gallium: move pipe_draw_info::start/count to the beginning and pad empty space

for memcmp and merging draw calls

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7056>

src/gallium/include/pipe/p_state.h

@@ -726,12 +726,6 @@ struct pipe_draw_indirect_info
  */
 struct pipe_draw_info
 {
-   ubyte index_size;  /**< if 0, the draw is not indexed. */
-   enum pipe_prim_type mode:8;  /**< the mode of the primitive */
-   unsigned primitive_restart:1;
-   unsigned has_user_indices:1; /**< if true, use index.user_buffer */
-   ubyte vertices_per_patch; /**< the number of vertices per patch */
-
    /**
     * Direct draws: start is the index of the first vertex
     * Non-indexed indirect draws: not used
@@ -740,6 +734,13 @@ struct pipe_draw_info
    unsigned start;
    unsigned count;  /**< number of vertices */
 
+   enum pipe_prim_type mode:8;  /**< the mode of the primitive */
+   ubyte vertices_per_patch; /**< the number of vertices per patch */
+   ubyte index_size;  /**< if 0, the draw is not indexed. */
+   bool primitive_restart:1;
+   bool has_user_indices:1; /**< if true, use index.user_buffer */
+   char _pad:6;             /**< padding for memcmp */
+
    unsigned start_instance; /**< first instance id */
    unsigned instance_count; /**< number of instances */
 

src/mesa/state_tracker/st_draw.c

@@ -183,6 +183,7 @@ st_draw_vbo(struct gl_context *ctx,
    info.restart_index = 0;
    info.start_instance = base_instance;
    info.instance_count = num_instances;
+   info._pad = 0;
 
    if (ib) {
       struct gl_buffer_object *bufobj = ib->obj;