[Mesa-dev] [PATCH] radeonsi: implement legacy RCP behavior to fix Unreal engine demos

[Roland Scheidegger]

Am 11.12.2014 um 09:55 schrieb Michel Dänzer:
> On 11.12.2014 07:49, Roland Scheidegger wrote:
>> Odd indeed. Maybe it was really meant for d3d10level9 shaders or
>> something (would allow to share more code compiling d3d9 or d3d10
>> shaders that way I guess, you could use all the same instructions and
>> just set that bit, and you said newer chips don't have the legacy
>> instructions so I guess that bit would help if they still have it).
>> d3d10 clearly forbids this (and so does GL 4.1 and up).
> 
> So at the latest when we get GL 4.1, we probably need some TGSI shader
> attribute to tell drivers not to enable this kind of clamping?
> 
> 

Maybe. In GL, an app _never_ could have relied on that clamping from
happening in the first place however (which is why it's surprising a
relatively new app would rely on this - I could understand it for
something from a time where hw didn't have NaNs).

Roland