Simplify weak lever

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 1fc0bf1e6c6455ea470ad7047d80c8a5d2e85ef5..eda7f2f771ad37bf9b8bd6fe58fc7124ae68a532 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -277,7 +277,7 @@ void MainThread::search() {
       std::map<Move, int64_t> votes;
       Value minScore = this->rootMoves[0].score;
 
-      // Find out minimum score and reset votes for moves which can be voted
+      // Find out minimum score
       for (Thread* th: Threads)
           minScore = std::min(minScore, th->rootMoves[0].score);
 
@@ -287,7 +287,14 @@ void MainThread::search() {
           votes[th->rootMoves[0].pv[0]] +=
               (th->rootMoves[0].score - minScore + 14) * int(th->completedDepth);
 
-          if (votes[th->rootMoves[0].pv[0]] > votes[bestThread->rootMoves[0].pv[0]])
+          if (bestThread->rootMoves[0].score >= VALUE_MATE_IN_MAX_PLY)
+          {
+              // Make sure we pick the shortest mate
+              if (th->rootMoves[0].score > bestThread->rootMoves[0].score)
+                  bestThread = th;
+          }
+          else if (   th->rootMoves[0].score >= VALUE_MATE_IN_MAX_PLY
+                   || votes[th->rootMoves[0].pv[0]] > votes[bestThread->rootMoves[0].pv[0]])
               bestThread = th;
       }
   }
@@ -1041,7 +1048,7 @@ moves_loop: // When in check, search starts from here
                   continue;
 
               // Prune moves with negative SEE (~10 Elo)
-              if (!pos.see_ge(move, Value(-29 * lmrDepth * lmrDepth)))
+              if (!pos.see_ge(move, Value(-(31 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth)))
                   continue;
           }
           else if (  (!givesCheck || !extension)
@@ -1114,6 +1121,13 @@ moves_loop: // When in check, search starts from here
                              + (*contHist[3])[movedPiece][to_sq(move)]
                              - 4000;
 
+              // Reset statScore to zero if negative and most stats shows >= 0
+              if (    ss->statScore < 0
+                  && (*contHist[0])[movedPiece][to_sq(move)] >= 0
+                  && (*contHist[1])[movedPiece][to_sq(move)] >= 0
+                  && thisThread->mainHistory[us][from_to(move)] >= 0)
+                  ss->statScore = 0;
+
               // Decrease/increase reduction by comparing opponent's stat score (~10 Elo)
               if (ss->statScore >= 0 && (ss-1)->statScore < 0)
                   r -= ONE_PLY;
@@ -1145,7 +1159,7 @@ moves_loop: // When in check, search starts from here
                                         : -stat_bonus(newDepth);
 
               if (move == ss->killers[0])
-                 bonus += bonus / 4;
+                  bonus += bonus / 4;
 
               update_continuation_histories(ss, movedPiece, to_sq(move), bonus);
           }