[Mesa-dev] [PATCH] radv: enable denorms for 64-bit and 16-bit floats

[Bas Nieuwenhuizen]

Looking at AMDGPUAsmPrinter::EmitProgramInfoSI in LLVM that is only
set for compute shaders. So fix radv to default to the proposed value
and fix LLVM to pass it through for all shaders?

On Thu, Jan 4, 2018 at 11:54 AM, Samuel Pitoiset
<samuel.pitoiset at gmail.com> wrote:
>
>
> On 12/28/2017 11:08 PM, Matt Arsenault wrote:
>>
>>
>>
>>> On Dec 28, 2017, at 16:55, Samuel Pitoiset <samuel.pitoiset at gmail.com>
>>> wrote:
>>>
>>> Similar to RadeonSI.
>>>
>>> This fixes:
>>>
>>> dEQP-VK.image.texel_view_compatible.graphic.basic.attachment_read.bc*r16g16b16a16_sfloat
>>> dEQP-VK.image.extended_usage_bit.attachment_write.r16_sfloat
>>>
>>> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
>>> ---
>>> src/amd/common/ac_nir_to_llvm.c | 14 ++++++++++++++
>>> 1 file changed, 14 insertions(+)
>>>
>>> diff --git a/src/amd/common/ac_nir_to_llvm.c
>>> b/src/amd/common/ac_nir_to_llvm.c
>>> index d9f2cb408c..9d9a1f911b 100644
>>> --- a/src/amd/common/ac_nir_to_llvm.c
>>> +++ b/src/amd/common/ac_nir_to_llvm.c
>>> @@ -6879,6 +6879,20 @@ static void
>>> ac_compile_llvm_module(LLVMTargetMachineRef tm,
>>>         /* +3 for scratch wave offset and VCC */
>>>         config->num_sgprs = MAX2(config->num_sgprs,
>>>                                  shader_info->num_input_sgprs + 3);
>>> +
>>> +       /* Enable 64-bit and 16-bit denormals, because there is no
>>> performance
>>> +        * cost.
>>> +        *
>>> +        * If denormals are enabled, all floating-point output modifiers
>>> are
>>> +        * ignored.
>>> +        *
>>> +        * Don't enable denormals for 32-bit floats, because:
>>> +        * - Floating-point output modifiers would be ignored by the hw.
>>> +        * - Some opcodes don't support denormals, such as v_mad_f32. We
>>> would
>>> +        *   have to stop using those.
>>> +        * - SI & CI would be very slow.
>>> +        */
>>> +       config->float_mode |= V_00B028_FP_64_DENORMS;
>>> }
>>
>>
>> This is set in the program binary. You should use that directly rather
>> than ignoring it
>
>
> Not sure to understand where that flag is set actually, and RadeonSI does a
> similar thing.
>
>
>>
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