/******************************************************************************* | |
* Copyright (c) 2000, 2004 IBM Corporation and others. | |
* All rights reserved. This program and the accompanying materials | |
* are made available under the terms of the Common Public License v1.0 | |
* which accompanies this distribution, and is available at | |
* http://www.eclipse.org/legal/cpl-v10.html | |
* | |
* Contributors: | |
* IBM Corporation - initial API and implementation | |
*******************************************************************************/ | |
package org.eclipse.wst.jsdt.internal.compiler.ast; | |
import org.eclipse.wst.jsdt.internal.compiler.ASTVisitor; | |
import org.eclipse.wst.jsdt.internal.compiler.impl.*; | |
import org.eclipse.wst.jsdt.internal.compiler.codegen.*; | |
import org.eclipse.wst.jsdt.internal.compiler.flow.*; | |
import org.eclipse.wst.jsdt.internal.compiler.lookup.*; | |
//dedicated treatment for the && | |
public class AND_AND_Expression extends BinaryExpression { | |
int rightInitStateIndex = -1; | |
int mergedInitStateIndex = -1; | |
public AND_AND_Expression(Expression left, Expression right, int operator) { | |
super(left, right, operator); | |
} | |
public FlowInfo analyseCode(BlockScope currentScope, FlowContext flowContext, FlowInfo flowInfo) { | |
Constant cst = this.left.optimizedBooleanConstant(); | |
boolean isLeftOptimizedTrue = cst != NotAConstant && cst.booleanValue() == true; | |
boolean isLeftOptimizedFalse = cst != NotAConstant && cst.booleanValue() == false; | |
if (isLeftOptimizedTrue) { | |
// TRUE && anything | |
// need to be careful of scenario: | |
// (x && y) && !z, if passing the left info to the right, it would | |
// be swapped by the ! | |
FlowInfo mergedInfo = left.analyseCode(currentScope, flowContext, flowInfo) | |
.unconditionalInits(); | |
mergedInfo = right.analyseCode(currentScope, flowContext, mergedInfo); | |
mergedInitStateIndex = currentScope.methodScope() | |
.recordInitializationStates(mergedInfo); | |
return mergedInfo; | |
} | |
FlowInfo leftInfo = left.analyseCode(currentScope, flowContext, flowInfo); | |
// need to be careful of scenario: | |
// (x && y) && !z, if passing the left info to the right, it would be | |
// swapped by the ! | |
FlowInfo rightInfo = leftInfo.initsWhenTrue().unconditionalInits().copy(); | |
rightInitStateIndex = currentScope.methodScope().recordInitializationStates(rightInfo); | |
int previousMode = rightInfo.reachMode(); | |
if (isLeftOptimizedFalse) { | |
rightInfo.setReachMode(FlowInfo.UNREACHABLE); | |
} | |
rightInfo = right.analyseCode(currentScope, flowContext, rightInfo); | |
FlowInfo trueMergedInfo = rightInfo.initsWhenTrue().copy(); | |
rightInfo.setReachMode(previousMode); // reset after trueMergedInfo got extracted | |
FlowInfo mergedInfo = FlowInfo.conditional( | |
trueMergedInfo, | |
leftInfo.initsWhenFalse().copy().unconditionalInits().mergedWith( | |
rightInfo.initsWhenFalse().copy().unconditionalInits())); | |
mergedInitStateIndex = currentScope.methodScope().recordInitializationStates(mergedInfo); | |
return mergedInfo; | |
} | |
/** | |
* Code generation for a binary operation | |
*/ | |
public void generateCode(BlockScope currentScope, CodeStream codeStream, boolean valueRequired) { | |
int pc = codeStream.position; | |
if (constant != Constant.NotAConstant) { | |
// inlined value | |
