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268 lines
8.5 KiB
268 lines
8.5 KiB
/*
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* Copyright (c) 2007, 2018, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*/
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package com.sun.org.apache.bcel.internal.generic;
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/* ====================================================================
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* The Apache Software License, Version 1.1
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*
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* Copyright (c) 2001 The Apache Software Foundation. All rights
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* reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. The end-user documentation included with the redistribution,
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* if any, must include the following acknowledgment:
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* "This product includes software developed by the
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* Apache Software Foundation (http://www.apache.org/)."
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* Alternately, this acknowledgment may appear in the software itself,
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* if and wherever such third-party acknowledgments normally appear.
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*
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* 4. The names "Apache" and "Apache Software Foundation" and
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* "Apache BCEL" must not be used to endorse or promote products
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* derived from this software without prior written permission. For
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* written permission, please contact apache@apache.org.
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*
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* 5. Products derived from this software may not be called "Apache",
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* "Apache BCEL", nor may "Apache" appear in their name, without
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* prior written permission of the Apache Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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* ====================================================================
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*
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* This software consists of voluntary contributions made by many
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* individuals on behalf of the Apache Software Foundation. For more
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* information on the Apache Software Foundation, please see
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* <http://www.apache.org/>.
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*/
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import java.io.*;
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import com.sun.org.apache.bcel.internal.util.ByteSequence;
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/**
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* Select - Abstract super class for LOOKUPSWITCH and TABLESWITCH instructions.
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*
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* @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
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* @see LOOKUPSWITCH
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* @see TABLESWITCH
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* @see InstructionList
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*/
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public abstract class Select extends BranchInstruction
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implements VariableLengthInstruction, StackProducer
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{
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protected int[] match; // matches, i.e., case 1: ...
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protected int[] indices; // target offsets
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protected InstructionHandle[] targets; // target objects in instruction list
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protected int fixed_length; // fixed length defined by subclasses
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protected int match_length; // number of cases
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protected int padding = 0; // number of pad bytes for alignment
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/**
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* Empty constructor needed for the Class.newInstance() statement in
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* Instruction.readInstruction(). Not to be used otherwise.
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*/
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Select() {}
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/**
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* (Match, target) pairs for switch.
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* `Match' and `targets' must have the same length of course.
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*
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* @param match array of matching values
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* @param targets instruction targets
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* @param target default instruction target
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*/
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Select(short opcode, int[] match, InstructionHandle[] targets,
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InstructionHandle target) {
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super(opcode, target);
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this.targets = targets;
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for(int i=0; i < targets.length; i++) {
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BranchInstruction.notifyTargetChanged(targets[i], this);
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}
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this.match = match;
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if((match_length = match.length) != targets.length)
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throw new ClassGenException("Match and target array have not the same length");
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indices = new int[match_length];
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}
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/**
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* Since this is a variable length instruction, it may shift the following
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* instructions which then need to update their position.
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*
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* Called by InstructionList.setPositions when setting the position for every
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* instruction. In the presence of variable length instructions `setPositions'
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* performs multiple passes over the instruction list to calculate the
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* correct (byte) positions and offsets by calling this function.
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*
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* @param offset additional offset caused by preceding (variable length) instructions
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* @param max_offset the maximum offset that may be caused by these instructions
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* @return additional offset caused by possible change of this instruction's length
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*/
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@Override
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protected int updatePosition(int offset, int max_offset) {
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position += offset; // Additional offset caused by preceding SWITCHs, GOTOs, etc.
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short old_length = length;
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/* Alignment on 4-byte-boundary, + 1, because of tag byte.
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*/
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padding = (4 - ((position + 1) % 4)) % 4;
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length = (short)(fixed_length + padding); // Update length
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return length - old_length;
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}
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/**
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* Dump instruction as byte code to stream out.
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* @param out Output stream
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*/
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@Override
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public void dump(DataOutputStream out) throws IOException {
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out.writeByte(opcode);
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for(int i=0; i < padding; i++) // Padding bytes
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out.writeByte(0);
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index = getTargetOffset(); // Write default target offset
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out.writeInt(index);
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}
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/**
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* Read needed data (e.g. index) from file.
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*/
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@Override
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protected void initFromFile(ByteSequence bytes, boolean wide) throws IOException
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{
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padding = (4 - (bytes.getIndex() % 4)) % 4; // Compute number of pad bytes
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for(int i=0; i < padding; i++) {
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bytes.readByte();
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}
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// Default branch target common for both cases (TABLESWITCH, LOOKUPSWITCH)
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index = bytes.readInt();
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}
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/**
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* @return mnemonic for instruction
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*/
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@Override
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public String toString(boolean verbose) {
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final StringBuilder buf = new StringBuilder(super.toString(verbose));
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if(verbose) {
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for(int i=0; i < match_length; i++) {
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String s = "null";
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if(targets[i] != null)
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s = targets[i].getInstruction().toString();
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buf.append("(").append(match[i]).append(", ")
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.append(s).append(" = {").append(indices[i]).append("})");
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}
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}
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else
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buf.append(" ...");
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return buf.toString();
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}
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/**
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* Set branch target for `i'th case
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*/
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public final void setTarget(int i, InstructionHandle target) {
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notifyTargetChanging(targets[i], this);
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targets[i] = target;
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notifyTargetChanged(targets[i], this);
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}
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/**
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* @param old_ih old target
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* @param new_ih new target
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*/
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@Override
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public void updateTarget(InstructionHandle old_ih, InstructionHandle new_ih) {
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boolean targeted = false;
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if(target == old_ih) {
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targeted = true;
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setTarget(new_ih);
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}
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for(int i=0; i < targets.length; i++) {
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if(targets[i] == old_ih) {
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targeted = true;
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setTarget(i, new_ih);
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}
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}
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if(!targeted)
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throw new ClassGenException("Not targeting " + old_ih);
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}
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/**
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* @return true, if ih is target of this instruction
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*/
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@Override
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public boolean containsTarget(InstructionHandle ih) {
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if(target == ih)
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return true;
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for(int i=0; i < targets.length; i++)
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if(targets[i] == ih)
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return true;
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return false;
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}
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/**
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* Inform targets that they're not targeted anymore.
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*/
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@Override
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void dispose() {
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super.dispose();
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for(int i=0; i < targets.length; i++)
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targets[i].removeTargeter(this);
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}
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/**
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* @return array of match indices
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*/
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public int[] getMatchs() { return match; }
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/**
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* @return array of match target offsets
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*/
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public int[] getIndices() { return indices; }
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/**
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* @return array of match targets
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*/
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public InstructionHandle[] getTargets() { return targets; }
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}
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