[Mesa-dev] [RFC 2/4] nir: Add a new ALU nir_op_imad

[Ilia Mirkin]

IMAD_S24 isn't src0 * src1 + src2 though. I think this could be called
imad24, which I suspect exits on many GPUs (nv50-era NVIDIA definitely
had this, and I think maxwell+ has a variant of this implemented by
XMAD):

(src0 * src1) & 0xffffff + src2

Cheers,

  -ilia

On Fri, Jan 25, 2019 at 10:49 AM Eduardo Lima Mitev <elima at igalia.com> wrote:
>
> ir3 compiler has an integer multiply-add instruction (IMAD_S24)
> that is used for different offset calculations in the backend.
> Since we intend to move some of these calculations to NIR, we need
> a new ALU op that can represent it.
> ---
>  src/compiler/nir/nir_opcodes.py | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/src/compiler/nir/nir_opcodes.py b/src/compiler/nir/nir_opcodes.py
> index d32005846a6..b61845fd514 100644
> --- a/src/compiler/nir/nir_opcodes.py
> +++ b/src/compiler/nir/nir_opcodes.py
> @@ -754,6 +754,7 @@ def triop_horiz(name, output_size, src1_size, src2_size, src3_size, const_expr):
>     [tuint, tuint, tuint], "", const_expr)
>
>  triop("ffma", tfloat, "src0 * src1 + src2")
> +triop("imad", tint, "src0 * src1 + src2")
>
>  triop("flrp", tfloat, "src0 * (1 - src2) + src1 * src2")
>
> --
> 2.20.1
>
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