Compute isSubtype and isSubclass using ClassSet/ClassHierarchyNode

pkg/compiler/lib/src/world.dart

Index: pkg/compiler/lib/src/world.dart
diff --git a/pkg/compiler/lib/src/world.dart b/pkg/compiler/lib/src/world.dart
index 25d9e8199cf586ffec1fe3c0b75bc3231dd65cb1..907ef5743dda447a5bff1dde3db694729b0e1454 100644
--- a/pkg/compiler/lib/src/world.dart
+++ b/pkg/compiler/lib/src/world.dart
@@ -472,6 +472,8 @@ abstract class ClosedWorldBase implements ClosedWorld, ClosedWorldRefiner {
 
   bool _checkClass(ClassEntity cls);
 
+  bool _checkInvariants(ClassEntity cls, {bool mustBeInstantiated: true});
+
   @override
   bool isInstantiated(ClassEntity cls) {
     assert(_checkClass(cls));
@@ -515,6 +517,21 @@ abstract class ClosedWorldBase implements ClosedWorld, ClosedWorldRefiner {
     return _resolverWorld.isImplemented(cls);
   }
 
+  /// Returns `true` if [x] is a subtype of [y], that is, if [x] implements an
+  /// instance of [y].
+  bool isSubtypeOf(ClassEntity x, ClassEntity y) {
+    assert(_checkInvariants(x));
+    assert(_checkInvariants(y, mustBeInstantiated: false));
+    return _classSets[y].hasSubtype(_classHierarchyNodes[x]);
+  }
+
+  /// Return `true` if [x] is a (non-strict) subclass of [y].
+  bool isSubclassOf(ClassEntity x, ClassEntity y) {
+    assert(_checkInvariants(x));
+    assert(_checkInvariants(y));
+    return _classHierarchyNodes[y].hasSubclass(_classHierarchyNodes[x]);
+  }
+
   /// Returns an iterable over the directly instantiated classes that extend
   /// [cls] possibly including [cls] itself, if it is live.
   Iterable<ClassEntity> subclassesOf(ClassEntity cls) {
@@ -927,33 +944,6 @@ class ClosedWorldImpl extends ClosedWorldBase {
         ;
   }
 
-  /// Returns `true` if [x] is a subtype of [y], that is, if [x] implements an
-  /// instance of [y].
-  bool isSubtypeOf(ClassElement x, ClassElement y) {
-    assert(_checkInvariants(x));
-    assert(_checkInvariants(y, mustBeInstantiated: false));
-
-    if (y == commonElements.objectClass) return true;
-    if (x == commonElements.objectClass) return false;
-    if (x.asInstanceOf(y) != null) return true;
-    if (y != commonElements.functionClass) return false;
-    return x.callType != null;
-  }
-
-  /// Return `true` if [x] is a (non-strict) subclass of [y].
-  bool isSubclassOf(ClassElement x, ClassElement y) {
-    assert(_checkInvariants(x));
-    assert(_checkInvariants(y));
-
-    if (y == commonElements.objectClass) return true;
-    if (x == commonElements.objectClass) return false;
-    while (x != null && x.hierarchyDepth >= y.hierarchyDepth) {
-      if (x == y) return true;
-      x = x.superclass;
-    }
-    return false;
-  }
-
   /// Returns an iterable over the common supertypes of the [classes].
   Iterable<ClassElement> commonSupertypesOf(Iterable<ClassElement> classes) {
     Iterator<ClassElement> iterator = classes.iterator;