[PATCH 0/4] Use __copysign in sincos wherever possible

Carlos O'Donell carlos@redhat.com
Tue Sep 27 19:10:00 GMT 2016


On 09/27/2016 01:49 PM, Siddhesh Poyarekar wrote:
> Hi,
> 
> The following set of patches is another set of cleanups to sin/cos functions
> and their helpers.  The key change is to replace ternary conditions in the code
> with copysign wherever applicable.  This results in improving performance of
> the SPEC2006 test tonto by 4.5%.
> 
> Siddhesh Poyarekar (4):
>   consolidate sign checks for slow2
>   Check n instead of k1 to decide on sign of sin/cos result
>   Use copysign instead of ternary conditions for positive constants
>   Use copysign instead of ternary for some sin/cos input ranges
> 
>  sysdeps/ieee754/dbl-64/s_sin.c | 80 ++++++++++++++++++++++--------------------
>  1 file changed, 41 insertions(+), 39 deletions(-)
> 

That's quiet a good improvement.

Is that a mean percentage improvement over some number of consecutive runs?

I'm just wondering if the 4.5% is noise, or a real performance gain.

-- 
Cheers,
Carlos.



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