[Bug c/69835] [6 Regression] -Wnonnull diagnoses parameter comparisons with NULL even when those could have changed

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69835

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 37703
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37703&action=edit
gcc6-pr69835.patch

Untested fix, which moves the warning from the FE to early uninit pass (i.e.
shortly after going into SSA).