From: MJZ1977 <37274752+MJZ1977@users.noreply.github.com>
Date: Wed, 29 Aug 2018 00:27:47 +0000 (+0200)
Subject: Fix bug with "excludedMove" for probcut
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=10bb2e6cdb5c8e7a34f1f1fbf3dd0cc0d0cf63ed

Fix bug with "excludedMove" for probcut

Bugfix: "excludedMove" has to be skipped in the probcut loop too.
If it is not skipped, the probcut can exit quickly with a wrong return
value corresponding to the excluded move. See the following forum
thread for a discussion:
https://groups.google.com/forum/?fromgroups=#!topic/fishcooking/GGithf_VwSU

STC :
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 17130 W: 3747 L: 3617 D: 9766
http://tests.stockfishchess.org/tests/view/5b8460c40ebc5902bdbb999a

LTC :
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 12387 W: 2064 L: 1930 D: 8393
http://tests.stockfishchess.org/tests/view/5b8466f90ebc5902bdbb9a21

To go further : it can be perhaps useful to tune the singular extension
search parameters.

Closes https://github.com/official-stockfish/Stockfish/pull/1754

Bench: 4308541
---

diff --git a/src/search.cpp b/src/search.cpp
index 03a8bfcd..1f6a1290 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -815,7 +815,7 @@ namespace {
 
         while (  (move = mp.next_move()) != MOVE_NONE
                && probCutCount < 3)
-            if (pos.legal(move))
+            if (move != excludedMove && pos.legal(move))
             {
                 probCutCount++;