optimize popcnt

no functional change
official-stockfish · Jan 20, 2025 · 5575a63 · 5575a63
1 parent 780aa75
commit 5575a63
Showing 1 changed file with 5 additions and 3 deletions.
diff --git a/src/bitboard.h b/src/bitboard.h
@@ -268,9 +268,11 @@ inline int popcount(Bitboard b) {
 
 #ifndef USE_POPCNT
 
-    static constexpr auto Mask = 0xFFFF;
-    return PopCnt16[b & Mask] + PopCnt16[(b >> 16) & Mask] + PopCnt16[(b >> 32) & Mask]
-         + PopCnt16[(b >> 48) & Mask];
+    std::uint16_t indicies[4];
+    std::memcpy(indicies, &b, sizeof(b));
+    return PopCnt16[indicies[0]] + PopCnt16[indicies[1]] + PopCnt16[indicies[2]]
+         + PopCnt16[indicies[3]];
+
 
 #elif defined(_MSC_VER)