http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58340
--- Comment #11 from Jeffrey A. Law <law at redhat dot com> --- I've found a minor error in the tree-ssa-threadedge.c changes. I can easily see how it affects Zhengong's testcase and I can speculate how it might be triggering the ia64 failure. I'm testing it on x86_64-unknown-linux-gnu at the moment. I'll spin up a test on ia64 at some point over the weekend as well.