[llvm] [RISCV] Split PseudoVFMIN, PseudoVFMAX PseudoVFSGNJ, PseudoVFSGNJN, and PseudoVFSGNJX by SEW (PR #88569)

[Pengcheng Wang via llvm-commits]

https://github.com/wangpc-pp approved this pull request.

LGTM.
(I didn't add these pseudos in my original patch just because I thought the cost of these pseudos may not be linear with EEW, so my patch contained only fp arithmetic IIRC.)

https://github.com/llvm/llvm-project/pull/88569