Re: Vector element groups

Abel Bernabeu


Sorry it took me a long time to provide feedback.

Yes, this is the kind of feature we could need for graphics and GPGPU-style SIMT. Many thanks for taking the time to think about how the idea behind Zediv can be introduced.

This is the kind of concept that is needed for designing with vectors for things that are typically designed with warps.

One comment I have is that groups of 3 elements are not power of two and turn out to be:
- popular for graphics
- demanded by OpenCL as well

Is there anything we can do from the graphics SIG to help drive this work?


On Fri, Jul 22, 2022 at 10:36 AM Krste Asanovic <krste@...> wrote:

>>>>> On Fri, 15 Jul 2022 09:10:49 -0700, Earl Killian <earl.killian@...> said:
| While I share some concern about the cited language, as this is a concept, and not a spec, I think the time to require checking
| would be when individual specs implement the concept. I would think it would require some pretty good justification to not have
| an exception.

On further thought, I do think it makes sense to require raising of an
illegal instruction exception when vl is not a multiple of element
group size rather than leaving reserved.  Will be updating the doc
with rationale.


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