[Mesa-dev] [PATCH 2/3] i965: Set dirty state for brw_draw_upload.c when num_instances changes.

[Kenneth Graunke]

On 10/31/2012 02:26 PM, Eric Anholt wrote:
> Otherwise, if we had a set of prims passed in with a num_instances varying
> between them, we wouldn't upload enough (or too much!) from user vertex
> arrays.
> ---
>   src/mesa/drivers/dri/i965/brw_draw.c |    5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_draw.c b/src/mesa/drivers/dri/i965/brw_draw.c
> index 1cfba29..22d18f9 100644
> --- a/src/mesa/drivers/dri/i965/brw_draw.c
> +++ b/src/mesa/drivers/dri/i965/brw_draw.c
> @@ -474,7 +474,10 @@ static bool brw_try_draw_prims( struct gl_context *ctx,
>         intel_batchbuffer_require_space(intel, estimated_max_prim_size, false);
>         intel_batchbuffer_save_state(intel);
>
> -      brw->num_instances = prim->num_instances;
> +      if (brw->num_instances != prim->num_instances) {
> +         brw->num_instances = prim->num_instances;
> +         brw->state.dirty.brw |= BRW_NEW_VERTICES;
> +      }
>         if (intel->gen < 6)
>   	 brw_set_prim(brw, &prim[i]);
>         else

I agree that BRW_NEW_VERTICES needs to be changed when num_instances 
changes.  However, it's already unconditionally flagged above:

    brw->vb.min_index = min_index;
    brw->vb.max_index = max_index;
    brw->state.dirty.brw |= BRW_NEW_VERTICES;

So I don't think you'll be able to observe any problems.  That said, I 
approve of this change anyway, because it's self-documentating and 
guards against potential problems.

For the series:
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>