[Mesa-dev] [PATCH] glsl: Do not vectorize vector array dereferences.

[Ian Romanick]

On 02/10/2014 01:09 PM, Matt Turner wrote:
> Array dereferences must have scalar indices, so we cannot vectorize
> them.
> 
> Reported-by: Andrew Guertin <lists at dolphinling.net>

Seems like the easy fix.

Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>

Candidate for 10.1?

> ---
>  src/glsl/opt_vectorize.cpp | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/src/glsl/opt_vectorize.cpp b/src/glsl/opt_vectorize.cpp
> index 8ee81f1..dba303d 100644
> --- a/src/glsl/opt_vectorize.cpp
> +++ b/src/glsl/opt_vectorize.cpp
> @@ -82,6 +82,7 @@ public:
>  
>     virtual ir_visitor_status visit_enter(ir_assignment *);
>     virtual ir_visitor_status visit_enter(ir_swizzle *);
> +   virtual ir_visitor_status visit_enter(ir_dereference_array *);
>     virtual ir_visitor_status visit_enter(ir_if *);
>     virtual ir_visitor_status visit_enter(ir_loop *);
>  
> @@ -289,6 +290,19 @@ ir_vectorize_visitor::visit_enter(ir_swizzle *ir)
>     return visit_continue;
>  }
>  
> +/* Upon entering an ir_array_dereference, remove the current assignment from
> + * further consideration. Since the index of an array dereference must scalar,
> + * we are not able to vectorize it.
> + *
> + * FINISHME: If all of scalar indices are identical we could vectorize.
> + */
> +ir_visitor_status
> +ir_vectorize_visitor::visit_enter(ir_dereference_array *ir)
> +{
> +   this->current_assignment = NULL;
> +   return visit_continue_with_parent;
> +}
> +
>  /* Since there is no statement to visit between the "then" and "else"
>   * instructions try to vectorize before, in between, and after them to avoid
>   * combining statements from different basic blocks.
>