I'm surprised that the GCC doesn't add some autodetection mechanism in it. As 'hubicka' mentions in another comment, GCC does have "multi-versioning" capabilit

I'm surprised that the GCC doesn't add some autodetection mechanism in it. As 'hubicka' mentions in another comment, GCC does have "multi-versioning" capability, but it doesn't use it by default. Instead, one needs to mark individual functions with GCC specific attributes, asking for versions with different capabilities to be created: https://lwn.net/Articles/691932/ https://lwn.net/Articles/691932/. This isn't necessarily a bad approach, but the fact that it seems be used rarely makes me wonder if some other more default approach that works with unmodified code might be an improvement.