search for: i64xi64

I think from the C compiler's point of view, it is going to want it to work for any size above an i64, i.e. all the way up to an i128 so that if the user of the C compiler does this computation with __uint128_t's then it will Do The Right Thing TM. Basically, you want unsigned long a, b, c, d; .... const __uint128_t u = (__uint128_t) a + b; const unsigned long v = u >> 64; const