Ah, OK. Can the optimizer's test suite be found anywhere under GitHub - apple/swift: The Swift Programming Language ? (I tried but couldn't find it.)
Is there some strategy for dealing with cases like these, except trusting that enough people will find the urge to perform enough experiments like this and file enough bugs?
Assuming that there are more people like me out there, ie non-compiler hackers yearning for increased efficiency and predictability of the optimizer, willing to spend some but not too much of their time helping to improve the situation in some way, what are some recommended ways to contribute?
(I wish there is some other way than filing individual bugs for each specific case we can find (for the most recent snapshot I guess), which would for example mean at least 6 bugs for the little demonstration in the OP.)