Ensure that all descriptors have a valid enumeration index, and replace NextEnumIndex with LastAdde…

src/factory.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 874 matching lines @@
                      isolate()->heap()->CopyCode(*code, reloc_info),
                      Code);
 }
 
 
 MUST_USE_RESULT static inline MaybeObject* DoCopyInsert(
     DescriptorArray* array,
     String* key,
     Object* value,
     PropertyAttributes attributes) {
-  CallbacksDescriptor desc(key, value, attributes);
+  CallbacksDescriptor desc(key, value, attributes, 0);
   MaybeObject* obj = array->CopyInsert(&desc);
   return obj;
 }
 
 
 // Allocate the new array.
 Handle<DescriptorArray> Factory::CopyAppendForeignDescriptor(
     Handle<DescriptorArray> array,
     Handle<String> key,
     Handle<Object> value,
@@ skipping 23 matching lines @@
   DescriptorArray::WhitenessWitness witness(*result);
 
   // Copy the descriptors from the array.
   for (int i = 0; i < descriptor_count; i++) {
     DescriptorArray::CopyFrom(result, i, array, i, witness);
   }
 
   // Fill in new callback descriptors.  Process the callbacks from
   // back to front so that the last callback with a given name takes
   // precedence over previously added callbacks with that name.
+  int added_descriptor_count = descriptor_count;
+  int next_enum = array->NextEnumerationIndex();
   for (int i = nof_callbacks - 1; i >= 0; i--) {
     Handle<AccessorInfo> entry =
         Handle<AccessorInfo>(AccessorInfo::cast(callbacks.get(i)));
     // Ensure the key is a symbol before writing into the instance descriptor.
     Handle<String> key =
         SymbolFromString(Handle<String>(String::cast(entry->name())));
     // Check if a descriptor with this name already exists before writing.
-    if (LinearSearch(*result, EXPECT_UNSORTED, *key, descriptor_count) ==
+    if (LinearSearch(*result, EXPECT_UNSORTED, *key, added_descriptor_count) ==
         DescriptorArray::kNotFound) {
-      CallbacksDescriptor desc(*key, *entry, entry->property_attributes());
-      result->Set(descriptor_count, &desc, witness);
-      descriptor_count++;
+      CallbacksDescriptor desc(*key,
+                               *entry,
+                               entry->property_attributes(),
+                               next_enum++);
+      result->Set(added_descriptor_count, &desc, witness);
+      added_descriptor_count++;
     }
   }
 
+  // Return the old descriptor array if there were no new elements.
+  if (added_descriptor_count == descriptor_count) return array;
+
   // If duplicates were detected, allocate a result of the right size
   // and transfer the elements.
-  if (descriptor_count < result->length()) {
-    Handle<DescriptorArray> new_result = NewDescriptorArray(descriptor_count);
-    for (int i = 0; i < descriptor_count; i++) {
+  if (added_descriptor_count < result->length()) {
+    Handle<DescriptorArray> new_result =
+        NewDescriptorArray(added_descriptor_count);
+    for (int i = 0; i < added_descriptor_count; i++) {
       DescriptorArray::CopyFrom(new_result, i, result, i, witness);
     }
     result = new_result;
   }
 
   // Sort the result before returning.
   result->Sort(witness);
+  ASSERT(result->NextEnumerationIndex() == next_enum);
   return result;
 }
 
 
 Handle<JSObject> Factory::NewJSObject(Handle<JSFunction> constructor,
                                       PretenureFlag pretenure) {
   CALL_HEAP_FUNCTION(
       isolate(),
       isolate()->heap()->AllocateJSObject(*constructor, pretenure), JSObject);
 }
@@ skipping 505 matching lines @@
 
 
 Handle<Object> Factory::ToBoolean(bool value) {
   return Handle<Object>(value
                         ? isolate()->heap()->true_value()
                         : isolate()->heap()->false_value());
 }
 
 
 } }  // namespace v8::internal