X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fsearch.cpp;h=dfc0e5bf79a9b1ef40064de18c85a603dad8ee26;hb=bae019b53e5c2bfcf0d69b4ebfc52b4f4de762eb;hp=b0bcc57a44ee05f8f71fe2205d187f25622613fb;hpb=13f70d0392ca3ce7f1c8e34dd0a10c3537d2fbab;p=stockfish

diff --git a/src/search.cpp b/src/search.cpp
index b0bcc57a..dfc0e5bf 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -2,7 +2,7 @@
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
   Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -716,7 +716,9 @@ namespace {
                 update_continuation_histories(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty);
             }
         }
-        return ttValue;
+
+        if (pos.rule50_count() < 90)
+            return ttValue;
     }
 
     // Step 5. Tablebases probe
@@ -825,10 +827,10 @@ namespace {
     // Step 9. Null move search with verification search (~40 Elo)
     if (   !PvNode
         && (ss-1)->currentMove != MOVE_NULL
-        && (ss-1)->statScore < 23405
+        && (ss-1)->statScore < 23397
         &&  eval >= beta
         &&  eval >= ss->staticEval
-        &&  ss->staticEval >= beta - 32 * depth + 317 - improving * 30
+        &&  ss->staticEval >= beta - 32 * depth + 292 - improving * 30
         && !excludedMove
         &&  pos.non_pawn_material(us)
         && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
@@ -1003,7 +1005,11 @@ moves_loop: // When in check, search starts from here
               // Futility pruning: parent node (~2 Elo)
               if (   lmrDepth < 6
                   && !inCheck
-                  && ss->staticEval + 255 + 182 * lmrDepth <= alpha)
+                  && ss->staticEval + 255 + 182 * lmrDepth <= alpha
+                  &&  thisThread->mainHistory[us][from_to(move)]
+                    + (*contHist[0])[movedPiece][to_sq(move)]
+                    + (*contHist[1])[movedPiece][to_sq(move)]
+                    + (*contHist[3])[movedPiece][to_sq(move)] < 30000)
                   continue;
 
               // Prune moves with negative SEE (~10 Elo)