https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113441
--- Comment #12 from JuzheZhong <juzhe.zhong at rivai dot ai> ---
(In reply to Richard Biener from comment #11)
> (In reply to Tamar Christina from comment #9)
> > There is a weird costing going on in the PHI nodes though:
> >
> > m_108 = PHI <m_92(16), m_111(5)> 1 times vector_stmt costs 0 in body
> > m_108 = PHI <m_92(16), m_111(5)> 2 times scalar_to_vec costs 0 in prologue
> >
> > they have collapsed to 0. which can't be right..
>
> Note this is likely because of the backend going wrong.
>
> bool
> vectorizable_phi (vec_info *,
> stmt_vec_info stmt_info, gimple **vec_stmt,
> slp_tree slp_node, stmt_vector_for_cost *cost_vec)
> {
> ..
>
> /* For single-argument PHIs assume coalescing which means zero cost
> for the scalar and the vector PHIs. This avoids artificially
> favoring the vector path (but may pessimize it in some cases). */
> if (gimple_phi_num_args (as_a <gphi *> (stmt_info->stmt)) > 1)
> record_stmt_cost (cost_vec, SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node),
> vector_stmt, stmt_info, vectype, 0, vect_body);
>
> You could check if we call this with sane values.
Do you mean it's RISC-V backend cost model issue ?
