[llvm-dev] How to support different versions of RVV ?

Alex Bradbury via llvm-dev
Mon, 05 Jul 2021 12:23:17 -0000

On Mon, 28 Jun 2021 at 03:04, 陆旭凡 via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
>
> Hello everyone. RVV 0.10 is now supported on the upstream LLVM RISC-V
backend. However, because some RISC-V-based chip manufacturers chose RVV 0.71
version as the vector extension at the beginning, and a large number of chips
that supported RVV 0.71 version are taped out. So can the community explore a
way or framework to support different versions of RVV?

Hi - please see here
<https://lists.llvm.org/pipermail/llvm-dev/2020-January/138364.html>
for a discussion on the standard policy for accepting not-yet-ratified
extensions. In the ideal case we wouldn't need to support pre-ratified
versions of the specification (as you've noted, the V support is
currently behind an experimental flag and we track the latest version
of the spec). However, I recognise there are cases where we may need
to be more flexible. The question comes down to how many potential
users there would be for RVV 0.71 support, who would be committing
resources to maintaining, and a consideration of any other costs of
trying to support multiple incompatible RVV versions simultaneously.

Do you have any more information on the chips targeting RVV 0.71?

Best,

Alex