[Bug tree-optimization/64058] [5/6 Regression] Performance degradation after r216304

[law at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64058

--- Comment #20 from Jeffrey A. Law <law at redhat dot com> ---
And FWIW, the test in this BZ is totally compromised on the trunk.  Two primary
reasons.  First DOM does a much better job at finding & eliminating redundant
loads.   Second, erroneous path isolation finds a store to *0, it wipes out the
RHS of that store allowing massive cleanups by DCE.

I'll see if I can reasonably derive a testcase from 68654.