if (valueRequired) | |
codeStream.generateConstant(constant, implicitConversion); | |
codeStream.recordPositionsFrom(pc, this.sourceStart); | |
return; | |
} | |
Constant cst = right.constant; | |
if (cst != NotAConstant) { | |
// <expr> && true --> <expr> | |
if (cst.booleanValue() == true) { | |
this.left.generateCode(currentScope, codeStream, valueRequired); | |
} else { | |
// <expr> && false --> false | |
this.left.generateCode(currentScope, codeStream, false); | |
if (valueRequired) codeStream.iconst_0(); | |
} | |
if (mergedInitStateIndex != -1) { | |
codeStream.removeNotDefinitelyAssignedVariables(currentScope, mergedInitStateIndex); | |
} | |
codeStream.generateImplicitConversion(implicitConversion); | |
codeStream.updateLastRecordedEndPC(codeStream.position); | |
codeStream.recordPositionsFrom(pc, this.sourceStart); | |
return; | |
} | |
Label falseLabel = new Label(codeStream), endLabel; | |
cst = left.optimizedBooleanConstant(); | |
boolean leftIsConst = cst != NotAConstant; | |
boolean leftIsTrue = leftIsConst && cst.booleanValue() == true; | |
cst = right.optimizedBooleanConstant(); | |
boolean rightIsConst = cst != NotAConstant; | |
boolean rightIsTrue = rightIsConst && cst.booleanValue() == true; | |
generateOperands : { | |
if (leftIsConst) { | |
left.generateCode(currentScope, codeStream, false); | |
if (!leftIsTrue) { | |
break generateOperands; // no need to generate right operand | |
} | |
} else { | |
left.generateOptimizedBoolean(currentScope, codeStream, null, falseLabel, true); | |
// need value, e.g. if (a == 1 && ((b = 2) > 0)) {} -> shouldn't initialize 'b' if a!=1 | |
} | |
if (rightInitStateIndex != -1) { | |
codeStream.addDefinitelyAssignedVariables(currentScope, rightInitStateIndex); | |
} | |
if (rightIsConst) { | |
right.generateCode(currentScope, codeStream, false); | |
} else { | |
right.generateOptimizedBoolean(currentScope, codeStream, null, falseLabel, valueRequired); | |
} | |
} | |
if (mergedInitStateIndex != -1) { | |
codeStream.removeNotDefinitelyAssignedVariables(currentScope, mergedInitStateIndex); | |
} | |
/* | |
* improving code gen for such a case: boolean b = i < 0 && false since | |
* the label has never been used, we have the inlined value on the | |
* stack. | |
*/ | |
if (valueRequired) { | |
if (leftIsConst && !leftIsTrue) { | |
codeStream.iconst_0(); | |
codeStream.updateLastRecordedEndPC(codeStream.position); | |
} else { | |
if (rightIsConst && !rightIsTrue) { | |
codeStream.iconst_0(); | |
codeStream.updateLastRecordedEndPC(codeStream.position); | |
} else { | |
codeStream.iconst_1(); | |
} | |
if (falseLabel.hasForwardReferences()) { | |
if ((bits & ValueForReturnMASK) != 0) { | |
codeStream.ireturn(); | |
falseLabel.place(); | |
codeStream.iconst_0(); | |
} else { | |
codeStream.goto_(endLabel = new Label(codeStream)); | |
codeStream.decrStackSize(1); | |
falseLabel.place(); | |
codeStream.iconst_0(); | |
endLabel.place(); | |
} | |
} else { | |
falseLabel.place(); | |
} | |
} | |
codeStream.generateImplicitConversion(implicitConversion); | |
codeStream.updateLastRecordedEndPC(codeStream.position); | |
} else { | |
falseLabel.place(); | |
} | |
} | |
/** | |
* Boolean operator code generation Optimized operations are: && | |
*/ | |
public void generateOptimizedBoolean(BlockScope currentScope, CodeStream codeStream, | |
Label trueLabel, Label falseLabel, boolean valueRequired) { | |
