/*******************************************************************************
* Copyright (c) 2000, 2011 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
* Stephan Herrmann - Contribution for bug 319201 - [null] no warning when unboxing SingleNameReference causes NPE
*******************************************************************************/
package org.eclipse.jdt.internal.compiler.ast;
import org.eclipse.jdt.internal.compiler.ASTVisitor;
import org.eclipse.jdt.internal.compiler.impl.*;
import org.eclipse.jdt.internal.compiler.codegen.*;
import org.eclipse.jdt.internal.compiler.flow.*;
import org.eclipse.jdt.internal.compiler.lookup.*;
//dedicated treatment for the ||
public class OR_OR_Expression extends BinaryExpression {
int rightInitStateIndex = -1;
int mergedInitStateIndex = -1;
public OR_OR_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 != Constant.NotAConstant && cst.booleanValue() == true;
boolean isLeftOptimizedFalse = cst != Constant.NotAConstant && cst.booleanValue() == false;
if (isLeftOptimizedFalse) {
// FALSE || 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 = this.left.analyseCode(currentScope, flowContext, flowInfo).unconditionalInits();
mergedInfo = this.right.analyseCode(currentScope, flowContext, mergedInfo);
this.mergedInitStateIndex =
currentScope.methodScope().recordInitializationStates(mergedInfo);
return mergedInfo;
}
FlowInfo leftInfo = this.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.initsWhenFalse().unconditionalCopy();
this.rightInitStateIndex =
currentScope.methodScope().recordInitializationStates(rightInfo);
int previousMode = rightInfo.reachMode();
if (isLeftOptimizedTrue){
if ((rightInfo.reachMode() & FlowInfo.UNREACHABLE) == 0) {
currentScope.problemReporter().fakeReachable(this.right);
rightInfo.setReachMode(FlowInfo.UNREACHABLE_OR_DEAD);
}
}
rightInfo = this.right.analyseCode(currentScope, flowContext, rightInfo);
if ((this.left.implicitConversion & TypeIds.UNBOXING) != 0) {
this.left.checkNPE(currentScope, flowContext, flowInfo);
}
if ((this.right.implicitConversion & TypeIds.UNBOXING) != 0) {
this.right.checkNPE(currentScope, flowContext, flowInfo);
}
// The definitely null variables in right info when true should not be missed out while merging
// https://bugs.eclipse.org/bugs/show_bug.cgi?id=299900
FlowInfo leftInfoWhenTrueForMerging = leftInfo.initsWhenTrue().unconditionalCopy().addPotentialInitializationsFrom(rightInfo.unconditionalInitsWithoutSideEffect());
FlowInfo mergedInfo = FlowInfo.conditional(
// merging two true initInfos for such a negative case: if ((t && (b = t)) || f) r = b; // b may not have been initialized
leftInfoWhenTrueForMerging.unconditionalInits().mergedWith(
rightInfo.safeInitsWhenTrue().setReachMode(previousMode).unconditionalInits()),
rightInfo.initsWhenFalse());
this.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 (this.constant != Constant.NotAConstant) {
// inlined value
if (valueRequired)
codeStream.generateConstant(this.constant, this.implicitConversion);
codeStream.recordPositionsFrom(pc, this.sourceStart);
return;
}
Constant cst = this.right.constant;
if (cst != Constant.NotAConstant) {
// <expr> || true --> true
if (cst.booleanValue() == true) {
this.left.generateCode(currentScope, codeStream, false);
if (valueRequired) codeStream.iconst_1();
} else {
// <expr>|| false --> <expr>
this.left.generateCode(currentScope, codeStream, valueRequired);
}
if (this.mergedInitStateIndex != -1) {
codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.mergedInitStateIndex);
}
codeStream.generateImplicitConversion(this.implicitConversion);
codeStream.updateLastRecordedEndPC(currentScope, codeStream.position);
codeStream.recordPositionsFrom(pc, this.sourceStart);
return;
}
BranchLabel trueLabel = new BranchLabel(codeStream), endLabel;
cst = this.left.optimizedBooleanConstant();
boolean leftIsConst = cst != Constant.NotAConstant;
boolean leftIsTrue = leftIsConst && cst.booleanValue() == true;
cst = this.right.optimizedBooleanConstant();
boolean rightIsConst = cst != Constant.NotAConstant;
boolean rightIsTrue = rightIsConst && cst.booleanValue() == true;
generateOperands : {
if (leftIsConst) {
this.left.generateCode(currentScope, codeStream, false);
if (leftIsTrue) {
break generateOperands; // no need to generate right operand
}
} else {
this.left.generateOptimizedBoolean(currentScope, codeStream, trueLabel, null, true);
// need value, e.g. if (a == 1 || ((b = 2) > 0)) {} -> shouldn't initialize 'b' if a==1
}
if (this.rightInitStateIndex != -1) {
codeStream.addDefinitelyAssignedVariables(currentScope, this.rightInitStateIndex);
}
if (rightIsConst) {
this.right.generateCode(currentScope, codeStream, false);
} else {
this.right.generateOptimizedBoolean(currentScope, codeStream, trueLabel, null, valueRequired);
}
}
if (this.mergedInitStateIndex != -1) {
codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.mergedInitStateIndex);
}
/*
* improving code gen for such a case: boolean b = i < 0 || true since
* the label has never been used, we have the inlined value on the
* stack.
