| /******************************************************************************* |
| * Copyright (c) 2000, 2020 IBM Corporation and others. |
| * |
| * This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License 2.0 |
| * which accompanies this distribution, and is available at |
| * https://www.eclipse.org/legal/epl-2.0/ |
| * |
| * SPDX-License-Identifier: EPL-2.0 |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| * Stephan Herrmann - Contributions for |
| * bug 319201 - [null] no warning when unboxing SingleNameReference causes NPE |
| * bug 349326 - [1.7] new warning for missing try-with-resources |
| * bug 345305 - [compiler][null] Compiler misidentifies a case of "variable can only be null" |
| * bug 403147 - [compiler][null] FUP of bug 400761: consolidate interaction between unboxing, NPE, and deferred checking |
| * Bug 415790 - [compiler][resource]Incorrect potential resource leak warning in for loop with close in try/catch |
| *******************************************************************************/ |
| 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.classfmt.ClassFileConstants; |
| import org.eclipse.jdt.internal.compiler.codegen.*; |
| import org.eclipse.jdt.internal.compiler.flow.*; |
| import org.eclipse.jdt.internal.compiler.lookup.*; |
| |
| public class WhileStatement extends Statement { |
| |
| public Expression condition; |
| public Statement action; |
| private BranchLabel breakLabel, continueLabel; |
| int preCondInitStateIndex = -1; |
| int condIfTrueInitStateIndex = -1; |
| int mergedInitStateIndex = -1; |
| |
| public WhileStatement(Expression condition, Statement action, int s, int e) { |
| |
| this.condition = condition; |
| this.action = action; |
| // remember useful empty statement |
| if (action instanceof EmptyStatement) action.bits |= IsUsefulEmptyStatement; |
| this.sourceStart = s; |
| this.sourceEnd = e; |
| } |
| |
| @Override |
| public FlowInfo analyseCode(BlockScope currentScope, FlowContext flowContext, FlowInfo flowInfo) { |
| |
| this.breakLabel = new BranchLabel(); |
| this.continueLabel = new BranchLabel(); |
| int initialComplaintLevel = (flowInfo.reachMode() & FlowInfo.UNREACHABLE) != 0 ? Statement.COMPLAINED_FAKE_REACHABLE : Statement.NOT_COMPLAINED; |
| |
| Constant cst = this.condition.constant; |
| boolean isConditionTrue = cst != Constant.NotAConstant && cst.booleanValue() == true; |
| boolean isConditionFalse = cst != Constant.NotAConstant && cst.booleanValue() == false; |
| |
| cst = this.condition.optimizedBooleanConstant(); |
| boolean isConditionOptimizedTrue = cst != Constant.NotAConstant && cst.booleanValue() == true; |
| boolean isConditionOptimizedFalse = cst != Constant.NotAConstant && cst.booleanValue() == false; |
| |
| this.preCondInitStateIndex = currentScope.methodScope().recordInitializationStates(flowInfo); |
| LoopingFlowContext condLoopContext; |
| FlowInfo condInfo = flowInfo.nullInfoLessUnconditionalCopy(); |
| |
| // we need to collect the contribution to nulls of the coming paths through the |
| // loop, be they falling through normally or branched to break, continue labels |
| // or catch blocks |
| condInfo = this.condition.analyseCode( |
| currentScope, |
| (condLoopContext = |
| new LoopingFlowContext(flowContext, flowInfo, this, null, |
| null, currentScope, true)), |
| condInfo); |
| this.condition.checkNPEbyUnboxing(currentScope, flowContext, flowInfo); |
| |
| LoopingFlowContext loopingContext; |
| FlowInfo actionInfo; |
| FlowInfo exitBranch; |
| if (this.action == null |
| || (this.action.isEmptyBlock() && currentScope.compilerOptions().complianceLevel <= ClassFileConstants.JDK1_3)) { |
| condLoopContext.complainOnDeferredFinalChecks(currentScope, |
| condInfo); |
| condLoopContext.complainOnDeferredNullChecks(currentScope, |
| condInfo.unconditionalInits()); |
| if (isConditionTrue) { |
| return FlowInfo.DEAD_END; |
| } else { |
| FlowInfo mergedInfo = flowInfo.copy().addInitializationsFrom(condInfo.initsWhenFalse()); |
| if (isConditionOptimizedTrue){ |
| mergedInfo.setReachMode(FlowInfo.UNREACHABLE_OR_DEAD); |
| } |
| this.mergedInitStateIndex = |
| currentScope.methodScope().recordInitializationStates(mergedInfo); |
| return mergedInfo; |
| } |
| } else { |
| // in case the condition was inlined to false, record the fact that there is no way to reach any |
| // statement inside the looping action |
| loopingContext = |
| new LoopingFlowContext( |
| flowContext, |
| flowInfo, |
| this, |
| this.breakLabel, |
