Avoid dictionary expansion during bootstrapping

src/objects.cc

 // Copyright 2006-2009 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 1226 matching lines @@
 }
 
 
 Object* JSObject::AddFastProperty(String* name,
                                   Object* value,
                                   PropertyAttributes attributes) {
   // Normalize the object if the name is an actual string (not the
   // hidden symbols) and is not a real identifier.
   StringInputBuffer buffer(name);
   if (!Scanner::IsIdentifier(&buffer) && name != Heap::hidden_symbol()) {
-    Object* obj = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES);
+    Object* obj = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES, 0);
     if (obj->IsFailure()) return obj;
     return AddSlowProperty(name, value, attributes);
   }
 
   DescriptorArray* old_descriptors = map()->instance_descriptors();
   // Compute the new index for new field.
   int index = map()->NextFreePropertyIndex();
 
   // Allocate new instance descriptors with (name, index) added
   FieldDescriptor new_field(name, index, attributes);
@@ skipping 17 matching lines @@
   if (allow_map_transition) {
     // Allocate new instance descriptors for the old map with map transition.
     MapTransitionDescriptor d(name, Map::cast(new_map), attributes);
     Object* r = old_descriptors->CopyInsert(&d, KEEP_TRANSITIONS);
     if (r->IsFailure()) return r;
     old_descriptors = DescriptorArray::cast(r);
   }
 
   if (map()->unused_property_fields() == 0) {
     if (properties()->length() > kMaxFastProperties) {
-      Object* obj = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES);
+      Object* obj = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES, 0);
       if (obj->IsFailure()) return obj;
       return AddSlowProperty(name, value, attributes);
     }
     // Make room for the new value
     Object* values =
         properties()->CopySize(properties()->length() + kFieldsAdded);
     if (values->IsFailure()) return values;
     set_properties(FixedArray::cast(values));
     new_map->set_unused_property_fields(kFieldsAdded - 1);
   } else {
@@ skipping 100 matching lines @@
       if (value->IsJSFunction()) {
         return AddConstantFunctionProperty(name,
                                            JSFunction::cast(value),
                                            attributes);
       } else {
         return AddFastProperty(name, value, attributes);
       }
     } else {
       // Normalize the object to prevent very large instance descriptors.
       // This eliminates unwanted N^2 allocation and lookup behavior.
-      Object* obj = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES);
+      Object* obj = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES, 0);
       if (obj->IsFailure()) return obj;
     }
   }
   return AddSlowProperty(name, value, attributes);
 }
 
 
 Object* JSObject::SetPropertyPostInterceptor(String* name,
                                              Object* value,
                                              PropertyAttributes attributes) {
@@ skipping 49 matching lines @@
   old_map->set_instance_descriptors(DescriptorArray::cast(new_descriptors));
   return result;
 }
 
 
 Object* JSObject::ConvertDescriptorToField(String* name,
                                            Object* new_value,
                                            PropertyAttributes attributes) {
   if (map()->unused_property_fields() == 0 &&
       properties()->length() > kMaxFastProperties) {
-    Object* obj = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES);
+    Object* obj = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES, 0);
     if (obj->IsFailure()) return obj;
     return ReplaceSlowProperty(name, new_value, attributes);
   }
 
   int index = map()->NextFreePropertyIndex();
   FieldDescriptor new_field(name, index, attributes);
   // Make a new DescriptorArray replacing an entry with FieldDescriptor.
   Object* descriptors_unchecked = map()->instance_descriptors()->
       CopyInsert(&new_field, REMOVE_TRANSITIONS);
   if (descriptors_unchecked->IsFailure()) return descriptors_unchecked;
@@ skipping 630 matching lines @@
     if (HasLocalElement(index)) return NONE;
     return ABSENT;
   }
   // Named property.
   LookupResult result;
   LocalLookup(name, &result);
   return GetPropertyAttribute(this, &result, name, false);
 }
 
