/*******************************************************************************
* Copyright (c) 2000, 2008 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.jdt.internal.compiler.codegen;
import java.util.Arrays;
import org.eclipse.jdt.internal.compiler.classfmt.ClassFileConstants;
import org.eclipse.jdt.internal.compiler.lookup.LocalVariableBinding;
public class BranchLabel extends Label {
private int[] forwardReferences = new int[10]; // Add an overflow check here.
private int forwardReferenceCount = 0;
BranchLabel delegate; //
// Label tagbits
public int tagBits;
public final static int WIDE = 1;
public final static int USED = 2;
public BranchLabel() {
// for creating labels ahead of code generation
}
/**
* @param codeStream org.eclipse.jdt.internal.compiler.codegen.CodeStream
*/
public BranchLabel(CodeStream codeStream) {
super(codeStream);
}
/**
* Add a forward refrence for the array.
*/
void addForwardReference(int pos) {
if (this.delegate != null) {
this.delegate.addForwardReference(pos);
return;
}
final int count = this.forwardReferenceCount;
if (count >= 1) {
int previousValue = this.forwardReferences[count - 1];
if (previousValue < pos) {
int length;
if (count >= (length = this.forwardReferences.length))
System.arraycopy(this.forwardReferences, 0, (this.forwardReferences = new int[2*length]), 0, length);
this.forwardReferences[this.forwardReferenceCount++] = pos;
} else if (previousValue > pos) {
int[] refs = this.forwardReferences;
// check for duplicates
for (int i = 0, max = this.forwardReferenceCount; i < max; i++) {
if (refs[i] == pos) return; // already recorded
}
int length;
if (count >= (length = refs.length))
System.arraycopy(refs, 0, (this.forwardReferences = new int[2*length]), 0, length);
this.forwardReferences[this.forwardReferenceCount++] = pos;
Arrays.sort(this.forwardReferences, 0, this.forwardReferenceCount);
}
} else {
int length;
if (count >= (length = this.forwardReferences.length))
System.arraycopy(this.forwardReferences, 0, (this.forwardReferences = new int[2*length]), 0, length);
this.forwardReferences[this.forwardReferenceCount++] = pos;
}
}
/**
* Makes the current label inline all references to the other label
*/
public void becomeDelegateFor(BranchLabel otherLabel) {
// other label is delegating to receiver from now on
otherLabel.delegate = this;
// all existing forward refs to other label are inlined into current label
final int otherCount = otherLabel.forwardReferenceCount;
if (otherCount == 0) return;
// need to merge the two sorted arrays of forward references
int[] mergedForwardReferences = new int[this.forwardReferenceCount + otherCount];
int indexInMerge = 0;
int j = 0;
int i = 0;
int max = this.forwardReferenceCount;
int max2 = otherLabel.forwardReferenceCount;
loop1 : for (; i < max; i++) {
final int value1 = this.forwardReferences[i];
for (; j < max2; j++) {
final int value2 = otherLabel.forwardReferences[j];
if (value1 < value2) {
mergedForwardReferences[indexInMerge++] = value1;
continue loop1;
} else if (value1 == value2) {
mergedForwardReferences[indexInMerge++] = value1;
j++;
continue loop1;
} else {
mergedForwardReferences[indexInMerge++] = value2;
}
}
mergedForwardReferences[indexInMerge++] = value1;
}
for (; j < max2; j++) {
mergedForwardReferences[indexInMerge++] = otherLabel.forwardReferences[j];
}
this.forwardReferences = mergedForwardReferences;
this.forwardReferenceCount = indexInMerge;
}
/*
* Put down a reference to the array at the location in the codestream.
*/
void branch() {
this.tagBits |= BranchLabel.USED;
if (this.delegate != null) {
this.delegate.branch();
return;
}
if (this.position == Label.POS_NOT_SET) {
addForwardReference(this.codeStream.position);
// Leave two bytes free to generate the jump afterwards
this.codeStream.position += 2;
this.codeStream.classFileOffset += 2;
} else {
/*
* Position is set. Write it if it is not a wide branch.
