[virglrenderer-devel] [PATCH 0/3] TGSI_FILE_HW_ATOMIC support

[Tomeu Vizoso]

On 07/19/2018 09:09 PM, Dave Airlie wrote:
> On 19 July 2018 at 23:41, Tomeu Vizoso <tomeu.vizoso at collabora.com> wrote:
>> Hi,
>>
>> just thought of sending this patches even if it's not the best moment to
>> merge them, just in case anyone is curious. I plan to rebase and resend
>> once SSBO and image support is merged in master.
>>
>> The need for this arises from Gallium otherwise implementing atomic
>> counters with SSBOs and reserving half of the shader blocks for that.
>> This is problematic because some dEQP tests assume that more than 6
>> blocks are available when drivers such as i915 provide 12 in the host.
> 
> I was wondering if we need to this far or could we just detect
> BUFFER[0], ATOMIC decls
> and convert those to atomic counters somehow?
> 
> The TGSI_FILE_HW_ATOMIC stuff is quite attunded to r600 hw atomics, and I'm
> not sure how well it maps to virgl, like it all the tests tpass with
> it, then maybe it
> should be fine.

Yeah, all *atomic_counter* tests in deqp 3.1 pass. I found that the hw 
atomics in TGSI matched quite well the GLSL specs, which is after all 
virgl's hw.

I also liked how similar it is to other decls, but was left a tiny bit 
uneasy by how many similar codepaths there are, to ssbos, images, ubos, 
etc. But I think that adding an abstraction of some sort to save code 
would just make things harder to read.

Cheers,

Tomeu

> Dave.
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