[llvm] [RISCV] Re-model RVV comparison instructions (PR #88868)

[Pengcheng Wang via llvm-commits]

wangpc-pp wrote:

> > I think, a long time ago I wondered if we should have a version of the compare pseudos that had the dest tied to v0 to avoid the early clobber. And let the 3 address instruction conversion break it if it needed. Similar to the _TIED instructions we have for VWADD.WV.
> 
> Thanks! I didn't know we can avoid the early clobber in this way, I will have a try!

I don't know if I understand correctly, I think this TIED pseudos way doesn't work for compare instructions. :-(

https://github.com/llvm/llvm-project/pull/88868