[Vm-dev] Integer overflow with BitBlt rule 20 and depth 32

[Eliot Miranda]

On Mon, Oct 26, 2009 at 1:04 PM, Juan Vuletich <juan at jvuletich.org> wrote:

>
> Hi Eliot,
>
> Eliot Miranda wrote:
>
>>
>> Hi Juan,
>>
>>
>> On Mon, Oct 26, 2009 at 11:07 AM, Juan Vuletich <juan at jvuletich.org<mailto:
>> juan at jvuletich.org>> wrote:
>>
>>
>>    Eliot Miranda wrote:
>>
>>
>>        On Mon, Oct 26, 2009 at 6:01 AM, Juan Vuletich
>>        <juan at jvuletich.org <mailto:juan at jvuletich.org>
>>        <mailto:juan at jvuletich.org <mailto:juan at jvuletich.org>>> wrote:
>>
>>
>>           Hi Folks,
>>
>>           I've just opened http://bugs.squeak.org/view.php?id=7407 ,
>>        with a
>>           description of the problem, several tests (based on Henrik's
>>           scripts) and the fix I propose.
>>
>>           David T. Lewis wrote:
>>
>>                On Sat, Oct 24, 2009 at 10:40:17AM -0300, Juan
>>        Vuletich wrote:
>>                                 What worries me a bit is the other changes
>> I needed
>>        to do
>>                   to be able to run the Smalltalk BitBlt simulation
>>        and to
>>                   do the translation. These are:
>>                   BitBltSimulator >> #oopForPointer:   "May be harmless"
>>                   CArrayAccessor >> #long32At:         "Why is this
>>        needed?"
>>                   CArrayAccessor >> #long32At:put:      "Why is this
>>        needed?"
>>
>>               I am just guessing here, but I think that BitBltSimulator
>>               expects to
>>               be used with an interpreter simulator, so perhaps if you
>>               initialize it
>>               with a simulator there will be no need to add these
>>        methods.
>>
>>                sim := BitBltSimulator new setInterpreter:
>>               InterpreterSimulator new
>>
>>               Dave
>>
>>           Given that BitBltSimulation calls #isIntegerObject: it
>>        looks like
>>           the ivar interpreterProxy should hold an InterpreterProxy
>>        (as it
>>           already does) and not an InterpreterSimulator. I did not add my
>>           patch to make simulation work to Mantis, as I'm not sure
>>        about them.
>>
>>
>>        When simulating the interpreterProxy inst var should hold the
>>        InterpreterSimulator, not the proxy.
>>
>>
>>    Maybe it should be an InterpreterSimulator when simulating the
>>    whole interpreter. When calling #copyBitsSimulated, it is set to
>>    an InterpreterProxy in #copyBitsFrom: .
>>
>>    Anyway, I'm asking for help on making #copyBitsSimulated work
>>    again, like it should do when called from BitBltTest. If nobody
>>    can help with that, I guess I'll open a Mantis issue for this
>>    problem, in the hope that some day it gets fixed.
>>
>>
>> Well with my current VM I see no problems; all 10 tests are green.  What
>> is the bug that you see?  How can I reproduce it?
>>
>> tia
>> Eliot
>>
>
> Thank you for caring about this issue!
>
> I apologize for not being clear. Check #testAlphaCompositingSimulated and
> #testAlphaCompositing2Simulated. Both do nothing if BitBltSimulation is not
> there. If you load VMMaker, both tests give errors. The VM in use should be
> irrelevant, this is pure Smalltalk.
>

I understand that.  I have an image containing BitBltSimulation and 5
different VMs :)  I'm developing Cog, a faster Squeak VM.  In my image with
BitBltSimulation present all 10 BitBltTest tests pass.  But I have done some
work on the simulator.

I am asking you to help me reproduce the bug and then I can export the fixes
from my VM to fix VMMaker.  What version of VMMaker are you using?



> It is a very bad idea to have a test do nothing under default conditions!
> (i.e. no special packages such as VMMaker loaded) That's why I moved both to
> a new class, that should be part of VMMaker, and removed that silly check
> for BitBltSimulation. This is included in the stuff I attached to
> http://bugs.squeak.org/view.php?id=7407 .
>
> Cheers,
> Juan Vuletich
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.squeakfoundation.org/pipermail/vm-dev/attachments/20091026/34ac9092/attachment.htm