[Mesa-dev] [PATCH] draw: fix key comparison with uninitialized value

[Brian Paul]

On 01/12/2016 10:49 AM, sroland at vmware.com wrote:
> From: Roland Scheidegger <sroland at vmware.com>
>
> Discovered by accident, valgrind was complaining (could have possibly caused
> us to create redundant geometry shader variants).
>
> v2: convinced by Brian and Jose, just use memset for both gs and vs keys,
> just as easy and less error prone.
> ---
>   src/gallium/auxiliary/draw/draw_llvm.c | 5 ++++-
>   src/gallium/auxiliary/draw/draw_llvm.h | 7 ++-----
>   2 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/src/gallium/auxiliary/draw/draw_llvm.c b/src/gallium/auxiliary/draw/draw_llvm.c
> index f25dafe..142d78a 100644
> --- a/src/gallium/auxiliary/draw/draw_llvm.c
> +++ b/src/gallium/auxiliary/draw/draw_llvm.c
> @@ -1861,6 +1861,8 @@ draw_llvm_make_variant_key(struct draw_llvm *llvm, char *store)
>
>      key = (struct draw_llvm_variant_key *)store;
>
> +   memset(key, 0, offsetof(struct draw_llvm_variant_key, vertex_element[0]));
> +
>      key->clamp_vertex_color = llvm->draw->rasterizer->clamp_vertex_color; /**/
>
>      /* Presumably all variants of the shader should have the same
> @@ -1883,7 +1885,6 @@ draw_llvm_make_variant_key(struct draw_llvm *llvm, char *store)
>      key->ucp_enable = llvm->draw->rasterizer->clip_plane_enable;
>      key->has_gs = llvm->draw->gs.geometry_shader != NULL;
>      key->num_outputs = draw_total_vs_outputs(llvm->draw);
> -   key->pad1 = 0;
>
>      /* All variants of this shader will have the same value for
>       * nr_samplers.  Not yet trying to compact away holes in the
> @@ -2315,6 +2316,8 @@ draw_gs_llvm_make_variant_key(struct draw_llvm *llvm, char *store)
>
>      key = (struct draw_gs_llvm_variant_key *)store;
>
> +   memset(key, 0, offsetof(struct draw_gs_llvm_variant_key, samplers[0]));
> +
>      key->num_outputs = draw_total_gs_outputs(llvm->draw);
>
>      /* All variants of this shader will have the same value for
> diff --git a/src/gallium/auxiliary/draw/draw_llvm.h b/src/gallium/auxiliary/draw/draw_llvm.h
> index f617a29..271433c 100644
> --- a/src/gallium/auxiliary/draw/draw_llvm.h
> +++ b/src/gallium/auxiliary/draw/draw_llvm.h
> @@ -311,12 +311,8 @@ struct draw_llvm_variant_key
>      unsigned need_edgeflags:1;
>      unsigned has_gs:1;
>      unsigned num_outputs:8;
> -   /*
> -    * it is important there are no holes in this struct
> -    * (and all padding gets zeroed).
> -    */
>      unsigned ucp_enable:PIPE_MAX_CLIP_PLANES;
> -   unsigned pad1:24-PIPE_MAX_CLIP_PLANES;
> +   /* note padding here - must use memset */
>
>      /* Variable number of vertex elements:
>       */
> @@ -332,6 +328,7 @@ struct draw_gs_llvm_variant_key
>      unsigned nr_samplers:8;
>      unsigned nr_sampler_views:8;
>      unsigned num_outputs:8;
> +   /* note padding here - must use memset */
>
>      struct draw_sampler_static_state samplers[1];
>   };
>

Reviewed-by: Brian Paul <brianp at vmware.com>