Re: [squeak-dev] Re: [Pharo-project] new Cog VMs

> Hi Igor,  Hi All,
>
> On Sun, Jan 2, 2011 at 4:11 PM, Igor Stasenko <[hidden email]> wrote:
>>
>> On 3 January 2011 00:15, Eliot Miranda <[hidden email]> wrote:
>> > Hi Martin, Hi All,
>> >     so find new VMs in VM.r2341/.  The linux crashes (certainly the one
>> > you
>> > suffered from Martin) seem to be caused by an optimization bug (but they
>> > could be caused by bad code generation, creating something that assumes
>> > ordering constraints which C doesn't guarantee).  I suspect the former
>> > because I don't see the crash when running exactly the same VM and image
>> > from a different directory; provoking the crash requires a particular
>> > path
>> > (go figure; I haven't pinned this down yet).
>> > So my "fix" is preventing a complex function being inlined into the main
>> > interpreter loop, removing the sources of some warnings, and lowering
>> > the
>> > optimization level of the gcc3x-cointerp.c file to -O1 from -O2 (my
>> > build
>> > environment, CentOS Linux 5.3, uses gcc 4.1.2).  I'm not proud of this
>> > "fix".  I've violated the Deutsch criterion by not diagnosing the cause
>> > of
>> > the bug so I can't stand behind this fix; it's a hack that appears to
>> > work
>> > and may have merely pushed the real bug further underground.  Alas I
>> > don't
>> > have time to do a better job. Hopefully it'll get those of you on linux
>> > going again.
>>
>> Eliot, if you remember, i also had crash issues on linux, and pinned down
>> it to
>> removing optimization from <something>heartbeat.c while keeping
>> gcc3x-cointerp.c to use
>>  same optimization flags as for rest of files.
>
> Indeed, quite right.  I happened to add a flag to turn off the heartbeat so
> I could debug the crash Matthew was seeing in starting up
> Squeak4.2-10856-beta.image (since single-stepping through machine code
> always gets interrupted by the heartbeat, it being an interval timer) and lo
> and behold the bug went away.  This is very worrying because it appears to
> imply that there's a serious bug in the linux kernel/gcc since delivering a
> software interrupt shouldn't corrupt registers, but it clearly does.  I'll
> try and pass it by someone who's an expert in this area.
> Anyway, now find a new linux VM in VM.r2346/ that seems fine with the
> interpreter and the cogit compiled at -02 but the heartbeat compiled at -O2.
>  Running this VM on CentOS 5.3 under Parallels I get
>     2839 run, 2796 passes, 7 expected failures, 24 failures, 11 errors, 0
> unexpected passes
> for the full test suite in Squeak4.2-10856-beta.image.
> So have at it.

> best
> Eliot
>>
>> I will start coding cmake config for Cog during next week and will be
>> able to check my previous
>> observations again.
>>
>> > best
>> > Eliot
>> > On Sat, Jan 1, 2011 at 11:16 PM, <[hidden email]> wrote:
>>
>> --
>> Best regards,
>> Igor Stasenko AKA sig.
>>
>
>