[FFmpeg-devel] [PATCH] avfilter, swresample, swscale: use fabs, fabsf instead of FFABS

Ganesh Ajjanagadde gajjanag at mit.edu
Thu Oct 15 23:25:19 CEST 2015


On Wed, Oct 14, 2015 at 6:54 AM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
> Hendrik Leppkes <h.leppkes <at> gmail.com> writes:
>
>> One thing I don't understand - why are we bothering
>> with something that at best comes out as "same speed"
>> from tests performed? (low number of runs are
>> irrelevant as they are not statistically significant).
>
> Since the patches apparently save a function call,
> the question is imo: Why is this not measurable?
> Shouldn't a function call always have a clear impact?

Unless I am completely off with asm (entirely possible, it is not my
area of interest) - there is no "call" for either and both are being
inlined. The difference is that fabs() and FFABS are being optimized
differently.

>
> Carl Eugen
>
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