[PATCH] Optimized generic expf and exp2f

[Wilco Dijkstra]

Arjan van de Ven wrote:
>
> I'm seeing a 16% throughput increase (not 1.5x) but still impressive.

Was that using the expf trace input or something else? And with wrapper?

> I do see different numerical answers between the two (I had to disable
> the code in my bench that detects differences) and sampling a few
> it seems that the C code is a little bit less accurate in places,
> likely a simpler polynomal.
> (for example for  20.636783599853515625    as input)

It's still way more accurate than necessary. The only reason is to
minimize ULP error for non-nearest rounding modes. If you don't
care about worst-case ULP for non-standard rounding modes, the
polynomial can be further simplified within 1ULP max error in round
to nearest.

Wilco