Re: GCC-4.5.0 comparison with previous releases and LLVM-2.7 on SPEC2000 for x86/x86_64

[Vladimir Makarov <vmakarov at redhat dot com>]

Vladimir Makarov wrote:
> Jan Hubicka wrote:
> > Seems like something sensitive for setup.  In our daily benchmarking LTO
> > fatster on wupwise (2116 compared to 1600), and facerec is 2003 
> > compared to
> > 2041 (so about the same).
> >
> > http://gcc.opensuse.org/SPEC/CFP/sb-frescobaldi.suse.de-ai-64/list.html
> > http://gcc.opensuse.org/SPEC/CFP/sb-frescobaldi.suse.de-ipa-64/list.html
> >
> > Did you test with -fwhole-program?
> >   
> Yes, I used -flto -fwhole-program.  All this info is on the page.  The 
> test machine are also not experimental ones (the both are Dell machines).
>
> I used the released sources may be a reason for the difference is in 
> different sources.  In any case, I'll check the current trunk on these 
> machines.
The following I got on the today trunk for x86_64 (2.93 GHz Core i7):

                                             wupwise
-O3                                           2670 
                                                           
-O3 -flto -fwhole-program                     2211
-O3 -ffast-math                               2753
-O3 -flto -fwhole-program -ffast-math         4325


So nothing is wrong with my test machine.  We simply measure different 
things.  You use -ffast-math, I don't use it.

For the comparison I used simple combination of options for GCC and 
LLVM.  For me it is obvious that GCC results can be improved more than 
LLVM by finding right options because it has much  more optimizations.

Still it would be nice to fix LTO SPEC2000 degradations when -ffast-math 
is not used.