[gcc r16-1027] tree-optimization/120357 - ICE with early break vectorization

[Richard Biener]

https://gcc.gnu.org/g:dce4da51ab66c3abb84448326910cd42f6fe2499

commit r16-1027-gdce4da51ab66c3abb84448326910cd42f6fe2499
Author: Richard Biener <rguenther@suse.de>
Date:   Fri May 30 14:11:47 2025 +0200

    tree-optimization/120357 - ICE with early break vectorization
    
    When doing early break vectorization of a loop with a conditional
    reduction the epilog creation code is confused as to before which exit
    to insert the conditional reduction induction IV update.  The
    following make sure this is done before the main IV exit.
    
            PR tree-optimization/120357
            * tree-vect-loop.cc (vect_create_epilog_for_reduction): Create
            the conditional reduction induction IV increment before the
            main IV exit.
    
            * gcc.dg/vect/vect-early-break_136-pr120357.c: New testcase.

Diff:
---
 gcc/testsuite/gcc.dg/vect/vect-early-break_136-pr120357.c | 13 +++++++++++++
 gcc/tree-vect-loop.cc                                     |  3 ++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/gcc/testsuite/gcc.dg/vect/vect-early-break_136-pr120357.c b/gcc/testsuite/gcc.dg/vect/vect-early-break_136-pr120357.c
new file mode 100644
index 000000000000..8a51cfc46a5d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-early-break_136-pr120357.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-add-options vect_early_break } */
+/* { dg-additional-options "-O3" } */
+
+char a;
+unsigned long long t[2][22];
+int u[22];
+void f(void)
+{
+  for (int v = 0; v < 22; v++)
+    for (_Bool w = 0; w < (u[v] < 0) + 1; w = 1)
+      a *= 0 != t[w][v];
+}
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 2d1a6883e6b8..8c5761d3c55d 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -6016,7 +6016,8 @@ vect_create_epilog_for_reduction (loop_vec_info loop_vinfo,
       /* Create an induction variable.  */
       gimple_stmt_iterator incr_gsi;
       bool insert_after;
-      vect_iv_increment_position (loop_exit, &incr_gsi, &insert_after);
+      vect_iv_increment_position (LOOP_VINFO_IV_EXIT (loop_vinfo),
+				  &incr_gsi, &insert_after);
       create_iv (series_vect, PLUS_EXPR, vec_step, NULL_TREE, loop, &incr_gsi,
 		 insert_after, &indx_before_incr, &indx_after_incr);