> It may surprise a lot of people to know that the JVM's bytecode is actually very, very much not cleanly mappable back to a normal processor's machine code or instruction set

I believe this is a very sensible decision: being too close to a real architecture would probably tie the bytecode to similar architectures too much and make it quite useless as opposed to compiling to an actual architecture.

The bytecode being abstract enough is likely a good thing to be able to achieve okay performance everywhere. Like, you wouldn't want the bytecode to specify a fixed number of registers.

What may also surprise many people thinking Java is a bloated language is that the Java bytecode is actually quite simple, straightforward to understand, clean and also very well documented. It's an interesting thing to look into, even for someone not involved day to day in some Java.