On Tue, Jun 23, 2026 at 12:54 PM Christopher Bazley via Sourceware
Forge <[email protected]> wrote:
>
> From: Christopher Bazley <[email protected]>
>
> 'nelts' is not the number of encoded elements in a VECTOR_CST; it
> is the number of patterns. Sometimes those interpretations coincide,
> as in the case of fixed length vector types (for which the number of
> elements per pattern is one), but not always.
>
> 'step' is not the step between the second and third element of
> a stepped pattern; it is the number of elements per pattern.
> This has led to confusion on the mailing list.
>
> Both variables are hereby renamed.
>
> gcc/ChangeLog:
>
> * tree.cc (build_vector_from_ctor): Rename variables.
> ---
> gcc/tree.cc | 16 ++++++++--------
> 1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/gcc/tree.cc b/gcc/tree.cc
> index ca713cec4d6a..b4c836b4a0a7 100644
> --- a/gcc/tree.cc
> +++ b/gcc/tree.cc
> @@ -2201,23 +2201,23 @@ build_vector_from_ctor (tree type, const
> vec<constructor_elt, va_gc> *v)
> if (vec_safe_length (v) == 0)
> return build_zero_cst (type);
>
> - unsigned HOST_WIDE_INT idx, nelts, step = 1;
> + unsigned HOST_WIDE_INT idx, npatterns, nelts_per_pattern = 1;
> tree value;
>
> /* If the vector is a VLA, build a VLA constant vector. */
> - if (!TYPE_VECTOR_SUBPARTS (type).is_constant (&nelts))
> + if (!TYPE_VECTOR_SUBPARTS (type).is_constant (&npatterns))
No, TYPE_VECTOR_SUBPARTS is the number of elements in 'type'.
> {
> - nelts = constant_lower_bound (TYPE_VECTOR_SUBPARTS (type));
> - gcc_assert (vec_safe_length (v) <= nelts);
> - step = 2;
> + npatterns = constant_lower_bound (TYPE_VECTOR_SUBPARTS (type));
> + gcc_assert (vec_safe_length (v) <= npatterns);
> + nelts_per_pattern = 2;
> }
>
> - tree_vector_builder vec (type, nelts, step);
> + tree_vector_builder vec (type, npatterns, nelts_per_pattern);
> FOR_EACH_CONSTRUCTOR_VALUE (v, idx, value)
> {
> if (TREE_CODE (value) == VECTOR_CST)
> {
> - /* If NELTS is constant then this must be too. */
> + /* If NPATTERNS is constant then this must be too. */
> unsigned int sub_nelts = VECTOR_CST_NELTS (value).to_constant ();
> for (unsigned i = 0; i < sub_nelts; ++i)
> vec.quick_push (VECTOR_CST_ELT (value, i));
> @@ -2225,7 +2225,7 @@ build_vector_from_ctor (tree type, const
> vec<constructor_elt, va_gc> *v)
> else
> vec.quick_push (value);
> }
> - while (vec.length () < nelts * step)
> + while (vec.length () < npatterns * nelts_per_pattern)
> vec.quick_push (build_zero_cst (TREE_TYPE (type)));
>
> return vec.build ();
> --
> 2.54.0
>
