Add infrastructure to keep track of references to prototypes.

src/runtime/runtime-object.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/debug.h"
 #include "src/runtime/runtime.h"
@@ skipping 972 matching lines @@
   // Get the property names.
   int next_copy_index = 0;
   int hidden_strings = 0;
   {
     PrototypeIterator iter(isolate, obj, PrototypeIterator::START_AT_RECEIVER);
     for (int i = 0; i < length; i++) {
       DCHECK(!iter.IsAtEnd());
       Handle<JSObject> jsproto =
           Handle<JSObject>::cast(PrototypeIterator::GetCurrent(iter));
       jsproto->GetOwnPropertyNames(*names, next_copy_index, filter);
-      if (i > 0) {
-        // Names from hidden prototypes may already have been added
-        // for inherited function template instances. Count the duplicates
-        // and stub them out; the final copy pass at the end ignores holes.
-        for (int j = next_copy_index;
-             j < next_copy_index + own_property_count[i]; j++) {
-          Object* name_from_hidden_proto = names->get(j);
+      // Names from hidden prototypes may already have been added
+      // for inherited function template instances. Count the duplicates
+      // and stub them out; the final copy pass at the end ignores holes.
+      for (int j = next_copy_index; j < next_copy_index + own_property_count[i];
+           j++) {
+        Object* name_from_hidden_proto = names->get(j);
+        if (isolate->IsInternallyUsedPropertyName(name_from_hidden_proto)) {

[ulan, 2014/12/15 15:40:36]

Shouldn't this also check (filter & STRING) == 0?

[Jakob Kummerow, 2014/12/15 16:18:49]

No, we don't need to do that any more, because calling
IsInternallyUsedPropertyName() on actually retrieved properties is a more
precise check than asking JSObject::HasHiddenProperties().

+          hidden_strings++;
+        } else {
           for (int k = 0; k < next_copy_index; k++) {
-            if (names->get(k) != isolate->heap()->hidden_string()) {
-              Object* name = names->get(k);
-              if (name_from_hidden_proto == name) {
-                names->set(j, isolate->heap()->hidden_string());
-                hidden_strings++;
-                break;
-              }
+            Object* name = names->get(k);
+            if (name_from_hidden_proto == name) {
+              names->set(j, isolate->heap()->hidden_string());
+              hidden_strings++;
+              break;
             }
           }
         }
       }
       next_copy_index += own_property_count[i];
 
-      // Hidden properties only show up if the filter does not skip strings.
-      if ((filter & STRING) == 0 && JSObject::HasHiddenProperties(jsproto)) {
-        hidden_strings++;
-      }
       iter.Advance();
     }
   }
 
   // Filter out name of hidden properties object and
   // hidden prototype duplicates.
   if (hidden_strings > 0) {
     Handle<FixedArray> old_names = names;
     names = isolate->factory()->NewFixedArray(names->length() - hidden_strings);
     int dest_pos = 0;
     for (int i = 0; i < total_property_count; i++) {
       Object* name = old_names->get(i);
-      if (name == isolate->heap()->hidden_string()) {
+      if (isolate->IsInternallyUsedPropertyName(name)) {
         hidden_strings--;
         continue;
       }
       names->set(dest_pos++, name);
     }
     DCHECK_EQ(0, hidden_strings);
   }
 
   return *isolate->factory()->NewJSArrayWithElements(names);
 }
@@ skipping 545 matching lines @@
 
 RUNTIME_FUNCTION(RuntimeReference_ClassOf) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_CHECKED(Object, obj, 0);
   if (!obj->IsJSReceiver()) return isolate->heap()->null_value();
   return JSReceiver::cast(obj)->class_name();
 }
 }
 }  // namespace v8::internal