[Mesa-dev] [RFC]: gallium: add new float comparison opcodes returning integer booleans

Fri Aug 9 12:17:15 PDT 2013

I was thinking it should just be part of the native_integer support
(glsl 1.30 basically) so it must be supported if you support that, and
it is always preferred in that case.
Though I won't implement it for other drivers (just llvmpipe/softpipe),
and just hope everybody will implement it so glsl can be switched to use
the new opcodes (so will only be used by internal code for now) as I
think this really makes sense. If not I guess could add a pipe flag and
make glsl act accordingly.

Roland

Am 09.08.2013 21:01, schrieb Brian Paul:
> Looks good to me.
> 
> Will you be a adding a new PIPE_SHADER_CAP_ flag so the driver can tell
> the state tracker which kind of comparison instructions it wants?
> 
> -Brian
> 
> On 08/09/2013 12:42 PM, Roland Scheidegger wrote:
>> This is a proposal for new comparison instructions, as the old ones
>> don't really fit modern (graphic or opencl I guess for that matter)
>> languages well.
>> If you've got objections, think the naming is crazy or whatnot I'm open
>> for suggestions :-). I would think this is not just a much better fit
>> for d3d10/glsl but for hw as well.
>>
>> Roland
>>
>> Am 09.08.2013 20:40, schrieb sroland at vmware.com:
>>> From: Roland Scheidegger <sroland at vmware.com>
>>>
>>> The old float comparison opcodes always return floats 0.0 and 1.0
>>> (clarified
>>> in docs these were really floats, was always the case) for legacy
>>> graphics.
>>> But everybody else (opengl,opencl,d3d10) just has to work around their
>>> return results (converting the returned float back to int/boolean).
>>> ---
>>>   src/gallium/docs/source/tgsi.rst |   84
>>> ++++++++++++++++++++++++++++++--------
>>>   1 file changed, 68 insertions(+), 16 deletions(-)
>>>
>>> diff --git a/src/gallium/docs/source/tgsi.rst
>>> b/src/gallium/docs/source/tgsi.rst
>>> index 949ad89..b7c40cf 100644
>>> --- a/src/gallium/docs/source/tgsi.rst
>>> +++ b/src/gallium/docs/source/tgsi.rst
>>> @@ -512,13 +512,13 @@ This instruction replicates its result.
>>>
>>>   .. math::
>>>
>>> -  dst.x = (src0.x == src1.x) ? 1 : 0
>>> +  dst.x = (src0.x == src1.x) ? 1.0F : 0.0F
>>>
>>> -  dst.y = (src0.y == src1.y) ? 1 : 0
>>> +  dst.y = (src0.y == src1.y) ? 1.0F : 0.0F
>>>
>>> -  dst.z = (src0.z == src1.z) ? 1 : 0
>>> +  dst.z = (src0.z == src1.z) ? 1.0F : 0.0F
>>>
>>> -  dst.w = (src0.w == src1.w) ? 1 : 0
>>> +  dst.w = (src0.w == src1.w) ? 1.0F : 0.0F
>>>
>>>
>>>   .. opcode:: SFL - Set On False
>>> @@ -538,13 +538,13 @@ This instruction replicates its result.
>>>
>>>   .. math::
>>>
>>> -  dst.x = (src0.x > src1.x) ? 1 : 0
>>> +  dst.x = (src0.x > src1.x) ? 1.0F : 0.0F
>>>
>>> -  dst.y = (src0.y > src1.y) ? 1 : 0
>>> +  dst.y = (src0.y > src1.y) ? 1.0F : 0.0F
>>>
>>> -  dst.z = (src0.z > src1.z) ? 1 : 0
>>> +  dst.z = (src0.z > src1.z) ? 1.0F : 0.0F
>>>
>>> -  dst.w = (src0.w > src1.w) ? 1 : 0
>>> +  dst.w = (src0.w > src1.w) ? 1.0F : 0.0F
>>>
>>>
