[llvm] [CodeGen] Distinguish zero-sized call frames from no call frame in MachineBB (PR #106964)

[Jay Foad via llvm-commits]

https://github.com/jayfoad commented:

> Distinguishing between instructions in a
> zero-sized call frame and instructions outside of call frames via the
> call frame size info stored in the MachineBBs is helpful to avoid nested
> CALLSEQs

Do you have an example of where this is useful?

https://github.com/llvm/llvm-project/pull/106964