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Re: gcc/gcc config.gcc config/sparc/linux.h config ...
- From: Brad Lucier <lucier at math dot purdue dot edu>
- To: toon at moene dot indiv dot nluug dot nl (Toon Moene)
- Cc: lucier at math dot purdue dot edu (Brad Lucier), davem at redhat dot com (David S. Miller), gcc-patches at gcc dot gnu dot org
- Date: Thu, 4 Apr 2002 14:09:42 -0500 (EST)
- Subject: Re: gcc/gcc config.gcc config/sparc/linux.h config ...
>
> Brad Lucier wrote:
>
> > Also, this is a performance increase of about a factor of 100, and it seems
> > to be extremely simple and clean; should it not also be installed on the
> > 3.1 branch?
>
> Are you sure you really *want* underflow-flushed-to-zero ? [ You're one
> of our (i.e., gcc testers') IEEE-conformant users - at least so I
> thought ]
It's only enabled with -funsafe-math-optimizations or -ffast-math, so,
to me, it's OK.
> I got about 40 % speedup on our Numerical Weather Forecasting code [on
> Alpha], but that's because underflows are (naturally) very rare in such
> code (it's not impossible, given enough careful programming effort, to
> eradicate them completely) ...
Certainly there are other computational scientists at Purdue who are not so
tied to IEEE semantics and who would benefit from this a lot.
Brad