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

[Ilia Mirkin]

On Fri, Jan 9, 2015 at 8:24 PM, Tobias Klausmann
<tobias.johannes.klausmann at 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 at 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.

> +            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...

> +      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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