>>>   .. opcode:: SIN - Sine
>>> @@ -560,26 +560,26 @@ This instruction replicates its result.
>>>
>>>   .. math::
>>>
>>> -  dst.x = (src0.x <= src1.x) ? 1 : 0
>>> +  dst.x = (src0.x <= src1.x) ? 1.0F : 0.0F
>>>
>>> -  dst.y = (src0.y <= src1.y) ? 1 : 0
>>> +  dst.y = (src0.y <= src1.y) ? 1.0F : 0.0F
>>>
>>> -  dst.z = (src0.z <= src1.z) ? 1 : 0
>>> +  dst.z = (src0.z <= src1.z) ? 1.0F : 0.0F
>>>
>>> -  dst.w = (src0.w <= src1.w) ? 1 : 0
>>> +  dst.w = (src0.w <= src1.w) ? 1.0F : 0.0F
>>>
>>>
>>>   .. opcode:: SNE - Set On Not Equal
>>>
>>>   .. math::
>>>
>>> -  dst.x = (src0.x != src1.x) ? 1 : 0
>>> +  dst.x = (src0.x != src1.x) ? 1.0F : 0.0F
>>>
>>> -  dst.y = (src0.y != src1.y) ? 1 : 0
>>> +  dst.y = (src0.y != src1.y) ? 1.0F : 0.0F
>>>
>>> -  dst.z = (src0.z != src1.z) ? 1 : 0
>>> +  dst.z = (src0.z != src1.z) ? 1.0F : 0.0F
>>>
>>> -  dst.w = (src0.w != src1.w) ? 1 : 0
>>> +  dst.w = (src0.w != src1.w) ? 1.0F : 0.0F
>>>
>>>
>>>   .. opcode:: STR - Set On True
>>> @@ -1325,6 +1325,19 @@ Support for these opcodes indicated by
>>> PIPE_SHADER_CAP_INTEGERS (all of them?)
>>>
>>>
>>>
>>> +.. opcode:: FSLT - Float Set On Less Than (ordered)
>>> +
>>> +.. math::
>>> +
>>> +  dst.x = (src0.x < src1.x) ? ~0 : 0
>>> +
>>> +  dst.y = (src0.y < src1.y) ? ~0 : 0
>>> +
>>> +  dst.z = (src0.z < src1.z) ? ~0 : 0
>>> +
>>> +  dst.w = (src0.w < src1.w) ? ~0 : 0
>>> +
>>> +
>>>   .. opcode:: ISLT - Signed Integer Set On Less Than
>>>
>>>   .. math::
>>> @@ -1351,6 +1364,19 @@ Support for these opcodes indicated by
>>> PIPE_SHADER_CAP_INTEGERS (all of them?)
>>>     dst.w = (src0.w < src1.w) ? ~0 : 0
>>>
>>>
>>> +.. opcode:: FSGE - Float Set On Greater Equal Than (ordered)
>>> +
>>> +.. math::
>>> +
>>> +  dst.x = (src0.x >= src1.x) ? ~0 : 0
>>> +
>>> +  dst.y = (src0.y >= src1.y) ? ~0 : 0
>>> +
>>> +  dst.z = (src0.z >= src1.z) ? ~0 : 0
>>> +
>>> +  dst.w = (src0.w >= src1.w) ? ~0 : 0
>>> +
>>> +
>>>   .. opcode:: ISGE - Signed Integer Set On Greater Equal Than
>>>
>>>   .. math::
>>> @@ -1377,6 +1403,19 @@ Support for these opcodes indicated by
>>> PIPE_SHADER_CAP_INTEGERS (all of them?)
>>>     dst.w = (src0.w >= src1.w) ? ~0 : 0
>>>
>>>
>>> +.. opcode:: FSEQ - Float Set On Equal (ordered)
>>> +
>>> +.. math::
>>> +
>>> +  dst.x = (src0.x == src1.x) ? ~0 : 0
>>> +
>>> +  dst.y = (src0.y == src1.y) ? ~0 : 0
>>> +
>>> +  dst.z = (src0.z == src1.z) ? ~0 : 0
>>> +
>>> +  dst.w = (src0.w == src1.w) ? ~0 : 0
>>> +
>>> +
>>>   .. opcode:: USEQ - Integer Set On Equal
>>>
>>>   .. math::
>>> @@ -1390,6 +1429,19 @@ Support for these opcodes indicated by
>>> PIPE_SHADER_CAP_INTEGERS (all of them?)
>>>     dst.w = (src0.w == src1.w) ? ~0 : 0
>>>
>>>
>>> +.. opcode:: FSNE - Float Set On Not Equal (unordered)
>>> +
>>> +.. math::
>>> +
>>> +  dst.x = (src0.x != src1.x) ? ~0 : 0
>>> +
>>> +  dst.y = (src0.y != src1.y) ? ~0 : 0
>>> +
>>> +  dst.z = (src0.z != src1.z) ? ~0 : 0
>>> +
>>> +  dst.w = (src0.w != src1.w) ? ~0 : 0
>>> +
>>> +
>>>   .. opcode:: USNE - Integer Set On Not Equal
>>>
>>>   .. math::
>>>