Enable futility pruning for PV nodes in qsearch

STC:

LLR: 4.20 (-2.94,2.94) [-3.00,1.00]
Total: 85573 W: 17195 L: 17125 D: 51253

LTC:

LLR: 2.94 (-2.94,2.94) [-3.00,1.00]
Total: 43385 W: 7298 L: 7214 D: 28873

Bench: 8080602

Resolves #206

diff --git a/src/search.cpp b/src/search.cpp
index 7e3f6ca58bd550d8cd525a69f0b0a618bfddc795..564653ef6672aed2ce6cc0125de2f4bc5e4a40ef 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1209,8 +1209,7 @@ moves_loop: // When in check and at SpNode search starts from here
                   : pos.gives_check(move, ci);
 
       // Futility pruning
                   : pos.gives_check(move, ci);
 
       // Futility pruning

-      if (   !PvNode
-          && !InCheck
+      if (   !InCheck

           && !givesCheck
           &&  futilityBase > -VALUE_KNOWN_WIN
           && !pos.advanced_pawn_push(move))
           && !givesCheck
           &&  futilityBase > -VALUE_KNOWN_WIN
           && !pos.advanced_pawn_push(move))


@@ -1219,13 +1218,13 @@ moves_loop: // When in check and at SpNode search starts from here
 
           futilityValue = futilityBase + PieceValue[EG][pos.piece_on(to_sq(move))];
 
 
           futilityValue = futilityBase + PieceValue[EG][pos.piece_on(to_sq(move))];
 

-          if (futilityValue < beta)
+          if (futilityValue <= alpha)

           {
               bestValue = std::max(bestValue, futilityValue);
               continue;
           }
 
           {
               bestValue = std::max(bestValue, futilityValue);
               continue;
           }
 

-          if (futilityBase < beta && pos.see(move) <= VALUE_ZERO)
+          if (futilityBase <= alpha && pos.see(move) <= VALUE_ZERO)

           {
               bestValue = std::max(bestValue, futilityBase);
               continue;
           {
               bestValue = std::max(bestValue, futilityBase);
               continue;


@@ -1239,8 +1238,7 @@ moves_loop: // When in check and at SpNode search starts from here
                        && !pos.can_castle(pos.side_to_move());
 
       // Don't search moves with negative SEE values
                        && !pos.can_castle(pos.side_to_move());
 
       // Don't search moves with negative SEE values

-      if (   !PvNode
-          && (!InCheck || evasionPrunable)
+      if (  (!InCheck || evasionPrunable)

           &&  type_of(move) != PROMOTION
           &&  pos.see_sign(move) < VALUE_ZERO)
           continue;
           &&  type_of(move) != PROMOTION
           &&  pos.see_sign(move) < VALUE_ZERO)
           continue;