[Mesa-dev] [PATCH v4] nir: Don't lower the local work group size if it's variable.

[Jason Ekstrand]

I think we still want to skip the lowering of SYSTEM_VALUE_LOCAL_GROUP_SIZE
when that flag is set.  I think this works, but we'll end up deleting one
load_local_group_size intrinsic and replacing it with another which is
pointless.

--Jason

On Mon, Nov 12, 2018 at 4:02 PM Plamena Manolova <
plamena.n.manolova at gmail.com> wrote:

> If the local work group size is variable it won't be available
> at compile time so we can't lower it in nir_lower_system_values().
>
> Signed-off-by: Plamena Manolova <plamena.n.manolova at gmail.com>
> ---
>  src/compiler/nir/nir_lower_system_values.c | 24 ++++++++++++++++++------
>  1 file changed, 18 insertions(+), 6 deletions(-)
>
> diff --git a/src/compiler/nir/nir_lower_system_values.c
> b/src/compiler/nir/nir_lower_system_values.c
> index bde7eb1180..fbc4057357 100644
> --- a/src/compiler/nir/nir_lower_system_values.c
> +++ b/src/compiler/nir/nir_lower_system_values.c
> @@ -31,12 +31,24 @@
>  static nir_ssa_def*
>  build_local_group_size(nir_builder *b)
>  {
> -   nir_const_value local_size;
> -   memset(&local_size, 0, sizeof(local_size));
> -   local_size.u32[0] = b->shader->info.cs.local_size[0];
> -   local_size.u32[1] = b->shader->info.cs.local_size[1];
> -   local_size.u32[2] = b->shader->info.cs.local_size[2];
> -   return nir_build_imm(b, 3, 32, local_size);
> +   nir_ssa_def *local_size;
> +
> +   /*
> +    * If the local work group size is variable it can't be lowered at this
> +    * point, but its intrinsic can still be used.
> +    */
> +   if (b->shader->info.cs.local_size_variable) {
> +      local_size = nir_load_local_group_size(b);
> +   } else {
> +      nir_const_value local_size_const;
> +      memset(&local_size_const, 0, sizeof(local_size_const));
> +      local_size_const.u32[0] = b->shader->info.cs.local_size[0];
> +      local_size_const.u32[1] = b->shader->info.cs.local_size[1];
> +      local_size_const.u32[2] = b->shader->info.cs.local_size[2];
> +      local_size = nir_build_imm(b, 3, 32, local_size_const);
> +   }
> +
> +   return local_size;
>  }
>
>  static bool
> --
> 2.11.0
>
>
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