Weak nodes

Bench: 1972379
SzilBalazs · Aug 10, 2023 · ac74a81 · ac74a81
1 parent cc9902b
commit ac74a81
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Showing 2 changed files with 6 additions and 3 deletions.
diff --git a/src/chess/constants.h b/src/chess/constants.h
@@ -122,7 +122,8 @@ enum Color {
 enum NodeType {
     ROOT_NODE,
     PV_NODE,
-    NON_PV_NODE
+    NON_PV_NODE,
+    WEAK_NODE
 };
 
 constexpr PieceType PIECE_TYPES_BY_VALUE[6] = {PAWN, KNIGHT, BISHOP, ROOK, QUEEN, KING};

diff --git a/src/search/search_thread.h b/src/search/search_thread.h
@@ -241,8 +241,9 @@ namespace search {
         Score search(Depth depth, Score alpha, Score beta, SearchStack *ss) {
             constexpr bool root_node = node_type == ROOT_NODE;
             constexpr bool non_root_node = !root_node;
-            constexpr bool pv_node = node_type != NON_PV_NODE;
+            constexpr bool pv_node = node_type == ROOT_NODE || node_type == PV_NODE;
             constexpr bool non_pv_node = !pv_node;
+            constexpr bool weak_node = node_type == WEAK_NODE;
 
             const chess::Move last_move = ss->ply >= 1 ? (ss - 1)->move : chess::NULL_MOVE;
             const Score mate_ply = -MATE_VALUE + ss->ply;
@@ -376,9 +377,10 @@ namespace search {
 
                     R -= pv_node;
                     R += !improving;
+                    R += weak_node;
 
                     Depth D = std::clamp(depth - R, 1, depth - 1);
-                    score = -search<NON_PV_NODE>(D, -alpha - 1, -alpha, ss + 1);
+                    score = -search<WEAK_NODE>(D, -alpha - 1, -alpha, ss + 1);
 
                     if (score > alpha && R > 0) {
                         score = -search<NON_PV_NODE>(depth - 1, -alpha - 1, -alpha, ss + 1);