[Libre-soc-dev] MVL unclear

[Lauri Kasanen]

On Fri, 21 May 2021 14:58:29 +0300
Lauri Kasanen <cand at gmx.com> wrote:

> > it's basically absolutely essentlal, and has been a fundamental part
> > of Cray-style Vectors for decades.
>
> Sorry, still not understanding why is it essential. To my reading, it's
> a completely useless duplication of VL, because you end up calling
> setvl with VL=MVL every time.

So after looking at it at all angles, all I see is a possible loop
optimization? Saving a couple instructions in the loop counter setting.

If you use it to prevent a user-supplied value from overwriting other
registers, that's just bad design, you need to check user-supplied
values anyway.

Is this correct?

- Lauri