[Mesa-dev] [Piglit] [RFC PATCH] arb_texture_barrier: call glTextureBarrier after each glDrawRangeElements

[Ilia Mirkin]

On Fri, Jun 24, 2016 at 2:56 PM, Alejandro Piñeiro <apinheiro at igalia.com> wrote:
> On 24/06/16 17:15, Ilia Mirkin wrote:
>> On Fri, Jun 24, 2016 at 10:42 AM, Alejandro Piñeiro
>> <apinheiro at igalia.com> wrote:
>>>
>>> On 24/06/16 12:17, Nicolai Hähnle wrote:
>>>> Hi Alejandro,
>>> Hi, thanks for the quick answer, more comments below.
>>>
>>>> my understanding of the spec is that the test should be correct as
>>>> originally written, i.e. with glTextureBarrier only between full
>>>> rectangle draws.
>>>>
>>>> FWIW, radeonsi passes the test as-is
>>> So on radeon-si all the 48 subtests (parameter combination of the base
>>> test) passes correctly?
>>>
>>>> (though I reduced the GLSL version requirement, which I'd ask you to
>>>> change as well before you push the test).
>>> It is ok to reduce the GLSL requirement from 440 to 400? If not I would
>>> need to change the loop on the shader.
>> Why not just use 330 so that it can run on all Intel GPUs? You just
>> need GL_ARB_gpu_shader5 right (for "indirect" texture access)? That's
>> supported on IVB+, and does not require fp64 support.
>
> Sounds good, thanks for the suggestion. Just sent a v2 patch to the
> piglit list downgrading the GLSL version need. Having said so, my
> question about the spec is still in the air, although after Nicolai
> feedback, it seems that the problem is on mesa for Intel drivers. Next
> Monday will try to run the test with other drivers and cards, with and
> without the patch.

I haven't carefully read what your test does. But what
NV_texture_barrier (and ARB_texture_barrier which is identical) do is
allow you to rasterize each pixel at most once in between barriers,
and still have the expectation that everything is OK. If your test
causes any pixels to have overdraw, then that is going into undefined
territory. If each pixel is only ever rasterized once between
barriers, the output should be well-defined.

  -ilia