hk: optimize out empty dispatches

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Mary Guillemard <mary.guillemard@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34638>

src/asahi/vulkan/hk_cmd_buffer.h

@@ -793,6 +793,9 @@ hk_dispatch_with_local_size(struct hk_cmd_buffer *cmd, struct hk_cs *cs,
                             struct hk_shader *s, struct agx_grid grid,
                             struct agx_workgroup local_size)
 {
+   if (agx_is_shader_empty(&s->b))
+      return;
+
    struct hk_device *dev = hk_cmd_buffer_device(cmd);
    uint32_t usc = hk_upload_usc_words(cmd, s, s->only_linked);
 

src/asahi/vulkan/hk_cmd_dispatch.c

@@ -87,6 +87,9 @@ static void
 dispatch(struct hk_cmd_buffer *cmd, struct agx_grid grid)
 {
    struct hk_shader *s = hk_only_variant(cmd->state.cs.shader);
+   if (agx_is_shader_empty(&s->b))
+      return;
+
    struct hk_cs *cs = hk_cmd_buffer_get_cs(cmd, true /* compute */);
    if (!cs)
       return;