Yup, these are often colloquially called "chicken bits" because you put them in if you're afraid your new feature won't work (It will generally just fall back t

Yup, these are often colloquially called "chicken bits" because you put them in if you're afraid your new feature won't work (It will generally just fall back to the previous battle-tested implementation). I often wonder how far back you can pare a modern CPU with these.