This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: Call for compiler help/advice: atomic builtins for v3
On 11/7/05, Paolo Carlini <pcarlini@suse.de> wrote:
> Richard Guenther wrote:
>
> >Richard is right - it's enough that the inlined version doesn't agree with
> >whatever smartness is in libgcc.
> >
> Like? If you are inlining atomic operations this means that you are
> passing -march=i686, therefore in order to run the code in the first
> place the machine has to be an i686, and libgcc certainly knows that.
You build like kdelibs for -march=i386, it gets the ool version. Now you
compile application foobar with -march=i686 and link against kdelibs.
You're screwed. You cannot possibly catch all these cases. Also, libgcc
does _not_ know the machine - it only knows the -march it was compiled
for. Inlining and transparently handling different sub-architecture just
does not play together well.
> In principle I can see now that you can do absolutely new things wrt
> atomic operations in the application and keep around an old libgcc, not
> even able to deal with the newer machine (which supports the former),
> but I'd like to see something less theoretical.
The solution with the same amount of problems like the libgcc solution, but
localized to libstdc++ would be to support installing a libstdc++ with support
for i386 disabled (and thus inlining using the builtins would be possible).
Richard.