Re-apply "Move the container tracer to the call graph inferrer.".

sdk/lib/_internal/compiler/implementation/inferrer/type_graph_nodes.dart

Index: sdk/lib/_internal/compiler/implementation/inferrer/type_graph_nodes.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/inferrer/type_graph_nodes.dart	(revision 27995)
+++ sdk/lib/_internal/compiler/implementation/inferrer/type_graph_nodes.dart	(working copy)
@@ -61,10 +61,14 @@
   }
 
   void addAssignment(TypeInformation assignment) {
-    if (abandonInferencing) return;
     // Cheap one-level cycle detection.
     if (assignment == this) return;
-    assignments.add(assignment);
+    if (!abandonInferencing) {
+      assignments.add(assignment);
+    }
+    // Even if we abandon inferencing on this [TypeInformation] we
+    // need to collect the users, so that phases that track where
+    // elements flow in still work.
     assignment.addUser(this);
   }
 
@@ -92,6 +96,17 @@
     assignments = const <TypeInformation>[];
     users = const <TypeInformation>[];
   }
+
+  bool reachedBy(TypeInformation info, TypeGraphInferrerEngine inferrer) {
+    return true;
+  }
+
+  accept(TypeInformationVisitor visitor);
+
+  /// The [Element] where this [TypeInformation] was created. May be
+  /// for some [TypeInformation] nodes, where we do not need to store
+  /// the information.
+  Element get owner => null;
 }
 
 /**
@@ -268,6 +283,12 @@
   }
 
   String toString() => 'Element $element $type';
+
+  accept(TypeInformationVisitor visitor) {
+    return visitor.visitElementTypeInformation(this);
+  }
+
+  Element get owner => element.getOutermostEnclosingMemberOrTopLevel();
 }
 
 /**
@@ -301,6 +322,8 @@
 
   /// Return an iterable over the targets of this call.
   Iterable<Element> get callees;
+
+  Element get owner => caller;
 }
 
 class StaticCallSiteTypeInformation extends CallSiteTypeInformation {
@@ -344,6 +367,14 @@
   }
 
   Iterable<Element> get callees => [calledElement.implementation];
+
+  bool reachedBy(TypeInformation info, TypeGraphInferrerEngine inferrer) {
+    return info == inferrer.types.getInferredTypeOf(calledElement);
+  }
+
+  accept(TypeInformationVisitor visitor) {
+    return visitor.visitStaticCallSiteTypeInformation(this);
+  }
 }
 
 class DynamicCallSiteTypeInformation extends CallSiteTypeInformation {
@@ -506,7 +537,17 @@
     super.giveUp(inferrer);
   }
 
-  String toString() => 'Call site $call ${receiver.type} $type';
+  bool reachedBy(TypeInformation info, TypeGraphInferrerEngine inferrer) {
+    return targets
+            .map((element) => inferrer.types.getInferredTypeOf(element))
+            .any((other) => other == info);
+  }
+
+  String toString() => 'Call site $call on ${receiver.type} $type';
+
+  accept(TypeInformationVisitor visitor) {
+    return visitor.visitDynamicCallSiteTypeInformation(this);
+  }
 }
 
 class ClosureCallSiteTypeInformation extends CallSiteTypeInformation {
@@ -529,10 +570,14 @@
   }
 
   Iterable<Element> get callees {
-    throw new UnsupportedError("Cannot compute callees of a closure.");
+    throw new UnsupportedError("Cannot compute callees of a closure call.");
   }
 
   String toString() => 'Closure call $call on $closure';
+
+  accept(TypeInformationVisitor visitor) {
+    return visitor.visitClosureCallSiteTypeInformation(this);
+  }
 }
 
 /**
@@ -569,6 +614,10 @@
   }
 
   String toString() => 'Type $type';
+
+  accept(TypeInformationVisitor visitor) {
+    return visitor.visitConcreteTypeInformation(this);
+  }
 }
 
 /**
@@ -602,23 +651,28 @@
   }
 
   String toString() => 'Narrow ${assignments.first} to $typeAnnotation $type';
+
+  accept(TypeInformationVisitor visitor) {
+    return visitor.visitNarrowTypeInformation(this);
+  }
 }
 
 /**
- * A [ContainerTypeInformation] is a [ConcreteTypeInformation] created
+ * A [ContainerTypeInformation] is a [TypeInformation] created
  * for each `List` instantiations.
  */
-class ContainerTypeInformation extends ConcreteTypeInformation {
-  final TypeInformation elementType;
+class ContainerTypeInformation extends TypeInformation {
+  final ElementInContainerTypeInformation elementType;
 
-  ContainerTypeInformation(containerType, this.elementType)
-      : super(containerType);
-
-  void addUser(TypeInformation user) {
-    elementType.addUser(user);
+  ContainerTypeInformation(containerType, this.elementType) {
+    type = containerType;
   }
 
   String toString() => 'Container type $type';
+
+  accept(TypeInformationVisitor visitor) {
+    return visitor.visitContainerTypeInformation(this);
+  }
 }
 
 /**
@@ -629,17 +683,27 @@
   final ContainerTypeMask container;
 
   ElementInContainerTypeInformation(elementType, this.container) {
-    // [elementType] is not null for const lists.
     if (elementType != null) addAssignment(elementType);
   }
 
+  bool get isInConstContainer {
+    LiteralList literal = container.allocationNode.asLiteralList();
+    return (literal != null) && literal.isConst();
+  }
+
   TypeMask refine(TypeGraphInferrerEngine inferrer) {
-    if (assignments.isEmpty) return inferrer.types.dynamicType.type;
+    if (!isInConstContainer) {
+      return inferrer.types.dynamicType.type;
+    }
     return container.elementType =
         inferrer.types.computeTypeMask(assignments);
   }
 
   String toString() => 'Element in container $type';
+
+  accept(TypeInformationVisitor visitor) {
+    return visitor.visitElementInContainerTypeInformation(this);
+  }
 }
 
 /**
@@ -658,4 +722,21 @@
   }
 
   String toString() => 'Phi $element $type';
+
+  accept(TypeInformationVisitor visitor) {
+    return visitor.visitPhiElementTypeInformation(this);
+  }
 }
+
+abstract class TypeInformationVisitor<T> {
+  T visitNarrowTypeInformation(NarrowTypeInformation info);
+  T visitPhiElementTypeInformation(PhiElementTypeInformation info);
+  T visitElementInContainerTypeInformation(
+      ElementInContainerTypeInformation info);
+  T visitContainerTypeInformation(ContainerTypeInformation info);
+  T visitConcreteTypeInformation(ConcreteTypeInformation info);
+  T visitClosureCallSiteTypeInformation(ClosureCallSiteTypeInformation info);
+  T visitStaticCallSiteTypeInformation(StaticCallSiteTypeInformation info);
+  T visitDynamicCallSiteTypeInformation(DynamicCallSiteTypeInformation info);
+  T visitElementTypeInformation(ElementTypeInformation info);
+}