There are multiple possible lessons to take from this. On the one hand you could say that "aliasing is the issue, clearly things should not be just allowed to a

There are multiple possible lessons to take from this. On the one hand you could say that "aliasing is the issue, clearly things should not be just allowed to alias each other willy-nilly". Or on the other hand you could come away thinking "I always mistrusted optimizers! They are just too brittle and unpredictable! Placating them is a never ending treadmill. I'll manually vectorize key parts"