if (constant != Constant.NotAConstant) { | |
super.generateOptimizedBoolean(currentScope, codeStream, trueLabel, falseLabel, | |
valueRequired); | |
return; | |
} | |
// <expr> && true --> <expr> | |
Constant cst = right.constant; | |
if (cst != NotAConstant && cst.booleanValue() == true) { | |
int pc = codeStream.position; | |
this.left.generateOptimizedBoolean(currentScope, codeStream, trueLabel, falseLabel, valueRequired); | |
if (mergedInitStateIndex != -1) { | |
codeStream.removeNotDefinitelyAssignedVariables(currentScope, mergedInitStateIndex); | |
} | |
codeStream.recordPositionsFrom(pc, this.sourceStart); | |
return; | |
} | |
cst = left.optimizedBooleanConstant(); | |
boolean leftIsConst = cst != NotAConstant; | |
boolean leftIsTrue = leftIsConst && cst.booleanValue() == true; | |
cst = right.optimizedBooleanConstant(); | |
boolean rightIsConst = cst != NotAConstant; | |
boolean rightIsTrue = rightIsConst && cst.booleanValue() == true; | |
// default case | |
generateOperands : { | |
if (falseLabel == null) { | |
if (trueLabel != null) { | |
// implicit falling through the FALSE case | |
Label internalFalseLabel = new Label(codeStream); | |
left.generateOptimizedBoolean(currentScope, codeStream, null, | |
internalFalseLabel, !leftIsConst); | |
// need value, e.g. if (a == 1 && ((b = 2) > 0)) {} -> shouldn't initialize 'b' if a!=1 | |
if (leftIsConst && !leftIsTrue) { | |
internalFalseLabel.place(); | |
break generateOperands; // no need to generate right operand | |
} | |
if (rightInitStateIndex != -1) { | |
codeStream | |
.addDefinitelyAssignedVariables(currentScope, rightInitStateIndex); | |
} | |
right.generateOptimizedBoolean(currentScope, codeStream, trueLabel, null, | |
valueRequired && !rightIsConst); | |
if (valueRequired && rightIsConst && rightIsTrue) { | |
codeStream.goto_(trueLabel); | |
codeStream.updateLastRecordedEndPC(codeStream.position); | |
} | |
internalFalseLabel.place(); | |
} | |
} else { | |
// implicit falling through the TRUE case | |
if (trueLabel == null) { | |
left.generateOptimizedBoolean(currentScope, codeStream, null, falseLabel, !leftIsConst); | |
// need value, e.g. if (a == 1 && ((b = 2) > 0)) {} -> shouldn't initialize 'b' if a!=1 | |
if (leftIsConst && !leftIsTrue) { | |
codeStream.goto_(falseLabel); | |
codeStream.updateLastRecordedEndPC(codeStream.position); | |
break generateOperands; // no need to generate right operand | |
} | |
if (rightInitStateIndex != -1) { | |
codeStream | |
.addDefinitelyAssignedVariables(currentScope, rightInitStateIndex); | |
} | |
right.generateOptimizedBoolean(currentScope, codeStream, null, falseLabel, | |
valueRequired && !rightIsConst); | |
if (valueRequired && rightIsConst && !rightIsTrue) { | |
codeStream.goto_(falseLabel); | |
codeStream.updateLastRecordedEndPC(codeStream.position); | |
} | |
} else { | |
// no implicit fall through TRUE/FALSE --> should never occur | |
} | |
} | |
} | |
if (mergedInitStateIndex != -1) { | |
codeStream.removeNotDefinitelyAssignedVariables(currentScope, mergedInitStateIndex); | |
} | |
} | |
public boolean isCompactableOperation() { | |
return false; | |
} | |
public void traverse(ASTVisitor visitor, BlockScope scope) { | |
if (visitor.visit(this, scope)) { | |
left.traverse(visitor, scope); | |
right.traverse(visitor, scope); | |
} | |
visitor.endVisit(this, scope); | |
} | |
} |