From: Marco Costalba <mcostalba@gmail.com>
Date: Mon, 14 Aug 2017 16:12:16 +0000 (-0700)
Subject: Fix incorrect StateInfo
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=232c50fed0b80a0f39322a925575f760648ae0a5;hp=232c50fed0b80a0f39322a925575f760648ae0a5

Fix incorrect StateInfo

We use Position::set() to set root position across
threads. But there are some StateInfo fields (previous,
pliesFromNull, capturedPiece) that cannot be deduced
from a fen string, so set() clears them and to not lose
the info we need to backup and later restore setupStates->back().
Note that setupStates is shared by threads but is accessed
in read-only mode.

This fixes regression introduced by df6cb446eaf21

Tested with 3 threads at STC:
LLR: 2.95 (-2.94,2.94) [-4.00,0.00]
Total: 14436 W: 2304 L: 2196 D: 9936

Bench: 5608839
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