| this.continueLabel, |
| currentScope, |
| true); |
| loopingContext.copyNullCheckedFieldsFrom(condLoopContext); |
| if (isConditionFalse) { |
| actionInfo = FlowInfo.DEAD_END; |
| } else { |
| actionInfo = condInfo.initsWhenTrue().copy(); |
| if (isConditionOptimizedFalse){ |
| actionInfo.setReachMode(FlowInfo.UNREACHABLE_OR_DEAD); |
| } |
| } |
| |
| // for computing local var attributes |
| this.condIfTrueInitStateIndex = |
| currentScope.methodScope().recordInitializationStates( |
| condInfo.initsWhenTrue()); |
| |
| if (this.action.complainIfUnreachable(actionInfo, currentScope, initialComplaintLevel, true) < Statement.COMPLAINED_UNREACHABLE) { |
| this.condition.updateFlowOnBooleanResult(actionInfo, true); |
| actionInfo = this.action.analyseCode(currentScope, loopingContext, actionInfo); |
| } |
| |
| // code generation can be optimized when no need to continue in the loop |
| exitBranch = flowInfo.copy(); |
| // need to start over from flowInfo so as to get null inits |
| int combinedTagBits = actionInfo.tagBits & loopingContext.initsOnContinue.tagBits; |
| if ((combinedTagBits & FlowInfo.UNREACHABLE) != 0) { |
| if ((combinedTagBits & FlowInfo.UNREACHABLE_OR_DEAD) != 0) |
| this.continueLabel = null; |
| exitBranch.addInitializationsFrom(condInfo.initsWhenFalse()); |
| actionInfo = actionInfo.mergedWith(loopingContext.initsOnContinue.unconditionalInits()); |
| condLoopContext.complainOnDeferredNullChecks(currentScope, |
| actionInfo, false); |
| loopingContext.complainOnDeferredNullChecks(currentScope, |
| actionInfo, false); |
| } else { |
| condLoopContext.complainOnDeferredFinalChecks(currentScope, |
| condInfo); |
| actionInfo = actionInfo.mergedWith(loopingContext.initsOnContinue.unconditionalInits()); |
| condLoopContext.complainOnDeferredNullChecks(currentScope, |
| actionInfo); |
| loopingContext.complainOnDeferredFinalChecks(currentScope, |
| actionInfo); |
| loopingContext.complainOnDeferredNullChecks(currentScope, |
| actionInfo); |
| exitBranch. |
| addPotentialInitializationsFrom( |
| actionInfo.unconditionalInits()). |
| addInitializationsFrom(condInfo.initsWhenFalse()); |
| } |
| if (loopingContext.hasEscapingExceptions()) { // https://bugs.eclipse.org/bugs/show_bug.cgi?id=321926 |
| FlowInfo loopbackFlowInfo = flowInfo.copy(); |
| if (this.continueLabel != null) { // we do get to the bottom |
| // loopback | (loopback + action): |
| loopbackFlowInfo = loopbackFlowInfo.mergedWith(loopbackFlowInfo.unconditionalCopy().addNullInfoFrom(actionInfo).unconditionalInits()); |
| } |
| loopingContext.simulateThrowAfterLoopBack(loopbackFlowInfo); |
| } |
| } |
| |
| // end of loop |
| FlowInfo mergedInfo = FlowInfo.mergedOptimizedBranches( |
| (loopingContext.initsOnBreak.tagBits & |
| FlowInfo.UNREACHABLE) != 0 ? |
| loopingContext.initsOnBreak : |
| flowInfo.addInitializationsFrom(loopingContext.initsOnBreak), // recover upstream null info |
| isConditionOptimizedTrue, |
| exitBranch, |
| isConditionOptimizedFalse, |
| !isConditionTrue /*while(true); unreachable(); */); |
| this.mergedInitStateIndex = currentScope.methodScope().recordInitializationStates(mergedInfo); |
| this.condition.updateFlowOnBooleanResult(mergedInfo, false); |
| return mergedInfo; |
| } |
| |
| /** |
| * While code generation |
| * |
| * @param currentScope org.eclipse.jdt.internal.compiler.lookup.BlockScope |
| * @param codeStream org.eclipse.jdt.internal.compiler.codegen.CodeStream |
| */ |
| @Override |
| public void generateCode(BlockScope currentScope, CodeStream codeStream) { |
| |
| if ((this.bits & IsReachable) == 0) { |
| return; |
| } |
| if (this.condition != null && this.condition.containsPatternVariable()) { |
| this.condition.addPatternVariables(currentScope, codeStream); |
| } |
| int pc = codeStream.position; |
| Constant cst = this.condition.optimizedBooleanConstant(); |
| boolean isConditionOptimizedFalse = cst != Constant.NotAConstant && cst.booleanValue() == false; |
| if (isConditionOptimizedFalse) { |
| this.condition.generateCode(currentScope, codeStream, false); |
| // May loose some local variable initializations : affecting the local variable attributes |
| if (this.mergedInitStateIndex != -1) { |
| codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.mergedInitStateIndex); |
| codeStream.addDefinitelyAssignedVariables(currentScope, this.mergedInitStateIndex); |
| } |
| codeStream.recordPositionsFrom(pc, this.sourceStart); |
| return; |
| } |
| |
| this.breakLabel.initialize(codeStream); |
