[llvm] [ArgPromotion] Handle pointer arguments of recursive calls (PR #78735)

[Vedant Paranjape via llvm-commits]

vedantparanjape-amd wrote:

> > @arsenm @jdoerfert I have addressed the comment, but I am stuck at one thing. The testcase: Transforms/ArgumentPromotion/pr42028-recursion.ll
> > ```
> > A -> B -> C
> >      ↑____|
> > ```
> > 
> > 
> >     
> >       
> >     
> > 
> >       
> >     
> > 
> >     
> >   
> > It has a SCC like this. Somehow, not able to handle the case with call instructions.
> 
> Handle in what way? It breaks, or is sub-optimal? If it's not broken, it doesn't need to be perfect in the first attempt

It breaks (SE), while handling that case, if we try to do argument promotion for such a case it will lead to recursion.

https://github.com/llvm/llvm-project/pull/78735