From what I remember of a deep dive post I read on this once, the ordering type bug / no-bug situations tend to be the result of incorrect optimizations. Changi

From what I remember of a deep dive post I read on this once, the ordering type bug / no-bug situations tend to be the result of incorrect optimizations. Changing the ordering will sometimes make the code look just different enough to go down a different (not bugged) optimization path. If you ever catch them still there with a "no optimizations" flag, then that's a pretty serious bug!