Avoid duplication of a hidden & inherited prototype's properties.

src/runtime.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 5783 matching lines @@
       jsproto = Handle<JSObject>(JSObject::cast(jsproto->GetPrototype()));
     }
   }
 
   // Allocate an array with storage for all the property names.
   Handle<FixedArray> names =
       isolate->factory()->NewFixedArray(total_property_count);
 
   // Get the property names.
   jsproto = obj;
-  int proto_with_hidden_properties = 0;
   int next_copy_index = 0;
+  int hidden_strings = 0;
   for (int i = 0; i < length; i++) {
     jsproto->GetLocalPropertyNames(*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 + local_property_count[i];
+           j++) {
+        Object* name_from_hidden_proto = names->get(j);
+        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;
+            }
+          }
+        }
+      }
+    }
     next_copy_index += local_property_count[i];
     if (jsproto->HasHiddenProperties()) {
-      proto_with_hidden_properties++;
+      hidden_strings++;
     }
     if (i < length - 1) {
       jsproto = Handle<JSObject>(JSObject::cast(jsproto->GetPrototype()));
     }
   }
 
-  // Filter out name of hidden properties object.
-  if (proto_with_hidden_properties > 0) {
+  // 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() - proto_with_hidden_properties);
+        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()) {
+        hidden_strings--;
         continue;
       }
       names->set(dest_pos++, name);
     }
+    ASSERT_EQ(0, hidden_strings);
   }
 
   return *isolate->factory()->NewJSArrayWithElements(names);
 }
 
 
 // Return the names of the local indexed properties.
 // args[0]: object
 RUNTIME_FUNCTION(MaybeObject*, Runtime_GetLocalElementNames) {
   HandleScope scope(isolate);
@@ skipping 9028 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal