Function RoundUpToPowerOfTwo

Bcore/src/main/cpp/base/bit_utils.h:128–133

template <typename T>
constexpr T RoundUpToPowerOfTwo(T x) {
  static_assert(std::is_integral<T>::value, "T must be integral");
  static_assert(std::is_unsigned<T>::value, "T must be unsigned");
  // NOTE: Undefined if x > (1 << (std::numeric_limits<T>::digits - 1)).
  return (x < 2u) ? x : static_cast<T>(1u) << (std::numeric_limits<T>::digits - CLZ(x - 1u));
}

// Return highest possible N - a power of two - such that val >= N.
template <typename T>