[Mesa-dev] [RFC 09/21] mesa: Generate a helper function for each extension

[Chad Versace]

On Mon 19 Oct 2015, Nanley Chery wrote:
> From: Nanley Chery <nanley.g.chery at intel.com>
> 
> Generate functions which determine if an extension is supported in the
> current context. Initially, enums were going to be explicitly used with
> _mesa_extension_supported(). The idea to embed the function and enums
> into generated helper functions was suggested by Kristian Høgsberg.
> 
> For performance, the function body no longer uses
> _mesa_extension_supported() and, as suggested by Chad Versace, the
> functions are also declared static inline.
> 
> Signed-off-by: Nanley Chery <nanley.g.chery at intel.com>
> ---
>  src/mesa/main/context.h    |  1 +
>  src/mesa/main/extensions.c | 22 +---------------------
>  src/mesa/main/extensions.h | 39 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 41 insertions(+), 21 deletions(-)

[...]

> diff --git a/src/mesa/main/extensions.h b/src/mesa/main/extensions.h
> index 595512a..24cc04d 100644
> --- a/src/mesa/main/extensions.h
> +++ b/src/mesa/main/extensions.h
> @@ -55,6 +55,45 @@ _mesa_get_extension_count(struct gl_context *ctx);
>  extern const GLubyte *
>  _mesa_get_enabled_extension(struct gl_context *ctx, GLuint index);
>  
> +
> +/**
> + * \brief An element of the \c extension_table.
> + */
> +struct extension {

In addition to Marek's comment, the struct should be prefixed too.

> +   /** Name of extension, such as "GL_ARB_depth_clamp". */
> +   const char *name;
> +
> +   /** Offset (in bytes) of the corresponding member in struct gl_extensions. */
> +   size_t offset;
> +
> +   /** Minimum version the extension requires for the given API
> +    * (see gl_api defined in mtypes.h)
> +    */
> +   GLuint version[API_OPENGL_LAST + 1];
> +
> +   /** Year the extension was proposed or approved.  Used to sort the 
> +    * extension string chronologically. */
> +   uint16_t year;
> +} extern const extension_table[];

[...]

> +/** Checks if the context suports a user-facing extension */
> +#define EXT(name_str, driver_cap, ...) \
> +static inline bool _mesa_has_##name_str(const struct gl_context *ctx) { \
> +      return ctx->Extensions.driver_cap && (ctx->Version >= \
> +             extension_table[MESA_EXTENSION_##name_str].version[ctx->API]); \
> +}
> +#include "extensions_table.h"
> +#undef EXT

The function should be formatted like this, to follow Mesa style:

  |static inline bool
  |_mesa_has_foo(...)
  |{
  |   ...
  |}