[Libre-soc-dev] results of phone call about simple-v prefix

[Lauri Kasanen]

On Fri, 27 Nov 2020 14:41:11 -0800
Jacob Lifshay <programmerjake at gmail.com> wrote:

> most other applications for SVP don't need to change vector length
> that often -- GPU shaders would set it at the beginning of the shader and
> not change it for the rest of the shader. Video stuff would probably not
> need to constantly change VL as well, since the most common operations
> would work on large blocks (8x8 or bigger) leaving plenty of time to change
> VL since the processor is multi-issue. We do need to double check with
> those working on Video.

Commonly the vector length won't change often. There are cases where it
would change inside a loop, say gathering data about a block to a
smaller block, then processing that smaller block. It's probably fine
to have an instruction change it.

- Lauri