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Re: -freduce-all-givs differs on P3 and P4
- From: <tm_gccmail at kloo dot net>
- To: Scott Robert Ladd <coyote at coyotegulch dot com>
- Cc: gcc mailing list <gcc at gcc dot gnu dot org>
- Date: Thu, 23 Oct 2003 15:58:25 -0700 (PDT)
- Subject: Re: -freduce-all-givs differs on P3 and P4
On Thu, 23 Oct 2003 tm_gccmail@kloo.net wrote:
> On Wed, 22 Oct 2003, Scott Robert Ladd wrote:
>
> > I made an odd discovery (at least in my mind) whilst exploring evolution
> > in different environments... consider these two command lines:
> >
> > A) gcc -lm -lrt -march=pentium3 \
> > -O3 \
> > -o lpbenchA lpbench.c
> >
> > B) gcc -lm -lrt -march=pentium3 \
> > -O3 -freduce-all-givs \
> > -o lpbenchB lpbench.c
> >
> > "B" runs 23.5% faster than "A" on a Pentium 3, due to the addition of
> > -freduce-all-givs. A very nice improvement.
>
...
Do you have any other benchmarks which exhibit anomalous behavior besides
the lpbench which you sent me?
Toshi