[Vm-dev] Re: I need help building Cog on 64bit Linux (new Squeak server)

Camillo Bruni camillobruni at gmail.com
Mon Feb 4 08:32:34 UTC 2013


On 2013-02-04, at 08:49, Igor Stasenko <siguctua at gmail.com> wrote:

> 
> On 28 January 2013 23:07, Nicolas Cellier
> <nicolas.cellier.aka.nice at gmail.com> wrote:
>> 
>> 2013/1/28 Ken Causey <ken at kencausey.com>:
>>> 
>>> Eliot said:
>>>> 
>>>> Hmmm.  Sorry to put you to this but what happens when you run the r2669,
>>>> r2672 and r2673 VMs from http://www.mirandabanda.org/files/Cog/VM/? If
>>>> these don't crash then it might be something to do with gcc 4.4.x.  But
>>>> I'd
>>>> have to take a look, and time is tight right now...  But if any of them do
>>>> work could you use them for the interim?
>>> 
>>> 
>>> Not a problem and thanks for the reply.
>>> 
>>> Well I started with 2673 and the tests are still running but it would have
>>> crashed by now if the same problem exists so it's looking like the gcc
>>> version is the issue.  I will try earlier gcc versions and report back.
>>> 
>>> It's a little disheartening that in this day and age we are tickling gcc
>>> issues when the same version of gcc is used to build the kernel and
>>> thousands upon thousands of Debian binaries which (by and large anyway) seem
>>> to be fine.
>>> 
>>> Ken
>> 
>> And the answer would be: don't rely on UB (Undefined Behavior)
>> Modern interpretation of the standards is that a compiler has a
>> license to ignore UB in order to perform optimizations... This is
>> because no one should rely on UB.
>> Unfortunately, the underlying C language is full of UB, and the signed
>> arithmetic model is particularly broken...
>> 
>> I doubt the thousands of packages have been working unchanged...
>> They work with army of programmers maintaining the code and chasing
>> the compiler warnings.
>> As long as we ignore the warnings, we are in danger.
>> As long as we have several hundreds warnings, there is no easy way to
>> analyze their dangerosity...
>> 
> 
> I cannot agree more.

well you mute them, right?


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