[Mesa-dev] [PATCH] i965: fix transform feedback with primitive restart

[Ian Romanick]

On 06/28/2012 04:12 PM, Jordan Justen wrote:
> When querying GL_PRIMITIVES_GENERATED, if primitive restart
> is also used, then take the software primitive restart
> path so GL_PRIMITIVES_GENERATED is returned correctly.
>
> GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN is also updated
> since it will also affected by the same issue.
>
> As noted in brw_primitive_restart.c, with further work we
> should be able to move this situation back to a hardware
> handled path.
>
> Signed-off-by: Jordan Justen<jordan.l.justen at intel.com>

Do we have piglit tests for this case?  Is it safe to assume that they 
fail without but pass with this patch?

> ---
>   src/mesa/drivers/dri/i965/brw_context.h           |    2 ++
>   src/mesa/drivers/dri/i965/brw_primitive_restart.c |   12 ++++++++++++
>   src/mesa/drivers/dri/i965/brw_queryobj.c          |    4 ++++
>   3 files changed, 18 insertions(+)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
> index 2c9f5ad..ee860f3 100644
> --- a/src/mesa/drivers/dri/i965/brw_context.h
> +++ b/src/mesa/drivers/dri/i965/brw_context.h
> @@ -1037,7 +1037,9 @@ struct brw_context
>         uint32_t svbi_0_max_index;
>         uint32_t offset_0_batch_start;
>         uint32_t primitives_generated;
> +      bool counting_primitives_generated;
>         uint32_t primitives_written;
> +      bool counting_primitives_written;

These should be grouped together for better packing.

>      } sol;
>
>      uint32_t render_target_format[MESA_FORMAT_COUNT];
> diff --git a/src/mesa/drivers/dri/i965/brw_primitive_restart.c b/src/mesa/drivers/dri/i965/brw_primitive_restart.c
> index 962ff18..02deba4 100644
> --- a/src/mesa/drivers/dri/i965/brw_primitive_restart.c
> +++ b/src/mesa/drivers/dri/i965/brw_primitive_restart.c
> @@ -69,6 +69,18 @@ can_cut_index_handle_prims(struct gl_context *ctx,
>                              GLuint nr_prims,
>                              const struct _mesa_index_buffer *ib)
>   {
> +   struct brw_context *brw = brw_context(ctx);
> +
> +   if (brw->sol.counting_primitives_generated ||
> +       brw->sol.counting_primitives_written) {
> +      /* Counting primitives generated in hardware is not currently
> +       * supported, so take the software path. We need to investigate
> +       * the *_PRIMITIVES_COUNT registers to allow this to be handled
> +       * entirely in hardware.
> +       */
> +      return false;
> +   }
> +
>      if (!can_cut_index_handle_restart_index(ctx, ib)) {
>         /* The primitive restart index can't be handled, so take
>          * the software path
> diff --git a/src/mesa/drivers/dri/i965/brw_queryobj.c b/src/mesa/drivers/dri/i965/brw_queryobj.c
> index 72b83f4..240fe32 100644
> --- a/src/mesa/drivers/dri/i965/brw_queryobj.c
> +++ b/src/mesa/drivers/dri/i965/brw_queryobj.c
> @@ -171,6 +171,7 @@ brw_begin_query(struct gl_context *ctx, struct gl_query_object *q)
>          * it a software counter.  So just reset the counter.
>          */
>         brw->sol.primitives_generated = 0;
> +      brw->sol.counting_primitives_generated = true;
>         break;
>
>      case GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN:
> @@ -178,6 +179,7 @@ brw_begin_query(struct gl_context *ctx, struct gl_query_object *q)
>          * it a software counter.  So just reset the counter.
>          */
>         brw->sol.primitives_written = 0;
> +      brw->sol.counting_primitives_written = true;
>         break;
>
>      default:
> @@ -249,6 +251,7 @@ brw_end_query(struct gl_context *ctx, struct gl_query_object *q)
>          * the query object.
>          */
>         query->Base.Result = brw->sol.primitives_generated;
> +      brw->sol.counting_primitives_generated = false;
>
>         /* And set brw->query.obj to NULL so that this query won't try to wait
>          * for any rendering to complete.
> @@ -262,6 +265,7 @@ brw_end_query(struct gl_context *ctx, struct gl_query_object *q)
>          * the query object.
>          */
>         query->Base.Result = brw->sol.primitives_written;
> +      brw->sol.counting_primitives_written = false;
>
>         /* And set brw->query.obj to NULL so that this query won't try to wait
>          * for any rendering to complete.