Ensure CopyElementsImpl is always executed so it fills in holes even if from_size is 0. Allow Fixed…

src/objects-inl.h

 // 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 2324 matching lines @@
 
 void SeededNumberDictionary::set_requires_slow_elements() {
   set(kMaxNumberKeyIndex, Smi::FromInt(kRequiresSlowElementsMask));
 }
 
 
 // ------------------------------------
 // Cast operations
 
 
+FixedDoubleArray* FixedDoubleArray::cast(Object* object) {

[Michael Starzinger (Google), 2012/11/19 12:55:46]

As discussed offline, I don't like this new casting function. It is lying about
the return type. Can we instead have a second
FixedDoubleArray::castButAllowEmptyFixedArray() that does this? That one would
still be lying about the return type, but at least the function name is scary
enough to let people know what's going on.

BTW, I am flexible about the name as long as it sounds complicated and scary. :)

+  ASSERT((object->IsFixedArray() && FixedArray::cast(object)->length() == 0) ||
+         object->IsFixedDoubleArray());
+  return reinterpret_cast<FixedDoubleArray*>(object);
+}
+
+
 CAST_ACCESSOR(FixedArray)
-CAST_ACCESSOR(FixedDoubleArray)
 CAST_ACCESSOR(DescriptorArray)
 CAST_ACCESSOR(DeoptimizationInputData)
 CAST_ACCESSOR(DeoptimizationOutputData)
 CAST_ACCESSOR(TypeFeedbackCells)
 CAST_ACCESSOR(SymbolTable)
 CAST_ACCESSOR(JSFunctionResultCache)
 CAST_ACCESSOR(NormalizedMapCache)
 CAST_ACCESSOR(ScopeInfo)
 CAST_ACCESSOR(CompilationCacheTable)
 CAST_ACCESSOR(CodeCacheHashTable)
@@ skipping 3188 matching lines @@
 #undef WRITE_UINT32_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_