diff --git a/gcc/testsuite/gcc.dg/torture/pr103237.c b/gcc/testsuite/gcc.dg/torture/pr103237.c
new file mode 100644
index 00000000000..f2399f9586e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr103237.c
@@ -0,0 +1,24 @@
+/* { dg-do run } */
+/* { dg-additional-options "-ftree-vectorize" } */
+
+int g1;
+unsigned int g2 = -1U;
+static void __attribute__((noipa))
+func_1()
+{
+  int *l_1 = &g1;
+  for (int g3a = 0; g3a != 4; g3a++)
+    for (int l_2 = 0; l_2 <= 3; l_2++)
+      {
+        unsigned int *l_3 = &g2;
+        *l_1 = *l_3 ^= 1;
+      }
+}
+int
+main()
+{
+  func_1();
+  if (g1 != -1)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index 1cd5dbcb6f7..73efdb96bad 100644
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -3567,6 +3567,17 @@ vect_is_simple_reduction (loop_vec_info loop_info, stmt_vec_info phi_info,
       return def_stmt_info;
     }
 
+  /* When the inner loop of a double reduction ends up with more than
+     one loop-closed PHI we have failed to classify alternate such
+     PHIs as double reduction, leading to wrong code.  See PR103237.  */
+  if (inner_loop_of_double_reduc && lcphis.length () != 1)
+    {
+      if (dump_enabled_p ())
+	dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+			 "unhandle double reduction\n");
+      return NULL;
+    }
+
   /* If this isn't a nested cycle or if the nested cycle reduction value
      is used ouside of the inner loop we cannot handle uses of the reduction
      value.  */