3.1.9: implement cutnode (#263)

vshcherbyna · web-flow · commit 8c3267c60d8b · 2022-11-20T02:34:10.000Z
http://chess.grantnet.us/test/29597/ ELO | 7.67 +- 4.46 (95%) SPRT | 10.0+0.10s Threads=1 Hash=8MB LLR | 2.95 (-2.94, 2.94) [0.00, 3.00] GAMES | N: 12504 W: 3492 L: 3216 D: 5796 http://chess.grantnet.us/test/29598/ ELO | 7.87 +- 4.45 (95%) SPRT | 60.0+0.60s Threads=1 Hash=64MB LLR | 2.95 (-2.94, 2.94) [0.00, 3.00] GAMES | N: 11744 W: 3088 L: 2822 D: 5834 BENCH: 3570544
diff --git a/src/search.cpp b/src/search.cpp
@@ -127,7 +127,7 @@ bool Search::isDraw()
     return false;
 }
 
-EVAL Search::abSearch(EVAL alpha, EVAL beta, int depth, int ply, bool isNull, bool rootNode, Move skipMove/*= 0*/)
+EVAL Search::abSearch(EVAL alpha, EVAL beta, int depth, int ply, bool isNull, bool rootNode, bool cutNode, Move skipMove/*= 0*/)
 {
     //
     //   qsearch
@@ -296,7 +296,7 @@ EVAL Search::abSearch(EVAL alpha, EVAL beta, int depth, int ply, bool isNull, bo
             int R = 5 + depth / 6 + std::min(3, (bestScore - beta) / 100);
 
             m_position.MakeNullMove();
-            EVAL nullScore = -abSearch(-beta, -beta + 1, depth - R, ply + 1, true, false);
+            EVAL nullScore = -abSearch(-beta, -beta + 1, depth - R, ply + 1, true, false, !cutNode);
             m_position.UnmakeNullMove();
 
             if (nullScore >= beta)
@@ -327,7 +327,7 @@ EVAL Search::abSearch(EVAL alpha, EVAL beta, int depth, int ply, bool isNull, bo
                     auto score = -qSearch(-betaCut, -betaCut + 1, ply, 0);
 
                     if (score >= betaCut)
-                        score = -abSearch(-betaCut, -betaCut + 1, depth - 4, ply + 1, false, false);
+                        score = -abSearch(-betaCut, -betaCut + 1, depth - 4, ply + 1, false, false, !cutNode);
 
                     m_position.UnmakeMove();
 
@@ -416,7 +416,7 @@ EVAL Search::abSearch(EVAL alpha, EVAL beta, int depth, int ply, bool isNull, bo
 
         if (depth >= 8 && !skipMove && hashMove == mv && !rootNode && !isCheckMateScore(hEntry.m_data.score) && (hEntry.m_data.type == HASH_BETA || hEntry.m_data.type == HASH_EXACT) && hEntry.m_data.depth >= depth - 3) {
             auto betaCut = hEntry.m_data.score - depth;
-            auto score = abSearch(betaCut - 1, betaCut, depth / 2, ply + 1, false, false, mv);
+            auto score = abSearch(betaCut - 1, betaCut, depth / 2, ply + 1, false, false, cutNode, mv);
 
             if (score < betaCut)
                 extension = 1;
@@ -443,41 +443,44 @@ EVAL Search::abSearch(EVAL alpha, EVAL beta, int depth, int ply, bool isNull, bo
 
             newDepth += extensionRequired(m_position.InCheck(), onPV, history.cmhistory, history.fmhistory) + extension;
 
-            EVAL e;
-            if (legalMoves == 1)
-                e = -abSearch(-beta, -alpha, newDepth, ply + 1, false, false);
-            else
-            {
-                //
-                //   lmr
-                //
+            //
+            //   lmr
+            //
 
-                int reduction = 0;
+            int reduction = 0;
 
