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Re: [squeak-dev] Re: Bug with valueWithReceiver:arguments:

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Antoine Marot

Re: [squeak-dev] Re: Bug with valueWithReceiver:arguments:

Hi all,

Do you know when this fix will be added in a new squeak vm release ?

I really need it for my thesis... So I tried to build the vm (without VMMaker since it doesn't want to be loaded...).

This is how I tried to fix the interp.c file (it's probably wrong since this doesn't fix anything) :

sqInt primitiveExecuteMethod(void) {

sqInt top;

sqInt successValue;

sqInt primIdx;

sqInt nArgs;

sqInt delta;

sqInt primBits;

/* begin popStack */

top = longAt(foo->stackPointer);

foo->stackPointer -= BytesPerWord;

foo->newMethod = top;

/* begin primitiveIndexOf: */

primBits = (((usqInt) (longAt((foo->newMethod + BaseHeaderSize) + (HeaderIndex << ShiftForWord)))) >> 1) & 268435967;

foo->primitiveIndex = (primBits & 511) + (((usqInt) primBits) >> 19);

/* begin success: */

successValue = (foo->argumentCount - 1) == ((((usqInt) (longAt((foo->newMethod + BaseHeaderSize) + (HeaderIndex << ShiftForWord)))) >> 25) & 15);

foo->successFlag = successValue && foo->successFlag;

if (foo->successFlag) {

foo->argumentCount -= 1;

/* begin executeNewMethod */

if (foo->primitiveIndex > 0) {

/* begin primitiveResponse */

if (DoBalanceChecks) {

nArgs = foo->argumentCount;

delta = foo->stackPointer - foo->activeContext;

}

primIdx = foo->primitiveIndex;

foo->successFlag = 1;

dispatchFunctionPointerOnin(primIdx, primitiveTable);

if (DoBalanceChecks) {

if (!(balancedStackafterPrimitivewithArgs(delta, primIdx, nArgs))) {

printUnbalancedStack(primIdx);

}

if (foo->successFlag) {

goto l1;

}

activateNewMethod();

/* begin quickCheckForInterrupts */

if ((foo->interruptCheckCounter -= 1) <= 0) {

checkForInterrupts();

}

l1: /* end executeNewMethod */;

foo->successFlag = 1;

} else {

/* begin unPop: */

foo->stackPointer += 1 * BytesPerWord;

}

Basically, I just added "foo->successFlag = 1;" after /* end executeNewMethod */;.

Cheers,

Antoine

Date: Oct 28, 2008; 12:55am
Author: Eliot Miranda-2
Squeak - Dev (http://www.nabble.com/Squeak---Dev-f14154.html)
Well I actually wrote the fix as

primitiveExecuteMethod
"receiver, args, then method are on top of stack. Execute method against receiver and args"
newMethod := self popStack.
primitiveIndex := self primitiveIndexOf: newMethod.
self success: argumentCount - 1 = (self argumentCountOf: newMethod).
successFlag
ifTrue: [argumentCount := argumentCount - 1.
self executeNewMethod.
"Recursive xeq affects successFlag"
successFlag := true]
ifFalse: [self unPop: 1]

to agree with the perform code. The fix is to ensure that successFlag is true.

Igor Stasenko

Re: [squeak-dev] Re: Bug with valueWithReceiver:arguments:

2008/11/20 Antoine Marot <[hidden email]>:
> Hi all,
> Do you know when this fix will be added in a new squeak vm release ?
> I really need it for my thesis... So I tried to build the vm (without
> VMMaker since it doesn't want to be loaded...).
> This is how I tried to fix the interp.c file (it's probably wrong since this
> doesn't fix anything) :

Yes, its wrong. Please try load VMMaker and fix code in smalltalk instead.
The C code is a mess, generated by VMMaker, and you should never do
anything with it, except some debugging and checking if it generates
code correctly.

--
Best regards,
Igor Stasenko AKA sig.

Antoine Marot

Re: [squeak-dev] Re: Bug with valueWithReceiver:arguments:

Thank you Igor for your reply.

I finally succeeded in making a VM :) (I still have to print my squeak
VM builder certificate and display it proudly ;) ).

Does anyone know approximately when this fix should be added to an
official release ? This bug seriously makes it hard for me to share my
code...

Best regards,

Antoine

---
Antoine Marot
Ph.D Student
Département d'Informatique
Université Libre de Bruxelles

Le 20-nov.-08 à 16:33, Igor Stasenko a écrit :

> 2008/11/20 Antoine Marot <[hidden email]>:
>> Hi all,
>> Do you know when this fix will be added in a new squeak vm release ?
>> I really need it for my thesis... So I tried to build the vm (without
>> VMMaker since it doesn't want to be loaded...).
>> This is how I tried to fix the interp.c file (it's probably wrong
>> since this
>> doesn't fix anything) :
>
> Yes, its wrong. Please try load VMMaker and fix code in smalltalk
> instead.
> The C code is a mess, generated by VMMaker, and you should never do
> anything with it, except some debugging and checking if it generates
> code correctly.
>
>
> --
> Best regards,
> Igor Stasenko AKA sig.
>

Klaus D. Witzel

[squeak-dev] Re: Bug with valueWithReceiver:arguments:

On Sun, 23 Nov 2008 15:38:42 +0100, Antoine Marot wrote:

> Thank you Igor for your reply.
>
> I finally succeeded in making a VM :) (I still have to print my squeak
> VM builder certificate and display it proudly ;) ).

Well done, congratulations :)

> Does anyone know approximately when this fix should be added to an
> official release ? This bug seriously makes it hard for me to share my
> code...

