Implement hot/cold code splitting

[MichalStrehovsky]

Port #74963 to NativeAot.

[cshung]

Hi @MichalStrehovsky, I had a prototype for this.

The prototype is able to turn on the CORJIT_FLAG_PROCSPLIT flag and interacts with the JIT under this mode.

Right now, it will perform the procedure split, generate the code, and place it in the binary.

End-to-end execution fails because we aren't generating the proper unwind data yet.

I am stuck trying to figure out how that works, in particular, if I wanted to generate a chained unwind info, I need the RVA to the associated runtime function record, but I can't find how the runtime function records are generated in NativeAOT.

[MichalStrehovsky]

Hi @MichalStrehovsky, I had a prototype for this.

Nice!

End-to-end execution fails because we aren't generating the proper unwind data yet.

Yep, this is the main unknown for me too. I don't know much (or anything, to be precise) about unwinding since I never had to work with that codebase.

Cc @VSadov

[MichalStrehovsky]

Once hot/cold splitting is available, we should re-measure #78370.