The neg induction vectorization code isn't prepared to deal with
single element vectors.
PR tree-optimization/114733
* tree-vect-loop.cc (vectorizable_nonlinear_induction): Reject
neg induction vectorization of single element vectors.
* gcc.dg/vect/pr114733.c: New testcase.
--- /dev/null
+/* { dg-additional-options "-O3" } */
+
+#include "tree-vect.h"
+
+long b = 1;
+signed char c;
+int d[25];
+
+int main()
+{
+ check_vect ();
+ for (signed char g = 0; g < 8; g += 1)
+ for (short h = 0; h < 25; h += 2) {
+ b *= -1;
+ c ^= d[h];
+ }
+ if (b != 1)
+ abort ();
+ return 0;
+}
switch (induction_type)
{
case vect_step_op_neg:
+ if (maybe_eq (TYPE_VECTOR_SUBPARTS (vectype), 1u))
+ return false;
if (TREE_CODE (init_expr) != INTEGER_CST
&& TREE_CODE (init_expr) != REAL_CST)
{