From 16cd38dba1c168e23982ee6d521a10bafc82ca14 Mon Sep 17 00:00:00 2001
From: Shawn Xu <xu107288696@gmail.com>
Date: Thu, 10 Apr 2025 10:00:27 -0700
Subject: [PATCH] Tweak TT Move Reduction by TT Move History

Passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 62496 W: 16197 L: 15844 D: 30455
Ptnml(0-2): 200, 7234, 16011, 7619, 184
https://tests.stockfishchess.org/tests/view/67f7fa9b31d7cf8afdc4609c

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 400470 W: 102068 L: 101012 D: 197390
Ptnml(0-2): 201, 43207, 112347, 44295, 185
https://tests.stockfishchess.org/tests/view/67f927b0cd501869c66975e0

Passed VVLTC Non-regression:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 125394 W: 32408 L: 32304 D: 60682
Ptnml(0-2): 3, 11702, 39188, 11796, 8
https://tests.stockfishchess.org/tests/view/6804c215cd501869c66986b9

closes https://github.com/official-stockfish/Stockfish/pull/5998

bench 1760988
---
 src/search.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/search.cpp b/src/search.cpp
index fe0e340b4..9a106e673 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1298,6 +1298,8 @@ moves_loop:  // When in check, search starts here
             if (!ttData.move)
                 r += 1156;
 
+            r -= ttMoveHistory / 8;
+
             // Note that if expected reduction is high, we reduce search depth here
             value = -search<NonPV>(pos, ss + 1, -(alpha + 1), -alpha,
                                    newDepth - (r > 3495) - (r > 5510 && newDepth > 2), !cutNode);