[llvm] [AArch64] Reland merge index address with large offset into base address (PR #79951)

[via llvm-commits]

vfdff wrote:

> FYI: I reverted [43ffe2e](https://github.com/llvm/llvm-project/commit/43ffe2eed0d9f73789dbe213023733d164999306) because of a buildbot breakage ([324b676](https://github.com/llvm/llvm-project/commit/324b676a3d0449add8d4e24047680125f9b9a716))

Thanks for your report, I'll take a look at it .would you please show how to build the above llvm ? My change doesn't touch the ppc target, and it is a little supprise to affact the ppc64-nest.ll under target PowerPC.

https://github.com/llvm/llvm-project/pull/79951