target/5505: Doubts about a patch for OSF

[Richard B. Kreckel]

Hi,

On Fri, 22 Feb 2002, Rainer Orth wrote:
> Richard B. Kreckel writes:
> 
> > Rainer, you probably know by now that this whole issue has nothing to do
> > at all with CLN?  It seems like your patch breaks anything when using
> 
> most likely, yes.
> 
> > -fno-exceptions.  Attached is a trial program that only uses doubles and
> 
> Only in combination with -O2, it seems.
> 
> > some STL containers.  (Sorry for not boiling it down from 100 to 10 lines,
> > I have unfortunately very little time right now.)
> 
> Please try to do so: my knowledge of C++ is close to zero, so a minimal
> testcase would help enormously.

Sure, I will, next week.  Sorry, again I am only for a couple of minutes
in my office...

> > Can you confirm this?  Otherwise we are back with the theory that my boxen
> > are broken / patched wrongly...
> 
> Not yet: I get a SEGV even if compiling without any special options:
> 
> > g++ -o minor minor.cc
> > ./minor
> permanent of 6x6-matrix
> c==4Segmentation fault
> 
> The crash happens in minor.c, l. 80:
> 
> 80                          Pkey[j] = Pkey[j-1]+1;
> 
> j = 0 at this point, so Pkey[j-1] is out of bounds.  The crash happens when
> compiling with Compaq cxx as well.

Sorry, silly me.  I've attached an old case and that index out of bound
has been fixed in the real sources ages ago.  However, the crash I see
seems to have nothing to do with this line!  Modifying the condition such
that j==0 does not happen still results in a crashing program when
compiled with -O2 -fno-exceptions and a working program when compiled with
-O2 alone.  There is an example modified accordingly attached to this
email and this time I have made sure it also runs with -lefence and stuff.

If you have some time, it would be nice if you could confirm the
dependence on -fno-exceptions before I start stripping that down.  Thanks!

Regards
    -richy.
-- 
Richard B. Kreckel
<Richard.Kreckel@Uni-Mainz.DE>
<http://wwwthep.physik.uni-mainz.de/~kreckel/>

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