[llvm] [RISCV] Move VMV0 elimination past machine SSA opts (PR #126850)

[Luke Lau via llvm-commits]

lukel97 wrote:

> Thanks for the quick response. Would you mind rolling back per https://llvm.org/docs/DeveloperPolicy.html#patch-reversion-policy as this breaks one of our internal toolchains. Otherwise we will soon be in a situation where crucial build jobs become non-functional, and we'd really like to avoid that.

I've pushed a fix at 35bf925f7ea95e71208a839cf4b02de2ee473f75, can you try it out and let me know if that fixes the issue in your internal toolchain?

Given that the fix was pretty small I wanted to avoid reverting given that the diff in this PR is quite large and has been in tree for nearly a week now, I hope that makes sense. 

https://github.com/llvm/llvm-project/pull/126850