[Mesa-dev] [PATCH 2/2] st/mesa: add GL_ARB_shader_atomic_counter_ops support

[Glenn Kennard]

On Thu, 10 Mar 2016 17:02:15 +0100, Ilia Mirkin <imirkin at alum.mit.edu> wrote:

> On Thu, Mar 10, 2016 at 10:57 AM, Nicolai Hähnle <nhaehnle at gmail.com> wrote:
>>> -   if (c->MaxCombinedAtomicBuffers > 0)
>>> +   if (c->MaxCombinedAtomicBuffers > 0) {
>>>         extensions->ARB_shader_atomic_counters = GL_TRUE;
>>> +      extensions->ARB_shader_atomic_counter_ops = GL_TRUE;
>>> +   }
>>
>>
>> I believe there's pre-GCN AMD hardware which can support atomic counters but
>> not atomic_counter_ops (at least according to what the closed driver
>> exposes, I haven't actually checked the docs), so there should probably be a
>> capability flag here.
>
> I assumed this was due to laziness... seems odd if the SSBO atomic ops
> can be supported, but those same ops can't be supported on atomic
> buffers. Glenn / Dave - do you guys happen to know what the pre-GCN hw
> is capable of?
>
>   -ilia
>

AFAIK Cayman supports atomic counter ops on SSBOs, evergreen only on counter
buffers, and earlier hardware does neither.


/Glenn