[gcc r17-3856] tree-optimization/127190 - ICE in vectorizable_lane_reducing

[Richard Biener]

https://gcc.gnu.org/g:439cd07b51676996889b1277afd46c1053d24ebc

commit r17-3856-g439cd07b51676996889b1277afd46c1053d24ebc
Author: Richard Biener <rguenther@suse.de>
Date:   Wed Sep 2 11:41:23 2026 +0200

    tree-optimization/127190 - ICE in vectorizable_lane_reducing
    
    The following properly fails analyzing a lane-reducing reduction
    when vect_get_num_copies_for_invariant fails instead of asserting
    it does not.  While analysis later verifies we can create the
    constant we use the info here for costing, so we have to fail
    early.
    
            PR tree-optimization/127190
            * tree-vect-loop.cc (vectorizable_lane_reducing): Fail
            when vect_get_num_copies_for_invariant does.

Diff:
---
 gcc/tree-vect-loop.cc | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index cb961440656d..19e7a6fa884f 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -6855,10 +6855,16 @@ vectorizable_lane_reducing (loop_vec_info loop_vinfo, stmt_vec_info stmt_info,
   /* Compute number of effective vector statements for costing from the
      number of input lanes allow for excess lanes in the last input vector.  */
   unsigned int ncopies_for_cost, excess_elts;
-  bool res = vect_get_num_copies_for_invariant (loop_vinfo, node_in,
-						&ncopies_for_cost,
-						&excess_elts);
-  gcc_assert (res && ncopies_for_cost >= 1);
+  if (!vect_get_num_copies_for_invariant (loop_vinfo, node_in,
+					  &ncopies_for_cost,
+					  &excess_elts))
+    {
+      if (dump_enabled_p ())
+	dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+			 "incompatible vector types for invariants\n");
+      return false;
+    }
+  gcc_assert (ncopies_for_cost >= 1);
 
   if (vect_is_emulated_mixed_dot_prod (slp_node))
     {