More *_STRING_WRAPPER_ELEMENTS fixes

src/elements.cc

 // 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.
 
 #include "src/elements.h"
 
 #include "src/arguments.h"
 #include "src/conversions.h"
 #include "src/factory.h"
 #include "src/messages.h"
@@ skipping 126 matching lines @@
   DCHECK((copy_size + static_cast<int>(to_start)) <= to_base->length() &&
          (copy_size + static_cast<int>(from_start)) <= from_base->length());
   if (copy_size == 0) return;
   FixedArray* from = FixedArray::cast(from_base);
   FixedArray* to = FixedArray::cast(to_base);
   DCHECK(IsFastSmiOrObjectElementsKind(from_kind) ||
          from_kind == FAST_STRING_WRAPPER_ELEMENTS);
   DCHECK(IsFastSmiOrObjectElementsKind(to_kind));
 
   WriteBarrierMode write_barrier_mode =
-      (IsFastObjectElementsKind(from_kind) && IsFastObjectElementsKind(to_kind))
+      ((IsFastObjectElementsKind(from_kind) &&
+        IsFastObjectElementsKind(to_kind)) ||
+       from_kind == FAST_STRING_WRAPPER_ELEMENTS)
           ? UPDATE_WRITE_BARRIER
           : SKIP_WRITE_BARRIER;
   for (int i = 0; i < copy_size; i++) {
     Object* value = from->get(from_start + i);
     to->set(to_start + i, value, write_barrier_mode);
   }
 }
 
 
 static void CopyDictionaryToObjectElements(
@@ skipping 2201 matching lines @@
     if (entry < length) {
       return;  // String contents are read-only.
     }
     BackingStoreAccessor::SetImpl(holder->elements(), entry - length, value);
   }
 
   static void AddImpl(Handle<JSObject> object, uint32_t index,
                       Handle<Object> value, PropertyAttributes attributes,
                       uint32_t new_capacity) {
     DCHECK(index >= static_cast<uint32_t>(GetString(*object)->length()));
-    if ((KindTraits::Kind == FAST_STRING_WRAPPER_ELEMENTS &&
-         object->GetElementsKind() == SLOW_STRING_WRAPPER_ELEMENTS) ||
-        BackingStoreAccessor::GetCapacityImpl(*object, object->elements()) !=
-            new_capacity) {
+    // Explicitly grow fast backing stores if needed. Dictionaries know how to
+    // extend their capacity themselves.
+    if (KindTraits::Kind == FAST_STRING_WRAPPER_ELEMENTS &&
+        (object->GetElementsKind() == SLOW_STRING_WRAPPER_ELEMENTS ||
+         BackingStoreAccessor::GetCapacityImpl(*object, object->elements()) !=
+             new_capacity)) {
       StringWrapperElementsAccessorSubclass::GrowCapacityAndConvertImpl(
           object, new_capacity);
     }
     BackingStoreAccessor::AddImpl(object, index, value, attributes,
                                   new_capacity);
   }
 
   static void ReconfigureImpl(Handle<JSObject> object,
                               Handle<FixedArrayBase> store, uint32_t entry,
                               Handle<Object> value,
@@ skipping 290 matching lines @@
     }
   }
 
   DCHECK(j == result_len);
   return result_array;
 }
 
 ElementsAccessor** ElementsAccessor::elements_accessors_ = NULL;
 }  // namespace internal
 }  // namespace v8