[FFmpeg-devel] [PATCH v2 1/2] swscale: Replace illegal vector keyword usage in altivec code

[Daniel Kolesa]

On Thu, Aug 8, 2019, at 14:32, Carl Eugen Hoyos wrote:
> Am Mi., 7. Aug. 2019 um 19:39 Uhr schrieb Daniel Kolesa <daniel at octaforge.org>:
> >
> > While this technically compiles in current ffmpeg, this is only
> > because ffmpeg is compiled in strict ISO C mode, which disables
> > the builtin 'vector' keyword for AltiVec/VSX. Instead this gets
> > replaced with a macro inside altivec.h, which defines vector to
> > be actually __vector, which accepts random types.
> >
> > Normally, the vector keyword should be used only with plain
> > scalar non-typedef types, such as unsigned int. But we have the
> > vec_(s|u)(8|16|32) macros, which can be used in a portable manner,
> > in util_altivec.h in libavutil.
> >
> > This is also consistent with other AltiVec/VSX code elsewhere in
> > the tree.
> >
> > Fixes #7861.
> 
> Since I cannot reproduce any issue with current FFmpeg on Power8
> using gcc-8.3.1, at least the commit message has to be changed,
> same for the other patch.

I don't see why that would need changing. For one, the commit message for the first patch describes exactly what is wrong and also the reason you can't reproduce it by default (which I also mentioned in the ticket). I believe the second patch's reproducibility is limited to more recent gcc (probably only 9.x series), it was reproduced by me, the other person in the ticket, as well as the Fedora project (see http://koji.rpmfusion.org/koji/taskinfo?taskID=341163).

Regards

> 
> Carl Eugen
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