[Mesa-dev] [PATCH] clover: Return the minimum required value for CL_DEVICE_SINGLE_FP_CONFIG

[Francisco Jerez]

Tom Stellard <tom at stellard.net> writes:

> On Thu, Mar 05, 2015 at 08:42:25PM +0200, Francisco Jerez wrote:
>> Tom Stellard <thomas.stellard at amd.com> writes:
>> 
>> > This means dropping CL_FP_DENORM from the current return value.
>> > ---
>> >  src/gallium/state_trackers/clover/api/device.cpp | 4 +++-
>> >  1 file changed, 3 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/src/gallium/state_trackers/clover/api/device.cpp b/src/gallium/state_trackers/clover/api/device.cpp
>> > index b1f556f..db3b931 100644
>> > --- a/src/gallium/state_trackers/clover/api/device.cpp
>> > +++ b/src/gallium/state_trackers/clover/api/device.cpp
>> > @@ -201,8 +201,10 @@ clGetDeviceInfo(cl_device_id d_dev, cl_device_info param,
>> >        break;
>> >  
>> >     case CL_DEVICE_SINGLE_FP_CONFIG:
>> > +      // This is the "mandated minimum single precision floating-point
>> > +      // capability"
>> 
>> Could you add that this is according to the OpenCL 1.1 specification?
>> OpenCL 1.2 is even weaker (CL_FP_INF_NAN is not required, only one of
>> CL_FP_ROUND_TO_ZERO or CL_FP_ROUND_TO_NEAREST is required, and no FP
>> capabilities at all are required for custom devices as Jan pointed out).
>> 
>> >        buf.as_scalar<cl_device_fp_config>() =
>> > -         CL_FP_DENORM | CL_FP_INF_NAN | CL_FP_ROUND_TO_NEAREST;
>> > +         CL_FP_INF_NAN | CL_FP_ROUND_TO_NEAREST;
>> 
>> I'm okay with this change, but I'm curious, is this motivated by your
>> architecture not supporting denorms?
>> 
>
> It can, but supporting them hurts performance.
>
Sounds like you want to advertise denorm support and rely on the
-cl-denorms-are-zero compiler option to decide whether to flush them to
zero or not?

> -Tom
>
>> >        break;
>> >  
>> >     case CL_DEVICE_DOUBLE_FP_CONFIG:
>> > -- 
>> > 2.0.4
>
>
>
>
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