[llvm] [InstCombine] Add support for GEPs in `simplifyNonNullOperand` (PR #128365)

[Nikita Popov via llvm-commits]

nikic wrote:

As far as I can tell, the transform on the provided IR is correct. Did you check your code under `-fsanitize=pointer-overflow`? Most likely, you are adding an offset to a null pointer, and that sanitizer should reliably detect that.

https://github.com/llvm/llvm-project/pull/128365