Re: We already have autonomous code generation
"Oh I wasn't even referring to an optimizing compiler."
Yeah, neither was I. I was referring to machine instructions, which back in the Olden Days one tried not to use in tight loops (using, say, shift & add for multiplying a constant with your variable, or even shift & subtract for the division equivalent). Changes in hardware are just one of the things that also drive changes in software languages.
My point was more toward the fact that what we regard as a compiler will change in the coming decades, because the languages we use will have more features 1 and (one hopes) more safeguards.
1. Julia, in fact has just-do-it operations in it that I could only dream about forty years ago.