[llvm] [IR] Add a helper `Function::isReturnNonNull` (PR #128107)

[Nikita Popov via llvm-commits]

https://github.com/nikic approved this pull request.

LGTM. Something you might want to consider though is that you could do different optimizations for both cases. In particular, for nonnull you can only look through inbounds gep, while for dereferenceable you can look through any gep. If you want to make use of that, then the helper is probably not going to be useful...

https://github.com/llvm/llvm-project/pull/128107