[Mesa-dev] [PATCH 07/10] nir: add imprecise flrp optimisation

[Matt Turner]

On Sat, Jan 7, 2017 at 3:58 AM, Timothy Arceri
<timothy.arceri at collabora.com> wrote:
> On BDW:
>
> total instructions in shared programs: 13061890 -> 13061877 (-0.00%)
> instructions in affected programs: 2441 -> 2428 (-0.53%)
> helped: 13
> HURT: 0
>
> total cycles in shared programs: 256612254 -> 256611784 (-0.00%)
> cycles in affected programs: 16418 -> 15948 (-2.86%)
> helped: 10
> HURT: 2
> ---
>  src/compiler/nir/nir_opt_algebraic.py | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py
> index fa9f3f1..7cee378 100644
> --- a/src/compiler/nir/nir_opt_algebraic.py
> +++ b/src/compiler/nir/nir_opt_algebraic.py
> @@ -111,6 +111,7 @@ optimizations = [
>     (('~flrp', a, b, 1.0), b),
>     (('~flrp', a, a, b), a),
>     (('~flrp', 0.0, a, b), ('fmul', a, b)),
> +   (('~flrp', a, 0.0, c), ('ffma', ('fneg', a), c, a), '!options->lower_ffma'),

I don't think we want to be generating ffma directly in nir_opt_algebraic?