[PATCH] x86_64: Add log1p with FMA

Paul Zimmermann Paul.Zimmermann@inria.fr
Mon Aug 21 12:31:58 GMT 2023


       Hi H.J.

> On Skylake, it changes log1p bench performance by:
> 
>         Before       After     Improvement
> max     63.349       58.347       8%
> min     4.448        5.651        -30%
> mean    12.0674      10.336       14%

the largest known error decreases from 0.903 ulp:

log1p 0 -1 -0x1.2c10396268852p-2 [1] [0.903] 0.902709 0.9027087876691803

to 0.899 ulp:

log1p 0 -1 -0x1.2bf183e0344b2p-2 [1] [0.899] 0.898172 0.8981716806917975

LGTM.

Paul

PS: the largest error for asinh is unchanged:
asinh 0 -1 -0x1.02657ff36d5f3p-2 [2] [1.92] 1.91356 1.913551236624182
and for atanh it seems to improve.


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