Re : [Help-smalltalk] About sp and thisContext->spOffset

[Mathieu Suen]

----- Message d'origine ----
> De : Paolo Bonzini <address@hidden>
> Objet : Re: [Help-smalltalk] About sp and thisContext->spOffset
> 
> On 08/26/2010 05:45 PM, Mathieu Suen wrote:
> > Hi,
> >
> > AFAIK sp  in a context take in account the temporaries.
> > This mean the if you have  1 temp sp is equal to 1 at the beginning of the
> > function (minus the fact  the is lazily sync but that is not my point)
> >  From that there is  something I don't understand:
> > In smalltalk I got the following  example:
> >
> >      | method |
> >       method := (STInST.RBParser parseMethod: 'foo ^12') jitMethodIn:  A.
> >      A methodDictionary at: #foo put:  method.
> >      A new foo printNl
> >
> > I would  expected to be FROM_INT(2) aka 5 since you have (A new) push on the
> >  stack.
> > What did I miss-understood?
> 
> Temporaries in the REPL are  kind of special because they must survive 
> multiple evaluations.  So,  they are treated as globals (or as instance 
> variables in  VisualGST).
> 
> Try wrapping your test with Eval [ ... ], which will delimit  the scope 
> of the "method" variable, and sp will be 2 as  expected.

Sorry I didn't mention it but the test above is written in a unit test:

    testReturn [
     | method |
    method := (STInST.RBParser parseMethod: 'foo ^12') jitMethodIn:  A.
    A methodDictionary at: #foo put:  method.
    A new foo printNl
    ]


But from this :

/* activate_new_context */
thisContext->spOffset =
    FROM_INT ((sp - thisContext->contextStack) - sendArgs);


It seems normal that spOffset is equal to FROM_INT(1).
So it mean also the the push if it were using spOffset should be:

push: object
memory storePointer: stackPointer
 ofObject: activeContext
 withValue: object.
stackPointer := stackPointer + 1.
Instead of:

push: object
stackPointer := stackPointer + 1.
memory storePointer: stackPointer
 ofObject: activeContext
 withValue: object

> 
> Paolo
>