[Mesa-dev] [PATCH v2 2/4] nvc0/ir: Handle reverse subop for OP_EXTBF when folding constant expressions

[Ilia Mirkin]

On Tue, Jun 3, 2014 at 4:58 PM, Tobias Klausmann
<tobias.johannes.klausmann at mni.thm.de> wrote:
> V2: Handle the instruction right (shift after reverse)
>
> Signed-off-by: Tobias Klausmann <tobias.johannes.klausmann at mni.thm.de>
> ---
>  src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
> index 58092f4..a214ffc 100644
> --- a/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
> +++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_peephole.cpp
> @@ -529,8 +529,20 @@ ConstantFolding::expr(Instruction *i,
>           lshift = 32 - width - offset;
>        }
>        switch (i->dType) {
> -      case TYPE_S32: res.data.s32 = (a->data.s32 << lshift) >> rshift; break;
> -      case TYPE_U32: res.data.u32 = (a->data.u32 << lshift) >> rshift; break;
> +      case TYPE_S32:
> +         if (i->subOp == NV50_IR_SUBOP_EXTBF_REV)
> +            res.data.s32 = util_bitreverse(a->data.s32);
> +         else
> +            res.data.s32 = a->data.s32;

Why not do this once outside of the switch statement? The two are
actually the same -- util_bitreverse doesn't care about
signed/unsigned, and res.data is a union.

> +         res.data.s32 = (res.data.s32 << lshift) >> rshift;
> +         break;
> +      case TYPE_U32:
> +         if (i->subOp == NV50_IR_SUBOP_EXTBF_REV)
> +            res.data.u32 = util_bitreverse(a->data.u32);
> +         else
> +            res.data.u32 = a->data.u32;
> +         res.data.u32 = (res.data.u32 << lshift) >> rshift;
> +         break;
>        default:
>           return;
>        }
> --
> 1.8.4.5
>