[Mesa-dev] [PATCH 1/3] gallium: add PIPE_CAP_SIGNED_VERTEX_BUFFER_OFFSET

[Ilia Mirkin]

On Thu, Oct 26, 2017 at 1:23 PM, Eric Anholt <eric at anholt.net> wrote:
> Marek Olšák <maraeo at gmail.com> writes:
>
>> From: Marek Olšák <marek.olsak at amd.com>
>
> Could you hit vc5, as well?
>
> I'm not clear on why this is a pipe_cap instead of just updating type or
> comments on the pipe structs to say what the new behavior is -- aren't
> most of us using 32-bit math that will wrap the same on addition?

I think it has to be signed everywhere, to support e.g. the negative
offsets passed in by some piglits. I remember a while ago I had to fix
a bug in translate code: 3de97ce9200e9fe96891e7e92ec83f0fc38d8693

draw-elements-base-vertex-neg is a good test for this. (Note that
nouveau does not use u_vbuf.)

  -ilia