Now that the MDBuilder helpers generating TBAA type and access descriptors in the new format are in place, we can teach clang to use them when requested.
There are more tests that we will need to rewrite during migration to the new format than I think we could handle with a single patch. I was going to address them with separate patches. Or, I can rewrite some most basic of them as part of this patch.
You can pass multiple -check-prefix arguments to FileCheck and it'll match all of them. You can use that to make your test change simpler: make the existing RUN check for both PATH and OLD-PATH and the new RUN check for both PATH and NEW-PATH, then change all the existing metadata matches to OLD-PATH.