https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95730
--- Comment #4 from Andrew Stubbs <ams at gcc dot gnu.org> --- In fact default_scalar_mode_supported_p does return *false* for TImode (because LONG_LONG_TYPE_SIZE == 64, and BITS_PER_WORD == 32). Therefore int128_t does not exist, as far as users are concerned. I'm not sure how that translates to the GCC internals, but trying to use TImode for anything other than moves is not going to work on GCN.
