[llvm] [RISCV] Implement `isLoadFromStackSlotPostFE` and ... (PR #184673)

[Craig Topper via llvm-commits]

topperc wrote:

> > What is the effect of this?
> 
> I want to use it in RDA post FE. That, in turn, I want to use to generate CFI's really late in the pipiline. I'll be posting all of those PRs soon

That should be in the PR description.

https://github.com/llvm/llvm-project/pull/184673