Make history heuristic param optional on move ordering to avoid allocating space in q search

src/search/move_ordering.rs

@@ -11,7 +11,7 @@ pub fn score_move(
     mv: Move,
     killer_move: Option<Move>,
     color: Color,
-    history_heuristic: &[[[i32; 64]; 64]; 2],
+    history_heuristic: Option<&[[[i32; 64]; 64]; 2]>,
     tt_move: Option<Move>,
 ) -> i32 {
     if Some(mv) == tt_move {
@@ -30,7 +30,9 @@ pub fn score_move(
         return 6;
     }
 
-    -history_heuristic[color][mv.src()][mv.dst()] + MAX_HISTORY + 6 + 1
+    history_heuristic.map_or(MAX_HISTORY + 6 + 1, |hh| {
+        -hh[color][mv.src()][mv.dst()] + MAX_HISTORY + 6 + 1
+    })
 }
 
 #[cfg(test)]
@@ -53,14 +55,7 @@ mod tests {
 
         let mut moves = vec![castle, queen_takes_pawn, pawn_takes_queen];
         moves.sort_unstable_by_key(|mv| {
-            score_move(
-                &game.mailbox,
-                *mv,
-                None,
-                game.current_player(),
-                &[[[0; 64]; 64]; 2],
-                None,
-            )
+            score_move(&game.mailbox, *mv, None, game.current_player(), None, None)
         });
 
         assert_eq!(moves, vec![pawn_takes_queen, queen_takes_pawn, castle]);
@@ -71,7 +66,7 @@ mod tests {
                 *mv,
                 None,
                 game.current_player(),
-                &[[[0; 64]; 64]; 2],
+                None,
                 Some(castle),
             )
         });

src/search/negamax.rs

@@ -101,7 +101,7 @@ pub fn negamax(
             *mv,
             game.killer[plies as usize],
             color,
-            &game.history_heuristic,
+            Some(&game.history_heuristic),
             entry.and_then(|entry| entry.mv),
         )
     });

src/search/quiescence.rs

@@ -48,7 +48,7 @@ pub fn quiescence(
             *mv,
             None,
             color,
-            &[[[0; 64]; 64]; 2],
+            None,
             entry.and_then(|entry| entry.mv),
         )
     });