I understand that what you need is "... method
valueWithReceiver:arguments: is used hugely with method wrappers" and you
need it without VM bug when a primitive fails.

Perhaps a stupid question (I don't know any other your requirements) but
instead of wrapping methods one could easily #perform: a selector on the
receiver. What would be the reason that you depend on
#valueWithReceiver:arguments: ? it cannot be performance since #perform:
needs some time as well.

/Klaus

>
> Best regards,
>
> Antoine
>
> ---
> Antoine Marot
> Ph.D Student
> Département d'Informatique
> Université Libre de Bruxelles
>
> Le 20-nov.-08 à 16:33, Igor Stasenko a écrit :
>
>> 2008/11/20 Antoine Marot <[hidden email]>:
>>> Hi all,
>>> Do you know when this fix will be added in a new squeak vm release ?
>>> I really need it for my thesis... So I tried to build the vm (without
>>> VMMaker since it doesn't want to be loaded...).
>>> This is how I tried to fix the interp.c file (it's probably wrong
>>> since this
>>> doesn't fix anything) :
>>
>> Yes, its wrong. Please try load VMMaker and fix code in smalltalk
>> instead.
>> The C code is a mess, generated by VMMaker, and you should never do
>> anything with it, except some debugging and checking if it generates
>> code correctly.
>>
>>
>> --Best regards,
>> Igor Stasenko AKA sig.
>>
>
>

Antoine Marot

Re: [squeak-dev] Re: Bug with valueWithReceiver:arguments:

>> Does anyone know approximately when this fix should be added to an
>> official release ? This bug seriously makes it hard for me to share
>> my code...
>
> I understand that what you need is "... method
> valueWithReceiver:arguments: is used hugely with method wrappers"
> and you need it without VM bug when a primitive fails.
>
> Perhaps a stupid question (I don't know any other your requirements)
> but instead of wrapping methods one could easily #perform: a
> selector on the receiver. What would be the reason that you depend
> on #valueWithReceiver:arguments: ? it cannot be performance since
> #perform: needs some time as well.
>
> /Klaus

The goal of my wrappers is to choose (depending on the context)
between the original method and an instrumented one.

The calling code is similar to this :

receiver
withArgs: args
executeMethod:
(context-condition
ifTrue: [transformedMethod]
ifFalse: [originalMethod] )

Note that I don't use #valueWithReceiver:, but the bug also appears
with that method.

Since #perform: goes through the method lookup process, it will loop
unless I use two new selectors. This solution has several
disadvantages like implying a second lookup process or not being
invisible (the new method dictionary entries appear in browsers and
are editable which is problematic).

Antoine

Klaus D. Witzel

[squeak-dev] Re: Bug with valueWithReceiver:arguments:

On Sun, 23 Nov 2008 17:51:42 +0100, Antoine Marot wrote:

>>> Does anyone know approximately when this fix should be added to an
>>> official release ? This bug seriously makes it hard for me to share my
>>> code...

Further to the below I checked http://bugs.squeak.org and there was not
report? I think you (or Frederic) have to report the bug before it
officially is one ...

>> I understand that what you need is "... method
>> valueWithReceiver:arguments: is used hugely with method wrappers" and
>> you need it without VM bug when a primitive fails.
>>
>> Perhaps a stupid question (I don't know any other your requirements)
>> but instead of wrapping methods one could easily #perform: a selector
>> on the receiver. What would be the reason that you depend on
>> #valueWithReceiver:arguments: ? it cannot be performance since
>> #perform: needs some time as well.
>>
>> /Klaus
>
> The goal of my wrappers is to choose (depending on the context) between
> the original method and an instrumented one.
>
> The calling code is similar to this :
>
> receiver
> withArgs: args
> executeMethod:
> (context-condition
> ifTrue: [transformedMethod]
> ifFalse: [originalMethod] )
>
> Note that I don't use #valueWithReceiver:, but the bug also appears with
> that method.
>
> Since #perform: goes through the method lookup process, it will loop
> unless I use two new selectors. This solution has several disadvantages
> like implying a second lookup process or not being invisible (the new
> method dictionary entries appear in browsers and are editable which is
> problematic).

Okay, understood (I think so ;) Perhaps there is a workaround (namely: the
Smalltalk simulator) for Squeak, which you can give a try:

The debugger apparently knows how to perform a primitive by number, look
at #tryPrimitive:withArgs: its implementor and sender.

If you do that and it returns (ContextPart primitiveFailToken) then do the
"primitiveFailed" part, using #withArgs:executeMethod: as above *but* on a
*clone* of the originalMethod into which you put primitive number 0
(repeat: the clone!).

HTH.

/Klaus

>
> Antoine
>

--
"If at first, the idea is not absurd, then there is no hope for it".
Albert Einstein

Antoine Marot

Re: [squeak-dev] Re: Bug with valueWithReceiver:arguments:

Le 23-nov.-08 à 19:39, Klaus D. Witzel a écrit :

>
> Further to the below I checked http://bugs.squeak.org and there was
> not report? I think you (or Frederic) have to report the bug before
> it officially is one ...
>

Ok, I'll do that :)

> Okay, understood (I think so ;) Perhaps there is a workaround
> (namely: the Smalltalk simulator) for Squeak, which you can give a
> try:
>
> The debugger apparently knows how to perform a primitive by number,
> look at #tryPrimitive:withArgs: its implementor and sender.
>
> If you do that and it returns (ContextPart primitiveFailToken) then
> do the "primitiveFailed" part, using #withArgs:executeMethod: as
> above *but* on a *clone* of the originalMethod into which you put
> primitive number 0 (repeat: the clone!).

Excellent idea ! Thank you very much !

Antoine