--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/strlenopt-41.c	Thu Oct 25 07:37:49 2018 +0900
@@ -0,0 +1,34 @@
+/* PR tree-optimization/83671 - fix for false positive reported by
+   -Wstringop-overflow does not work with inlining
+   Verify that the length the empty string is folded to zero even at -O1
+   regardless of offset into it.
+   Also verify that the length of a non-empty string isn't folded given
+   a variable offset.
+   { dg-do compile }
+   { dg-options "-O1 -fdump-tree-optimized" } */
+
+#include "strlenopt.h"
+
+inline unsigned length (const char *s)
+{
+  return __builtin_strlen (s);
+}
+
+void check_length_cst (int i)
+{
+  unsigned len = length (&""[i]);
+
+  if (len)
+    __builtin_abort ();
+}
+
+void check_length_var (int i)
+{
+  unsigned len = length (&"1"[i]);
+
+  if (len != 1)
+    __builtin_abort ();
+}
+
+/* { dg-final { scan-tree-dump-times "abort" 1 "optimized" } }
+   { dg-final { scan-tree-dump-times "strlen" 1 "optimized" } } */