[Mesa-dev] [PATCH 15/19] i965: Change type of brw_context.primitive from GLenum to hardware primitive

[Eric Anholt]

On Fri, 23 Sep 2011 17:37:45 -0700, Chad Versace <chad at chad-versace.us> wrote:
> For example, GL_TRIANLES is converted to _3DPRIM_TRILIST.

missing a "G"

> -static const GLenum reduced_prim[GL_POLYGON+1] = {  
> -   GL_POINTS,
> -   GL_LINES,
> -   GL_LINES,
> -   GL_LINES,
> -   GL_TRIANGLES,
> -   GL_TRIANGLES,
> -   GL_TRIANGLES,
> -   GL_TRIANGLES,
> -   GL_TRIANGLES,
> -   GL_TRIANGLES
> +static const GLenum
> +brw_get_reduced_prim(uint32_t hw_prim)
> +{
> +   switch (hw_prim) {
> +   case _3DPRIM_POINTLIST:  return GL_POINTS;
> +   case _3DPRIM_LINELIST:   return GL_LINES;
> +   case _3DPRIM_LINELOOP:   return GL_LINES;
> +   case _3DPRIM_LINESTRIP:  return GL_LINES;
> +   case _3DPRIM_TRILIST:    return GL_TRIANGLES;
> +   case _3DPRIM_TRISTRIP:   return GL_TRIANGLES;
> +   case _3DPRIM_TRIFAN:     return GL_TRIANGLES;
> +   case _3DPRIM_QUADLIST:   return GL_TRIANGLES;
> +   case _3DPRIM_QUADSTRIP:  return GL_TRIANGLES;
> +   case _3DPRIM_POLYGON:    return GL_TRIANGLES;
> +   default:                 assert(0); return 0;
> +   }
>  };

I always get scared by changes from tables to switch statements in hot
paths because I don't trust gcc.  I haven't tested to see whether it
does the wrong thing, though.

> @@ -79,41 +83,40 @@ static const GLenum reduced_prim[GL_POLYGON+1] = {
>   * programs be immune to the active primitive (ie. cope with all
>   * possibilities).  That may not be realistic however.
>   */
> -static GLuint brw_set_prim(struct brw_context *brw,
> +static void brw_set_prim(struct brw_context *brw,
>  			   const struct _mesa_prim *prim)
>  {
>     struct gl_context *ctx = &brw->intel.ctx;
> -   GLenum mode = prim->mode;
> +   uint32_t hw_prim;
>  
>     DBG("PRIM: %s\n", _mesa_lookup_enum_by_nr(prim->mode));
>  
>     /* Slight optimization to avoid the GS program when not needed:
>      */
> -   if (mode == GL_QUAD_STRIP &&
> -       ctx->Light.ShadeModel != GL_FLAT &&
> -       ctx->Polygon.FrontMode == GL_FILL &&
> -       ctx->Polygon.BackMode == GL_FILL)
> -      mode = GL_TRIANGLE_STRIP;
> -
> -   if (prim->mode == GL_QUADS && prim->count == 4 &&
> +   if (prim->mode == GL_QUAD_STRIP &&
>         ctx->Light.ShadeModel != GL_FLAT &&
>         ctx->Polygon.FrontMode == GL_FILL &&
>         ctx->Polygon.BackMode == GL_FILL) {
> -      mode = GL_TRIANGLE_FAN;
> +      hw_prim = _3DPRIM_TRISTRIP;
> +   } else if (prim->mode == GL_QUADS && prim->count == 4 &&
> +	      ctx->Light.ShadeModel != GL_FLAT &&
> +	      ctx->Polygon.FrontMode == GL_FILL &&
> +	      ctx->Polygon.BackMode == GL_FILL) {
> +      hw_prim = _3DPRIM_TRIFAN;
> +   } else {
> +      hw_prim = prim_to_hw_prim[prim->mode];
>     }

Hmm, you know, this little optimization only matters to pre-snb (I would
guess that it's a marginally bad thing on snb).  That doesn't leave much
of this function shared between the two.

> -   if (mode != brw->primitive) {
> -      brw->primitive = mode;
> +   if (hw_prim != brw->primitive) {
> +      brw->primitive = hw_prim;
>        brw->state.dirty.brw |= BRW_NEW_PRIMITIVE;
>  
>        if (brw->intel.gen < 6 &&
> -	  reduced_prim[mode] != brw->intel.reduced_primitive) {
> -	 brw->intel.reduced_primitive = reduced_prim[mode];
> +	  brw->intel.reduced_primitive != brw_get_reduced_prim(hw_prim)) {
> +	 brw->intel.reduced_primitive = brw_get_reduced_prim(hw_prim);
>  	 brw->state.dirty.brw |= BRW_NEW_REDUCED_PRIMITIVE;
>        }
>     }
> -
> -   return prim_to_hw_prim[mode];
>  }
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