Erlang bytecodes and/or VM description?

[David Hopwood]

Thomas Lindgren wrote:
> Andrew Lentvorski <bsder@REDACTED> wrote:
> 
>>Is there a concise reference of the Erlang bytescodes and/or VM 
>>description somewhere?
>>
>>It seems like I have to go back to about R7B to look at an emulator
>>that is clean (as opposed to having lots of HiPE stuff scattered inside).
> 
> It depends on what you want to do. There used to be a
> BEAM bytecode reference, but I think the format and
> instructions change mildly every now and then, both
> with new releases and with different targets. 
> 
> For example, I believe some instruction sequences can
> be merged into superinstructions by the loader, and/or
> otherwise specialized or optimized. This can lead to
> hundreds of nearly identical instruction variants, so
> some patience and experience is needed to decipher
> them.

This might seem like a pointed question, but I'll ask it anyway:
how does one maintain a VM without accurate documentation of the
executable format it implements? I know I couldn't do it.

-- 
David Hopwood <david.nospam.hopwood@REDACTED>