That image is so misleading. Stay Classy Nvidia.
Basically from what I can find, the super low end AMD cards (such as the 5450) aren't GCN.
GCN cards are basically everything from the 74xx to the R9 2xx. So that includes cards like the r7 240, the rebadged 8xxx series and all of the fast stuff, like the 7990, 295x2 etc etc.