There's no word about the rationale behind this decision. AMD still plans to offer an explicit API path to code primitive shaders, but without an implicit driver path this means a lot more effort is required from game developers (aka dead on arrival).
The move was revealed by Golem.de editor Marc Sauter, commenting as "y33H@" on 3DCenter.org forums. In layman's terms, AMD at its Vega graphics architecture reveal, promised a driver that would sense where primitive shaders would benefit unoptimized games and automatically develop primitive shaders for them. That plan has been scrapped. What AMD is now offering is an API so developers can make primitive shaders on their own dime.Before the launch of Vega, former AMD RTG head Raja Koduri promised programmers wouldn't need to do anything special to take advantage of the improvements in Vega. Koduri is now working at Intel, to enhance the chip giant's future GPUs.
Via: TPU