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

[Timothy Arceri]

On Mon, Jul 3, 2017, at 10:16 AM, Jason Ekstrand wrote:
> I'd like the chance to look at these, please.  I'm on vacation today and 
> tomorrow though.

Ping! 

> 
> 
> On July 3, 2017 7:19:04 AM funfunctor at folklore1984.net wrote:
> 
> > 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;
> >
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>