Do current JIT implementation already have something to control specialization? I have heard many times for example that JavaScript engines will specialize hot paths.
To the best of my knowledge (which isn’t great) .NET has multiple compilation levels for functions, using more time after a method has been called a few times. But starts with a pretty fast but naive compilation. It also, I believe, specialises everything all the time, but (probably because of the multi-level compilation) that doesn’t seem to be a practical problem.