strict aliasing issue in action

[Lisandro Dalcin]

Please, try the small example attached. You will see in action the
issues related to strict aliasing with current PETSc state. The
example is perhpas a bit artificial, but you know, bad things can
always happen, and worse if that happens with optimization, as it is
much hard to debug.

- Use a optimized build for $PETSC_ARCH with a recent GCC (I used
4.1.1 in my Fedora 6 box)

- First, build the example disabling strict aliasing. Run it, and you
will get the expected output.

$ make SA_FLAG=-fno-strict-aliasing
$ main
v->refct: 1

- Next, build the example enabling strict aliasing. Run it, and you
will get unexpected output
$ make SA_FLAG=-fstrict-aliasing
$ main
v->refct: 11

I realy thing we have to take this seriously. That the reason I'm
trying to solve this at home. I'm near to finishing it. After that, I
would ask you to create a clone in your server, in order to push it
and you test it.



-- 
Lisandro Dalcín
---------------
Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
PTLC - Güemes 3450, (3000) Santa Fe, Argentina
Tel/Fax: +54-(0)342-451.1594