Re: [PATCH v2] nv50/ir: Handle OP_CVT when folding constant expressions

[Tobias Klausmann <tobias.johannes.klausmann-AqjdNwhu20eELgA04lAiVw@public.gmane.org>]

On 11.01.2015 01:58, Ilia Mirkin wrote:
> On Fri, Jan 9, 2015 at 8:24 PM, Tobias Klausmann
> <tobias.johannes.klausmann@mni.thm.de> wrote:
>> Folding for conversions: F32->(U{16/32}, S{16/32}) and (U{16/32}, {S16/32})->F32
>>
>> Signed-off-by: Tobias Klausmann <tobias.johannes.klausmann@mni.thm.de>
>> ---
>> V2: beat me, whip me, split out F64
>>
>>   .../drivers/nouveau/codegen/nv50_ir_peephole.cpp   | 81 ++++++++++++++++++++++
>>   1 file changed, 81 insertions(+)
>>
>> diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
>> index 9a0bb60..741c74f 100644
>> --- a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
>> +++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
>> @@ -997,6 +997,87 @@ ConstantFolding::opnd(Instruction *i, ImmediateValue &imm0, int s)
>>         i->op = OP_MOV;
>>         break;
>>      }
>> +   case OP_CVT: {
>> +      Storage res;
>> +      bld.setPosition(i, true); /* make sure bld is init'ed */
>> +      switch(i->dType) {
>> +      case TYPE_U16:
>> +         switch (i->sType) {
>> +         case TYPE_F32:
>> +            if (i->saturate)
>> +               res.data.u16 = util_iround(CLAMP(imm0.reg.data.f32, 0,
>> +                                                UINT16_MAX));
> Where did this saturate stuff come from? It doesn't make sense to
> saturate to a non-float dtype. I'd go ahead and just
> assert(!i->saturate) in the int dtype cases.
>
> One does wonder what the hw does if the float doesn't fit in the
> destination... whether it saturates or not. I don't hugely care
> though.
Actually i can't remember why that was added in the first place, i'll go 
ahead and follow your advice here.

>> +            else
>> +               res.data.u16 = util_iround(imm0.reg.data.f32);
>> +            break;
>> +         default:
>> +            return;
>> +         }
>> +         i->setSrc(0, bld.mkImm(res.data.u16));
>> +         break;
>> +      case TYPE_U32:
>> +         switch (i->sType) {
>> +         case TYPE_F32:
>> +            if (i->saturate)
>> +               res.data.u32 = util_iround(CLAMP(imm0.reg.data.f32, 0,
>> +                                                UINT32_MAX));
>> +            else
>> +               res.data.u32 = util_iround(imm0.reg.data.f32);
>> +            break;
>> +         default:
>> +            return;
>> +         }
>> +         i->setSrc(0, bld.mkImm(res.data.u32));
>> +         break;
>> +      case TYPE_S16:
>> +         switch (i->sType) {
>> +         case TYPE_F32:
>> +            if (i->saturate)
>> +               res.data.s16 = util_iround(CLAMP(imm0.reg.data.f32, INT16_MIN,
>> +                                                INT16_MAX));
>> +            else
>> +               res.data.s16 = util_iround(imm0.reg.data.f32);
>> +            break;
>> +         default:
>> +            return;
>> +         }
>> +         i->setSrc(0, bld.mkImm(res.data.s16));
>> +         break;
>> +      case TYPE_S32:
>> +         switch (i->sType) {
>> +         case TYPE_F32:
>> +            if (i->saturate)
>> +               res.data.s32 = util_iround(CLAMP(imm0.reg.data.f32, INT32_MIN,
>> +                                               INT32_MAX));
>> +            else
>> +               res.data.s32 = util_iround(imm0.reg.data.f32);
>> +            break;
>> +         default:
>> +            return;
>> +         }
>> +         i->setSrc(0, bld.mkImm(res.data.s32));
>> +         break;
>> +      case TYPE_F32:
>> +         switch (i->sType) {
>> +         case TYPE_U16: res.data.f32 = (float) imm0.reg.data.u16; break;
>> +         case TYPE_U32: res.data.f32 = (float) imm0.reg.data.u32; break;
>> +         case TYPE_S16: res.data.f32 = (float) imm0.reg.data.s16; break;
>> +         case TYPE_S32: res.data.f32 = (float) imm0.reg.data.s32; break;
>> +         default:
>> +            return;
>> +         }
>> +         i->setSrc(0, bld.mkImm(res.data.f32));
>> +         break;
>> +      default:
>> +         return;
>> +      }
>> +      i->setType(i->dType); /* Remove i->sType, which we don't need anymore */
>> +      i->setSrc(1, NULL);
> How can src(1) be set? OP_CVT only has the one arg...
Agreed, its NULL anyway.
>> +      i->op = OP_MOV;
>> +
>> +      i->src(0).mod = Modifier(0); /* Clear the already applied modifier */
>> +      break;
>> +   }
>>      default:
>>         return;
>>      }
>> --
>> 2.2.1
>>
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