First GCN 2.0 is a superset of capabilities beyond GCN 1.0. GCN 1.0 is also only compatible with OpenCL 1.2. GCN 2.0 is compatible with new feature specified in OpenCL 2.0 spec. So to get to answer your looking for if you develop an OpenCL 1.2 program it will run on GCN 1.0, 1.1, and 2.0 enabled GPU's. We JIT the program from OpenCL source to proper GCN machine instructions for you.