https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57534
--- Comment #27 from Jeffrey A. Law <law at redhat dot com> --- WRT c#21. There is a good paper from Click on an integrated GVN/GCM/reassoc. "Combining Analyses, Combining Optimizations" It was published in PLDI. I've probably got a copy here if you want it.
