RISC-V Vector 1.0 Support: If and where to start?

[JakeSaphhire]

Hello,

RISC-V's Vector extension was ratified a few years back and recently vector-supporting boards have come out, many based on the octo-core Spacemit K1/M1. I have been using one such board for a while now, with gnuradio and more, but the performance is quite lacking: when profiling with volk_profile, the generic is around an order of magnitude faster than the alternatives

All that to say, I think RVV 1.0 has many instructions useful for volk and I am willing to help but I have no idea where to start. If this is in the project's plans, is there a roadmap?

[jdemel]

Thanks for your interest in the topic.

We don't have a fixed roadmap. Though, we're interested in adding support for as many platforms as possible, as long as this is supportable. Risc-V checks all those boxes.

We build and test on Risc-V already. Next steps that would be great to tackle are

• add another Risc-V machine with the vector extension enabled. Smth like the -mavx flags for x86.
• Add checks to dynamically detect the presence of the vector extension, preferably via cpu_features
• Start to add kernels that use Risc-V vector intrinsics.

Especially, the infrastructure together with a first kernel for Risc-V would be great. More optimized kernels should be addable way easier afterwards. Depending on the compiler, it may be already very beneficial to have the extension and vector machine available. That needs benchmarking of course.

[balister]

What compiler are you using? I'm told gcc 14 has support for riscv vector instructions.