yep, I was more talking about instruction semantics, not really the encoding itself.
And even with fixes since software should come as assembly source files ultimately with risc-v, we should be sort of very fine, even if the encoding does change. We are not talking about absurdely and grotesquely complex c++ compiler backends!
Why? That makes no sense. Its like, lets do 100 of man years of work so maybe we can do a few % better on encoding if you will do better at all.