[Bug driver/39851] New: gcc -Q --help=target does not list extensions selected by -march=

["amonakov at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>]

Even though -march=nocona enables SSE2 and SSE3 extensions, gcc -Q
--help=target does not list them as enabled.  This may be confusing to the user
(see http://gcc.gnu.org/ml/gcc-help/2009-04/msg00293.html ):

$ gcc -Q --help=target -march=nocona | grep msse[23]
  -msse2                                [disabled]
  -msse3                                [disabled]

-msse[23] would be enabled in gcc/config/i386/i386.c:override_options(), called
from toplev.c:process_options(), which is in turn called from do_compile(). 
OTOH, --help=target is processed in decode_options(), which is executed before
do_compile.  It would be nice if --help=target processing could see options
overridden by target backend.


-- 
           Summary: gcc -Q --help=target does not list extensions selected
                    by -march=
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: driver
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: amonakov at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39851