[Mesa-dev] [PATCH 1/2] tgsi: add texture-type info to texture instructions

[Rob Clark]

On Thu, Jun 4, 2015 at 3:22 PM, Rob Clark <robdclark at gmail.com> wrote:
> On Thu, Jun 4, 2015 at 3:11 PM, Jose Fonseca <jfonseca at vmware.com> wrote:
>> On 04/06/15 19:50, Rob Clark wrote:
>>>
>>> On Thu, Jun 4, 2015 at 2:14 PM, Jose Fonseca <jfonseca at vmware.com> wrote:
>>>>
>>>> I think we had a discussion about this on mesa3d-dev a while ago.  I
>>>> don't
>>>> recall the conclusions but I wish I did.
>>>>
>>>> We have tgsi_return_type.  Why isn't this enough?  Or better, why isn't
>>>> being used for this?
>>>
>>>
>>> mostly arbitrary reasons.. the unorm/snorm values don't really make
>>> sense here, so it didn't quite seem to fit (plus would have needed
>>> another bit, although I guess that isn't really an issue)
>>>
>>> Or if the question was, why not include the type information in the
>>> decl rather than the instr?  Well.. that at least is more awkward for
>>> the implementation, since the information is part of the instruction
>>> for both GLSL IR and NIR (and at the end of the day, that is also
>>> where I need the info in my compiler)
>>
>>
>> IIUC, GLSL also has this information readily available in the sampler
>> declaration:
>>
>>   uniform  sampler2D ftex;
>>   uniform isampler2D itex;
>>   uniform usampler2D utex;
>>
>> So isn't this a double standard?  After all, if the argument here is
>>
>>   "GLSL IR / NIR has this info readily available, so let's pass it to the
>> TGSI",
>>
>> then the same rationale should apply to
>>
>>   "GLSL has this info readily available on the sampler declaration, so lets'
>> pass it to GLSL IR/NIR 's declarations."
>>
>
> ok, possibly GLSL IR has this info also in the decl.. tbh I'm not a
> GLSL IR expert.  I just figured out my way around since I know where I
> want the info in NIR, and then looked at where it came from in
> glsl_to_nir.
>
> But at any rate, NIR only has it on the tex instruction.  So my point
> about having it in the decl making it more akward for tgsi-to-nir and
> my compiler still stands. ;-)
>
>>
>> I want to avoid having two places for this info in TGSI: in decl and in
>> instruction, as that's a recipe for bugs and complexity.  _Specially_ when
>> the decl is imposed for D3D10 support, while the inst is mere a matter of
>> internal Mesa convention...
>>
>
> having the information duplicated (or at least in the instruction) is
> more convenient for the consumer of tgsi.  If you are worried about
> bugs/inconsistencies then something similar to nir_validate_shader()
> for tgsi would have seemed like a better direction.
>
> BR,
> -R
>
>>
>> In short, I'm fine in in principle with piping this info through, but lets
>> come up a decent generalization.  In particular, lets try get this in the
>> decls so it's consistent.

oh, hmm, the sampler-view thing looks like a rather longer path to get
what I need.. since it isn't even used currently..

BR,
-R

>>
>>
>> Jose
>>