Simplify move generation (1/2)

STC:
LLR: 2.95 (-2.94,2.94) {-1.25,0.25}
Total: 29792 W: 2611 L: 2545 D: 24636
Ptnml(0-2): 94, 1982, 10659, 2086, 75
https://tests.stockfishchess.org/tests/view/604fe5b62433018de7a38ba8

LTC:
LLR: 2.92 (-2.94,2.94) {-0.75,0.25}
Total: 22040 W: 826 L: 777 D: 20437
Ptnml(0-2): 8, 646, 9664, 693, 9
https://tests.stockfishchess.org/tests/view/604fec892433018de7a38bac

Closes https://github.com/official-stockfish/Stockfish/pull/3399

No functional change

diff --git a/src/movegen.cpp b/src/movegen.cpp
index c5d76afa43b0bc59e7b43b94174ef08dcb694d70..d8c4370ac83505334f2e0a550dc8b8329a825ec6 100644 (file)
--- a/src/movegen.cpp
+++ b/src/movegen.cpp
@@ -182,17 +182,12 @@ namespace {
 
     Bitboard bb = piecesToMove & pos.pieces(Pt);
 
-    if (!bb)
-        return moveList;
-
-    [[maybe_unused]] const Bitboard checkSquares = pos.check_squares(Pt);
-
     while (bb) {
         Square from = pop_lsb(&bb);
 
         Bitboard b = attacks_bb<Pt>(from, pos.pieces()) & target;
         if constexpr (Checks)
-            b &= checkSquares;
+            b &= pos.check_squares(Pt);
 
         while (b)
             *moveList++ = make_move(from, pop_lsb(&b));