Re: [PATCH 0/9] Optimized expf, exp2f, logf, log2f and powf

["H.J. Lu" <hjl dot tools at gmail dot com>]

On September 24, 2017 8:53:33 AM GMT+08:00, Arjan van de Ven <arjan@linux.intel.com> wrote:
>>>>
>>>
>>> now i added these to an nsz/math branch so others can test it.
>>>
>> 
>> I created hjl/nsz/math branch to replace x86-64 assembly versions of
>> e_expf with generic
>> e_expf.c.  I got
>> 
>
><snip results>
>
>all results are <= 1ulp
>
>> 
>> Test suite completed:
>>    356 test cases plus 352 tests for exception flags and
>>      352 tests for errno executed.
>>    6 errors occurred.
>> [hjl@gnu-efi-2 build-x86_64-linux]$
>> 
>> Arjan, have you measured performance assembly versions of expf vs
>generic expf?
>> 
>
>the generic expf is faster than the ASM version; the generic version
>has an order 3 polyinomal
>while the ASM version has an order 4.
>In addition, the embedding of the errno stuff is a big deal (I already
>had that for exp() in my
>own project) since the exp[f]() code knows exactly when it's not needed
>at all (the fast path)
>
>so we really should move x86-64 over to this generic version if the
>1ulp is acceptable

Agreed. I think 1 up is acceptable. I will prepare a patch
to do that.

H.J.
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