| |
| // generate condition |
| if (this.continueLabel == null) { |
| // no need to reverse condition |
| if (this.condition.constant == Constant.NotAConstant) { |
| this.condition.generateOptimizedBoolean( |
| currentScope, |
| codeStream, |
| null, |
| this.breakLabel, |
| true); |
| } |
| } else { |
| this.continueLabel.initialize(codeStream); |
| if (!(((this.condition.constant != Constant.NotAConstant) |
| && (this.condition.constant.booleanValue() == true)) |
| || (this.action == null) |
| || this.action.isEmptyBlock())) { |
| int jumpPC = codeStream.position; |
| codeStream.goto_(this.continueLabel); |
| codeStream.recordPositionsFrom(jumpPC, this.condition.sourceStart); |
| } |
| } |
| // generate the action |
| BranchLabel actionLabel = new BranchLabel(codeStream); |
| if (this.action != null) { |
| actionLabel.tagBits |= BranchLabel.USED; |
| // Required to fix 1PR0XVS: LFRE:WINNT - Compiler: variable table for method appears incorrect |
| if (this.condIfTrueInitStateIndex != -1) { |
| // insert all locals initialized inside the condition into the action generated prior to the condition |
| codeStream.addDefinitelyAssignedVariables( |
| currentScope, |
| this.condIfTrueInitStateIndex); |
| } |
| actionLabel.place(); |
| this.action.generateCode(currentScope, codeStream); |
| // May loose some local variable initializations : affecting the local variable attributes |
| if (this.preCondInitStateIndex != -1) { |
| codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.preCondInitStateIndex); |
| } |
| } else { |
| actionLabel.place(); |
| } |
| // output condition and branch back to the beginning of the repeated action |
| if (this.continueLabel != null) { |
| this.continueLabel.place(); |
| this.condition.generateOptimizedBoolean( |
| currentScope, |
| codeStream, |
| actionLabel, |
| null, |
| true); |
| } |
| |
| // May loose some local variable initializations : affecting the local variable attributes |
| if (this.mergedInitStateIndex != -1) { |
| codeStream.removeNotDefinitelyAssignedVariables(currentScope, this.mergedInitStateIndex); |
| codeStream.addDefinitelyAssignedVariables(currentScope, this.mergedInitStateIndex); |
| } |
| this.breakLabel.place(); |
| codeStream.recordPositionsFrom(pc, this.sourceStart); |
| } |
| |
| @Override |
| public void resolve(BlockScope scope) { |
| TypeBinding type = this.condition.resolveTypeExpecting(scope, TypeBinding.BOOLEAN); |
| this.condition.computeConversion(scope, type, type); |
| if (this.action != null) |
| this.action.resolve(scope); |
| } |
| |
| @Override |
| public StringBuffer printStatement(int tab, StringBuffer output) { |
| |
| printIndent(tab, output).append("while ("); //$NON-NLS-1$ |
| this.condition.printExpression(0, output).append(')'); |
| if (this.action == null) |
| output.append(';'); |
| else |
| this.action.printStatement(tab + 1, output); |
| return output; |
| } |
| |
| @Override |
| public void traverse( |
| ASTVisitor visitor, |
| BlockScope blockScope) { |
| |
| if (visitor.visit(this, blockScope)) { |
| this.condition.traverse(visitor, blockScope); |
| if (this.action != null) |
| this.action.traverse(visitor, blockScope); |
| } |
| visitor.endVisit(this, blockScope); |
| } |
| |
| @Override |
| public boolean doesNotCompleteNormally() { |
| Constant cst = this.condition.constant; |
| boolean isConditionTrue = cst == null || cst != Constant.NotAConstant && cst.booleanValue() == true; |
| cst = this.condition.optimizedBooleanConstant(); |
| boolean isConditionOptimizedTrue = cst == null ? true : cst != Constant.NotAConstant && cst.booleanValue() == true; |
| return (isConditionTrue || isConditionOptimizedTrue) && (this.action == null || !this.action.breaksOut(null)); |
| } |
| |
| @Override |
| public boolean completesByContinue() { |
| return this.action.continuesAtOuterLabel(); |
| } |
| |
| @Override |
| public boolean canCompleteNormally() { |
| Constant cst = this.condition.constant; |
| boolean isConditionTrue = cst == null || cst != Constant.NotAConstant && cst.booleanValue() == true; |
| cst = this.condition.optimizedBooleanConstant(); |
| boolean isConditionOptimizedTrue = cst == null ? true : cst != Constant.NotAConstant && cst.booleanValue() == true; |
| if (!(isConditionTrue || isConditionOptimizedTrue)) |
| return true; |
| return this.action != null && this.action.breaksOut(null); |
| } |
| |
| @Override |
| public boolean continueCompletes() { |
| return this.action.continuesAtOuterLabel(); |
| } |
| } |