Remove nmpColor

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 4463b42aaed89e51aa561e81b30419b4abe62104..04299dbd887e26cf721df70ef4fd39bb7d1d73e5 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -802,7 +802,7 @@ namespace {
         &&  ss->staticEval >= beta - 20 * depth - improvement / 13 + 253 + complexity / 25
         && !excludedMove
         &&  pos.non_pawn_material(us)
-        && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
+        && (ss->ply >= thisThread->nmpMinPly))
     {
         assert(eval - beta >= 0);
 
@@ -830,9 +830,8 @@ namespace {
             assert(!thisThread->nmpMinPly); // Recursive verification is not allowed
 
             // Do verification search at high depths, with null move pruning disabled
-            // for us, until ply exceeds nmpMinPly.
+            // until ply exceeds nmpMinPly.
             thisThread->nmpMinPly = ss->ply + 3 * (depth-R) / 4;
-            thisThread->nmpColor = us;
 
             Value v = search<NonPV>(pos, ss, beta-1, beta, depth-R, false);
 
@@ -1018,16 +1017,18 @@ moves_loop: // When in check, search starts here
               {
                   if (depth < 2 - capture)
                       continue;
-                  // don't prune move if a heavy enemy piece (KQR) is under attack after the exchanges
-                  Bitboard leftEnemies = (pos.pieces(~us, QUEEN, ROOK) | pos.pieces(~us, KING)) & occupied;
+                  // Don't prune the move if opp. King/Queen/Rook is attacked by a slider after the exchanges.
+                  // Since in see_ge we don't update occupied when the king recaptures, we also don't prune the
+                  // move when the opp. King gets a discovered slider attack DURING the exchanges.
+                  Bitboard leftEnemies = pos.pieces(~us, ROOK, QUEEN, KING) & occupied;
                   Bitboard attacks = 0;
                   occupied |= to_sq(move);
                   while (leftEnemies && !attacks)
                   {
                       Square sq = pop_lsb(leftEnemies);
-                      attacks |= pos.attackers_to(sq, occupied) & pos.pieces(us) & occupied;
-                      // exclude Queen/Rook(s) which were already threatened before SEE
-                      if (attacks && (sq != pos.square<KING>(~us) && (pos.attackers_to(sq, pos.pieces()) & pos.pieces(us))))
+                      attacks = pos.attackers_to(sq, occupied) & pos.pieces(us) & occupied;
+                      // Exclude Queen/Rook(s) which were already threatened before SEE
+                      if (attacks && sq != pos.square<KING>(~us) && (pos.attackers_to(sq, pos.pieces()) & pos.pieces(us)))
                           attacks = 0;
                   }
                   if (!attacks)