From: Joost VandeVondele <Joost.VandeVondele@gmail.com>
Date: Tue, 9 Apr 2019 14:51:39 +0000 (+0200)
Subject: Give penalty for all early quiets of prev. ply
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=42d271f23c255a87133d33392e3b2c66991e3960

Give penalty for all early quiets of prev. ply

passed STC:
LLR: 2.94 (-2.94,2.94) [-3.00,1.00]
Total: 32884 W: 7283 L: 7184 D: 18417
http://tests.stockfishchess.org/tests/view/5cacb1b20ebc5925cf00ce97

passed LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 22869 W: 3920 L: 3803 D: 15146
http://tests.stockfishchess.org/tests/view/5cacbd760ebc5925cf00cfce

Bench: 3723099
---

diff --git a/src/search.cpp b/src/search.cpp
index 645b1f9c..cb6c5d44 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -623,9 +623,8 @@ namespace {
                 if (!pos.capture_or_promotion(ttMove))
                     update_quiet_stats(pos, ss, ttMove, nullptr, 0, stat_bonus(depth));
 
-                // Extra penalty for a quiet TT or main killer move in previous ply when it gets refuted
-                if (    ((ss-1)->moveCount == 1 || (ss-1)->currentMove == (ss-1)->killers[0])
-                     && !pos.captured_piece())
+                // Extra penalty for early quiet moves of the previous ply
+                if ((ss-1)->moveCount <= 2 && !pos.captured_piece())
                         update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
             }
             // Penalty for a quiet ttMove that fails low