According to a LinkedIn profile, both Zen and K12 should have been taped out already. So this is a fact, as it isn't speculated based on sparse information. Interestingly the same guy (you have to find him yourself, if you need to), who only talks about CPU cores, mentions his working on 16nm and 14nm FinFet designs. So there will be one design made by TSMC and one by Globalfoundries. K12 by the first and Zen by the latter I suppose. And here is the snippet:
