Implement class hierarchy analysis in the VM.

runtime/vm/class_finalizer.cc

 // Copyright (c) 2012, 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.
 
 #include "vm/class_finalizer.h"
 
 #include "vm/flags.h"
 #include "vm/heap.h"
 #include "vm/isolate.h"
 #include "vm/longjump.h"
@@ skipping 1104 matching lines @@
     // Check for illegal self references.
     GrowableArray<intptr_t> visited_aliases;
     if (!IsAliasCycleFree(cls, &visited_aliases)) {
       const String& name = String::Handle(cls.Name());
       const Script& script = Script::Handle(cls.script());
       ReportError(script, cls.token_pos(),
                   "typedef '%s' illegally refers to itself",
                   name.ToCString());
     }
     cls.Finalize();
+    // Signature classes extend Object. No need to add this class to the direct
+    // subclasses of Object.
+    ASSERT(super_type.IsNull() || super_type.IsObjectType());
     return;
   }
   // Finalize factory class, if any.
   if (cls.is_interface()) {
     if (cls.HasFactoryClass()) {
       const Class& factory_class = Class::Handle(cls.FactoryClass());
       if (!factory_class.is_finalized()) {
         FinalizeClass(factory_class, generating_snapshot);
         // Finalizing the factory class may indirectly finalize this interface.
         if (cls.is_finalized()) {
@@ skipping 26 matching lines @@
     if (lib.native_entry_resolver() == NULL) {
       const String& cls_name = String::Handle(cls.Name());
       const String& lib_name = String::Handle(lib.url());
       const Script& script = Script::Handle(cls.script());
       ReportError(script, cls.token_pos(),
                   "class '%s' is trying to extend a native fields class, "
                   "but library '%s' has no native resolvers",
                   cls_name.ToCString(), lib_name.ToCString());
     }
   }
+  // Add this class to the direct subclasses of the superclass, unless the
+  // superclass is Object.
+  if (!super_type.IsNull() && !super_type.IsObjectType()) {
+    ASSERT(!super_class.IsNull());
+    super_class.AddDirectSubclass(cls);
+  }
 }
 
 
 bool ClassFinalizer::IsSuperCycleFree(const Class& cls) {
   Class& test1 = Class::Handle(cls.raw());
   Class& test2 = Class::Handle(cls.SuperClass());
   // A finalized class has been checked for cycles.
   // Using the hare and tortoise algorithm for locating cycles.
   while (!test1.is_finalized() &&
          !test2.IsNull() && !test2.is_finalized()) {
@@ skipping 319 matching lines @@
 void ClassFinalizer::ReportError(const char* format, ...) {
   va_list args;
   va_start(args, format);
   const Error& error = Error::Handle(
       Parser::FormatError(Script::Handle(), -1, "Error", format, args));
   va_end(args);
   ReportError(error);
 }
 
 }  // namespace dart