https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91103
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #1)
> So when the vectorizer has the need to use strided stores it would be
> cheapest
> to spill the vector and do N element loads and stores? I guess we can easily
> get bottle-necked by the load/store op bandwith here? That is, the
> vectorizer needs
>
> for (lane)
> dest[stride * lane] = vector[lane];
>
> thus store a specific (constant) lane of a vector to memory, for each
> vector lane. (we could use a scatter store here but only AVX512 has that
> and builing the index vector could be tricky and not supported for all
> element types)
Indeed ICC seems to spill for AVX and AVX512 for
typedef int vsi __attribute__((vector_size(SIZE)));
void foo (vsi v, int *p, int *o)
{
for (int i = 0; i < sizeof(vsi)/4; ++i)
p[o[i]] = v[i];
}
