[Mesa-dev] mediump support: future work

Samuel Pitoiset samuel.pitoiset at gmail.com
Tue May 5 07:41:18 UTC 2020

On RADV, we already support fp16 with the LLVM backend (not saying it's 
always optimized though) and with ACO it should be mostly working but 
not yet enabled because I think we would like fast packed math support 
first and I'm not sure if fp16 I/O are implemented.

There is also some missing fp16 optimizations in the ACO backend which 
makes some games (eg. Youngblood) a bit slower if fp16 
features/extensions are exposed but the gap should be filled soon hopefully.

I think the most important thing missing is a SLP vectorizer in NIR for us.

On 5/4/20 8:43 PM, Marek Olšák wrote:
> Hi,
> This is the status of mediump support in Mesa. What I listed is what 
> AMD GPUs can do. "Yes" means what Mesa supports.
> *Feature* 	*FP16 support* 	*Int16 support*
> ALU 	Yes 	No
> Uniforms 	No 	No
> VS in 	No 	No
> VS out / FS in 	No 	No
> FS out 	No 	No
> TCS, TES, GS out / in 	No 	No
> Sampler coordinates (only coord, derivs, lod, bias; not offset and 
> compare) 	No 	---
> Image coordinates 	--- 	No
> Return value from samplers (incl. sampler buffers) 	Yes
> 	No
> Return value from image loads (incl. image buffers) 	No 	No
> Data source for image stores (incl. image buffers) 	No 	No
> If 16-bit sampler/image instructions are surrounded by conversions, 
> promote them to 32 bits 	No 	No
> Please let me know if you don't see the table correctly.
> I'd like to know if I can enable some of them using the existing FP16 
> CAP. The only drivers supporting FP16 are currently Freedreno and 
> Panfrost.
> Thanks,
> Marek
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> mesa-dev at lists.freedesktop.org
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