Comment by VorpalWay

Not yet that I know of, though perhaps LLVM might be able to infer simple cases (when loading from a known constant for example).

Pattern types could potentially maybe in the future allow for the compiler to know more details though. They are a nightly feature, and afaik only for enums, integers and pointers so far. The idea would be that you can define a custom type such as "an integer between 7 and 45" and everything else become niches for niche optimisation (e.g. for `Option<MyFunkyInt>` some of those impossible values would be used to represent the None case of the wrapping Option).

But I could envisage a future in which you could say "f64 without NaN" which would both make those available for niches and potentially tell LLVM about this. However, we are very far from any of that currently. And it might not be what you want, since you would need to add checks when you perform operations to ensure the value doesn't suddenly become a NaN. Which is way more complicated than ensuring integers don't become, say, zero. It will likely be much harder to optimise away the checks.