[FFmpeg-devel] [PATCH] configure, avutil/libm: add fmax, fmaxf, fmin, fminf support

Ganesh Ajjanagadde gajjanag at mit.edu
Thu Oct 15 17:12:18 CEST 2015

On Thu, Oct 15, 2015 at 10:18 AM, Hendrik Leppkes <h.leppkes at gmail.com> wrote:
> On Thu, Oct 15, 2015 at 4:04 PM, Derek Buitenhuis
> <derek.buitenhuis at gmail.com> wrote:
>> On 10/15/2015 1:18 PM, Ganesh Ajjanagadde wrote:
>>> It has been demonstrated that using libc provided floating point
>>> functions is beneficial, in the context of fabs() vs FFABS.
>>> Unfortunately, MSVC 2012 (and earlier) lack the ISO C99 fmax, fmaxf,
>>> fmin, fminf functions. This patch adds them, thus making their usage in
>>> FFmpeg safe.
>> We previously had at least fmin emulation in libm.h, but it
>> caused problems on some systems and was removed.
>> Carl and Michael should remember.
> See 4436a8f44dedc83767b3d9da9beb85d1fae2ca30

Thanks for the reference, patch dropped.
-ffinite-math (and some other floating point optimizations) look
interesting and could be useful in libavfilter. I will look at this a
little more carefully.

Of course, we should never enable associative optimizations - that
would be bad from an accuracy standpoint.

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