/******************************************************************************* * 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 * Stephen Herrmann <stephan@cs.tu-berlin.de> - Contributions for * bug 133125 - [compiler][null] need to report the null status of expressions and analyze them simultaneously * bug 292478 - Report potentially null across variable assignment * bug 324178 - [null] ConditionalExpression.nullStatus(..) doesn't take into account the analysis of condition itself *******************************************************************************/ package org.eclipse.che.ide.ext.java.jdt.internal.compiler.ast; import org.eclipse.che.ide.ext.java.jdt.internal.compiler.ASTVisitor; import org.eclipse.che.ide.ext.java.jdt.internal.compiler.ClassFileConstants; import org.eclipse.che.ide.ext.java.jdt.internal.compiler.codegen.BranchLabel; import org.eclipse.che.ide.ext.java.jdt.internal.compiler.flow.FlowContext; import org.eclipse.che.ide.ext.java.jdt.internal.compiler.flow.FlowInfo; import org.eclipse.che.ide.ext.java.jdt.internal.compiler.flow.UnconditionalFlowInfo; import org.eclipse.che.ide.ext.java.jdt.internal.compiler.impl.Constant; import org.eclipse.che.ide.ext.java.jdt.internal.compiler.lookup.BaseTypeBinding; import org.eclipse.che.ide.ext.java.jdt.internal.compiler.lookup.BlockScope; import org.eclipse.che.ide.ext.java.jdt.internal.compiler.lookup.LookupEnvironment; import org.eclipse.che.ide.ext.java.jdt.internal.compiler.lookup.TypeBinding; public class ConditionalExpression extends OperatorExpression { public Expression condition, valueIfTrue, valueIfFalse; public Constant optimizedBooleanConstant; public Constant optimizedIfTrueConstant; public Constant optimizedIfFalseConstant; // for local variables table attributes int trueInitStateIndex = -1; int falseInitStateIndex = -1; int mergedInitStateIndex = -1; // we compute and store the null status during analyseCode (https://bugs.eclipse.org/324178): private int nullStatus = FlowInfo.UNKNOWN; public ConditionalExpression(Expression condition, Expression valueIfTrue, Expression valueIfFalse) { this.condition = condition; this.valueIfTrue = valueIfTrue; this.valueIfFalse = valueIfFalse; this.sourceStart = condition.sourceStart; this.sourceEnd = valueIfFalse.sourceEnd; } @Override public FlowInfo analyseCode(BlockScope currentScope, FlowContext flowContext, FlowInfo flowInfo) { int initialComplaintLevel = (flowInfo.reachMode() & FlowInfo.UNREACHABLE) != 0 ? Statement.COMPLAINED_FAKE_REACHABLE : Statement.NOT_COMPLAINED; Constant cst = this.condition.optimizedBooleanConstant(); boolean isConditionOptimizedTrue = cst != Constant.NotAConstant && cst.booleanValue() == true; boolean isConditionOptimizedFalse = cst != Constant.NotAConstant && cst.booleanValue() == false; int mode = flowInfo.reachMode(); flowInfo = this.condition.analyseCode(currentScope, flowContext, flowInfo, cst == Constant.NotAConstant); // process the if-true part FlowInfo trueFlowInfo = flowInfo.initsWhenTrue().copy(); if (isConditionOptimizedFalse) { if ((mode & FlowInfo.UNREACHABLE) == 0) { trueFlowInfo.setReachMode(FlowInfo.UNREACHABLE_OR_DEAD); } if (!isKnowDeadCodePattern(this.condition) || currentScope.compilerOptions().reportDeadCodeInTrivialIfStatement) { this.valueIfTrue.complainIfUnreachable(trueFlowInfo, currentScope, initialComplaintLevel); } } this.trueInitStateIndex = currentScope.methodScope().recordInitializationStates(trueFlowInfo); trueFlowInfo = this.valueIfTrue.analyseCode(currentScope, flowContext, trueFlowInfo); // process the if-false part FlowInfo falseFlowInfo = flowInfo.initsWhenFalse().copy(); if (isConditionOptimizedTrue) { if ((mode & FlowInfo.UNREACHABLE) == 