CallGraph in immutable pass

Hello,
is there any way I can access CallGraph from immutable pass via getAnalysis?
As I understand it, this may not be possible, because immutable pass don't have runOn method and is never actually planned. But I'm not 100% sure how this works, so I don't know if there is some other way.
Thanks,
Robert Barucak

Your understanding is correct – this is impossible. What are you really trying to do?

I'm working on implementation of some fancier alias analysis algorithm. I have experienced strange behavior when I registered my AA (as module pass) into AA group. Somehow I was unable to get correct DataLayout from AA interface. So I wanted to try to make it immutable, just like other AA implementations.
Anyway, thanks for clarification.

Currently, LLVM's pass manager infrastructure and especially the immutable
pass based alias analysis group makes stateful alias analyses essentially
impossible to do well, and largely require gross hacks. There is a thread I
started many months ago about revamping the pass management in LLVM, and
this is one motivating concern although not my primary concern.