| /******************************************************************************* |
| * Copyright (c) 2000, 2009 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.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); |
| } |
| } |
| rightInfo = this.right.analyseCode(currentScope, flowContext, rightInfo); |
| 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 |
| leftInfo.initsWhenTrue().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)) { |
| 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); |
| } |
| } |
