[llvm] [InstCombine] Modify zero-indexed GEPs in place rather than cloning (PR #185053)

[Manasij Mukherjee via llvm-commits]

manasij7479 wrote:

Would it make sense to create a new instruction and `replaceAllUsesWith` instead of modifying the GEP in place? 

https://github.com/llvm/llvm-project/pull/185053