[Bug tree-optimization/117780] -fsanitize=undefined -O1 false positive ‘%s’ directive argument is null [-Wformat-truncation=]

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117780

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---

  if (c_5 == 0B)
    goto <bb 3>; [0.00%]
  else
    goto <bb 5>; [100.00%]

  <bb 3> [count: 0]:
  __builtin___ubsan_handle_nonnull_arg (&*.Lubsan_data0);
  _14 = strlen (0B);
  snprintf (&aj, _14, &am, 0B);


It comes from jump threading where it is checking that the argument to strlen
was non-null.