I saw the same changes in the following review: https://reviews.llvm.org/D17438
I don't know in that way I could determine that atomic variable was initialized by macro ATOMIC_VAR_INIT. Anyway I added check that atomic variables can be initialize only in global scope.
I think that we can discuss this change.
I suggest removing this comment.
If you are going to add other diagnostic messages specific to OpenCL atomics, then separate them from this list of unordered diagnostics similar to pipe built-in functions below.