From 47763080b97eb272cc336a066994b27b480d337e Mon Sep 17 00:00:00 2001
From: MinetaS <skdty87@gmail.com>
Date: Wed, 30 Oct 2024 21:30:21 +0900
Subject: [PATCH] Remove moveCountPruning in search.cpp

The definition of moveCountPruning may cause confusion by implying that
the variable is unconstrained. However, once it is set to true, it
should not be reset to false, otherwise it would break the internal
logic of MovePicker.

Several patches have overlooked this constraint.

The implementation approach was suggested by Disservin.

No functional change
---
 src/movepick.cpp | 4 +++-
 src/movepick.h   | 4 +++-
 src/search.cpp   | 8 ++++----
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/movepick.cpp b/src/movepick.cpp
index b6802b1b..517088d9 100644
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -223,7 +223,7 @@ Move MovePicker::select(Pred filter) {
 // This is the most important method of the MovePicker class. We emit one
 // new pseudo-legal move on every call until there are no more moves left,
 // picking the move with the highest score from a list of generated moves.
-Move MovePicker::next_move(bool skipQuiets) {
+Move MovePicker::next_move() {
 
     auto quiet_threshold = [](Depth d) { return -3330 * d; };
 
@@ -329,4 +329,6 @@ Move MovePicker::next_move(bool skipQuiets) {
     return Move::none();  // Silence warning
 }
 
+void MovePicker::skip_quiet_moves() { skipQuiets = true; }
+
 }  // namespace Stockfish
diff --git a/src/movepick.h b/src/movepick.h
index 64d2c1be..388fdf17 100644
--- a/src/movepick.h
+++ b/src/movepick.h
@@ -208,7 +208,8 @@ class MovePicker {
                const PawnHistory*,
                int);
     MovePicker(const Position&, Move, int, const CapturePieceToHistory*);
-    Move next_move(bool skipQuiets = false);
+    Move next_move();
+    void skip_quiet_moves();
 
    private:
     template<PickType T, typename Pred>
@@ -230,6 +231,7 @@ class MovePicker {
     int                          threshold;
     Depth                        depth;
     int                          ply;
+    bool                         skipQuiets = false;
     ExtMove                      moves[MAX_MOVES];
 };
 
diff --git a/src/search.cpp b/src/search.cpp
index f73a3a48..0a003990 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -850,12 +850,11 @@ Value Search::Worker::search(
 
     value = bestValue;
 
-    int  moveCount        = 0;
-    bool moveCountPruning = false;
+    int moveCount = 0;
 
     // Step 12. Loop through all pseudo-legal moves until no moves remain
     // or a beta cutoff occurs.
-    while ((move = mp.next_move(moveCountPruning)) != Move::none())
+    while ((move = mp.next_move()) != Move::none())
     {
         assert(move.is_ok());
 
@@ -901,7 +900,8 @@ Value Search::Worker::search(
         if (!rootNode && pos.major_material(us) && bestValue > VALUE_MATED_IN_MAX_PLY)
         {
             // Skip quiet moves if movecount exceeds our FutilityMoveCount threshold (~8 Elo)
-            moveCountPruning = moveCount >= futility_move_count(improving, depth);
+            if (moveCount >= futility_move_count(improving, depth))
+                mp.skip_quiet_moves();
 
             // Reduced depth of the next LMR search
             int lmrDepth = newDepth - r;