But consider, for it to be worth asking, it's got to be something that's very difficult to infer, or the compiler wouldn't need to ask. That means it will proba

But consider, for it to be worth asking, it's got to be something that's very difficult to infer, or the compiler wouldn't need to ask. That means it will probably be difficult for you to infer as well. In practice, you might have to profile all possible options, which would quickly turn into a major project if you're asked more than a handful of questions. And, of course, even if you can figure it out, that alignment annotation you just made is only optimal on the one target. Even on x86 it will depend on what instructions are available.