From: Fanael Linithien <fanael4@gmail.com>
Date: Sun, 9 Aug 2020 14:20:45 +0000 (+0200)
Subject: Provide vectorized NNUE code for SSE2 and MMX targets
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=21df37d7fd4dcc9b4a9c319382cc43685c0259c8;hp=21df37d7fd4dcc9b4a9c319382cc43685c0259c8

Provide vectorized NNUE code for SSE2 and MMX targets

This patch allows old x86 CPUs, from AMD K8 (which the x86-64 baseline
targets) all the way down to the Pentium MMX, to benefit from NNUE with
comparable performance hit versus hand-written eval as on more modern
processors.

NPS of the bench with NNUE enabled on a Pentium III 1.13 GHz (using the
MMX code):
  master: 38951
  this patch: 80586

NPS of the bench with NNUE enabled using baseline x86-64 arch, which is
how linux distros are likely to package stockfish, on a modern CPU
(using the SSE2 code):
  master: 882584
  this patch: 1203945

closes https://github.com/official-stockfish/Stockfish/pull/2956

No functional change.
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