[Bug tree-optimization/57230] [4.7/4.8/4.9 Regression] tree-ssa-strlen incorrectly optimizes a strlen to 0

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57230

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 30086
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30086&action=edit
gcc49-pr57230.patch

And untested improvement for 4.9+ only.