This is the mail archive of the
mailing list for the GCC project.
Re: How bad is fast-math?
- To: Jean Francois Martinez <jfm2 at club-internet dot fr>
- Subject: Re: How bad is fast-math?
- From: Michael Meissner <meissner at cygnus dot com>
- Date: Tue, 29 May 2001 19:02:21 -0400
- Cc: gcc at gcc dot gnu dot org
- References: <email@example.com>
On Wed, May 30, 2001 at 12:25:50AM +0200, Jean Francois Martinez wrote:
> According to the doc fast-math generates incorrect code. Has the situation
> changed? In case it has doc should be updated, in case it hasn't name
> should be changed and become something derogatory since there are people who
> see the fast in fast-math and use it without further investigation. It is
> being used in aLinux distribution and I have seen it recommended in a Linux
In general, it depends on what you consider the correct code to be :-)
If your code never encounters infinities and denormals, and never passes an out
of range argument to an intrinsic function, then -ffast-math will certainly
generate faster code on some machines. I can't say how well that matches up
with the numeric code out there. I would imagine many codes don't stray into
these dark corners (but then again, many do go into that territory).
Michael Meissner, Red Hat, Inc. (GCC group)
PMB 198, 174 Littleton Road #3, Westford, Massachusetts 01886, USA
Work: firstname.lastname@example.org phone: +1 978-486-9304
Non-work: email@example.com fax: +1 978-692-4482