https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78067
--- Comment #1 from Bernd Edlinger <bernd.edlinger at hotmail dot de> --- I think in the case of x86 longlong.h does not define COUNT_LEADING_ZEROS_0 but nevertheless count_leading_zero is defined to __builtin_clz and seems to return the correct result, but I don't know if that will always be the case, or why longlong.h does not define COUNT_LEADING_ZEROS_0 to 64.
