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by jasonmc 5359 days ago
"You realize that Java requires a nontrivial bytecode verifier too, right? IIRC the bytecode verifier, and certainly the compiler, require abstract interpretation to convert the stack-oriented bytecode to a virtual register-based one."

It seems like you are talking about Dalvik VM (Android). Java class files (stack bytecode) are actually converted to Dakvik's register bytecode ahead of time. (Before installation on the mobile device.) I'm unsure if Dalvik bytecode is verified or not.
1 comments
ootachi 5359 days ago
No, I'm talking about the verifier [1]. In particular: "There are no operand stack overflows or underflows." That requires abstract interpretation.

And every performant Java interpreter is required to convert the stack machine to vregs in order to perform register allocation. That requires abstract interpretation too.

[1]: http://java.sun.com/docs/white/langenv/Security.doc3.html

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jasonmc 5359 days ago
Sure, but I'd be willing to bet that performance impact of the the verifier is insignificant for all but the most trivial of programs.
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