-                if (depth >= 3 && quietMove && legalMoves > 1 + 2 * rootNode) {
-                    reduction = m_logLMRTable[std::min(depth, 63)][std::min(legalMoves, 63)];
+            if (depth >= 3 && quietMove && legalMoves > 1 + 2 * rootNode) {
+                reduction = m_logLMRTable[std::min(depth, 63)][std::min(legalMoves, 63)];
 
-                    if (onPV)
-                        reduction -= 2;
+                reduction += cutNode;
 
-                    reduction -= mv == m_killerMoves[ply][0]
-                              || mv == m_killerMoves[ply][1];
+                if (onPV)
+                    reduction -= 2;
 
-                    reduction -= std::max(-2, std::min(2, (history.history + history.cmhistory + history.fmhistory) / 5000));
+                reduction -= mv == m_killerMoves[ply][0]
+                    || mv == m_killerMoves[ply][1];
 
-                    if (reduction >= newDepth)
-                        reduction = newDepth - 1;
-                    else if (reduction < 0)
-                        reduction = 0;
-                }
+                reduction -= std::max(-2, std::min(2, (history.history + history.cmhistory + history.fmhistory) / 5000));
+
+                if (reduction >= newDepth)
+                    reduction = newDepth - 1;
+                else if (reduction < 0)
+                    reduction = 0;
+            }
 
-                e = -abSearch(-alpha - 1, -alpha, newDepth - reduction, ply + 1, false, false);
+            EVAL e;
+
+            if (reduction) {
+                e = -abSearch(-alpha - 1, -alpha, newDepth - reduction, ply + 1, false, false, true);
 
-                if (e > alpha && reduction > 0)
-                    e = -abSearch(-alpha - 1, -alpha, newDepth, ply + 1, false, false);
-                if (e > alpha && e < beta)
-                    e = -abSearch(-beta, -alpha, newDepth, ply + 1, false, false);
+                if (e > alpha)
+                    e = -abSearch(-alpha - 1, -alpha, newDepth, ply + 1, false, false, !cutNode);
             }
+            else if (!onPV || legalMoves > 1)
+                e = -abSearch(-alpha - 1, -alpha, newDepth, ply + 1, false, false, !cutNode);
+
+            if (onPV && (legalMoves == 1 || e > alpha))
+                e = -abSearch(-beta, -alpha, newDepth, ply + 1, false, false, false);
 
             m_position.UnmakeMove();
 
@@ -1076,7 +1079,7 @@ uint64_t Search::startSearch(Time time, int depth, bool ponderSearch, bool bench
         EVAL beta  = std::min(m_score + aspiration, CHECKMATE_SCORE);
 
         while (aspiration <= CHECKMATE_SCORE) {
-            auto score = abSearch(alpha, beta, m_depth, 0, false, true);
+            auto score = abSearch(alpha, beta, m_depth, 0, false, true, false);
 
             if (m_flags & SEARCH_TERMINATED)
                 break;
diff --git a/src/search.h b/src/search.h
@@ -90,7 +90,7 @@ class Search
 #if defined (SYZYGY_SUPPORT)
     Move tableBaseRootSearch();
 #endif
-    EVAL abSearch(EVAL alpha, EVAL beta, int depth, int ply, bool isNull, bool rootNode, Move skipMove = 0);
+    EVAL abSearch(EVAL alpha, EVAL beta, int depth, int ply, bool isNull, bool rootNode, bool cutNode, Move skipMove = 0);
     EVAL qSearch(EVAL alpha, EVAL beta, int ply, int depth, bool isNull = false);
     inline int extensionRequired(bool inCheck, bool onPV, int cmhistory, int fmhistory);
     bool ProbeHash(TEntry & hentry);
diff --git a/src/uci.cpp b/src/uci.cpp
@@ -30,7 +30,7 @@
 #include <iostream>
 #include <sstream>
 
-const std::string VERSION = "3.1.8";
+const std::string VERSION = "3.1.9";
 
 #if defined(ENV64BIT)
     #if defined(_BTYPE)
