[llvm] [AMDGPU] Add backward compatibility layer for kernarg preloading (PR #119167)

[Janek van Oirschot via llvm-commits]

JanekvO wrote:

> I'm looking for a better way to do the padding here

Adding padding sounds very akin to the `.align` assembly directive. It may not suit your needs since, AFAICT, you're trying to fill with a size rather than align the block with padding but perhaps the way MBB alignment is controlled/padded may give some inspiration on an approach?

https://github.com/llvm/llvm-project/pull/119167