LMR Simplification

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index c15cd7537e6a8589160842f596a735b1f377317a..a769284193abe04b0b5ac0bd0b07124dccf93559 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1160,7 +1160,6 @@ moves_loop: // When in check, search starts from here
       // re-searched at full depth.
       if (    depth >= 3
           &&  moveCount > 1 + 2 * rootNode + 2 * (PvNode && abs(bestValue) < 2)
-          && (!rootNode || thisThread->best_move_count(move) == 0)
           && (  !captureOrPromotion
               || moveCountPruning
               || ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha
@@ -1169,13 +1168,6 @@ moves_loop: // When in check, search starts from here
       {
           Depth r = reduction(improving, depth, moveCount);
 
-          // Decrease reduction at non-check cut nodes for second move at low depths
-          if (   cutNode
-              && depth <= 10
-              && moveCount <= 2
-              && !ss->inCheck)
-              r--;
-
           // Decrease reduction if the ttHit running average is large
           if (thisThread->ttHitAverage > 509 * TtHitAverageResolution * TtHitAverageWindow / 1024)
               r--;
@@ -1197,7 +1189,7 @@ moves_loop: // When in check, search starts from here
 
           // Decrease reduction if ttMove has been singularly extended (~3 Elo)
           if (singularQuietLMR)
-              r -= 1 + formerPv;
+              r--;
 
           if (!captureOrPromotion)
           {
@@ -1565,7 +1557,9 @@ moves_loop: // When in check, search starts from here
       }
 
       // Do not search moves with negative SEE values
-      if (!ss->inCheck && !pos.see_ge(move))
+      if (   !ss->inCheck
+          && !(givesCheck && pos.is_discovery_check_on_king(~pos.side_to_move(), move))
+          && !pos.see_ge(move))
           continue;
 
       // Speculative prefetch as early as possible