I'm not sure a fully correct production optimizing compiler is that feasible. LLVM gets multiple miscompilation reports per week (from what I've haphazardly seen observing the issue tracker).

Theoretically changing the order of the passes in the optimization pipeline shouldn't cause any correctness issues, but the fact is that the ordering in the default compilation pipelines is the one that is most tested, so there will probably be bugs exposed when fuzzing the pass ordering.