Handle labelled continue statements

pkg/compiler/lib/src/js_model/locals.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.js_model.locals;
 
 import 'package:kernel/ast.dart' as ir;
 
 import '../closure.dart';
 import '../common.dart';
@@ skipping 199 matching lines @@
       ir.TreeNode search = node;
       bool needsLabel = false;
       while (search != node.target) {
         if (_canBeBreakTarget(search)) {
           needsLabel = search != body;
           break;
         }
         search = search.parent;
       }
       if (needsLabel) {
-        target.addLabel(node.target, 'label${labelIndex++}',
-            isBreakTarget: true);
+        if (target.labels.isEmpty) {

[Siggi Cherem (dart-lang), 2017/08/25 00:38:50]

nit: consider adding a helper function instead to do:

var label = _getOrCreateLabel(target, node.target);
label.isBreakTarget = true;

Then we have a single place to maintain the invariant that there is only one
label per target

[Johnni Winther, 2017/08/25 07:11:51]

Done.

+          target.addLabel(node.target, 'label${labelIndex++}',
+              isBreakTarget: true);
+        } else {
+          JLabelDefinition label = target.labels.single;
+          label.isBreakTarget = true;
+        }
       }
     } else if (_canBeContinueTarget(parent)) {
       // We have code like
       //
       //     for (int i = 0; i < 10; i++) l1: {
       //        break l1:
       //     }
       //
       // and can therefore use the for loop as a continue target.
       target = _getJumpTarget(parent);
       target.isContinueTarget = true;
       breaksAsContinue.add(node);
+      ir.TreeNode search = node;
+      bool needsLabel = false;
+      while (search != node.target) {
+        if (_canBeContinueTarget(search)) {
+          needsLabel = search != body;
+          break;
+        }
+        search = search.parent;
+      }
+      if (needsLabel) {
+        if (target.labels.isEmpty) {
+          target.addLabel(node.target, 'label${labelIndex++}',
+              isContinueTarget: true);
+        } else {
+          JLabelDefinition label = target.labels.single;
+          label.isContinueTarget = true;
+        }
+      }
     } else {
       target = _getJumpTarget(node.target);
       target.isBreakTarget = true;
     }
     jumpTargetMap[node] = target;
     super.visitBreakStatement(node);
   }
 }
 
 class JJumpTarget extends JumpTarget<ir.Node> {
   final MemberEntity memberContext;
   final int nestingLevel;
   List<LabelDefinition<ir.Node>> _labels;
+  final bool isSwitch;
+  final bool isSwitchCase;
 
-  JJumpTarget(this.memberContext, this.nestingLevel);
+  JJumpTarget(this.memberContext, this.nestingLevel,
+      {this.isSwitch: false, this.isSwitchCase: false});
 
   bool isBreakTarget = false;
   bool isContinueTarget = false;
-  bool isSwitch = false;
 
   @override
   Entity get executableContext => memberContext;
 
   @override
   LabelDefinition<ir.Node> addLabel(ir.Node label, String labelName,
-      {bool isBreakTarget: false}) {
+      {bool isBreakTarget: false, bool isContinueTarget: false}) {
     _labels ??= <LabelDefinition<ir.Node>>[];
     LabelDefinition<ir.Node> labelDefinition = new JLabelDefinition(
-        this, label, labelName,
-        isBreakTarget: isBreakTarget);
+        this, labelName,
+        isBreakTarget: isBreakTarget, isContinueTarget: isContinueTarget);
     _labels.add(labelDefinition);
     return labelDefinition;
   }
 
   @override
   List<LabelDefinition<ir.Node>> get labels {
     return _labels ?? const <LabelDefinition<ir.Node>>[];
   }
 
   @override
@@ skipping 16 matching lines @@
       sb.write(',labels=');
       sb.write(_labels);
     }
     sb.write(')');
     return sb.toString();
   }
 }
 
 class JLabelDefinition extends LabelDefinition<ir.Node> {
   final JumpTarget<ir.Node> target;
-  final ir.Node label;
   final String labelName;
-  final bool isBreakTarget;
-  final bool isContinueTarget;
+  bool isBreakTarget;
+  bool isContinueTarget;
 
-  JLabelDefinition(this.target, this.label, this.labelName,
+  JLabelDefinition(this.target, this.labelName,
       {this.isBreakTarget: false, this.isContinueTarget: false});
 
   @override
   String get name => labelName;
   String toString() {
     StringBuffer sb = new StringBuffer();
     sb.write('JLabelDefinition(');
-    sb.write('label=');
-    sb.write(label);
     sb.write(',labelName=');
     sb.write(labelName);
     sb.write(',isBreakTarget=');
     sb.write(isBreakTarget);
     sb.write(',isContinueTarget=');
     sb.write(isContinueTarget);
     sb.write(')');
     return sb.toString();
   }
 }
@@ skipping 18 matching lines @@
       sb.write(memberContext.enclosingClass.name);
       sb.write('.');
     }
     sb.write(memberContext.name);
     sb.write('#');
     sb.write(name);
     sb.write(')');
     return sb.toString();
   }
 }