Add support for VNNI
Adds support for Vector Neural Network Instructions (avx512), as available on Intel Cascade Lake
The _mm512_dpbusd_epi32() intrinsic (vpdpbusd instruction) is taylor made for NNUE.
on a cascade lake CPU (AWS C5.24x.large, gcc 10) NNUE eval is at roughly 78% nps of classical
(single core test)
bench 1024 1 24 default depth:
target classical NNUE ratio
vnni
2207232 1725987 78.20
avx512
2216789 1671734 75.41
avx2
2194006 1611263 73.44
modern
2185001 1352469 61.90
closes https://github.com/official-stockfish/Stockfish/pull/2987
No functional change
projects / stockfish / commit