X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=e28b866e9cb26b2bc26c5bc5460a6e091aa2ef81;hp=8da12118d21979d3941e984743fb6f5e8794235c;hb=2d4e2bc62a4ee3fa93004755d4b93fa466d1e93e;hpb=3f610e2b13340ca65d0f9d63aa0cb8da92e80117

diff --git a/src/search.cpp b/src/search.cpp
index 8da12118..e28b866e 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1148,7 +1148,8 @@ namespace {
 
         UndoInfo u;
         pos.do_null_move(u);
-        Value nullValue = -search(pos, ss, -(beta-1), depth-4*OnePly, ply+1, false, threadID);
+        int R = (depth > 7 ? 4 : 3);
+        Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
         pos.undo_null_move(u);
 
         if (nullValue >= beta)
@@ -1468,6 +1469,18 @@ namespace {
     // Update transposition table
     TT.store(pos, value_to_tt(bestValue, ply), depth, MOVE_NONE, VALUE_TYPE_EXACT);
 
+    // Update killers only for good check moves
+    Move m = ss[ply].currentMove;
+    if (alpha >= beta && ok_to_history(pos, m)) // Only non capture moves are considered
+    {
+        // Wrong to update history when depth is <= 0
+
+        if (m != ss[ply].killer1)
+        {
+            ss[ply].killer2 = ss[ply].killer1;
+            ss[ply].killer1 = m;
+        }
+    }
     return bestValue;
   }
 
@@ -2142,13 +2155,11 @@ namespace {
 
 
   // ok_to_history() returns true if a move m can be stored
-  // in history. Should be a non capturing move.
+  // in history. Should be a non capturing move nor a promotion.
 
   bool ok_to_history(const Position& pos, Move m) {
 
-    return    pos.square_is_empty(move_to(m))
-          && !move_promotion(m)
-          && !move_is_ep(m);
+    return !pos.move_is_capture(m) && !move_promotion(m);
   }
 
 
@@ -2161,8 +2172,11 @@ namespace {
     H.success(pos.piece_on(move_from(m)), m, depth);
 
     for (int i = 0; i < moveCount - 1; i++)
-        if (ok_to_history(pos, movesSearched[i]) && m != movesSearched[i])
+    {
+        assert(m != movesSearched[i]);
+        if (ok_to_history(pos, movesSearched[i]))
             H.failure(pos.piece_on(move_from(movesSearched[i])), movesSearched[i]);
+    }
   }
 
   // fail_high_ply_1() checks if some thread is currently resolving a fail