[gcc r17-2417] Improve dump when SLP fails to compute lane extraction insertion points

https://gcc.gnu.org/g:ab9d428a577b85cef3832bb92d6d3d0bb07e7ad5

commit r17-2417-gab9d428a577b85cef3832bb92d6d3d0bb07e7ad5
Author: Richard Biener <[email protected]>
Date:   Wed Jul 15 13:20:55 2026 +0200

    Improve dump when SLP fails to compute lane extraction insertion points
    
    The following helps debugging.
    
            * tree-vect-slp.cc (vect_bb_slp_mark_live_stmts): Enhance
            dumping in the failure case.

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 ff11b392305d..7abf0faa765e 100644
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -9082,7 +9082,8 @@ vect_bb_slp_mark_live_stmts (bb_vec_info bb_vinfo, slp_tree node,
 		    if (dump_enabled_p ())
 		      dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
 				       "Cannot determine insertion place for "
-				       "lane extract\n");
+				       "lane extract of %T at node %p\n",
+				       DEF_FROM_PTR (def_p), (void *)node);
 		    can_insert = false;
 		    break;
 		  }