[Bug target/117544] Lack of vsetvli after function call for whole register move

[palmer at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117544

--- Comment #1 from Palmer Dabbelt <palmer at gcc dot gnu.org> ---
(In reply to Kito Cheng from comment #0)
> I'm not sure if it's reasonable to ask the Linux kernel maintainers to fix
> this by keeping VILL consistent across system calls.

That doesn't fix the problem: we'll still be trashing the state on syscalls, so
you'll just get invalid data instead of the trap.

(Still looking at the rest of it)