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/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2001 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Apache" and "Apache Software Foundation" and
* "Apache BCEL" must not be used to endorse or promote products
* derived from this software without prior written permission. For
* written permission, please contact [email protected].
*
* 5. Products derived from this software may not be called "Apache",
* "Apache BCEL", nor may "Apache" appear in their name, without
* prior written permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* .
*/
package org.aspectj.apache.bcel.generic;
import java.io.DataOutputStream;
import java.io.IOException;
import org.aspectj.apache.bcel.Constants;
import org.aspectj.apache.bcel.classfile.ConstantPool;
/**
* Abstract super class for branching instructions like GOTO, IFEQ, etc.. Branch instructions may have a variable length, namely
* GOTO, JSR, LOOKUPSWITCH and TABLESWITCH. A branch instruction may be talking in terms of absolute destination (targetIndex) or
* about an instruction it doesnt yet know the position if (targetInstruction). targetInstruction (if set) overrides targetIndex
*
* @see InstructionList
* @version $Id: InstructionBranch.java,v 1.6 2009/10/05 17:35:36 aclement Exp $
* @author M. Dahm
*/
public class InstructionBranch extends Instruction implements InstructionTargeter {
private static final int UNSET = -1;
protected int targetIndex = UNSET; // Branch target relative to this
// instruction
protected InstructionHandle targetInstruction; // Target object in
// instruction list
protected int positionOfThisInstruction; // for calculating relative branch
// destinations!
public InstructionBranch(short opcode, InstructionHandle target) {
super(opcode);
setTarget(target);
}
public InstructionBranch(short opcode, int index) {
super(opcode);
this.targetIndex = index;
}
public InstructionBranch(short opcode) {
super(opcode);
}
public void dump(DataOutputStream out) throws IOException {
int target = getTargetOffset();
if (Math.abs(target) >= 32767 && opcode != GOTO_W && opcode != JSR_W) {
throw new ClassGenException("Branch target offset too large for short. Instruction: " + getName().toUpperCase() + "("
+ opcode + ")");
}
out.writeByte(opcode);
switch (opcode) {
case GOTO_W:
case JSR_W:
out.writeInt(target);
break;
case IF_ACMPEQ:
case IF_ACMPNE:
case IF_ICMPEQ:
case IF_ICMPGE:
case IF_ICMPGT:
case IF_ICMPLE:
case IF_ICMPLT:
case IF_ICMPNE:
case IFEQ:
case IFLE:
case IFLT:
case IFGT:
case IFNE:
case IFGE:
case IFNULL:
case IFNONNULL:
case GOTO:
case JSR:
out.writeShort(target);
break;
default:
throw new IllegalStateException("Don't know how to write out " + getName().toUpperCase());
}
}
protected int getTargetOffset() {
if (targetInstruction == null && targetIndex == UNSET) {
throw new ClassGenException("Target of " + super.toString(true) + " is unknown");
}
if (targetInstruction == null) {
return targetIndex;
} else {
return targetInstruction.getPosition() - positionOfThisInstruction;
}
}
/**
* Called by InstructionList.setPositions when setting the position for every instruction. In the presence of variable length
* instructions `setPositions' performs multiple passes over the instruction list to calculate the correct (byte) positions and
* offsets by calling this function.
