[Mesa-dev] [PATCH v4] gallium/util: Break recursion in pipe_resource_reference

[Michel Dänzer]

From: Michel Dänzer <michel.daenzer at amd.com>

It calling itself recursively prevented it from being inlined, resulting
in a copy being generated in every compilation unit referencing it. This
bloated the text segment of the Gallium mega-driver *_dri.so by ~4%,
and might also have impacted performance.

Fixes: ecd6fce2611e ("mesa/st: support lowering multi-planar YUV")
v2:
* Add comment above pipe_resource_next_reference [Samuel Pitoiset]
v3:
* Use loop to unreference the full chain of resources referenced via
  the next members [Timothy Arceri]
v4:
* Stop chasing ->next chain at the first sub-resource which isn't
  destroyed [Nicolai Hähnle]

Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>
---
 src/gallium/auxiliary/util/u_inlines.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/gallium/auxiliary/util/u_inlines.h b/src/gallium/auxiliary/util/u_inlines.h
index 6a3d5043cf..4fc683a574 100644
--- a/src/gallium/auxiliary/util/u_inlines.h
+++ b/src/gallium/auxiliary/util/u_inlines.h
@@ -137,8 +137,14 @@ pipe_resource_reference(struct pipe_resource **ptr, struct pipe_resource *tex)
 
    if (pipe_reference_described(&(*ptr)->reference, &tex->reference, 
                                 (debug_reference_descriptor)debug_describe_resource)) {
-      pipe_resource_reference(&old_tex->next, NULL);
-      old_tex->screen->resource_destroy(old_tex->screen, old_tex);
+      /* Avoid recursion, which would prevent inlining this function */
+      do {
+         struct pipe_resource *next = old_tex->next;
+
+         old_tex->screen->resource_destroy(old_tex->screen, old_tex);
+         old_tex = next;
+      } while (pipe_reference_described(&old_tex->reference, NULL,
+                                        (debug_reference_descriptor)debug_describe_resource));
    }
    *ptr = tex;
 }
-- 
2.11.0