 
-Object* JSObject::NormalizeProperties(PropertyNormalizationMode mode) {
+Object* JSObject::NormalizeProperties(PropertyNormalizationMode mode,
+                                      int expected_additional_properties) {
   if (!HasFastProperties()) return this;
 
   // The global object is always normalized.
   ASSERT(!IsGlobalObject());
 
   // Allocate new content.
+  int property_count = map()->NumberOfDescribedProperties();
+  if (expected_additional_properties > 0) {
+    property_count += expected_additional_properties;
+  } else {
+    property_count += 2;  // Make space for two more properties.
+  }
   Object* obj =
-      StringDictionary::Allocate(map()->NumberOfDescribedProperties() * 2 + 4);
+      StringDictionary::Allocate(property_count * 2);
   if (obj->IsFailure()) return obj;
   StringDictionary* dictionary = StringDictionary::cast(obj);
 
   DescriptorArray* descs = map()->instance_descriptors();
   for (int i = 0; i < descs->number_of_descriptors(); i++) {
     PropertyDetails details = descs->GetDetails(i);
     switch (details.type()) {
       case CONSTANT_FUNCTION: {
         PropertyDetails d =
             PropertyDetails(details.attributes(), NORMAL, details.index());
@@ skipping 119 matching lines @@
 }
 
 
 Object* JSObject::DeletePropertyPostInterceptor(String* name, DeleteMode mode) {
   // Check local property, ignore interceptor.
   LookupResult result;
   LocalLookupRealNamedProperty(name, &result);
   if (!result.IsValid()) return Heap::true_value();
 
   // Normalize object if needed.
-  Object* obj = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES);
+  Object* obj = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES, 0);
   if (obj->IsFailure()) return obj;
 
   return DeleteNormalizedProperty(name, mode);
 }
 
 
 Object* JSObject::DeletePropertyWithInterceptor(String* name) {
   HandleScope scope;
   Handle<InterceptorInfo> interceptor(GetNamedInterceptor());
   Handle<String> name_handle(name);
@@ skipping 176 matching lines @@
         return DeletePropertyPostInterceptor(name, mode);
       }
       return DeletePropertyWithInterceptor(name);
     }
     if (!result.IsLoaded()) {
       return JSObject::cast(this)->DeleteLazyProperty(&result,
                                                       name,
                                                       mode);
     }
     // Normalize object if needed.
-    Object* obj = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES);
+    Object* obj = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES, 0);
     if (obj->IsFailure()) return obj;
     // Make sure the properties are normalized before removing the entry.
     return DeleteNormalizedProperty(name, mode);
   }
 }
 
 
 // Check whether this object references another object.
 bool JSObject::ReferencesObject(Object* obj) {
   AssertNoAllocation no_alloc;
@@ skipping 312 matching lines @@
         element_dictionary()->Set(index, structure, details);
     if (dict->IsFailure()) return dict;
 
     // If name is an index we need to stay in slow case.
     NumberDictionary* elements = NumberDictionary::cast(dict);
     elements->set_requires_slow_elements();
     // Set the potential new dictionary on the object.
     set_elements(NumberDictionary::cast(dict));
   } else {
     // Normalize object to make this operation simple.
-    Object* ok = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES);
+    Object* ok = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES, 0);
     if (ok->IsFailure()) return ok;
 
     // For the global object allocate a new map to invalidate the global inline
     // caches which have a global property cell reference directly in the code.
     if (IsGlobalObject()) {
       Object* new_map = map()->CopyDropDescriptors();
       if (new_map->IsFailure()) return new_map;
       set_map(Map::cast(new_map));
     }
 
@@ skipping 5099 matching lines @@
   if (break_point_objects()->IsUndefined()) return 0;
   // Single beak point.
   if (!break_point_objects()->IsFixedArray()) return 1;
   // Multiple break points.
   return FixedArray::cast(break_point_objects())->length();
 }
 #endif
 
 
 } }  // namespace v8::internal