also here are the slides for GCN architecture crash curse
these are from Layla Mah (@MissQuickstep) | Twitter
AMD Graphics & VR Architect
he twited those on feb-12-2014
also Graham Sellers
Graham Sellers (@grahamsellers) | Twitter
he is the opengl guy on amd
and author of the book "opengl super bible"
twit him, maybe he answer your question more directly