Comment by fijal

If you want to see an advanced Python compiler, have a look at PyPy. While CPython bytecode compiler is "dump", it's as smart as it can be. You can do crazy stuff with speculative replacing of bytecodes with guards and type-specific bytecodes, but then you might as well create a full just in time compiler. It's incredibly hard to create optimizations on bytecode level without changing semantics, which Python rightly stayed away from.