Fix for a smi stores optimization on x64 with a test case.

src/flag-definitions.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 216 matching lines @@
 DEFINE_bool(trace_pretenuring_statistics, false,
             "trace allocation site pretenuring statistics")
 DEFINE_bool(track_fields, true, "track fields with only smi values")
 DEFINE_bool(track_double_fields, true, "track fields with double values")
 DEFINE_bool(track_heap_object_fields, true, "track fields with heap values")
 DEFINE_bool(track_computed_fields, true, "track computed boilerplate fields")
 DEFINE_implication(track_double_fields, track_fields)
 DEFINE_implication(track_heap_object_fields, track_fields)
 DEFINE_implication(track_computed_fields, track_fields)
 DEFINE_bool(smi_binop, true, "support smi representation in binary operations")
-DEFINE_bool(smi_x64_store_opt, false, "optimized stores of smi on x64")
 
 // Flags for optimization types.
 DEFINE_bool(optimize_for_size, false,
             "Enables optimizations which favor memory size over execution "
             "speed.")
 
 // Flags for data representation optimizations
 DEFINE_bool(unbox_double_arrays, true, "automatically unbox arrays of doubles")
 DEFINE_bool(string_slices, true, "use string slices")
 
@@ skipping 646 matching lines @@
 #undef DEFINE_ALIAS_float
 #undef DEFINE_ALIAS_args
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META
 #undef FLAG_MODE_DEFINE_IMPLICATIONS
 
 #undef COMMA