Problem with target_flags_explicit and configure_default_options

[Steve Ellcey]

This is a followup mail to http://gcc.gnu.org/ml/gcc/2012-05/msg00400.html
now that I understand my problem better and can change the subject line to
reflect that.

I am trying to determine if a user specified the '-msynci' flag on his or her
GCC compile line or if it is on by default because when GCC was configured
and built it was configured with '--with-synci'.  David Edelsohn pointed me
at target_flags_explicit and I thought that was what I wanted but it doesn't
work because of how the '--with-synci' configure option is handled.

When I configure GCC with '--with-synci' the configure script puts
'synci' into the configure_default_options array and then the GCC
driver uses this array to add the '-msynci' flag to the cc1 call.
So now when cc1 checks target_flags_explicit for the MASK_SYNCI bit
it finds that it is set because the driver added it, even though it is
not on the users gcc command line and I cannot tell if the user had
-msynci on his or her GCC command line or if the driver added it automatically.

Does anyone have any ideas on telling the two cases apart?

Steve Ellcey
sellcey@mips.com