[clang] [llvm] [BPF] Support Stack Arguments (PR #189060)

[via cfe-commits]

4ast wrote:

> we can enforce r12 based stores like below:
> 
> * r12 based stores must be before a call in the same basic block
> * there should not be any r12 based loads between the first stores and the call.
>   The above is exactly what the llvm generates.

we cannot do it. There are too many restrictions already. All current restrictions need to be removed.
I guess it's fine just doing the max across all and reserver in the prologue for now.

https://github.com/llvm/llvm-project/pull/189060