Tweak futility pruning

locutus2 · snicolet · commit 56d5504f6548 · 2020-01-07T11:18:50.000+01:00
Exclude moves with a good history total from futility pruning. This adds a condition for quiet futility pruning: history total has to be low. STC: LLR: 2.94 (-2.94,2.94) {-1.00,3.00} Total: 20095 W: 4503 L: 4342 D: 11250 Ptnml(0-2): 362, 2380, 4422, 2486, 388 http://tests.stockfishchess.org/tests/view/5e0d7c5387585b1706b68370 LTC: LLR: 2.94 (-2.94,2.94) {0.00,2.00} Total: 53016 W: 8587 L: 8302 D: 36127 Ptnml(0-2): 353, 5397, 14751, 5545, 423 http://tests.stockfishchess.org/tests/view/5e0e30d062fb773bb7047e95 Closes #2472 Bench: 5215200
diff --git a/src/search.cpp b/src/search.cpp
@@ -1003,7 +1003,11 @@ namespace {
               // 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)
