Increment descriptor array slack for prototypes by a constant rather than 50%

src/objects-inl.h

 // Copyright 2012 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.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 5074 matching lines @@
 SMI_ACCESSORS(InterceptorInfo, flags, kFlagsOffset)
 BOOL_ACCESSORS(InterceptorInfo, flags, can_intercept_symbols,
                kCanInterceptSymbolsBit)
 BOOL_ACCESSORS(InterceptorInfo, flags, all_can_read, kAllCanReadBit)
 BOOL_ACCESSORS(InterceptorInfo, flags, non_masking, kNonMasking)
 
 ACCESSORS(CallHandlerInfo, callback, Object, kCallbackOffset)
 ACCESSORS(CallHandlerInfo, data, Object, kDataOffset)
 
 ACCESSORS(TemplateInfo, tag, Object, kTagOffset)
+SMI_ACCESSORS(TemplateInfo, number_of_properties, kNumberOfProperties)
 ACCESSORS(TemplateInfo, property_list, Object, kPropertyListOffset)
 ACCESSORS(TemplateInfo, property_accessors, Object, kPropertyAccessorsOffset)
 
 ACCESSORS(FunctionTemplateInfo, serial_number, Object, kSerialNumberOffset)
 ACCESSORS(FunctionTemplateInfo, call_code, Object, kCallCodeOffset)
 ACCESSORS(FunctionTemplateInfo, prototype_template, Object,
           kPrototypeTemplateOffset)
 ACCESSORS(FunctionTemplateInfo, parent_template, Object, kParentTemplateOffset)
 ACCESSORS(FunctionTemplateInfo, named_property_handler, Object,
           kNamedPropertyHandlerOffset)
@@ skipping 1833 matching lines @@
 void Map::ClearCodeCache(Heap* heap) {
   // No write barrier is needed since empty_fixed_array is not in new space.
   // Please note this function is used during marking:
   //  - MarkCompactCollector::MarkUnmarkedObject
   //  - IncrementalMarking::Step
   DCHECK(!heap->InNewSpace(heap->empty_fixed_array()));
   WRITE_FIELD(this, kCodeCacheOffset, heap->empty_fixed_array());
 }
 
 
-int Map::SlackForArraySize(int old_size, int size_limit) {
+int Map::SlackForArraySize(bool is_prototype_map, int old_size,
+                           int size_limit) {
   const int max_slack = size_limit - old_size;
-  CHECK(max_slack >= 0);
+  CHECK_LE(0, max_slack);
   if (old_size < 4) return Min(max_slack, 1);
-  return Min(max_slack, old_size / 2);
+  if (is_prototype_map) return Min(max_slack, 4);
+  return Min(max_slack, old_size / 4);
 }
 
 
 void JSArray::set_length(Smi* length) {
   // Don't need a write barrier for a Smi.
   set_length(static_cast<Object*>(length), SKIP_WRITE_BARRIER);
 }
 
 
 bool JSArray::SetLengthWouldNormalize(Heap* heap, uint32_t new_length) {
@@ skipping 348 matching lines @@
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_