empty constructor needed for Instruction.readInstruction. 35 * Not to be used otherwise. 36 */ JsrInstruction()37 JsrInstruction() { 38 } 39 40 41 /** @return return address type 42 */ 43 @Override getType( final ConstantPoolGen cp )44 public Type getType( final ConstantPoolGen cp ) { 45 return new ReturnaddressType(physicalSuccessor()); 46 } 47 48 49 /** 50 * Returns an InstructionHandle to the physical successor 51 * of this JsrInstruction. <B>For this method to work, 52 * this JsrInstruction object must not be shared between 53 * multiple InstructionHandle objects!</B> 54 * Formally, there must not be InstructionHandle objects 55 * i, j where i != j and i.getInstruction() == this == 56 * j.getInstruction(). 57 * @return an InstructionHandle to the "next" instruction that 58 * will be executed when RETurned from a subroutine. 59 */ physicalSuccessor()60 public InstructionHandle physicalSuccessor() { 61 InstructionHandle ih = super.getTarget(); 62 // Rewind! 63 while (ih.getPrev() != null) { 64 ih = ih.getPrev(); 65 } 66 // Find the handle for "this" JsrInstruction object. 67 while (ih.getInstruction() != this) { 68 ih = ih.getNext(); 69 } 70 final InstructionHandle toThis = ih; 71 while (ih != null) { 72 ih = ih.getNext(); 73 if ((ih != null) && (ih.getInstruction() == this)) { 74 throw new RuntimeException("physicalSuccessor() called on a shared JsrInstruction."); 75 } 76 } 77 // Return the physical successor 78 return toThis.getNext(); 79 } 80 } 81