[Mesa-dev] [PATCH] radeonsi: enable 32-bit denormals on VI+

[Samuel Pitoiset]

On 01/11/2017 07:00 PM, Roland Scheidegger wrote:
> I don't think there's any glsl, es or otherwise, specification which
> would require denorms (since obviously lots of hw can't do it, d3d10
> forbids them), with any precision qualifier. Hence these look like bugs
> of the test suite to me?
> (Irrespective if it's a good idea or not to enable denormals, which I
> don't realy know.)

That test works on NVIDIA hw (both with blob and nouveau) and IIRC it 
also works on Intel hw. I don't think it's buggy there.

>
> Roland
>
>
> Am 11.01.2017 um 18:29 schrieb Samuel Pitoiset:
>> Only VI can do 32-bit denormals at full rate while previous
>> generations can do it only for 64-bit and 16-bit.
>>
>> This fixes some dEQP tests with the highp type qualifier.
>>
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99343
>> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
>> ---
>>  src/gallium/drivers/radeonsi/si_shader.c | 11 ++++++++---
>>  1 file changed, 8 insertions(+), 3 deletions(-)
>>
>> diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
>> index 5dfbd6603a..e9cb11883f 100644
>> --- a/src/gallium/drivers/radeonsi/si_shader.c
>> +++ b/src/gallium/drivers/radeonsi/si_shader.c
>> @@ -6361,8 +6361,10 @@ int si_compile_llvm(struct si_screen *sscreen,
>>
>>  	si_shader_binary_read_config(binary, conf, 0);
>>
>> -	/* Enable 64-bit and 16-bit denormals, because there is no performance
>> -	 * cost.
>> +	/* Enable denormals when there is no performance cost.
>> +	 *
>> +	 * Only VI can do 32-bit denormals at full rate while previous
>> +	 * generations can do it only for 64-bit and 16-bit.
>>  	 *
>>  	 * If denormals are enabled, all floating-point output modifiers are
>>  	 * ignored.
>> @@ -6373,7 +6375,10 @@ int si_compile_llvm(struct si_screen *sscreen,
>>  	 *   have to stop using those.
>>  	 * - SI & CI would be very slow.
>>  	 */
>> -	conf->float_mode |= V_00B028_FP_64_DENORMS;
>> +	if (sscreen->b.chip_class >= VI)
>> +		conf->float_mode |= V_00B028_FP_ALL_DENORMS;
>> +	else
>> +		conf->float_mode |= V_00B028_FP_64_DENORMS;
>>
>>  	FREE(binary->config);
>>  	FREE(binary->global_symbol_offsets);
>>
>