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 020import java.io.DataOutputStream; 021import java.io.IOException; 022 023/** 024 * GOTO - Branch always (to relative offset, not absolute address) 025 * 026 */ 027public class GOTO extends GotoInstruction implements VariableLengthInstruction { 028 029 /** 030 * Empty constructor needed for Instruction.readInstruction. 031 * Not to be used otherwise. 032 */ 033 GOTO() { 034 } 035 036 037 public GOTO(final InstructionHandle target) { 038 super(org.apache.bcel.Const.GOTO, target); 039 } 040 041 042 /** 043 * Dump instruction as byte code to stream out. 044 * @param out Output stream 045 */ 046 @Override 047 public void dump( final DataOutputStream out ) throws IOException { 048 super.setIndex(getTargetOffset()); 049 final short _opcode = getOpcode(); 050 if (_opcode == org.apache.bcel.Const.GOTO) { 051 super.dump(out); 052 } else { // GOTO_W 053 super.setIndex(getTargetOffset()); 054 out.writeByte(_opcode); 055 out.writeInt(super.getIndex()); 056 } 057 } 058 059 060 /** 061 * Called in pass 2 of InstructionList.setPositions() in order to update 062 * the branch target, that may shift due to variable length instructions. 063 * 064 * @param offset additional offset caused by preceding (variable length) instructions 065 * @param max_offset the maximum offset that may be caused by these instructions 066 * @return additional offset caused by possible change of this instruction's length 067 */ 068 @Override 069 protected int updatePosition( final int offset, final int max_offset ) { 070 final int i = getTargetOffset(); // Depending on old position value 071 setPosition(getPosition() + offset); // Position may be shifted by preceding expansions 072 if (Math.abs(i) >= (Short.MAX_VALUE - max_offset)) { // to large for short (estimate) 073 super.setOpcode(org.apache.bcel.Const.GOTO_W); 074 final short old_length = (short) super.getLength(); 075 super.setLength(5); 076 return super.getLength() - old_length; 077 } 078 return 0; 079 } 080 081 082 /** 083 * Call corresponding visitor method(s). The order is: 084 * Call visitor methods of implemented interfaces first, then 085 * call methods according to the class hierarchy in descending order, 086 * i.e., the most specific visitXXX() call comes last. 087 * 088 * @param v Visitor object 089 */ 090 @Override 091 public void accept( final Visitor v ) { 092 v.visitVariableLengthInstruction(this); 093 v.visitUnconditionalBranch(this); 094 v.visitBranchInstruction(this); 095 v.visitGotoInstruction(this); 096 v.visitGOTO(this); 097 } 098}