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Comment by pifflesnort | Hacker News Reader

> It's not. Asm.js is pretty much just assembly.

No, it's not. Have you even read http://asmjs.org/spec/latest/ ?

It's a rather high-level bytecode, expressed by constraining JavaScript to a specific subset of the language, interpreted according to rules that are considerably more specific than those specified in the JavaScript spec.

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It essentially exposes a load-store architecture, exactly as the assembly language of RISC processors does. There are some minor differences, such as the control structures and an infinite register file, but those aren't really relevant to reverse engineering. (IDA has been able to figure out control structures and local variables for a long time now.)

Would you call Java's or Dalvik's bytecode assembly?

Yes. But note that, even so, there is a large distinction between Java or Dalvik bytecode and asm.js: the memory model of Java and Dalvik bytecode is defined in terms of high-level class types, object instances, and properties, while the memory model of asm.js is a large array, 8 bits wide by X MB long. Naturally, the latter is much lower-level and more difficult to decompile…

In that case, I think we just have some differing definitions.

Given who he is, I imagine pcwalton is far more familiar with it than you are. Either way, you're wrong. Bytecode is not human readable which, as even your definition states, asm.js clearly is.

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