[Mesa-dev] [PATCH 3/3] mesa: optimize _mesa_attr_zero_aliases_vertex()

[Marek Olšák]

For the series:

Reviewed-by: Marek Olšák <marek.olsak at amd.com>

Marek

On Mon, Aug 21, 2017 at 8:56 PM, Brian Paul <brianp at vmware.com> wrote:
> After the context is initialized, the API and context flags won't
> change.  So, we can compute whether vertex attribute 0 aliases
> vertex position just once.
>
> This should make the glVertexAttrib*() functions a little quicker.
>
> No Piglit regressions with llvmpipe.
> ---
>  src/mesa/main/context.c | 17 +++++++++++++++++
>  src/mesa/main/mtypes.h  |  3 +++
>  src/mesa/main/varray.h  | 14 ++------------
>  3 files changed, 22 insertions(+), 12 deletions(-)
>
> diff --git a/src/mesa/main/context.c b/src/mesa/main/context.c
> index b4b7b6e..842edf0 100644
> --- a/src/mesa/main/context.c
> +++ b/src/mesa/main/context.c
> @@ -1607,6 +1607,23 @@ handle_first_current(struct gl_context *ctx)
>        }
>     }
>
> +   /* Determine if generic vertex attribute 0 alias the conventional
> +    * glVertex position.
> +    */
> +   {
> +      const bool is_forward_compatible_context =
> +         ctx->Const.ContextFlags & GL_CONTEXT_FLAG_FORWARD_COMPATIBLE_BIT;
> +
> +      /* In OpenGL 3.1 attribute 0 becomes non-magic, just like in OpenGL ES
> +       * 2.0.  Note that we cannot just check for API_OPENGL_COMPAT here because
> +       * that will erroneously allow this usage in a 3.0 forward-compatible
> +       * context too.
> +       */
> +      ctx->AttribZeroAliasesVertex = (ctx->API == API_OPENGLES
> +                                      || (ctx->API == API_OPENGL_COMPAT
> +                                          && !is_forward_compatible_context));
> +   }
> +
>     /* We can use this to help debug user's problems.  Tell them to set
>      * the MESA_INFO env variable before running their app.  Then the
>      * first time each context is made current we'll print some useful
> diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
> index 49eb7d5..a8fa045 100644
> --- a/src/mesa/main/mtypes.h
> +++ b/src/mesa/main/mtypes.h
> @@ -4972,6 +4972,9 @@ struct gl_context
>     GLboolean RasterDiscard;  /**< GL_RASTERIZER_DISCARD */
>     GLboolean IntelConservativeRasterization; /**< GL_INTEL_CONSERVATIVE_RASTERIZATION */
>
> +   /** Does glVertexAttrib(0) alias glVertex()? */
> +   bool AttribZeroAliasesVertex;
> +
>     /**
>      * \name Hooks for module contexts.
>      *
> diff --git a/src/mesa/main/varray.h b/src/mesa/main/varray.h
> index 730f7cf..ba74ae6 100644
> --- a/src/mesa/main/varray.h
> +++ b/src/mesa/main/varray.h
> @@ -73,19 +73,9 @@ _mesa_update_client_array(struct gl_context *ctx,
>  }
>
>  static inline bool
> -_mesa_attr_zero_aliases_vertex(struct gl_context *ctx)
> +_mesa_attr_zero_aliases_vertex(const struct gl_context *ctx)
>  {
> -   const bool is_forward_compatible_context =
> -      ctx->Const.ContextFlags & GL_CONTEXT_FLAG_FORWARD_COMPATIBLE_BIT;
> -
> -   /* In OpenGL 3.1 attribute 0 becomes non-magic, just like in OpenGL ES
> -    * 2.0.  Note that we cannot just check for API_OPENGL_COMPAT here because
> -    * that will erroneously allow this usage in a 3.0 forward-compatible
> -    * context too.
> -    */
> -   return (ctx->API == API_OPENGLES
> -           || (ctx->API == API_OPENGL_COMPAT
> -               && !is_forward_compatible_context));
> +   return ctx->AttribZeroAliasesVertex;
>  }
>
>  extern void
> --
> 1.9.1
>
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