https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79217
--- Comment #5 from H. Peter Anvin <hpa at zytor dot com> --- As noted on bug 79219 there are a few issues with simply relying on __int128, even if 32 bits is the natural "limb" size on a 32-bit architecture. a) it requires algorithms to be implemented using lengthy (source-code-wise) multi-precision to be portable between 32- and 64-bit architectures. b) it seems likely that getting __intN where N > CHAR_BIT*sizeof(uintmax_t) into a standard would be very hard, and thus would not be possible to standard-track (although it could be used as an implementation on gcc using a header inline, of course.)
