[llvm] Handle GEPs with negative offset and 'nuw' attribute (PR #117147)

[Nikita Popov via llvm-commits]

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

This change is incorrect, you are trying to work around an issue somewhere else, but your PR description doesn't have enough information to determine where.

`gep inbounds nuw` with a negative offset returns a poison value, and you should *not* try to suppress that fact.

https://github.com/llvm/llvm-project/pull/117147