Save stalemates in TT

When there aren't legal moves after
a search, instead of returning imediately,
save bestValue in TT as in the usual case.

There is really no reason to special case
this one.

With this patch is fully fixed (again) follwing
position:

    7k/6p1/6B1/5K1P/8/8/8/8 w - - 0 1

Also in SMP case.

bench: 8802105

diff --git a/src/search.cpp b/src/search.cpp
index dfe690b4d6498ec65c016c200696acb39175ca15..3d755586d9885c9ee2310307e0feffee808e3d20 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1017,18 +1017,18 @@ moves_loop: // When in check and at SpNode search starts from here
     // must be mate or stalemate. If we are in a singular extension search then
     // return a fail low score.
     if (!moveCount)
     // must be mate or stalemate. If we are in a singular extension search then
     // return a fail low score.
     if (!moveCount)

-        return  excludedMove ? alpha
-              : inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()];
+        bestValue = excludedMove ? alpha
+                   :     inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()];
+
+    // Quiet best move: update killers, history, countermoves and followupmoves
+    else if (bestValue >= beta && !pos.capture_or_promotion(bestMove) && !inCheck)
+        update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount - 1);

 
     TT.store(posKey, value_to_tt(bestValue, ss->ply),
              bestValue >= beta  ? BOUND_LOWER :
              PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
              depth, bestMove, ss->staticEval);
 
 
     TT.store(posKey, value_to_tt(bestValue, ss->ply),
              bestValue >= beta  ? BOUND_LOWER :
              PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
              depth, bestMove, ss->staticEval);
 

-    // Quiet best move: update killers, history, countermoves and followupmoves
-    if (bestValue >= beta && !pos.capture_or_promotion(bestMove) && !inCheck)
-        update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount - 1);
-

     assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
 
     return bestValue;
     assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
 
     return bestValue;