--- /dev/null
+/*******************************************************************************
+ * 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.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 Label 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 |= IsUsefulEmptyStatementMASK;
+ sourceStart = s;
+ sourceEnd = e;
+ }
+
+ public FlowInfo analyseCode(
+ BlockScope currentScope,
+ FlowContext flowContext,
+ FlowInfo flowInfo) {
+
+ breakLabel = new Label();
+ continueLabel = new Label();
+
+ Constant cst = this.condition.constant;
+ boolean isConditionTrue = cst != NotAConstant && cst.booleanValue() == true;
+ boolean isConditionFalse = cst != NotAConstant && cst.booleanValue() == false;
+
+ cst = this.condition.optimizedBooleanConstant();
+ boolean isConditionOptimizedTrue = cst != NotAConstant && cst.booleanValue() == true;
+ boolean isConditionOptimizedFalse = cst != NotAConstant && cst.booleanValue() == false;
+
+ preCondInitStateIndex =
+ currentScope.methodScope().recordInitializationStates(flowInfo);
+ LoopingFlowContext condLoopContext;
+ FlowInfo postCondInfo =
+ this.condition.analyseCode(
+ currentScope,
+ (condLoopContext =
+ new LoopingFlowContext(flowContext, this, null, null, currentScope)),
+ flowInfo);
+
+ LoopingFlowContext loopingContext;
+ FlowInfo actionInfo;
+ if (action == null
+ || (action.isEmptyBlock() && currentScope.environment().options.complianceLevel <= ClassFileConstants.JDK1_3)) {
+ condLoopContext.complainOnFinalAssignmentsInLoop(currentScope, postCondInfo);
+ if (isConditionTrue) {
+ return FlowInfo.DEAD_END;
+ } else {
+ FlowInfo mergedInfo = postCondInfo.initsWhenFalse().unconditionalInits();
+ if (isConditionOptimizedTrue){
+ mergedInfo.setReachMode(FlowInfo.UNREACHABLE);
+ }
+ 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,
+ this,
+ breakLabel,
+ continueLabel,
+ currentScope);
+ if (isConditionFalse) {
+ actionInfo = FlowInfo.DEAD_END;
+ } else {
+ actionInfo = postCondInfo.initsWhenTrue().copy();
+ if (isConditionOptimizedFalse){
+ actionInfo.setReachMode(FlowInfo.UNREACHABLE);
+ }
+ }
+
+ // for computing local var attributes
+ condIfTrueInitStateIndex =
+ currentScope.methodScope().recordInitializationStates(
+ postCondInfo.initsWhenTrue());
+
+ if (!this.action.complainIfUnreachable(actionInfo, currentScope, false)) {
+ actionInfo = this.action.analyseCode(currentScope, loopingContext, actionInfo);
+ }
+
+ // code generation can be optimized when no need to continue in the loop
+ if (!actionInfo.isReachable() && !loopingContext.initsOnContinue.isReachable()) {
+ continueLabel = null;
+ } else {
+ // TODO (philippe) should simplify in one Loop context
+ condLoopContext.complainOnFinalAssignmentsInLoop(currentScope, postCondInfo);
+ actionInfo = actionInfo.mergedWith(loopingContext.initsOnContinue.unconditionalInits());
+ loopingContext.complainOnFinalAssignmentsInLoop(currentScope, actionInfo);
+ }
+ }
+
+ // end of loop
+ FlowInfo mergedInfo = FlowInfo.mergedOptimizedBranches(
+ loopingContext.initsOnBreak,
+ isConditionOptimizedTrue,
+ postCondInfo.initsWhenFalse(),
+ isConditionOptimizedFalse,
+ !isConditionTrue /*while(true); unreachable(); */);
+ mergedInitStateIndex = currentScope.methodScope().recordInitializationStates(mergedInfo);
+ return mergedInfo;
+ }
+
+ /**
+ * While code generation
+ *
+ * @param currentScope org.eclipse.jdt.internal.compiler.lookup.BlockScope
+ * @param codeStream org.eclipse.jdt.internal.compiler.codegen.CodeStream
+ */
+ public void generateCode(BlockScope currentScope, CodeStream codeStream) {
+
+ if ((bits & IsReachableMASK) == 0) {
+ return;
+ }
+ int pc = codeStream.position;
+ breakLabel.initialize(codeStream);
+
+ // generate condition
+ if (continueLabel == null) {
+ // no need to reverse condition
+ if (condition.constant == NotAConstant) {
+ condition.generateOptimizedBoolean(
+ currentScope,
+ codeStream,
+ null,
+ breakLabel,
+ true);
+ }
+ } else {
+ continueLabel.initialize(codeStream);
+ if (!(((condition.constant != NotAConstant)
+ && (condition.constant.booleanValue() == true))
+ || (action == null)
+ || action.isEmptyBlock())) {
+ int jumpPC = codeStream.position;
+ codeStream.goto_(continueLabel);
+ codeStream.recordPositionsFrom(jumpPC, condition.sourceStart);
+ }
+ }
+ // generate the action
+ Label actionLabel;
+ (actionLabel = new Label(codeStream)).place();
+ if (action != null) {
+ // Required to fix 1PR0XVS: LFRE:WINNT - Compiler: variable table for method appears incorrect
+ if (condIfTrueInitStateIndex != -1) {
+ // insert all locals initialized inside the condition into the action generated prior to the condition
+ codeStream.addDefinitelyAssignedVariables(
+ currentScope,
+ condIfTrueInitStateIndex);
+ }
+ action.generateCode(currentScope, codeStream);
+ // May loose some local variable initializations : affecting the local variable attributes
+ if (preCondInitStateIndex != -1) {
+ codeStream.removeNotDefinitelyAssignedVariables(
+ currentScope,
+ preCondInitStateIndex);
+ }
+
+ }
+ // output condition and branch back to the beginning of the repeated action
+ if (continueLabel != null) {
+ continueLabel.place();
+ condition.generateOptimizedBoolean(
+ currentScope,
+ codeStream,
+ actionLabel,
+ null,
+ true);
+ }
+ breakLabel.place();
+
+ // May loose some local variable initializations : affecting the local variable attributes
+ if (mergedInitStateIndex != -1) {
+ codeStream.removeNotDefinitelyAssignedVariables(currentScope, mergedInitStateIndex);
+ codeStream.addDefinitelyAssignedVariables(currentScope, mergedInitStateIndex);
+ }
+ codeStream.recordPositionsFrom(pc, this.sourceStart);
+ }
+
+ public void resolve(BlockScope scope) {
+
+ TypeBinding type = condition.resolveTypeExpecting(scope, BooleanBinding);
+ condition.implicitWidening(type, type);
+ if (action != null)
+ action.resolve(scope);
+ }
+
+ public StringBuffer printStatement(int tab, StringBuffer output) {
+
+ printIndent(tab, output).append("while ("); //$NON-NLS-1$
+ condition.printExpression(0, output).append(')');
+ if (action == null)
+ output.append(';');
+ else
+ action.printStatement(tab + 1, output);
+ return output;
+ }
+
+ public void traverse(
+ ASTVisitor visitor,
+ BlockScope blockScope) {
+
+ if (visitor.visit(this, blockScope)) {
+ condition.traverse(visitor, blockScope);
+ if (action != null)
+ action.traverse(visitor, blockScope);
+ }
+ visitor.endVisit(this, blockScope);
+ }
+}
projects / org.ibex.tool.git / blobdiff