*/
this.codeStream.writePosition(this);
}
}
/*
* No support for wide branches yet
*/
void branchWide() {
this.tagBits |= BranchLabel.USED;
if (this.delegate != null) {
this.delegate.branchWide();
return;
}
if (this.position == Label.POS_NOT_SET) {
addForwardReference(this.codeStream.position);
// Leave 4 bytes free to generate the jump offset afterwards
this.tagBits |= BranchLabel.WIDE;
this.codeStream.position += 4;
this.codeStream.classFileOffset += 4;
} else { //Position is set. Write it!
this.codeStream.writeWidePosition(this);
}
}
public int forwardReferenceCount() {
if (this.delegate != null) this.delegate.forwardReferenceCount();
return this.forwardReferenceCount;
}
public int[] forwardReferences() {
if (this.delegate != null) this.delegate.forwardReferences();
return this.forwardReferences;
}
public void initialize(CodeStream stream) {
this.codeStream = stream;
this.position = Label.POS_NOT_SET;
this.forwardReferenceCount = 0;
this.delegate = null;
}
public boolean isCaseLabel() {
return false;
}
public boolean isStandardLabel(){
return true;
}
/*
* Place the label. If we have forward references resolve them.
*/
public void place() { // Currently lacking wide support.
// if ((this.tagBits & USED) == 0 && this.forwardReferenceCount == 0) {
// return;
// }
//TODO how can position be set already ? cannot place more than once
if (this.position == Label.POS_NOT_SET) {
this.position = this.codeStream.position;
this.codeStream.addLabel(this);
int oldPosition = this.position;
boolean isOptimizedBranch = false;
if (this.forwardReferenceCount != 0) {
isOptimizedBranch = (this.forwardReferences[this.forwardReferenceCount - 1] + 2 == this.position) && (this.codeStream.bCodeStream[this.codeStream.classFileOffset - 3] == Opcodes.OPC_goto);
if (isOptimizedBranch) {
if (this.codeStream.lastAbruptCompletion == this.position) {
this.codeStream.lastAbruptCompletion = -1;
}
this.codeStream.position = (this.position -= 3);
this.codeStream.classFileOffset -= 3;
this.forwardReferenceCount--;
if (this.codeStream.lastEntryPC == oldPosition) {
this.codeStream.lastEntryPC = this.position;
}
// end of new code
if ((this.codeStream.generateAttributes & (ClassFileConstants.ATTR_VARS | ClassFileConstants.ATTR_STACK_MAP_TABLE | ClassFileConstants.ATTR_STACK_MAP)) != 0) {
LocalVariableBinding locals[] = this.codeStream.locals;
for (int i = 0, max = locals.length; i < max; i++) {
LocalVariableBinding local = locals[i];
if ((local != null) && (local.initializationCount > 0)) {
if (local.initializationPCs[((local.initializationCount - 1) << 1) + 1] == oldPosition) {
// we want to prevent interval of size 0 to have a negative size.
// see PR 1GIRQLA: ITPJCORE:ALL - ClassFormatError for local variable attribute
local.initializationPCs[((local.initializationCount - 1) << 1) + 1] = this.position;
}
if (local.initializationPCs[(local.initializationCount - 1) << 1] == oldPosition) {
local.initializationPCs[(local.initializationCount - 1) << 1] = this.position;
}
}
}
}
if ((this.codeStream.generateAttributes & ClassFileConstants.ATTR_LINES) != 0) {
// we need to remove all entries that is beyond this.position inside the pcToSourcerMap table
this.codeStream.removeUnusedPcToSourceMapEntries();
}
}
}
for (int i = 0; i < this.forwardReferenceCount; i++) {
this.codeStream.writePosition(this, this.forwardReferences[i]);
}
// For all labels placed at that position we check if we need to rewrite the jump
// offset. It is the case each time a label had a forward reference to the current position.
// Like we change the current position, we have to change the jump offset. See 1F4IRD9 for more details.
if (isOptimizedBranch) {
this.codeStream.optimizeBranch(oldPosition, this);
}
}
}
/**
* Print out the receiver
*/
public String toString() {
String basic = getClass().getName();
basic = basic.substring(basic.lastIndexOf('.')+1);
StringBuffer buffer = new StringBuffer(basic);
buffer.append('@').append(Integer.toHexString(hashCode()));
buffer.append("(position=").append(this.position); //$NON-NLS-1$
if (this.delegate != null) buffer.append("delegate=").append(this.delegate); //$NON-NLS-1$
buffer.append(", forwards = ["); //$NON-NLS-1$
for (int i = 0; i < this.forwardReferenceCount - 1; i++)
buffer.append(this.forwardReferences[i] + ", "); //$NON-NLS-1$
if (this.forwardReferenceCount >= 1)
buffer.append(this.forwardReferences[this.forwardReferenceCount-1]);
buffer.append("] )"); //$NON-NLS-1$
return buffer.toString();
}
}