[Vm-dev] normalSend, specialObjectsArray and VM

[Mariano Martinez Peck]

On Fri, May 7, 2010 at 11:10 PM, Igor Stasenko <siguctua at gmail.com> wrote:

>
> On 7 May 2010 23:04, Eliot Miranda <eliot.miranda at gmail.com> wrote:
> >
> >
> >
> > On Fri, May 7, 2010 at 2:30 AM, Mariano Martinez Peck <
> marianopeck at gmail.com> wrote:
> >>
> >>
> >> Hi folks. I need to intercept ALL message sends. For the moment, I
> intercepted in Interpreter >> normalSend
> >>
> >> But now, I have a question: I know there is that specialObjectArray that
> contain objects that may be accessed by the VM.
> >>
> >> So, the first question is, they are only ACCESSED and to things with
> pointers or they also send messages to those objects from the VM?
> >
> > Only accessed. The Interpreter has specialObjectsArray as one of its
> object references (along with nil, true, false) and indexes it with indices
> stored in class variables such
> as SpecialSelectors, CharacterTable, ClassMessage et al.  See implementors
> and senders of splObj:.
> >>
> >> If the VM really send messages to those object, how that is done ?  The
> code goes also by normalSend ? Or they go from somewhere else that I am not
> intercepting.
> >
> > At the bottom the VM has to access objects directly to avoid infinite
> regress.  So the only sends are in response to send bytecodes, the perform:
> primitives, and other edge cases (looking up run:with:in: in the
> invoke-object-as-method prim and looking up a callback entry point in the
> Alien FFI).
>
> there's also a limited set of selectors, for which VM does not a
> normal send, but skips the standard lookup procedure, like with #class
> message.
>


Thanks Igor. I could see #class does not the normal way. It was logic as it
already has the pointer there ;)

Now I wonder...to avoid those special cases, do you think it makes sense to
intercept in commonSend rather than commonSend ?  or it would be the same ?

Thanks!

Mariano




>
> >>
> >> Thank you very much.
> >>
> >> Mariano
> >
> > chers
> > Eliot
> >
> >
>
>
>
> --
> Best regards,
> Igor Stasenko AKA sig.
>
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