[Vm-dev] Another JIT + GCC issue?

[Igor Stasenko]

On 5 April 2012 20:04, Eliot Miranda <eliot.miranda at gmail.com> wrote:
>
> Hi Igor,
>
> On Thu, Apr 5, 2012 at 9:14 AM, Igor Stasenko <siguctua at gmail.com> wrote:
>>
>>
>> Hi Eliot & all,
>>
>> i & Esteban were investigating what is wrong with crash on windoze
>> (see http://code.google.com/p/pharo/issues/detail?id=5568)
>>
>> what we found:
>>
>> - a stack vm runs given snippet well.
>> - a cog vm crashing horribly or throws an exception  (see below)
>>
>> - if i set -O1 optimization for gcc3x-cointerp.c then everything is _FINE_
>> but if you build with -O2, there is interesting issue with this.
>>
>> If you start a fresh 1.4 image and run a following snippet in workspace:
>>
>> | oldm window aForm startPoint endPoint |
>> oldm := DisplayObject>>#slideFrom:to:nSteps:delay: .
>> "self assert: (DisplayObject>>#slideFrom:to:nSteps:delay:  ~~oldm)."
>> window := SystemWindow allInstances first.
>> aForm := window imageForm offset: 0 at 0.
>> startPoint := (-194 at 61).
>> endPoint := (276.0 at 134.0).
>> aForm
>>        slideFrom: startPoint
>>        to: endPoint
>>        nSteps: 12
>>        delay: 15.
>>
>> At first run it shows a DNU: Smallinteger>>DNU #extent: (or just crashes).
>>
>> It looks like something happens with stack, since receiver should be a Point,
>> and if you open the debugger and evaluate the corresponding line:
>> newLoc := locationBlock value
>> it will print
>> (-76 at 79)
>> as expected
>>
>> next, if you close the debugger and run the very same doit again, bug
>> disappears and no longer reproducible, and everything works as it
>> should be.
>> So, i presume it is related to place where a compiled method is jit-ed
>> for a first time, and invoked .. but if it is already jited ,
>> everything runs smoothly.
>>
>> The compiler version i using on my machine: gcc.exe (GCC) 4.6.1
>> The compiler used on jenkins slave machine: GCC 4.5.2
>>
>> And, of course, concerning why this doesn't crashing on Eliot's VMs :
>> well, since it is related to compiler optimization(s),
>> and VM code is a lil-bit different in a branch we using on Jenkins, it
>> could happen that this is not an issue in one case, while causing
>> problems in another one.
>> Another option (not necessary impossible), that we missed some
>> critical fix when merging code from Eliot's branch :)
>
>
> One thing to do would be to compile my source tree with your compiler.  I compile my windows VM using gcc 3.4.x, so that mine doesn't crash could be to do with that.  My source tree is http://www.squeakvm.org/svn/squeak/branches/Cog.
>

any idea how to install this version of gcc in mingw?

>>
>>
>> So, for the time till the cause of it can be found i will change the
>> configuration to build windows Cog VMs gcc3x-cointerp.c with -O1 flag.
>>
>> --
>> Best regards,
>> Igor Stasenko.
>
>
>
>
> --
> best,
> Eliot
>
>



-- 
Best regards,
Igor Stasenko.