No voting for TB loss / mate.

Just as we pick the shortest mate also make sure we stave off mate as long as possible.

https://github.com/official-stockfish/Stockfish/pull/2603

bench: 5138771

diff --git a/src/search.cpp b/src/search.cpp
index 38d3204c8449d3f0f3b607e0fd2f25e036889450..ad5b364d41d780db779c6b2ce88fa7524987acad 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -280,7 +280,7 @@ void MainThread::search() {
       std::map<Move, int64_t> votes;
       Value minScore = this->rootMoves[0].score;
 
       std::map<Move, int64_t> votes;
       Value minScore = this->rootMoves[0].score;
 

-      // Find out minimum score
+      // Find minimum score

       for (Thread* th: Threads)
           minScore = std::min(minScore, th->rootMoves[0].score);
 
       for (Thread* th: Threads)
           minScore = std::min(minScore, th->rootMoves[0].score);
 


@@ -290,14 +290,15 @@ void MainThread::search() {
           votes[th->rootMoves[0].pv[0]] +=
               (th->rootMoves[0].score - minScore + 14) * int(th->completedDepth);
 
           votes[th->rootMoves[0].pv[0]] +=
               (th->rootMoves[0].score - minScore + 14) * int(th->completedDepth);
 

-          if (bestThread->rootMoves[0].score >= VALUE_TB_WIN_IN_MAX_PLY)
+          if (abs(bestThread->rootMoves[0].score) >= VALUE_TB_WIN_IN_MAX_PLY)

           {
           {

-              // Make sure we pick the shortest mate / TB conversion
+              // Make sure we pick the shortest mate / TB conversion or stave off mate the longest

               if (th->rootMoves[0].score > bestThread->rootMoves[0].score)
                   bestThread = th;
           }
           else if (   th->rootMoves[0].score >= VALUE_TB_WIN_IN_MAX_PLY
               if (th->rootMoves[0].score > bestThread->rootMoves[0].score)
                   bestThread = th;
           }
           else if (   th->rootMoves[0].score >= VALUE_TB_WIN_IN_MAX_PLY

-                   || votes[th->rootMoves[0].pv[0]] > votes[bestThread->rootMoves[0].pv[0]])
+                   || (   th->rootMoves[0].score > VALUE_TB_LOSS_IN_MAX_PLY
+                       && votes[th->rootMoves[0].pv[0]] > votes[bestThread->rootMoves[0].pv[0]]))

               bestThread = th;
       }
   }
               bestThread = th;
       }
   }