0) { falseFlowInfo.setReachMode(FlowInfo.UNREACHABLE_OR_DEAD); } if (!isKnowDeadCodePattern(this.condition) || currentScope.compilerOptions().reportDeadCodeInTrivialIfStatement) { this.valueIfFalse.complainIfUnreachable(falseFlowInfo, currentScope, initialComplaintLevel); } } this.falseInitStateIndex = currentScope.methodScope().recordInitializationStates(falseFlowInfo); falseFlowInfo = this.valueIfFalse.analyseCode(currentScope, flowContext, falseFlowInfo); // merge if-true & if-false initializations FlowInfo mergedInfo; if (isConditionOptimizedTrue) { mergedInfo = trueFlowInfo.addPotentialInitializationsFrom(falseFlowInfo); this.nullStatus = this.valueIfTrue.nullStatus(trueFlowInfo); } else if (isConditionOptimizedFalse) { mergedInfo = falseFlowInfo.addPotentialInitializationsFrom(trueFlowInfo); this.nullStatus = this.valueIfFalse.nullStatus(falseFlowInfo); } else { // this block must meet two conflicting requirements (see https://bugs.eclipse.org/324178): // (1) For null analysis of "Object o2 = (o1 != null) ? o1 : new Object();" we need to distinguish // the paths *originating* from the evaluation of the condition to true/false respectively. // This is used to determine the possible null status of the entire conditional expression. // (2) For definite assignment analysis (JLS 16.1.5) of boolean conditional expressions of the form // "if (c1 ? expr1 : expr2) use(v);" we need to check whether any variable v will be definitely // assigned whenever the entire conditional expression evaluates to true (to reach the then branch). // I.e., we need to collect flowInfo *towards* the overall outcome true/false // (regardless of the evaluation of the condition). // to support (1) use the infos of both branches originating from the condition for computing the nullStatus: computeNullStatus(trueFlowInfo, falseFlowInfo); // to support (2) we split the true/false branches according to their inner structure. Consider this: // if (b ? false : (true && (v = false))) return v; -- ok // - expr1 ("false") has no path towards true (mark as unreachable) // - expr2 ("(true && (v = false))") has a branch towards true on which v is assigned. // -> merging these two branches yields: v is assigned // - the paths towards false are irrelevant since the enclosing if has no else. cst = this.optimizedIfTrueConstant; boolean isValueIfTrueOptimizedTrue = cst != null && cst != Constant.NotAConstant && cst.booleanValue() == true; boolean isValueIfTrueOptimizedFalse = cst != null && cst != Constant.NotAConstant && cst.booleanValue() == false; cst = this.optimizedIfFalseConstant; boolean isValueIfFalseOptimizedTrue = cst != null && cst != Constant.NotAConstant && cst.booleanValue() == true; boolean isValueIfFalseOptimizedFalse = cst != null && cst != Constant.NotAConstant && cst.booleanValue() == false; UnconditionalFlowInfo trueFlowTowardsTrue = trueFlowInfo.initsWhenTrue().unconditionalCopy(); UnconditionalFlowInfo falseFlowTowardsTrue = falseFlowInfo.initsWhenTrue().unconditionalCopy(); UnconditionalFlowInfo trueFlowTowardsFalse = trueFlowInfo.initsWhenFalse().unconditionalInits(); UnconditionalFlowInfo falseFlowTowardsFalse = falseFlowInfo.initsWhenFalse().unconditionalInits(); if (isValueIfTrueOptimizedFalse) { trueFlowTowardsTrue.setReachMode(FlowInfo.UNREACHABLE_OR_DEAD); } if (isValueIfFalseOptimizedFalse) { falseFlowTowardsTrue.setReachMode(FlowInfo.UNREACHABLE_OR_DEAD); } if (isValueIfTrueOptimizedTrue) { trueFlowTowardsFalse.setReachMode(FlowInfo.UNREACHABLE_OR_DEAD); } if (isValueIfFalseOptimizedTrue) { falseFlowTowardsFalse.setReachMode(FlowInfo.UNREACHABLE_OR_DEAD); } mergedInfo = FlowInfo.conditional(trueFlowTowardsTrue.mergedWith(falseFlowTowardsTrue), trueFlowTowardsFalse.mergedWith(falseFlowTowardsFalse)); } this.mergedInitStateIndex = currentScope.methodScope().recordInitializationStates(mergedInfo); mergedInfo.setReachMode(mode); return mergedInfo; } private void computeNullStatus(FlowInfo trueBranchInfo, FlowInfo falseBranchInfo) { // given that the condition cannot be optimized to a constant // we now merge the nullStatus from both branches: int ifTrueNullStatus = this.valueIfTrue.nullStatus(trueBranchInfo); int ifFalseNullStatus = this.valueIfFalse.nullStatus(falseBranchInfo); if (ifTrueNullStatus == ifFalseNullStatus) { this.nullStatus = ifTrueNullStatus; return; } // is there a chance of null (or non-null)? -> potentially null etc. // https://bugs.eclipse.org/bugs/show_bug.cgi?id=133125 int status = 0; int combinedStatus = ifTrueNullStatus | ifFalseNullStatus; if ((combinedStatus & (FlowInfo.NULL | FlowInfo.POTENTIALLY_NULL)) != 0) { status |= FlowInfo.POTENTIALLY_NULL; } if ((combinedStatus & (FlowInfo.NON_NULL | FlowInfo.POTENTIALLY_NON_NULL)) != 0) { status |= FlowInfo.POTENTIALLY_NON_NULL; } if ((combinedStatus & (FlowInfo.UNKNOWN | FlowInfo.POTENTIALLY_UNKNOWN)) != 0) { status |= FlowInfo.POTENTIALLY_UNKNOWN; } if (status > 0) { this.nullStatus = status; } } /** * Code generation for the conditional operator ?: * * @param currentScope * org.eclipse.che.ide.java.client.internal.compiler.lookup.BlockScope * @param codeStream * org.eclipse.che.ide.java.client.internal.compiler.codegen.CodeStream * @param valueRequired * boolean */ @Override public void generateCode(BlockScope currentScope, boolean valueRequired) { BranchLabel falseLabel; if (this.constant != Constant.NotAConstant) { return; } Constant cst = this.condition.optimizedBooleanConstant(); boolean needTruePart = !(cst != Constant.NotAConstant && cst.booleanValue() == false); boolean needFalsePart = !(cst != Constant.NotAConstant && cst.booleanValue() == true); // Generate code for the condition falseLabel = new BranchLabel(); falseLabel.tagBits |= BranchLabel.USED; this.condition.generateOptimizedBoolean(currentScope, null, falseLabel, cst == Constant.NotAConstant); // Then code generation if (needTruePart) { this.valueIfTrue.generateCode(currentScope, valueRequired); } if (needFalsePart) { this.valueIfFalse.generateCode(currentScope, valueRequired); } } /** Optimized boolean code generation for the conditional operator ?: */ @Override public void generateOptimizedBoolean(BlockScope currentScope, BranchLabel trueLabel, BranchLabel falseLabel, boolean valueRequired) { if ((this.constant != Constant.NotAConstant) && (this.constant.typeID() == T_boolean) // constant || ((this.valueIfTrue.implicitConversion & IMPLICIT_CONVERSION_MASK) >> 4) != T_boolean) { // non boolean values super.generateOptimizedBoolean(currentScope, trueLabel, falseLabel, valueRequired); return; } Constant cst = this.condition.constant; Constant condCst = this.condition.optimizedBooleanConstant(); boolean needTruePart = !(((cst != Constant.NotAConstant) && (cst.booleanValue() == false)) || ((condCst != Constant.NotAConstant) && (condCst .booleanValue() == false))); boolean needFalsePart = !(((cst != Constant.NotAConstant) && (cst.booleanValue() == true)) || ((condCst != Constant.NotAConstant) && (condCst .booleanValue() == true))); // Generate code for the condition boolean needConditionValue = (cst == Constant.NotAConstant) && (condCst == Constant.NotAConstant); this.condition.generateOptimizedBoolean(currentScope, null, new BranchLabel(), needConditionValue); // Then code generation if (needTruePart) { this.valueIfTrue.generateOptimizedBoolean(currentScope, trueLabel, falseLabel, valueRequired); if (needFalsePart) { // Jump over the else part JumpEndif: { if (falseLabel == null) { if (trueLabel != null) { // implicit falling through the FALSE case cst = this.optimizedIfTrueConstant; boolean isValueIfTrueOptimizedTrue = cst != null && cst != Constant.NotAConstant && cst.booleanValue() == true; if (isValueIfTrueOptimizedTrue) { break JumpEndif; // no need to jump over, since branched to true already } } } else { // implicit falling through the TRUE case if (trueLabel == null) { cst = this.optimizedIfTrueConstant; boolean isValueIfTrueOptimizedFalse = cst != null && cst != Constant.NotAConstant && cst.booleanValue() == false; if (isValueIfTrueOptimizedFalse) { break JumpEndif; // no need to jump over, since branched to false already } } else { // no implicit fall through TRUE/FALSE --> should never occur } } } // No need to decrement codestream stack size // since valueIfTrue was already consumed by branch bytecode } } if (needFalsePart) { this.valueIfFalse.generateOptimizedBoolean(currentScope, trueLabel, falseLabel, valueRequired); } } @Override public int nullStatus(FlowInfo flowInfo) { return this.nullStatus; } @Override public Constant optimizedBooleanConstant() { return this.optimizedBooleanConstant == null ? this.constant : this.optimizedBooleanConstant; } @Override public StringBuffer printExpressionNoParenthesis(int indent, StringBuffer output) { this.condition.printExpression(indent, output).append(" ? "); //$NON-NLS-1$ this.valueIfTrue.printExpression(0, output).append(" : "); //$NON-NLS-1$ return this.valueIfFalse.printExpression(0, output); } @Override public TypeBinding resolveType(BlockScope scope) { // JLS3 15.25 this.constant = Constant.NotAConstant; LookupEnvironment env = scope.environment(); boolean use15specifics = scope.compilerOptions().sourceLevel >= ClassFileConstants.JDK1_5; TypeBinding conditionType = this.condition.resolveTypeExpecting(scope, TypeBinding.BOOLEAN); this.condition.computeConversion(scope, TypeBinding.BOOLEAN, conditionType); if (this.valueIfTrue instanceof CastExpression) { this.valueIfTrue.bits |= DisableUnnecessaryCastCheck; // will check later on } TypeBinding originalValueIfTrueType = this.valueIfTrue.resolveType(scope); if (this.valueIfFalse instanceof CastExpression) { this.valueIfFalse.bits |= DisableUnnecessaryCastCheck; // will check later on } TypeBinding originalValueIfFalseType = this.valueIfFalse.resolveType(scope); if (conditionType == null || originalValueIfTrueType == null || originalValueIfFalseType == null) { return null; } TypeBinding valueIfTrueType = originalValueIfTrueType; TypeBinding valueIfFalseType = originalValueIfFalseType; if (use15specifics && valueIfTrueType != valueIfFalseType) { if (valueIfTrueType.isBaseType()) { if (valueIfFalseType.isBaseType()) { // bool ? baseType : baseType if (valueIfTrueType == TypeBinding.NULL) { // bool ? null : 12 --> Integer valueIfFalseType = env.computeBoxingType(valueIfFalseType); // boxing } else if (valueIfFalseType == TypeBinding.NULL) { // bool ? 12 : null --> Integer valueIfTrueType = env.computeBoxingType(valueIfTrueType); // boxing } } else { // bool ? baseType : nonBaseType TypeBinding unboxedIfFalseType = valueIfFalseType.isBaseType() ? valueIfFalseType : env.computeBoxingType(valueIfFalseType); if (valueIfTrueType.isNumericType() && unboxedIfFalseType.isNumericType()) { valueIfFalseType = unboxedIfFalseType; // unboxing } else if (valueIfTrueType != TypeBinding.NULL) { // bool ? 