*/
if (valueRequired) {
if (leftIsConst && leftIsTrue) {
codeStream.iconst_1();
codeStream.updateLastRecordedEndPC(currentScope, codeStream.position);
} else {
if (rightIsConst && rightIsTrue) {
codeStream.iconst_1();
codeStream.updateLastRecordedEndPC(currentScope, codeStream.position);
} else {
codeStream.iconst_0();
}
if (trueLabel.forwardReferenceCount() > 0) {
if ((this.bits & IsReturnedValue) != 0) {
codeStream.generateImplicitConversion(this.implicitConversion);
codeStream.generateReturnBytecode(this);
trueLabel.place();
codeStream.iconst_1();
} else {
codeStream.goto_(endLabel = new BranchLabel(codeStream));
codeStream.decrStackSize(1);
trueLabel.place();
codeStream.iconst_1();
endLabel.place();
}
} else {
trueLabel.place();
}
}
codeStream.generateImplicitConversion(this.implicitConversion);
codeStream.updateLastRecordedEndPC(currentScope, codeStream.position);
} else {
trueLabel.place();
}
}
/**
* Boolean operator code generation Optimized operations are: ||
*/
public void generateOptimizedBoolean(BlockScope currentScope, CodeStream codeStream, BranchLabel trueLabel, BranchLabel falseLabel, boolean valueRequired) {
if (this.constant != Constant.NotAConstant) {
super.generateOptimizedBoolean(currentScope, codeStream, trueLabel, falseLabel, valueRequired);
return;
}
// <expr> || false --> <expr>
Constant cst = this.right.constant;
if (cst != Constant.NotAConstant && cst.booleanValue() == false) {
int pc = codeStream.position;
this.left.generateOptimizedBoolean(currentScope, codeStream, trueLabel, falseLabel, valueRequired);
if (this.mergedInitStateIndex != -1) {
codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.mergedInitStateIndex);
}
codeStream.recordPositionsFrom(pc, this.sourceStart);
return;
}
cst = this.left.optimizedBooleanConstant();
boolean leftIsConst = cst != Constant.NotAConstant;
boolean leftIsTrue = leftIsConst && cst.booleanValue() == true;
cst = this.right.optimizedBooleanConstant();
boolean rightIsConst = cst != Constant.NotAConstant;
boolean rightIsTrue = rightIsConst && cst.booleanValue() == true;
// default case
generateOperands : {
if (falseLabel == null) {
if (trueLabel != null) {
// implicit falling through the FALSE case
this.left.generateOptimizedBoolean(currentScope, codeStream, trueLabel, null, !leftIsConst);
// need value, e.g. if (a == 1 || ((b = 2) > 0)) {} -> shouldn't initialize 'b' if a==1
if (leftIsTrue) {
if (valueRequired) codeStream.goto_(trueLabel);
codeStream.updateLastRecordedEndPC(currentScope, codeStream.position);
break generateOperands; // no need to generate right operand
}
if (this.rightInitStateIndex != -1) {
codeStream.addDefinitelyAssignedVariables(currentScope, this.rightInitStateIndex);
}
this.right.generateOptimizedBoolean(currentScope, codeStream, trueLabel, null, valueRequired && !rightIsConst);
if (valueRequired && rightIsTrue) {
codeStream.goto_(trueLabel);
codeStream.updateLastRecordedEndPC(currentScope, codeStream.position);
}
}
} else {
// implicit falling through the TRUE case
if (trueLabel == null) {
BranchLabel internalTrueLabel = new BranchLabel(codeStream);
this.left.generateOptimizedBoolean(currentScope, codeStream, internalTrueLabel, null, !leftIsConst);
// need value, e.g. if (a == 1 || ((b = 2) > 0)) {} -> shouldn't initialize 'b' if a==1
if (leftIsTrue) {
internalTrueLabel.place();
break generateOperands; // no need to generate right operand
}
if (this.rightInitStateIndex != -1) {
codeStream
.addDefinitelyAssignedVariables(currentScope, this.rightInitStateIndex);
}
this.right.generateOptimizedBoolean(currentScope, codeStream, null, falseLabel, valueRequired && !rightIsConst);
if (valueRequired && rightIsConst && !rightIsTrue) {
codeStream.goto_(falseLabel);
codeStream.updateLastRecordedEndPC(currentScope, codeStream.position);
}
internalTrueLabel.place();
} else {
// no implicit fall through TRUE/FALSE --> should never occur
}
}
}
if (this.mergedInitStateIndex != -1) {
codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.mergedInitStateIndex);
}
}
public boolean isCompactableOperation() {
return false;
}
/**
* @see org.eclipse.jdt.internal.compiler.ast.BinaryExpression#resolveType(org.eclipse.jdt.internal.compiler.lookup.BlockScope)
*/
public TypeBinding resolveType(BlockScope scope) {
TypeBinding result = super.resolveType(scope);
// check whether comparing identical expressions
Binding leftDirect = Expression.getDirectBinding(this.left);
if (leftDirect != null && leftDirect == Expression.getDirectBinding(this.right)) {
if (!(this.right instanceof Assignment))
scope.problemReporter().comparingIdenticalExpressions(this);
}
return result;
}
public void traverse(ASTVisitor visitor, BlockScope scope) {
if (visitor.visit(this, scope)) {
this.left.traverse(visitor, scope);
this.right.traverse(visitor, scope);
}
visitor.endVisit(this, scope);
}
}