[runtime/heap] Introduce CopyFixedArrayUpTo to match CopyFixedArrayAndGrow, copying to a smaller ar…

src/builtins.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/builtins.h"
 
 #include "src/api.h"
 #include "src/api-natives.h"
 #include "src/arguments.h"
 #include "src/base/once.h"
@@ skipping 1851 matching lines @@
     Handle<JSObject> js_object = Handle<JSObject>::cast(receiver);
     DCHECK(!js_object->HasNamedInterceptor());
     DCHECK(!js_object->IsAccessCheckNeeded());
     DCHECK(!js_object->map()->has_hidden_prototype());
     DCHECK(js_object->HasFastProperties());
     if (js_object->elements() == isolate->heap()->empty_fixed_array()) {
       keys = isolate->factory()->NewFixedArray(enum_length);
       if (enum_length != 0) {
         Handle<FixedArray> cache(
             js_object->map()->instance_descriptors()->GetEnumCache());
-        keys = isolate->factory()->NewFixedArray(enum_length);
-        for (int i = 0; i < enum_length; i++) {
-          keys->set(i, cache->get(i));
-        }
+        keys = isolate->factory()->CopyFixedArrayUpTo(cache, enum_length);
       }
     }
   }
 
   if (keys.is_null()) {
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
         isolate, keys,
         JSReceiver::GetKeys(receiver, OWN_ONLY, ENUMERABLE_STRINGS,
                             CONVERT_TO_STRING));
   }
@@ skipping 2501 matching lines @@
 BUILTIN_LIST_C(DEFINE_BUILTIN_ACCESSOR_C)
 BUILTIN_LIST_A(DEFINE_BUILTIN_ACCESSOR_A)
 BUILTIN_LIST_H(DEFINE_BUILTIN_ACCESSOR_H)
 BUILTIN_LIST_DEBUG_A(DEFINE_BUILTIN_ACCESSOR_A)
 #undef DEFINE_BUILTIN_ACCESSOR_C
 #undef DEFINE_BUILTIN_ACCESSOR_A
 
 
 }  // namespace internal
 }  // namespace v8