-malign-double

[Satish Balay]

On Sat, 14 Nov 2009, Lisandro Dalcin wrote:

> On Fri, Nov 13, 2009 at 11:09 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

> > The IBM BlueGene doesn't like 4 byte aligned doubles and sends a bus error
> > after a certain number are generated, Thus I was motivated to make PETSc a
> > bit clearer on that.
> >
> 
> But then the compiler in the BlueGene does not -malign-double by
> default? That would be weird and annoying...

Malloc() returns 16 byte aligned types. I'm not sure what happens in
structs.. [I'm guessing datatypes do get aligned properly]

The issue came up with us malloc()ing a big array and spliting it up
between (double* array) and (double array). This [manual] split didn't
happen on a '8'byte boundary.

Satish