[Mesa-dev] [PATCH v2 3/3] glsl: disable array splitting for AoA

[funfunctor at folklore1984.net]

On 2017-07-03 08:47, 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.
> 
> V2: skip splitting of AoA of matrices too.

Reviewed-by: Edward O'Callaghan <funfunctor at folklore1984.net>

> ---
>  src/compiler/glsl/opt_array_splitting.cpp | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/src/compiler/glsl/opt_array_splitting.cpp
> b/src/compiler/glsl/opt_array_splitting.cpp
> index fb6d77b..d2e81665 100644
> --- a/src/compiler/glsl/opt_array_splitting.cpp
> +++ b/src/compiler/glsl/opt_array_splitting.cpp
> @@ -140,6 +140,29 @@
> 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]
> +    */
> +   if (var->type->is_array() && var->type->fields.array->is_array())
> +      return NULL;
> +
>     foreach_in_list(variable_entry, entry, &this->variable_list) {
>        if (entry->var == var)
>           return entry;