[llvm] [AArch64] Pair far-offset LDP/STP via base-address CSE and base-register adjustment (PR #222646)

[via llvm-commits]

whokeke wrote:

> > Far offsets fail to pair for two different reasons depending on sign,
> > addressed by two independent commits (no file overlap, each revertable
> > on its own):
> 
> Is there a reason you didn't try to commit these as independent PRs? This makes the work easier to review

Thanks for the suggestion; I have split the work into two PRs. Please take a look and share your valuable feedback. I really appreciate your time.

https://github.com/llvm/llvm-project/pull/223682
https://github.com/llvm/llvm-project/pull/223684

https://github.com/llvm/llvm-project/pull/222646