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
