[Mesa-dev] [PATCH v3] gallium/util: Break recursion in pipe_resource_reference

[Nicolai Hähnle]

On 14.06.2017 05:39, Michel Dänzer wrote:
> 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.

Did you update the size measurement?


> 
> 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]
> 
> Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>
> ---
>   src/gallium/auxiliary/util/u_inlines.h | 13 ++++++++++++-
>   1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/src/gallium/auxiliary/util/u_inlines.h b/src/gallium/auxiliary/util/u_inlines.h
> index 6a3d5043cf..08326da03d 100644
> --- a/src/gallium/auxiliary/util/u_inlines.h
> +++ b/src/gallium/auxiliary/util/u_inlines.h
> @@ -137,8 +137,19 @@ 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);
> +      struct pipe_resource *next = old_tex->next;
> +
>         old_tex->screen->resource_destroy(old_tex->screen, old_tex);
> +
> +      /* Avoid recursion, which would prevent inlining this function */
> +      while (next) {
> +         old_tex = next;
> +         next = old_tex->next;
> +         old_tex->next = NULL;

Is this really necessary? I don't think so, but if it is, it's probably 
necessary above as well. Either way, it's best to be consistent about it.

Cheers,
Nicolai


> +         if (pipe_reference_described(&old_tex->reference, NULL,
> +                                      (debug_reference_descriptor)debug_describe_resource))
> +            old_tex->screen->resource_destroy(old_tex->screen, old_tex);
> +      }
>      }
>      *ptr = tex;
>   }
> 


-- 
Lerne, wie die Welt wirklich ist,
Aber vergiss niemals, wie sie sein sollte.