[gcc(refs/users/rguenth/heads/vect-force-slp)] Guard SLP optimize latch edge discovery

[Richard Biener <rguenth@gcc.gnu.org>]

https://gcc.gnu.org/g:a44166ac67ecfb06cb15a39f9f9626538809588a

commit a44166ac67ecfb06cb15a39f9f9626538809588a
Author: Richard Biener <rguenther@suse.de>
Date:   Fri Sep 29 12:57:59 2023 +0200

    Guard SLP optimize latch edge discovery
    
    When inserting additional VEC_PERM nodes it seems we can run
    is_cfg_latch_edge but given there's eventually no representative
    we should avoid ICEing on it.
    
            * tree-vect-slp.cc (vect_optimize_slp_pass::is_cfg_latch_edge):
            VER_PERM node use is never the destination of a latch.

Diff:
---
 gcc/tree-vect-slp.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
index 30ed123d100..4c7ad976963 100644
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -4306,7 +4306,8 @@ vect_optimize_slp_pass::is_cfg_latch_edge (graph_edge *ud)
   slp_tree use = m_vertices[ud->src].node;
   slp_tree def = m_vertices[ud->dest].node;
   if (SLP_TREE_DEF_TYPE (use) != vect_internal_def
-      || SLP_TREE_DEF_TYPE (def) != vect_internal_def)
+      || SLP_TREE_DEF_TYPE (def) != vect_internal_def
+      || SLP_TREE_CODE (use) == VEC_PERM_EXPR)
     return false;
 
   stmt_vec_info use_rep = vect_orig_stmt (SLP_TREE_REPRESENTATIVE (use));