vc4: Just stream out fallback IB contents.

The idea I had when I wrote the original shadow code was that you'd see a
set_index_buffer to the IB, then a bunch of draws out of it.  What's
actually happening in openarena is that set_index_buffer occurs at every
draw, so we end up making a new shadow BO every time, and converting more
of the BO than is actually used in the draw.

While I could maybe come up with a better caching scheme, for now just
do the simple thing that doesn't result in a new shadow IB allocation
per draw.

Improves performance of isosurf in drawelements mode by 58.7967% +/-
3.86152% (n=8).

1 files changed, 4 insertions, 2 deletions

diff --git a/src/gallium/drivers/vc4/vc4_resource.h b/src/gallium/drivers/vc4/vc4_resource.h
index 2ed848bc7b9..b3cba8f2f65 100644
--- a/src/gallium/drivers/vc4/vc4_resource.h
+++ b/src/gallium/drivers/vc4/vc4_resource.h
@@ -107,8 +107,10 @@ struct pipe_resource *vc4_resource_create(struct pipe_screen *pscreen,
                                           const struct pipe_resource *tmpl);
 void vc4_update_shadow_baselevel_texture(struct pipe_context *pctx,
                                          struct pipe_sampler_view *view);
-void vc4_update_shadow_index_buffer(struct pipe_context *pctx,
-                                    const struct pipe_index_buffer *ib);
+struct pipe_resource *vc4_get_shadow_index_buffer(struct pipe_context *pctx,
+                                                  const struct pipe_index_buffer *ib,
+                                                  uint32_t count,
+                                                  uint32_t *offset);
 void vc4_dump_surface(struct pipe_surface *psurf);
 
 #endif /* VC4_RESOURCE_H */