[Bug target/80845] nvptx backend generates cvt.u32.u32

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80845

--- Comment #3 from Tom de Vries <vries at gcc dot gnu.org> ---
Likewise, a split reg example in gcc/testsuite/gcc.target/nvptx/abi-vararg-2.c:
...
//(insn 29 27 30 4
//     (set (reg:DI 40)
//          (subreg:DI (reg:TI 23) 0))  5 {*movdi_insn}
//     (nil))
                cvt.u64.u64     %r40, %r23$0;   // 29   *movdi_insn/1
...

With dst_inner == DI and src_inner == TI we end up printing cvt.u64.u64 instead
of mov.u64.