Guard against UB in lsb/msb

[stockfish] / src / bitboard.cpp

diff --git a/src/bitboard.cpp b/src/bitboard.cpp
index 4ea69ebc757df81fbea8f70d79e1d54c7d568446..ba1af2f2865f28865791178206add9752a392889 100644 (file)
--- a/src/bitboard.cpp
+++ b/src/bitboard.cpp
@@ -81,11 +81,13 @@ namespace {
 /// Software fall-back of lsb() and msb() for CPU lacking hardware support
 
 Square lsb(Bitboard b) {
+  assert(b);
   return BSFTable[bsf_index(b)];
 }
 
 Square msb(Bitboard b) {
 
+  assert(b);
   unsigned b32;
   int result = 0;