Replacing NIR with SPIR-V?

Dave Airlie airlied at
Sun Jan 23 21:14:22 UTC 2022

On Mon, 24 Jan 2022 at 06:52, Abel Bernabeu
<abel.bernabeu at> wrote:
> Dave,
> Am glad for the Mesa community to support the RISC-V effort with the advice given so far.
> I hear your concerns regarding performance. I am familiar with the Larabee case and know some of the people who worked on that. However, I am not here to discuss what is the RISC-V strategy for graphics beyond the fact that there is a NIR backend planned. That would be offtopic for this list.

We are pretty flexible on our topics since we moved most of the day to
day work to gitlab :-)

With the current chip architectures and possible vector extensions to
RISC-V, I think using llvmpipe and your current LLVM backend would be
as efficient as you can get, modulo optimising things more for
possible use cases you have. You might be able to add some fixed
function blocks to enhance things like texturing or blending.

I would think having a NIR backend would only really show usefulness
if you moved to a SIMT architecture, now you may have plans in that
area, and that might give you more reason to do NIR. Having a SIMT
architecture would be more around designing a GPU and you'd no longer
be considering it a RISC-V cpu at all that case and running general
purpose tasks would not be a goal.

> Join the Graphics and ML SIG at RISC-V and let us discuss it there.
> First join RISC-V as an individual contributor, strategic member or community member:
> Then join the Graphics and ML SIG through the Working Groups Portal. Feel free to ask for details privately.

Thanks for the info, I'll see if I can manage that, but my time is
pretty stretched out here.


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