[Mesa-dev] [PATCH 1/2] ac/nir: fix interp mode for nir_intrinsic_interp_var_at_sample

[Nicolai Hähnle]

On 18.04.2018 14:36, Samuel Pitoiset wrote:
> 
> 
> On 04/18/2018 12:19 PM, Nicolai Hähnle wrote:
>> On 17.04.2018 15:08, Samuel Pitoiset wrote:
>>> This fixes the following CTS tests:
>>> dEQP-VK.pipeline.multisample_interpolation.sample_interpolate_at_consistency.* 
>>>
>>>
>>> This restores the previous behaviour, maybe the CTS tests
>>> were wrong?
>>>
>>> Fixes: 22b116171f8 ("radv: fix interp at sample code.")
>>> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
>>> ---
>>>   src/amd/common/ac_nir_to_llvm.c | 3 +++
>>>   1 file changed, 3 insertions(+)
>>>
>>> diff --git a/src/amd/common/ac_nir_to_llvm.c 
>>> b/src/amd/common/ac_nir_to_llvm.c
>>> index 45405d30fe8..b0631ad41a8 100644
>>> --- a/src/amd/common/ac_nir_to_llvm.c
>>> +++ b/src/amd/common/ac_nir_to_llvm.c
>>> @@ -2710,6 +2710,9 @@ static LLVMValueRef visit_interp(struct 
>>> ac_nir_context *ctx,
>>>           location = INTERP_CENTROID;
>>>           break;
>>>       case nir_intrinsic_interp_var_at_sample:
>>> +        location = INTERP_SAMPLE;
>>> +        src0 = get_src(ctx, instr->src[0]);
>>> +        break;
>>
>> This makes no sense. Consider the code below; it will compute 
>> src_c{0,1} in the nir_intrinsic_interp_var_at_sample case, but by 
>> setting location == INTERP_SAMPLE, those values will never actually be 
>> used.
>>
>> Is it possible that the test uses sample rate shading, and the sample 
>> number passed into the intrinsic coincides with the sample number of 
>> the PS invocation?
> 
> Right, that makes no sense actually...
> 
> Yes, sample rate shading is enabled but I don't know if the sample 
> number coincides.

In that case, is it possible that the at_center interpolation 
accidentally gets the sample location? Just stabbing in the dark, 
admittedly...

Cheers,
Nicolai


> 
>>
>> Cheers,
>> Nicolai
>>
>>
>>>       case nir_intrinsic_interp_var_at_offset:
>>>           location = INTERP_CENTER;
>>>           src0 = get_src(ctx, instr->src[0]);
>>>
>>
>>


-- 
Lerne, wie die Welt wirklich ist,
Aber vergiss niemals, wie sie sein sollte.