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The easiest option is runtime dispatch, for instance by using compiler support for function clones: https://lwn.net/Articles/691932/ https://lwn.net/Articles/69

• kevincox 4y ago
  Yes. To provide a quick summary, the compiler generates multiple versions of the code, then at runtime does feature detection and picks the best supported implementation. Generally this will only be done for particular functions or blocks that will get a notable benefit from these extra instructions to avoid too much code bloat (unlikely to significantly affect performance but will raise binary size).