[llvm] [Codegen][NewPM] Explicitly Nest Passes in CodegenPassBuilder (PR #169867)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

> wdyt about consolidating all of the wrappers into one wrapper? that seems like fewer parameters everywhere and I don't see a downside to this

Done. I think it makes some of the APIs nicer (e.g., we do not need to pass in a FPM/MFPM to `addModule` to assert). And we end up with a lot less parameter passing. The one advantage to separating out the wrappers is that we could avoid passing in the MPM Wrapper to certain overrideable functions to restrict them to only adding function passes. But I could easily see there being a lot of churn there with downstream targets (or even upstream ones) needing to add module passes at those points.

https://github.com/llvm/llvm-project/pull/169867