[Mesa-dev] [PATCH] nir: fix loop iteration count calculation for floats

[Jason Ekstrand]

Drp...

Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>

On Jan 3, 2017 7:00 PM, "Timothy Arceri" <timothy.arceri at collabora.com>
wrote:

> Fixes performance regression in SynMark PSPom caused by loops with float
> counters not always unrolling.
>
> For example:
>
>    for (float i = 0.02; i < 0.9; i += 0.11)
>       ...
> ---
>  src/compiler/nir/nir_loop_analyze.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/src/compiler/nir/nir_loop_analyze.c
> b/src/compiler/nir/nir_loop_analyze.c
> index 71cbe3c..a5f464a 100644
> --- a/src/compiler/nir/nir_loop_analyze.c
> +++ b/src/compiler/nir/nir_loop_analyze.c
> @@ -384,8 +384,8 @@ get_iteration(nir_op cond_op, nir_const_value
> *initial, nir_const_value *step,
>     case nir_op_flt:
>     case nir_op_feq:
>     case nir_op_fne: {
> -      int32_t initial_val = initial->f32[0];
> -      int32_t span = limit->f32[0] - initial_val;
> +      float initial_val = initial->f32[0];
> +      float span = limit->f32[0] - initial_val;
>        iter = span / step->f32[0];
>        break;
>     }
> --
> 2.9.3
>
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