[FFmpeg-devel] [PATCH] PPC64: Add versions of functions in libswscale/input.c optimized for POWER8 VSX SIMD.

[Dan Parrot]

On Tue, 2016-07-05 at 15:45 +0000, Carl Eugen Hoyos wrote:
> Dan Parrot <dan.parrot <at> mail.com> writes:
> 
> > These results for START_TIMER/STOP_TIMER are with ffmpeg 
> > compiled using GCC 6.1.1
> 
> I believe your results indicate that -cpuflags 0 has no 
> effect on vsx.
> On x86, this would be a blocker.
> 
> While I would prefer if you had tested with vanilla 
> gcc instead of a version patched by a distributor, no 
> more comments from me.

Just to be clear, I am not making any claims about any special patching
in GCC 6.1.1. All I am saying about GCC is that version 5.3.1 produces
suboptimal SIMD sequences; 6.1.1 gives much better SIMD sequences. Both
versions are preinstalled on Fedora images in the IBM cloud. I have no
way of knowing how those versions of GCC behave on different machines.