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# Re: Simplify floating point conversions

> On Tue, Nov 05, 2002 at 06:14:00PM +0100, Jan Hubicka wrote:
> > Hi,
> > this patch makes us to simplify some of the floating point operations to
> > narrower mode when conversions are present. This include
> > +,-,/,*,abs,neg,sqrt/sin/cos/exp.
> > I believe it is IEEE safe, but some expert would be welcome.
>
> You should have commented this. It should not take someone 5
Oops...
> minutes to even figure out what's going on here. To be sure, it's
>
> (float)sqrtl(x) -> sqrtf((float)x)
It does just (float)sqrt((float)x)->sqrtf(x)
This is common in C code when you call sqrt on float value.
Honza
>
> correct? Well, clearly this fails for X = 2**(127 * 2), since
> X is not representable as a float, but its square root is. It
> would not be hard to identify similar problems with every other
> operation on your list except for ABS/NEG.
>
>
> r~