https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115217
--- Comment #2 from Jeffrey A. Law <law at gcc dot gnu.org> --- So the usual way to handle register pairs is to use wider modes or wider types depending on the context rather than special constraints. So in theory if you need a register pair, use a [u]int64_t for rv32 and [u]int128_t in C/C++ code. Now I suspect various internal bits aren't really ready for that, but that's the path I'd suggest.
