I'm an "auto-vectorization skeptic" in many ways, but it's also the case that there will be other parts of your program that will benefit from being able to gen

I'm an "auto-vectorization skeptic" in many ways, but it's also the case that there will be other parts of your program that will benefit from being able to generate (for example) AVX2 instructions beyond a few specialized functions. If there is to be a CPU-specific dispatch mechanism, it should be more like a small binary/shell script that exec-s an entirely CPU-specific binary, dependent on runtime detection (cpuid, etc.). Dependent on your distribution mechanism, you might only download the appropriate binary. But if you do this, please remember to keep your binary sizes reasonable.