Refine futility pruning for parent nodes

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 1dfadd21ab6b0009fc2817754036d130e7a1c00e..807d261472fc091b96f7aaf71ec46c784a1f810a 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -817,7 +817,7 @@ namespace {
 
     // Step 7. Futility pruning: child node (~50 Elo).
     // The depth condition is important for mate finding.
-    if (   !PvNode
+    if (   !ss->ttPv
         &&  depth < 9
         &&  eval - futility_margin(depth, improving) >= beta
         &&  eval < 15000) // 50% larger than VALUE_KNOWN_WIN, but smaller than TB wins.
@@ -1054,17 +1054,21 @@ moves_loop: // When in check, search starts here
           }
           else
           {
+              int history =   (*contHist[0])[movedPiece][to_sq(move)]
+                            + (*contHist[1])[movedPiece][to_sq(move)]
+                            + (*contHist[3])[movedPiece][to_sq(move)];
+
               // Continuation history based pruning (~20 Elo)
-              if (lmrDepth < 5
-                  && (*contHist[0])[movedPiece][to_sq(move)]
-                  + (*contHist[1])[movedPiece][to_sq(move)]
-                  + (*contHist[3])[movedPiece][to_sq(move)] < -3000 * depth + 3000)
+              if (   lmrDepth < 5
+                  && history < -3000 * depth + 3000)
                   continue;
 
+              history += thisThread->mainHistory[us][from_to(move)];                  
+
               // Futility pruning: parent node (~5 Elo)
               if (   !ss->inCheck
                   && lmrDepth < 8
-                  && ss->staticEval + 172 + 145 * lmrDepth <= alpha)
+                  && ss->staticEval + 142 + 139 * lmrDepth + history / 64 <= alpha)
                   continue;
 
               // Prune moves with negative SEE (~20 Elo)