Porting r9456 to x64 (Optimize KeyedStoreGeneric for Smi arrays).

src/x64/macro-assembler-x64.h

 // Copyright 2011 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 841 matching lines @@
   void CheckFastObjectElements(Register map,
                                Label* fail,
                                Label::Distance distance = Label::kFar);
 
   // Check if a map for a JSObject indicates that the object has fast smi only
   // elements.  Jump to the specified label if it does not.
   void CheckFastSmiOnlyElements(Register map,
                                 Label* fail,
                                 Label::Distance distance = Label::kFar);
 
+  // Check to see if maybe_number can be stored as a double in
+  // FastDoubleElements. If it can, store it at the index specified by key in
+  // the FastDoubleElements array elements, otherwise jump to fail.
+  // Note that key must not be smi-tagged.
+  void StoreNumberToDoubleElements(Register maybe_number,
+                                   Register elements,
+                                   Register key,
+                                   XMMRegister xmm_scratch,
+                                   Label* fail);
+
   // Check if the map of an object is equal to a specified map and
   // branch to label if not. Skip the smi check if not required
   // (object is known to be a heap object)
   void CheckMap(Register obj,
                 Handle<Map> map,
                 Label* fail,
                 SmiCheckType smi_check_type);
 
   // Check if the map of an object is equal to a specified map and branch to a
   // specified target if equal. Skip the smi check if not required (object is
@@ skipping 560 matching lines @@
     masm->popfd();                                                        \
   }                                                                       \
   masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_MACRO_ASSEMBLER_X64_H_