[llvm] [AArch64] merge index address with large offset into base address (PR #75343)

[David Green via llvm-commits]

https://github.com/davemgreen approved this pull request.

Thanks. Every time we write patches like this they end up going wrong in some way. Please make sure you've run some decent testing and keep an eye if this might have gone wrong. From what I can tell it LGTM though. Cheers

https://github.com/llvm/llvm-project/pull/75343