[clang] [llvm] [InstCombine] Relax singleUse for GEP(p,add(x,constant)) to 2 GEPs (PR #209551)

[Yingwei Zheng via cfe-commits]

https://github.com/dtcxzyw requested changes to this pull request.

A correctness issue was identified by [llvm-hackme](https://github.com/dtcxzyw/llvm-hackme). Please see the [issue comment](https://github.com/llvm/llvm-project/pull/209551#issuecomment-5063274646) for details.

https://github.com/llvm/llvm-project/pull/209551