// 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;
}
// 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);
}
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