[llvm] [AMDGPU] Set register bank for i1 register copies (PR #96155)

[Petar Avramovic via llvm-commits]

petar-avramovic wrote:

 > // The calling convention is to be updated such that i1 function arguments
 // or return values are assigned to SGPRs without promoting to i32.

I was not aware of this. Why do you want to change calling convention?

BTW, there is planned rework for reg bank select coming soon. You can't really do much with special casing S1. 

https://github.com/llvm/llvm-project/pull/96155