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Re: Draft "Unsafe fp optimizations" project description.
- To: dewar at gnat dot com
- Subject: Re: Draft "Unsafe fp optimizations" project description.
- From: Toon Moene <toon at moene dot indiv dot nluug dot nl>
- Date: Sun, 05 Aug 2001 20:35:31 +0200
- CC: tprince at computer dot org, gcc at gcc dot gnu dot org, lucier at math dot purdue dot edu
- Organization: Moene Computational Physics, Maartensdijk, The Netherlands
- References: <20010805155146.64031F2B78@nile.gnat.com>
> First a question: Just how useful *is* -ffast-match "now", does anyone have
> measurements to contribute. And if there are programs where it helps
> significantly, are there any analyses of why and how.
It all depends on what you mean by "now". -ffast-math (no c :-) enables
underflow-to-zero on ia64 and alpha. On my alpha (I've never even seen
a ia64 workstation, but they seem to exist), forcing the processor to
treat underflow-as-zero meant an 1.8 times speed up on our Numerical
Weather Forecasting system.
Toon Moene - mailto:email@example.com - phoneto: +31 346 214290
Saturnushof 14, 3738 XG Maartensdijk, The Netherlands
Maintainer, GNU Fortran 77: http://gcc.gnu.org/onlinedocs/g77_news.html
Join GNU Fortran 95: http://g95.sourceforge.net/ (under construction)