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

[Alexander Kornienko via llvm-commits]

alexfh 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.

It turned out to be even more subtle: the optimization removed the last access to a global variable, which triggered an elimination of another global variable together with its dynamic initializer, which served the purpose of registering a certain type to a global registry.  So ultimately, no issue with this commit. Thanks for checking!


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