[llvm] [AMDGPU] ISel for @llvm.amdgcn.cs.chain intrinsic (PR #68186)

[Nicolai Hähnle via llvm-commits]

https://github.com/nhaehnle commented:

The high-level flow looks very reasonable to me, but I did notice a test problem.

https://github.com/llvm/llvm-project/pull/68186