[Bug tree-optimization/69174] [6 Regression] ICE (segfault) in operand_equal_p

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69174

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
Ok, so we have an interleaving store of size 3 (and thus also the SLP group
size is 3) but an interleaved load of size 4 (with gaps).  Ideally we'd not
treat
that load as interleaved but we do.  The size 3 SLP requires unrolling 8 times
(8 * 3 -> 24 elements).  The grouped load is strided and in this case

          ncopies = SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node);
          if (slp_perm)
            dr_chain.create (ncopies);

is off.  See

          /* For SLP permutation support we need to load the whole group,
             not only the number of vector stmts the permutation result
             fits in.  */
          if (slp_perm)
            vec_num = (group_size * vf + nunits - 1) / nunits;
          else
            vec_num = SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node);