[Dune] gcc 4.4 problem

[Oliver Sander]

I can.

sander at haile:~/dune/dune-grid/dune/grid/test$ g++-4.4 --version
g++-4.4 (Debian 4.4.2-3) 4.4.2

make test-ug

[...]

../../../dune/grid/uggrid/uggridentity.hh:52: warning: dereferencing 
pointer ‘<anonymous>’ does break strict-aliasing rules
../../../dune/grid/uggrid/uggridindexsets.hh:281: note: initialized from 
here

[repeat ad nauseam]

--
Oliver

Carsten Gräser schrieb:
> Dear all,
> the problem does not occur if I compile with '-O3 -fno-strict-aliasing.'
> Adding '-Wstrict-aliasing' shows many warnings that the strict aliasing
> rule is broken. Most of them in the EntityPointer base class.
>
> While trying to reduce the problem I found out that my gcc-4.4.1 even
> complains about this for test-ug and test-alu2dsimplex in dune-grid
> with '-O3 -Wstrict-aliasing'. The same holds true for -O3 -Wall.
>
> Can anyone reproduce this ?
>
> Regards
> Carsten
>
> Carsten Gräser schrieb:
>   
>> Dear all,
>> since using gcc 4.4.1 I have a strange problem with UGGrid.
>> For 2 intersection iterators faceA and faceB the following
>> conditional (checking if the normals are not parallel) always
>> evaluates to true even if the product is 1.
>>
>> if (faceA->unitOuterNormal(FieldVector<ctype,dim-1>(0)) *
>>     faceB->unitOuterNormal(FieldVector<ctype,dim-1>(0)) < 0.95)
>>
>> The strange thing is that this only happens with '-O3 -funroll-loops'.
>> Even more strange: If I sent the computed value (or bool) to std::cout
>> before or after the condition everything works correctly.
>>
>> With gcc-4.3 or using ALUGrid there are no problems.
>>
>> Seems to my like a compiler bug. However it is nearly impossible
>> to extract a test case. Did anyone of you have similar problems ?
>>
>> Regards
>> Carsten
>>
>>     
>
>
>   


-- 
************************************************************************
* Oliver Sander                ** email: sander at mi.fu-berlin.de        *
* Freie Universität Berlin     ** phone: + 49 (30) 838 75348           *
* Institut für Mathematik      ** URL  : page.mi.fu-berlin.de/~sander  *
* Arnimallee 6                 ** -------------------------------------*
* 14195 Berlin, Germany        ** Member of MATHEON (www.matheon.de)   *
************************************************************************