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

[via llvm-commits]

vfdff wrote:

hi , thurstond
    I try to reproduce the issue with your instructions locally, and I don't see obvious build error information, but only get a binary  **llvm_build0/bin/llc**. but **llvm_build0/bin/llc -verify-machineinstrs llvm-project/llvm/test/CodeGen/PowerPC/ppc64-nest.ll** doesn't crash on my aarch64 machine. I suspect my local compilation is incomplete for some reason ?
```
~/source/scratch_dir » find . -name "llc"
./llvm_build_ubsan/tools/llc
./llvm_build0/bin/llc
./llvm_build0/tools/llc
------------------------------------------------------------
~/source/scratch_dir » ls
build.log  libcxx_build_ubsan  llvm_build0  llvm_build_ubsan  llvm-project  llvm-zorg
```

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