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
