tnl: assert that num_instances > 0

diff --git a/src/mesa/tnl/t_draw.c b/src/mesa/tnl/t_draw.c
index bdb893e..858b828 100644 (file)
--- a/src/mesa/tnl/t_draw.c
+++ b/src/mesa/tnl/t_draw.c
@@ -468,6 +468,8 @@ void _tnl_draw_prims( struct gl_context *ctx,
               break;
         }
 
+         assert(prim[i].num_instances > 0);
+
         /* Binding inputs may imply mapping some vertex buffer objects.
          * They will need to be unmapped below.
          */