Many data-/number-crunching C libraries already do dynamic-link-time or runtime cpu feature detection and select appropriate implementations. E.g. glibc already

Many data-/number-crunching C libraries already do dynamic-link-time or runtime cpu feature detection and select appropriate implementations. E.g. glibc already has bunch of specialized assembly impls for many of the string operations https://github.com/bminor/glibc/tree/master/sysdeps/x86_64/multiarch https://github.com/bminor/glibc/tree/master/sysdeps/x86_64/m...