[Mesa-dev] [PATCH 06/11] glsl: add SYSTEM_VALUE_VERTEX_CNT

[Ilia Mirkin]

On Wed, Sep 16, 2015 at 7:30 PM, Rob Clark <robdclark at gmail.com> wrote:
> On Sun, Sep 13, 2015 at 11:51 AM, Rob Clark <robdclark at gmail.com> wrote:
>> From: Rob Clark <robclark at freedesktop.org>
>>
>> Used internally in freedreno/ir3 to calc stream-out position.  Seems
>> like a generic enough way to implement stream-out (using str instrs),
>> plus it avoids compiler warnings by sneaking in a non-enum value in
>> switch statements.
>>
>> Signed-off-by: Rob Clark <robclark at freedesktop.org>
>
> Anyone got any strong opinions about this?  At least a Meh'd-by?  I'd
> like to push the freedreno/ir3 conversion to
> varying_slot_/frag_result_/etc, but need a way to handle my internal
> vtxcnt sysval, but don't want to step on any toes..
>
> I could alternatively do something like SYSTEM_VALUE_DRIVERn which
> gets re-#defined in freedreno/ir3?

It's definitely a bit weird to define these driver-specific things
that generic things know nothing about. I think it made a lot more
sense when it was completely driver-private with a TGSI semantic. Any
reason you can't just do that here? Start defining private ones
starting at SYSTEM_VALUE_MAX?

>
> BR,
> -R
>
>> ---
>>  src/glsl/shader_enums.h | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/src/glsl/shader_enums.h b/src/glsl/shader_enums.h
>> index d054b87..fb4bcd0 100644
>> --- a/src/glsl/shader_enums.h
>> +++ b/src/glsl/shader_enums.h
>> @@ -402,6 +402,12 @@ typedef enum
>>     SYSTEM_VALUE_TESS_LEVEL_INNER, /**< TES input */
>>     /*@}*/
>>
>> +   /**
>> +    * Driver internal vertex-count, used (for example) for drivers to
>> +    * calculate stride for stream-out outputs.  Not externally visible.
>> +    */
>> +   SYSTEM_VALUE_VERTEX_CNT,
>> +
>>     SYSTEM_VALUE_MAX             /**< Number of values */
>>  } gl_system_value;
>>
>> --
>> 2.4.3
>>
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