12 : new Integer(12) --> int valueIfFalseType = env.computeBoxingType(valueIfFalseType); // unboxing } } } else if (valueIfFalseType.isBaseType()) { // bool ? nonBaseType : baseType TypeBinding unboxedIfTrueType = valueIfTrueType.isBaseType() ? valueIfTrueType : env.computeBoxingType(valueIfTrueType); if (unboxedIfTrueType.isNumericType() && valueIfFalseType.isNumericType()) { valueIfTrueType = unboxedIfTrueType; // unboxing } else if (valueIfFalseType != TypeBinding.NULL) { // bool ? new Integer(12) : 12 --> int valueIfTrueType = env.computeBoxingType(valueIfTrueType); // unboxing } } else { // bool ? nonBaseType : nonBaseType TypeBinding unboxedIfTrueType = env.computeBoxingType(valueIfTrueType); TypeBinding unboxedIfFalseType = env.computeBoxingType(valueIfFalseType); if (unboxedIfTrueType.isNumericType() && unboxedIfFalseType.isNumericType()) { valueIfTrueType = unboxedIfTrueType; valueIfFalseType = unboxedIfFalseType; } } } // Propagate the constant value from the valueIfTrue and valueIFFalse expression if it is possible Constant condConstant, trueConstant, falseConstant; if ((condConstant = this.condition.constant) != Constant.NotAConstant && (trueConstant = this.valueIfTrue.constant) != Constant.NotAConstant && (falseConstant = this.valueIfFalse.constant) != Constant.NotAConstant) { // all terms are constant expression so we can propagate the constant // from valueIFTrue or valueIfFalse to the receiver constant this.constant = condConstant.booleanValue() ? trueConstant : falseConstant; } if (valueIfTrueType == valueIfFalseType) { // harmed the implicit conversion this.valueIfTrue.computeConversion(scope, valueIfTrueType, originalValueIfTrueType); this.valueIfFalse.computeConversion(scope, valueIfFalseType, originalValueIfFalseType); if (valueIfTrueType == TypeBinding.BOOLEAN) { this.optimizedIfTrueConstant = this.valueIfTrue.optimizedBooleanConstant(); this.optimizedIfFalseConstant = this.valueIfFalse.optimizedBooleanConstant(); if (this.optimizedIfTrueConstant != Constant.NotAConstant && this.optimizedIfFalseConstant != Constant.NotAConstant && this.optimizedIfTrueConstant.booleanValue() == this.optimizedIfFalseConstant.booleanValue()) { // a ? true : true / a ? false : false this.optimizedBooleanConstant = this.optimizedIfTrueConstant; } else if ((condConstant = this.condition.optimizedBooleanConstant()) != Constant.NotAConstant) { // Propagate the optimized boolean constant if possible this.optimizedBooleanConstant = condConstant.booleanValue() ? this.optimizedIfTrueConstant : this.optimizedIfFalseConstant; } } return this.resolvedType = valueIfTrueType; } // Determine the return type depending on argument types // Numeric types if (valueIfTrueType.isNumericType() && valueIfFalseType.isNumericType()) { // (Short x Byte) or (Byte x Short)" if ((valueIfTrueType == TypeBinding.BYTE && valueIfFalseType == TypeBinding.SHORT) || (valueIfTrueType == TypeBinding.SHORT && valueIfFalseType == TypeBinding.BYTE)) { this.valueIfTrue.computeConversion(scope, TypeBinding.SHORT, originalValueIfTrueType); this.valueIfFalse.computeConversion(scope, TypeBinding.SHORT, originalValueIfFalseType); return this.resolvedType = TypeBinding.SHORT; } // <Byte|Short|Char> x constant(Int) ---> <Byte|Short|Char> and reciprocally if ((valueIfTrueType == TypeBinding.BYTE || valueIfTrueType == TypeBinding.SHORT || valueIfTrueType == TypeBinding.CHAR) && (valueIfFalseType == TypeBinding.INT && this.valueIfFalse.isConstantValueOfTypeAssignableToType( valueIfFalseType, valueIfTrueType))) { this.valueIfTrue.computeConversion(scope, valueIfTrueType, originalValueIfTrueType); this.valueIfFalse.computeConversion(scope, valueIfTrueType, originalValueIfFalseType); return this.resolvedType = valueIfTrueType; } if ((valueIfFalseType == TypeBinding.BYTE || valueIfFalseType == TypeBinding.SHORT || valueIfFalseType == TypeBinding.CHAR) && (valueIfTrueType == TypeBinding.INT && this.valueIfTrue.isConstantValueOfTypeAssignableToType( valueIfTrueType, valueIfFalseType))) { this.valueIfTrue.computeConversion(scope, valueIfFalseType, originalValueIfTrueType); this.valueIfFalse.computeConversion(scope, valueIfFalseType, originalValueIfFalseType); return