[Bug tree-optimization/61009] Incorrect jump threading in dom

[law at redhat dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=61009

--- Comment #7 from Jeffrey A. Law <law at redhat dot com> ---
I see what's happening here...  I need to think about how best to handle this
situation.  Oh how threading across loop backedges perilous.