On 03.10.2010, at 12:45, Mariano Martinez Peck wrote:

On Sun, Oct 3, 2010 at 12:42 PM, Bert Freudenberg <bert@freudenbergs.de> wrote:
What exactly are you trying to do?

hehehe sorry. I am trying to "detect unused objects".

What for?

 When do you consider an object to be "used"? 

When it receives a message. This is why I changed #normalSend

Thanks in advance,


Neither the class nor the compiled method "receive a message". Plus there are many ways an object "appears" to receive a message but isn't really. E.g. a Float won't receive #+ because that is short-circuited in the bytecodes. A super send does not use "normalSend". Etc.

Judging from your test cases, if an objects is just passed as an argument, you do not consider it to be used. What if you send it the #class message? What if you identity-compare it (==)?  Should that count as "used"?

Maybe if you let us in on the bigger picture we could help you better.

- Bert -

On 03.10.2010, at 12:12, Mariano Martinez Peck wrote:

Hi. I have a related question once again with this topic. I've changed Interpreter >> normalSend to something like this:

    "Send a message, starting lookup with the receiver's class."
    "Assume: messageSelector and argumentCount have been set, and that
    the receiver and arguments have been pushed onto the stack,"
    "Note: This method is inlined into the interpreter dispatch loop."
    | rcvr |
    self inline: true.
    self sharedCodeNamed: 'normalSend' inCase: 131.
    rcvr := self internalStackValue: argumentCount.
    ((self isIntegerObject: rcvr) not and: [hasToTrace])
        ifTrue: [
            self internalTurnOnUsedBit: rcvr.
    lkupClass := self fetchClassOf: rcvr.
    receiverClass := lkupClass.
    self commonSend.

So...if it is not a SmallInetger and if the flag is on, I turn on a bit.

The question is, if I send a normal message to a normal object. Example:

| anObject |
anObject := MyClass new.
anObject foo

Now...I am sure that "anObject" was marked with the bit. But what about:
a) the compiled method  MyClass >> #foo
b) MyClass

should they be marked?

In other words:

self deny: (unUsed primitiveGetUsedBit: anObject).
    self deny: (unUsed primitiveGetUsedBit: anObject class).
    self deny: (unUsed primitiveGetUsedBit: (anObject class >> #foo)).
     anObject foo.

    self assert: (unUsed primitiveGetUsedBit: anObject).
    self assert: (unUsed primitiveGetUsedBit: anObject class).
    self assert: (unUsed primitiveGetUsedBit: (anObject class >> #foo)).

should all the asserts pass?  I ask because I don't know how CompiledMethods are executed (they receive a normalSend like any other object?) nor how class are accessed.

Thanks in advance,


On Tue, May 11, 2010 at 5:43 PM, Igor Stasenko <siguctua@gmail.com> wrote:

On 11 May 2010 17:40, Mariano Martinez Peck <marianopeck@gmail.com> wrote:
>> >
>> > 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 ?
>> >
>> err... commonSend or commonSend? i think it would be the same :)
> hahahah sorry, I meant commonSend instead of normalSend.
>> the other point, where you can try intercept a send is cache lookup.
> internalFindNewMethod  ?

I don't know, maybe :)

> Thanks
> Mariano