Replacing NIR with SPIR-V?

Marek Olšák maraeo at
Fri Jan 21 11:19:56 UTC 2022

> - Does it make sense to move to SPIR-V?

No, it doesn't make any sense whatsoever.


On Wed, Jan 19, 2022 at 8:17 PM Abel Bernabeu <
abel.bernabeu at> wrote:

> Hi,
> My name Abel Bernabeu and I currently chair the Graphics and ML Special
> Interest Group within RISC-V.
> As part of my work for RISC-V I am currently looking at what is needed for
> supporting a graphics product that uses a (potentially extended) RISC-V ISA
> for its shading cores. My initial focus has been on analyzing the
> functional gap between RISC-V and SPIR-V, assuming that whatever is needed
> for a modern graphics accelerator is inevitably present on SPIR-V.
> Now, the thing is that most of the potential adopters on our committee
> will likely be interested in using mesa for developing their drivers and
> that means using NIR as intermediate representation. Thus, I also need to
> consider NIR when looking at the functional gap, doubling the amount of
> work during the analysis.
> Why is mesa using NIR as intermediate representation rather than SPIR-V?
> It would make my life easier if mesa used SPIR-V rather than NIR for
> communicating the front-end and the backends.
> I know it is a lot of work to migrate to SPIR-V, but I am interested in
> knowing what is the opinion of the mesa developers:
> - My understanding is that when mesa adopted NIR, there was no SPIR-V. Was
> a comparison made after the SPIR-V ratification?
> - Does it make sense to move to SPIR-V?
> - Is it feasible in terms of functionality supported by SPIR-V?
> - Is the cost worth the potential advantage of using a more commonly
> adopted standard?
> Thanks in advance for your time and thoughts.
> Regards.
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