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RE: Performance loss with gfortran on 64-bit Linux
- From: "Menezes, Evandro" <evandro dot menezes at amd dot com>
- To: "'Andrew Pinski'" <pinskia at physics dot uc dot edu>, "'Uros Bizjak'" <ubizjak at gmail dot com>
- Cc: "'FX Coudert'" <fxcoudert at gmail dot com>, fortran at gcc dot gnu dot org
- Date: Tue, 25 Jul 2006 11:37:52 -0500
- Subject: RE: Performance loss with gfortran on 64-bit Linux
- Organization: AMD
Andrew,
> This is caused by x86_64's glibc not using the assembly written x87
> code. I think
> someone else has reported this before. It might be a good thing to
> report
> this to glibc.
We tried to submit 64-bit optimized math routines to GLIBC which are faster
and more accurate than x87, yet unsuccessfully (see
http://sources.redhat.com/ml/libc-alpha/2006-03/msg00089.html
http://sources.redhat.com/ml/libc-alpha/2006-05/msg00078.html).
FWIW, to avoid such situations, I'd much rather go the way that Richard
Guenther proposed in the GCC Summit to bring them into libgcc-math. As we
stated at the BOFS on this subject, our routines are portable to other
architectures and are wholly owned by AMD, so we'd be free to donate them
under any license.
--
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Evandro Menezes AMD Austin, TX