this.resolvedType = valueIfFalseType; } // Manual binary numeric promotion // int if (BaseTypeBinding.isNarrowing(valueIfTrueType.id, T_int) && BaseTypeBinding.isNarrowing(valueIfFalseType.id, T_int)) { this.valueIfTrue.computeConversion(scope, TypeBinding.INT, originalValueIfTrueType); this.valueIfFalse.computeConversion(scope, TypeBinding.INT, originalValueIfFalseType); return this.resolvedType = TypeBinding.INT; } // long if (BaseTypeBinding.isNarrowing(valueIfTrueType.id, T_long) && BaseTypeBinding.isNarrowing(valueIfFalseType.id, T_long)) { this.valueIfTrue.computeConversion(scope, TypeBinding.LONG, originalValueIfTrueType); this.valueIfFalse.computeConversion(scope, TypeBinding.LONG, originalValueIfFalseType); return this.resolvedType = TypeBinding.LONG; } // float if (BaseTypeBinding.isNarrowing(valueIfTrueType.id, T_float) && BaseTypeBinding.isNarrowing(valueIfFalseType.id, T_float)) { this.valueIfTrue.computeConversion(scope, TypeBinding.FLOAT, originalValueIfTrueType); this.valueIfFalse.computeConversion(scope, TypeBinding.FLOAT, originalValueIfFalseType); return this.resolvedType = TypeBinding.FLOAT; } // double this.valueIfTrue.computeConversion(scope, TypeBinding.DOUBLE, originalValueIfTrueType); this.valueIfFalse.computeConversion(scope, TypeBinding.DOUBLE, originalValueIfFalseType); return this.resolvedType = TypeBinding.DOUBLE; } // Type references (null null is already tested) if (valueIfTrueType.isBaseType() && valueIfTrueType != TypeBinding.NULL) { if (use15specifics) { valueIfTrueType = env.computeBoxingType(valueIfTrueType); } else { scope.problemReporter().conditionalArgumentsIncompatibleTypes(this, valueIfTrueType, valueIfFalseType); return null; } } if (valueIfFalseType.isBaseType() && valueIfFalseType != TypeBinding.NULL) { if (use15specifics) { valueIfFalseType = env.computeBoxingType(valueIfFalseType); } else { scope.problemReporter().conditionalArgumentsIncompatibleTypes(this, valueIfTrueType, valueIfFalseType); return null; } } if (use15specifics) { // >= 1.5 : LUB(operand types) must exist TypeBinding commonType = null; if (valueIfTrueType == TypeBinding.NULL) { commonType = valueIfFalseType; } else if (valueIfFalseType == TypeBinding.NULL) { commonType = valueIfTrueType; } else { commonType = scope.lowerUpperBound(new TypeBinding[]{valueIfTrueType, valueIfFalseType}); } if (commonType != null) { this.valueIfTrue.computeConversion(scope, commonType, originalValueIfTrueType); this.valueIfFalse.computeConversion(scope, commonType, originalValueIfFalseType); return this.resolvedType = commonType.capture(scope, this.sourceEnd); } } else { // < 1.5 : one operand must be convertible to the other if (valueIfFalseType.isCompatibleWith(valueIfTrueType)) { this.valueIfTrue.computeConversion(scope, valueIfTrueType, originalValueIfTrueType); this.valueIfFalse.computeConversion(scope, valueIfTrueType, originalValueIfFalseType); return this.resolvedType = valueIfTrueType; } else if (valueIfTrueType.isCompatibleWith(valueIfFalseType)) { this.valueIfTrue.computeConversion(scope, valueIfFalseType, originalValueIfTrueType); this.valueIfFalse.computeConversion(scope, valueIfFalseType, originalValueIfFalseType); return this.resolvedType = valueIfFalseType; } } scope.problemReporter().conditionalArgumentsIncompatibleTypes(this, valueIfTrueType, valueIfFalseType); return null; } @Override public void traverse(ASTVisitor visitor, BlockScope scope) { if (visitor.visit(this, scope)) { this.condition.traverse(visitor, scope); this.valueIfTrue.traverse(visitor, scope); this.valueIfFalse.traverse(visitor, scope); } visitor.endVisit(this, scope); } }