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Re: How bad is fast-math?


On Wednesday 30 May 2001 01:02, Michael Meissner wrote:
> 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 magazine
>
> 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).

Use in glibc would be certainly foolish.   And I think it is being done.

					JFM


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