vf_bwdif: add AVX512 implementation

I also tried replacing some of the instructions by more elaborate ones
using masks, but I found no performance gain significant enough to be worth
maintaining two code paths, so this implementation merely replaces the AVX2
implementation by drop-in AVX512 equivalents.

bwdif8_c:                                             6362.2 ( 1.00x)
bwdif8_sse2:                                          1004.9 ( 6.33x)
bwdif8_ssse3:                                          946.0 ( 6.73x)
bwdif8_avx2:                                           477.9 (13.31x)
bwdif8_avx512:                                         273.3 (23.28x)

bwdif10_c:                                            6341.5 ( 1.00x)
bwdif10_sse2:                                          872.4 ( 7.27x)
bwdif10_ssse3:                                         803.4 ( 7.89x)
bwdif10_avx2:                                          416.7 (15.22x)
bwdif10_avx512:                                        224.3 (28.27x)

Realtime test at 3840x2160 yuv420p:

avx2:   frame=20000 fps=3370 q=-0.0 Lsize=N/A time=00:06:40.00 bitrate=N/A speed=67.4x elapsed=0:00:05.93
avx512: frame=20000 fps=5077 q=-0.0 Lsize=N/A time=00:06:40.00 bitrate=N/A speed= 102x elapsed=0:00:03.93

The use of this function is gated behind avx512icl so that it doesn't
downclock on Skylake.

0 files changed, 0 insertions, 0 deletions