[llvm] [FuncAttrs] Relax norecurse attribute inference (PR #139943)

[Nikita Popov via llvm-commits]

nikic wrote:

I'm not really familiar with it, but it's worth noting that the LazyCallGraph structure represented the call graph as SCCs nested inside RefSCCs, where the latter also represents things like potential calls from outside the module or taking references to functions that may later get called.

We usually do inference on SCCs, but I feel like it might make sense to infer norecurse on RefSCC. Would a trivial RefSCC (single element without self-edge) be norecurse without any further analysis?

https://github.com/llvm/llvm-project/pull/139943