From 73475b198d3fd79b2a23972f4260d17b582e0cce Mon Sep 17 00:00:00 2001
From: Jakub Ciolek <jakub@ciolek.dev>
Date: Sun, 11 Jan 2026 17:24:58 +0100
Subject: [PATCH] Remove prefetching in Position::do_null_move

Passed non-regression STC, Hash=16:

LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 60704 W: 15709 L: 15522 D: 29473
Ptnml(0-2): 169, 6589, 16649, 6776, 169
https://tests.stockfishchess.org/tests/view/6963d381f6d2e8deff76918f

Passed non-regression STC SMP, Hash=512:

LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 313512 W: 80151 L: 80231 D: 153130
Ptnml(0-2): 376, 35492, 85111, 35390, 387
https://tests.stockfishchess.org/tests/view/696e1684e5a70879bd3fe38f

closes https://github.com/official-stockfish/Stockfish/pull/6545

No functional change
---
 src/position.cpp | 3 +--
 src/position.h   | 2 +-
 src/search.cpp   | 2 +-
 3 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/position.cpp b/src/position.cpp
index 218be153d..52f10a333 100644
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -1211,7 +1211,7 @@ void Position::do_castling(Color               us,
 
 // Used to do a "null move": it flips
 // the side to move without executing any move on the board.
-void Position::do_null_move(StateInfo& newSt, const TranspositionTable& tt) {
+void Position::do_null_move(StateInfo& newSt) {
 
     assert(!checkers());
     assert(&newSt != st);
@@ -1228,7 +1228,6 @@ void Position::do_null_move(StateInfo& newSt, const TranspositionTable& tt) {
     }
 
     st->key ^= Zobrist::side;
-    prefetch(tt.first_entry(key()));
 
     st->pliesFromNull = 0;
 
diff --git a/src/position.h b/src/position.h
index a136c0729..e02a400d3 100644
--- a/src/position.h
+++ b/src/position.h
@@ -143,7 +143,7 @@ class Position {
                  const TranspositionTable* tt,
                  const SharedHistories*    worker);
     void undo_move(Move m);
-    void do_null_move(StateInfo& newSt, const TranspositionTable& tt);
+    void do_null_move(StateInfo& newSt);
     void undo_null_move();
 
     // Static Exchange Evaluation
diff --git a/src/search.cpp b/src/search.cpp
index 44cd97c91..309e63a9b 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -569,7 +569,7 @@ void Search::Worker::do_move(
 }
 
 void Search::Worker::do_null_move(Position& pos, StateInfo& st, Stack* const ss) {
-    pos.do_null_move(st, tt);
+    pos.do_null_move(st);
     ss->currentMove                   = Move::null();
     ss->continuationHistory           = &continuationHistory[0][0][NO_PIECE][0];
     ss->continuationCorrectionHistory = &continuationCorrectionHistory[NO_PIECE][0];