C++ also provides countl_zero: https://en.cppreference.com/w/cpp/numeric/countl_zero.html. We currently use our own for maximum portability.

I considered computing the table at compile time (you can do it in C++ using constexpr) but decided against it not to add compile-time overhead, however small. The table never changes so I'd rather not make users pay for recomputing it every time.