[Bug tree-optimization/92819] [10 Regression] Worse code generated on avx2 due to simplify_vector_constructor

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92819

--- Comment #3 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
I guess the issue is specific to 2-element vectors: { 0, 3 } can be seen as
inserting element 1 of the second vector into the first, of the first element
of the second vector into the second.