https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107702
--- Comment #2 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- (Where "check for any high bits being set" needs appropriate adjustment in the case of negative values for conversion from signed __int128, e.g. "the high 64 bits aren't the sign-extension of the low 64 bits" would be an appropriate condition to know there must be an overflow.)
