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Converting floor to rint
> Jan Hubicka <firstname.lastname@example.org> writes:
> | > On Wed, Nov 06, 2002 at 06:54:41PM +0100, Jan Hubicka wrote:
> | > > + For fast math it would be safe probably to convert (float)sqrt(x)
> | > > + into sqrt((float)x), but in strict mode the argument can overflow. */
> | >
> | > I don't believe this to be true.
> | What you don't believe?
> Likew RTH, I, skeptical that your assertion is right.
> | That in ffast-math we can do the transformation?
> Do we really need to do that transformation? That is is there any
> real evidence that it brings any real benefit?
> I would be reluctant to include it even in -funsafe-math.
On the related note. How bad would you consider converting
floor(x) into rint(x-0.5) in the fast-math mode?
That transformation would do a miracles for i386, where rint is faster
than floor by quite a lot and should suffice for 3D application in
reliablility. I can imagine it to fail only for very large numbers...
> -- Gaby