Avoid incremental marking write-barrier when constructing descriptor arrays.

src/factory.cc

 // Copyright 2011 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 813 matching lines @@
     Handle<DescriptorArray> array,
     Handle<Object> descriptors) {
   v8::NeanderArray callbacks(descriptors);
   int nof_callbacks = callbacks.length();
   Handle<DescriptorArray> result =
       NewDescriptorArray(array->number_of_descriptors() + nof_callbacks);
 
   // Number of descriptors added to the result so far.
   int descriptor_count = 0;
 
+  // Ensure that marking will not progress and change color of objects.
+  DescriptorArray::WhitenessWitness witness(*result);
+
   // Copy the descriptors from the array.
   for (int i = 0; i < array->number_of_descriptors(); i++) {
     if (array->GetType(i) != NULL_DESCRIPTOR) {
-      result->CopyFrom(descriptor_count++, *array, i);
+      result->CopyFrom(descriptor_count++, *array, i, witness);
     }
   }
 
   // Number of duplicates detected.
   int duplicates = 0;
 
   // 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.
   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 (result->LinearSearch(*key, descriptor_count) ==
         DescriptorArray::kNotFound) {
       CallbacksDescriptor desc(*key, *entry, entry->property_attributes());
-      result->Set(descriptor_count, &desc);
+      result->Set(descriptor_count, &desc, witness);
       descriptor_count++;
     } else {
       duplicates++;
     }
   }
 
   // If duplicates were detected, allocate a result of the right size
   // and transfer the elements.
   if (duplicates > 0) {
     int number_of_descriptors = result->number_of_descriptors() - duplicates;
     Handle<DescriptorArray> new_result =
         NewDescriptorArray(number_of_descriptors);
     for (int i = 0; i < number_of_descriptors; i++) {
-      new_result->CopyFrom(i, *result, i);
+      new_result->CopyFrom(i, *result, i, witness);
     }
     result = new_result;
   }
 
   // Sort the result before returning.
-  result->Sort();
+  result->Sort(witness);
   return result;
 }
 
 
 Handle<JSObject> Factory::NewJSObject(Handle<JSFunction> constructor,
                                       PretenureFlag pretenure) {
   CALL_HEAP_FUNCTION(
       isolate(),
       isolate()->heap()->AllocateJSObject(*constructor, pretenure), JSObject);
 }
@@ skipping 459 matching lines @@
 
 
 Handle<Object> Factory::ToBoolean(bool value) {
   return Handle<Object>(value
                         ? isolate()->heap()->true_value()
                         : isolate()->heap()->false_value());
 }
 
 
 } }  // namespace v8::internal