[Vm-dev] Re: [Pharo-dev] The Second Coming of Java article

David T. Lewis lewis at mail.msen.com
Wed Nov 27 03:01:43 UTC 2013

On Tue, Nov 26, 2013 at 01:30:40PM -0800, Eliot Miranda wrote:
> On Tue, Nov 26, 2013 at 12:49 PM, phil at highoctane.be <phil at highoctane.be>wrote:
> > FWIW, I'd love to have a working Pharo bytecode interpreter that works.
> > VMMaker currently doesn't have one it seems (earlier experiments didn't
> > worked for me).
> >
> > I am very interested with the VM, read the blue book, understand the
> > primitives, can somewhat read bytecode but what is needed now is the
> > ability to run/debug a VM inside Pharo itself. GDB'ing is okay but a pain
> > in the ass to understand what's going on.
> >
> > Also read the Tour of the OE of Tim Rowledge and Porting the VM etc.
> >
> > Also looked at the VMMaker package (Interpreter and Object Memory) + Slang.
> >
> > Now, getting an working interpreter would help me reach the next step. I
> > am not talking about the Stack interpreter, but the plain Interpreter.
> >
> > Any plans?
> >
> David Lewis and I want to see the Cog branch and the VMMaker proper merged
> and I definitely want the standard Interpreter to be married to Spur.  But
> I have no cycles to do this, and I don't think David has many either.
>  Volunteers welcome.

Fully agree :-)

With respect to the interpreter simulator, the simulators tend to get
bit rotted when not used, but I think that overall they are in reasonable
shape.  Granted that we currently have to fumble around with multiple code
bases, but it's fair to say that if you want to run a Cog/StackInterpreter/Spur
simulator, you can use the appropriate classes in the oscog branch (after
all, that is what Eliot is using for his active development, and it's quite
unlikely that he could do this without a working simulator). And if you
want to run an image using the classic interpreter, you should use the
interpreter simulator in the "trunk" VMMaker branch. 

I realize this may be a bit confusing, but as Eliot says there are only
so may free cycles available, so if someone wants to help ...

I just tried loading an image into the ("trunk") InterpreterSimulator
and found a problem in loading an image that had been saved from Cog.
This would be a problem if you wanted to load a Pharo image into the
InterpreterSimulator to try running bytecodes using a simple interpreter.
The fix is in VMMaker-dtl.330 in the source.squeak.org/VMMaker repository.
Hopefully it works for you now, please give it a try.


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