[Mesa-dev] [PATCH 3/3] glsl: disable array splitting for AoA

[Timothy Arceri]

On 30/06/17 12:45, Timothy Arceri wrote:
> While it produces functioning code the pass creates worse code
> for arrays of arrays. See the comment added in this patch for more
> detail.
> ---
>   src/compiler/glsl/opt_array_splitting.cpp | 26 ++++++++++++++++++++++++++
>   1 file changed, 26 insertions(+)
> 
> diff --git a/src/compiler/glsl/opt_array_splitting.cpp b/src/compiler/glsl/opt_array_splitting.cpp
> index fb6d77b..b3d4599 100644
> --- a/src/compiler/glsl/opt_array_splitting.cpp
> +++ b/src/compiler/glsl/opt_array_splitting.cpp
> @@ -140,6 +140,32 @@ ir_array_reference_visitor::get_variable_entry(ir_variable *var)
>      if (var->type->is_unsized_array())
>         return NULL;
>   
> +   /* FIXME: arrays of arrays are not handled correctly by this pass so we
> +    * skip it for now. While the pass will create functioning code it actually
> +    * produces worse code.
> +    *
> +    * For example the array:
> +    *
> +    *    int[3][2] a;
> +    *
> +    * ends up being split up into:
> +    *
> +    *    int[3][2] a_0;
> +    *    int[3][2] a_1;
> +    *    int[3][2] a_2;
> +    *
> +    * And we end up referencing each of these new arrays for example:
> +    *
> +    *    a[0][1] will be turned into a_0[0][1]
> +    *    a[1][0] will be turned into a_1[1][0]
> +    *    a[2][0] will be turned into a_2[2][0]
> +    *
> +    * For now we continue to split AoA of matrices to avoid CTS regressions.
> +    */
> +   if (var->type->is_array() && var->type->fields.array->is_array() &&
> +       !var->type->without_array()->is_matrix())

Actually with the previous patch it can be disabled for AoA of matrices 
too. I've made this change locally.


> +      return NULL;
> +
>      foreach_in_list(variable_entry, entry, &this->variable_list) {
>         if (entry->var == var)
>            return entry;
>