The diff is uploaded to Phabricator:
https://reviews.llvm.org/D143647
I would be happy to address questions/concern and revise as necessary. In particular, it seems to me that if the idea of having a bytecode version that can grow independently from Attributes/Types is what we would like to pursue, we may need to agree on a custom versioning id (for example, one or more integers).