"no previous systematic approaches including random testing have found any bugs in the mem2reg and gvn passes"<p>Uh?
This is demonstrably false. A quick trip to llvm bugzilla will show you that.
Zhengdong Su's C fuzzing has found basically endless bugs in GVN (and we fuzz NewGVN as well), and many bugs in GVN are well known at this point.<p>We just told him to not waste his time on GVN because they aren't sanely fixable without rearchitecting (hence, NewGVN).<p>Things like this frustrate me because a simple question on the llvm dev mailing list would have also elicited the correct answer.<p>(and yes, i already emailed the paper authors about this after i wrote this comment :P)