On Sun, 2005-06-12 at 11:21 +0200, Uros Bizjak wrote: > Hello! > > There is an interesting comparison of SPEC scores between gcc and icc: > http://people.redhat.com/dnovillo/spec2000.i686/gcc/individual-run-ratio.html > . A quick look at the graphs shows a big differences in achieved scores > between gcc and icc, mostly in SpecFP tests. I was trying to find some > information on this matter, but none can be found in the archives on > gcc's site. > > An interesting examples are: > -177.mesa (this is a c test), where icc is almost 40% faster
SSE Vectorization, I believe. > -178.galgel, where icc is again 40% faster This is because of a better fortran *library*, not compiler. IIRC, it's all in matmul. > -179.art, where llvm is more than 1.5x faster than both gcc and icc taken care of on struct-reorg. > -187.facere, where icc is 100% faster than gcc No idea. > -189.lucas, where icc is 60% faster No idea, though i'd imagine its the same issue. > I think I'm not the only person, that finds these results rather > "dissapointing". As Scott is currently writing a paper on gcc's FP > performance, perhaps someone has an explanation, why gcc's results are > so low on Pentium4 for these tests? I could tell you why for PPC (where we aren't that far behind xlc or icc on a lot of them, if you use the right options), but no clue for x86. > > Uros.