*
* @param offset additional offset caused by preceding (variable length) instructions
* @param max_offset the maximum offset that may be caused by these instructions
* @return additional offset caused by possible change of this instruction's length
*/
protected int updatePosition(int offset, int max_offset) {
int i = getTargetOffset();
positionOfThisInstruction += offset;
if (Math.abs(i) >= 32767 - max_offset && opcode != JSR_W && opcode != GOTO_W) {
// Try and promote it to wide if we can
if (opcode == JSR || opcode == GOTO) {
if (opcode == JSR) {
opcode = JSR_W;
} else {
opcode = GOTO_W;
}
return 2; // instruction jump destination grows from a short to a long
} else {
throw new IllegalStateException("Unable to pack method, jump (with opcode=" + opcode + ") is too far: "
+ Math.abs(i));
}
}
return 0;
}
/**
* Long output format:
*
* @param verbose long/short format switch
* @return mnemonic for instruction
*/
public String toString(boolean verbose) {
String s = super.toString(verbose);
String t = "null";
if (verbose) {
if (targetInstruction != null) {
if (targetInstruction.getInstruction() == this) {
t = "";
} else if (targetInstruction.getInstruction() == null) {
t = "";
} else {
t = targetInstruction.getInstruction().toString(false);
}
}
} else {
if (targetInstruction != null) {
targetIndex = getTargetOffset();
t = "" + (targetIndex + positionOfThisInstruction);
}
}
return s + " -> " + t;
}
/**
* @return target offset in byte code
*/
public final int getIndex() {
return targetIndex;
}
/**
* @return target of branch instruction
*/
public InstructionHandle getTarget() {
return targetInstruction;
}
/**
* Set branch target
*
* @param target branch target
*/
public void setTarget(InstructionHandle target) {
notifyTarget(this.targetInstruction, target, this);
this.targetInstruction = target;
}
/**
* Used by BranchInstruction, LocalVariableGen, CodeExceptionGen
*/
static final void notifyTarget(InstructionHandle oldHandle, InstructionHandle newHandle, InstructionTargeter t) {
if (oldHandle != null) {
oldHandle.removeTargeter(t);
}
if (newHandle != null) {
newHandle.addTargeter(t);
}
}
/**
* Update the target destination for this instruction. If an oldHandle is provided it is checked to verify that is where the
* target currently points to before changing it.
*
* @param oldHandle old target
* @param newHandle new target
*/
public void updateTarget(InstructionHandle oldHandle, InstructionHandle newHandle) {
if (targetInstruction == oldHandle) {
setTarget(newHandle);
} else {
throw new ClassGenException("Not targeting " + oldHandle + ", but " + targetInstruction);
}
}
/**
* @return true, if ih is target of this instruction
*/
public boolean containsTarget(InstructionHandle ih) {
return targetInstruction == ih;
}
/**
* Inform target that it's not targeted anymore.
*/
void dispose() {
setTarget(null);
targetIndex = -1;
positionOfThisInstruction = -1;
}
public Type getType(ConstantPool cp) {
if ((Constants.instFlags[opcode] & Constants.JSR_INSTRUCTION) != 0) {
return new ReturnaddressType(physicalSuccessor());
}
return super.getType(cp);
}
/**
* Returns an InstructionHandle to the physical successor of this JsrInstruction. For this method to work, this
* JsrInstruction object must not be shared between multiple InstructionHandle objects! Formally, there must not be
* InstructionHandle objects i, j where i != j and i.getInstruction() == this == j.getInstruction().
*
* @return an InstructionHandle to the "next" instruction that will be executed when RETurned from a subroutine.
*/
public InstructionHandle physicalSuccessor() {
InstructionHandle ih = this.targetInstruction;
// Rewind!
while (ih.getPrev() != null) {
ih = ih.getPrev();
}
// Find the handle for "this" JsrInstruction object.
while (ih.getInstruction() != this) {
ih = ih.getNext();
}
InstructionHandle toThis = ih;
while (ih != null) {
ih = ih.getNext();
if (ih != null && ih.getInstruction() == this) {
throw new RuntimeException("physicalSuccessor() called on a shared JsrInstruction.");
}
}
// Return the physical successor
return toThis.getNext();
}
public boolean isIfInstruction() {
return (Constants.instFlags[opcode] & Constants.IF_INST) != 0;
}
/**
* Only equal if they are the same branch instruction - otherwise too risky as the targets may only temporarily be pointing at
* the same destination.
*/
public boolean equals(Object other) {
return this == other;
}
public int hashCode() {
int result = 17;
result = opcode * 37 + result;
return result;
}
}
