Simplification in LMR

G-Lorenz · vondele · commit 910d26b5c30b · 2021-07-26T07:48:58.000+02:00
This commit removes the `!captureOrPromotion` condition from ttCapture reduction and from good/bad history reduction (similar to #3619). passed STC: https://tests.stockfishchess.org/tests/view/60fc734ad8a6b65b2f3a7922 LLR: 2.97 (-2.94,2.94) <-2.50,0.50> Total: 48680 W: 3855 L: 3776 D: 41049 Ptnml(0-2): 118, 3145, 17744, 3206, 127 passed LTC: https://tests.stockfishchess.org/tests/view/60fce7d5d8a6b65b2f3a794c LLR: 2.93 (-2.94,2.94) <-2.50,0.50> Total: 86528 W: 2471 L: 2450 D: 81607 Ptnml(0-2): 28, 2203, 38777, 2232, 24 closes #3629 Bench: 4951406
diff --git a/src/search.cpp b/src/search.cpp
@@ -1159,21 +1159,18 @@ namespace {
           if (cutNode && move != ss->killers[0])
               r += 2;
 
-          if (!captureOrPromotion)
-          {
-              // Increase reduction if ttMove is a capture (~3 Elo)
-              if (ttCapture)
-                  r++;
-
-              ss->statScore =  thisThread->mainHistory[us][from_to(move)]
-                             + (*contHist[0])[movedPiece][to_sq(move)]
-                             + (*contHist[1])[movedPiece][to_sq(move)]
-                             + (*contHist[3])[movedPiece][to_sq(move)]
-                             - 4923;
-
-              // Decrease/increase reduction for moves with a good/bad history (~30 Elo)
-              r -= ss->statScore / 14721;
-          }
+          // Increase reduction if ttMove is a capture (~3 Elo)
+          if (ttCapture)
+              r++;
+
+          ss->statScore =  thisThread->mainHistory[us][from_to(move)]
+                         + (*contHist[0])[movedPiece][to_sq(move)]
+                         + (*contHist[1])[movedPiece][to_sq(move)]
+                         + (*contHist[3])[movedPiece][to_sq(move)]
+                         - 4923;
+
+          // Decrease/increase reduction for moves with a good/bad history (~30 Elo)
+          r -= ss->statScore / 14721;
 
           // In general we want to cap the LMR depth search at newDepth. But if
           // reductions are really negative and movecount is low, we allow this move
