Re: [PATCH] Fixup tree_nop_conversion_p WRT BLKmode vector types

On Wed, Aug 19, 2026 at 4:15 AM Richard Biener <[email protected]> wrote:
>
> This special-cases BLKmode vector types appropriately.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu.
>
> OK?

Ok.

>
>         * tree.cc (tree_nop_conversion_p): Special case two BLKmode
>         types.
> ---
>  gcc/tree.cc | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>
> diff --git a/gcc/tree.cc b/gcc/tree.cc
> index 19069eb5960..52313fbd129 100644
> --- a/gcc/tree.cc
> +++ b/gcc/tree.cc
> @@ -12462,6 +12462,19 @@ tree_nop_conversion_p (const_tree outer_type, const_tree inner_type)
>           || TREE_CODE (inner_type) == OFFSET_TYPE))
>      return TYPE_PRECISION (outer_type) == TYPE_PRECISION (inner_type);
>
> +  if (TYPE_MODE (outer_type) == BLKmode
> +      && TYPE_MODE (inner_type) == BLKmode)
> +    {
> +      if (VECTOR_TYPE_P (outer_type)
> +         && VECTOR_TYPE_P (inner_type)
> +         && known_eq (TYPE_VECTOR_SUBPARTS (outer_type),
> +                      TYPE_VECTOR_SUBPARTS (inner_type))
> +         && (TYPE_MODE (TREE_TYPE (outer_type))
> +             == TYPE_MODE (TREE_TYPE (inner_type))))
> +       return true;
> +      return false;
> +    }
> +
>    /* Otherwise fall back on comparing machine modes (e.g. for
>       aggregate types, floats).  */
>    return TYPE_MODE (outer_type) == TYPE_MODE (inner_type);
> --
> 2.51.0