Message 384466 - Python tracker

> The gist seems to be to have extra opcodes that only work for certain situations (e.g. INT_BINARY_ADD). In a hot function we can rewrite opcodes with their specialized counterpart. The new opcode contains a guard that rewrites itself back if the guard fails (and then it stays unoptimized).

This is also roughly what I suggested in https://bugs.python.org/msg379333. Except that I don't think it's necessary to add new opcodes.