The example here is trivially safe but more general SIMD safety is going to be extremely difficult to analyze for safety, possibly intractable. For example, it

The example here is trivially safe but more general SIMD safety is going to be extremely difficult to analyze for safety, possibly intractable. For example, it is perfectly legal to dereference a vector pointer that references illegal memory if you mask the illegal addresses. This is a useful trick and common in e.g. idiomatic AVX-512 code. The mask registers are almost always computed at runtime so it would be effectively impossible to determine if a potentially illegal dereference is actually illegal at compile-time. I suspect we’ll be hand-rolling unsafe SIMD for a long time. The different ISAs are too different, inconsistent, and weird. A compiler that could make this clean and safe is like fusion power, it has always been 10 years away my entire career.