[Bug tree-optimization/59322] [4.9 Regression] ICE with segfault on valid code at -O1, -O2, and -O3 on x86_64-linux-gnu

[law at redhat dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59322

--- Comment #4 from Jeffrey A. Law <law at redhat dot com> ---
Thanks for the bug report.  It hits a hunk of code which I've looked at a few
times in the last couple months and haven't been able to convince myself it's
correct or desirable.

In create_edge_and_update_destination_phis, we clone a jump threading path onto
the newly created edge.

That path has a reference to an edge that later gets removed.

Then we look at the path and fault.