This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: Comparison of GCC-4.6.1 and LLVM-2.9 on x86/x86-64 targets
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Vladimir Makarov <vmakarov at redhat dot com>
- Cc: "gcc.gcc.gnu.org" <gcc at gcc dot gnu dot org>
- Date: Thu, 8 Sep 2011 10:47:38 +0200
- Subject: Re: Comparison of GCC-4.6.1 and LLVM-2.9 on x86/x86-64 targets
- References: <4E678A9B.3040303@redhat.com>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Wed, Sep 07, 2011 at 11:15:39AM -0400, Vladimir Makarov wrote:
> This year I used -Ofast -flto -fwhole-program instead of
> -O3 for GCC and -O3 -ffast-math for LLVM for comparison of peak
> performance. I could improve GCC performance even more by using
> other GCC possibilities (like support of AVX insns, Graphite optimizations
> and even some experimental stuff like LIPO) but I wanted to give LLVM
> some chances too. Probably an experienced user in LLVM could improve
> LLVM performance too. So I think it is a fair comparison.
-march=native in addition would be nice to see, that can make significant
difference, especially on AVX capable CPUs. I guess LLVM equivalent would
be -march=corei7 -mtune=corei7 and, if it works, -mavx too (though, the only
time I've tried LLVM 2.9 it crashed on almost anything with -mavx).
Jakub