Compute KernelClosureRepresentationInfo.variableIsUsedInTryOrSync

pkg/compiler/lib/src/kernel/closure.dart

+// Copyright (c) 2016, 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.
+
+import 'package:kernel/ast.dart' as ir;
+
+import '../closure.dart';
+import '../common/tasks.dart';
+import '../elements/entities.dart';
+import '../world.dart';
+import 'element_map.dart';
+import 'kernel_backend_strategy.dart';
+
+class KernelClosureDataBuilder extends ir.Visitor {
+  final KernelToLocalsMap _localsMap;
+  final KernelClosureRepresentationInfo info;
+
+  bool _inTry = false;
+
+  KernelClosureDataBuilder(this._localsMap, ThisLocal thisLocal)
+      : info = new KernelClosureRepresentationInfo(thisLocal);
+
+  @override
+  defaultNode(ir.Node node) {
+    node.visitChildren(this);
+  }
+
+  @override
+  visitTryCatch(ir.TryCatch node) {
+    bool oldInTry = _inTry;
+    _inTry = true;
+    node.visitChildren(this);
+    _inTry = oldInTry;
+  }
+
+  @override
+  visitTryFinally(ir.TryFinally node) {
+    bool oldInTry = _inTry;
+    _inTry = true;
+    node.visitChildren(this);
+    _inTry = oldInTry;
+  }
+
+  @override
+  visitVariableGet(ir.VariableGet node) {
+    if (_inTry) {
+      info.registerUsedInTryOrSync(_localsMap.getLocal(node.variable));
+    }
+  }
+}
+
+/// Closure conversion code using our new Entity model. Closure conversion is
+/// necessary because the semantics of closures are slightly different in Dart
+/// than JavaScript. Closure conversion is separated out into two phases:
+/// generation of a new (temporary) representation to store where variables need
+/// to be hoisted/captured up at another level to re-write the closure, and then
+/// the code generation phase where we generate elements and/or instructions to
+/// represent this new code path.
+///
+/// For a general explanation of how closure conversion works at a high level,
+/// check out:
+/// http://siek.blogspot.com/2012/07/essence-of-closure-conversion.html or
+/// http://matt.might.net/articles/closure-conversion/.
+class KernelClosureConversionTask extends ClosureConversionTask<ir.Node> {
+  final KernelToElementMap _elementMap;
+  final GlobalLocalsMap _globalLocalsMap;
+  Map<Entity, ClosureRepresentationInfo> _infoMap =
+      <Entity, ClosureRepresentationInfo>{};
+
+  KernelClosureConversionTask(
+      Measurer measurer, this._elementMap, this._globalLocalsMap)
+      : super(measurer);
+
+  /// The combined steps of generating our intermediate representation of
+  /// closures that need to be rewritten and generating the element model.
+  /// Ultimately these two steps will be split apart with the second step
+  /// happening later in compilation just before codegen. These steps are
+  /// combined here currently to provide a consistent interface to the rest of
+  /// the compiler until we are ready to separate these phases.
+  @override
+  void convertClosures(Iterable<MemberEntity> processedEntities,
+      ClosedWorldRefiner closedWorldRefiner) {
+    // TODO(efortuna): implement.
+  }
+
+  /// TODO(johnniwinther,efortuna): Implement this.
+  @override
+  ClosureAnalysisInfo getClosureAnalysisInfo(ir.Node node) {
+    return const ClosureAnalysisInfo();
+  }
+
+  /// TODO(johnniwinther,efortuna): Implement this.
+  @override
+  LoopClosureRepresentationInfo getClosureRepresentationInfoForLoop(
+      ir.Node loopNode) {
+    return const LoopClosureRepresentationInfo();
+  }
+
+  @override
+  ClosureRepresentationInfo getClosureRepresentationInfo(Entity entity) {
+    return _infoMap.putIfAbsent(entity, () {
+      if (entity is MemberEntity) {
+        ir.Member node = _elementMap.getMemberNode(entity);
+        ThisLocal thisLocal;
+        if (entity.isInstanceMember) {
+          thisLocal = new ThisLocal(entity);
+        }
+        KernelClosureDataBuilder builder = new KernelClosureDataBuilder(
+            _globalLocalsMap.getLocalsMap(entity), thisLocal);
+        node.accept(builder);
+        return builder.info;
+      }
+
+      /// TODO(johnniwinther,efortuna): Implement this.
+      return const ClosureRepresentationInfo();
+    });
+  }
+}
+
+// TODO(johnniwinther): Add unittest for the computed
+// [ClosureRepresentationInfo].
+class KernelClosureRepresentationInfo extends ClosureRepresentationInfo {
+  final ThisLocal thisLocal;
+  final Set<Local> _localsUsedInTryOrSync = new Set<Local>();
+
+  KernelClosureRepresentationInfo(this.thisLocal);
+
+  void registerUsedInTryOrSync(Local local) {
+    _localsUsedInTryOrSync.add(local);
+  }
+
+  bool variableIsUsedInTryOrSync(Local variable) =>
+      _localsUsedInTryOrSync.contains(variable);
+}