Re: Profiled libraries on freebsd-current

On Wed, May 04, 2022 at 01:22:57PM -0700, John Baldwin wrote:
> On 5/4/22 12:53 PM, Steve Kargl wrote:
> > On Wed, May 04, 2022 at 11:12:55AM -0700, John Baldwin wrote:
> > 
> > I don't know the entire FreeBSD ecosystem.  Do people
> > use FreeBSD on embedded systems (e.g., nanobsd) where
> > libthr may be stripped out?  Thus, --enable-threads=no
> > is needed.
> 
> If they do, they are also using a constrained userland and
> probably are not shipping a GCC binary either.  However, it's
> not clear to me what --enable-threads means.
> 
> Does this enable -pthread as an option?  If so, that should
> definitely just always be on.  It's still an option users have
> to opt into via a command line flag and doesn't prevent
> building non-threaded programs.
> 
> If it's enabling use of threads at runtime within GCC itself,
> I'd say that also should probably just be allowed to be on.
> 
> I can't really imagine what else it might mean (and I doubt
> it means the latter).
> 

AFAICT, it controls whether -lpthread is automatically added to
the command line.  In the case of -pg, it is -lpthread_p.
The relevant lines are

#ifdef FBSD_NO_THREADS
#define FBSD_LIB_SPEC "							\
  %{pthread: %eThe -pthread option is only supported on FreeBSD when gcc \
is built with the --enable-threads configure-time option.}		\
  %{!shared:								\
    %{!pg: -lc}								\
    %{pg:  -lc_p}							\
  }"
#else
#define FBSD_LIB_SPEC "							\
  %{!shared:								\
    %{!pg: %{pthread:-lpthread} -lc}					\
    %{pg:  %{pthread:-lpthread_p} -lc_p}				\
  }									\
  %{shared:								\
    %{pthread:-lpthread} -lc						\
  }"
#endif

Ed is wondering if one can get rid of FBSD_NO_THREADS. With the
pending removal of WITH_PROFILE, the above reduces to

#define FBSD_LIB_SPEC "                                                 \
  %{!shared:                                                            \
    %{pthread:-lpthread} -lc                                            \
  }                                                                     \
  %{shared:                                                             \
    %{pthread:-lpthread} -lc                                            \
  }"

If one can do the above, then freebsd-nthr.h is no longer needed
and can be deleted and config.gcc's handling of --enable-threads
can be updated/removed.

-- 
Steve