I don't believe that dllexport declarations make sense. This is the only case of a dllexport declaration in LLVM testing. Dllimport/export was introduced here: https://reviews.llvm.org/D1110, looking at the tests added and the commentary it doesn't seem that dllexport declarations were an imagined use case.
These CHECKs were unused in the original version of this test: https://github.com/llvm/llvm-project/commit/6cb074493420dcc1922e2a1d066806dae3051172.
Looks like CHECK-STATIC-EXPORT-IA is also an unused prefix, unless I'm mistaken.