Re: [power-gnu-discuss] -te500v2 and packed attribute

["S. Couture & K. Musgrove" <muscou@xxxxxxxxxxxx>]

Mark Mitchell wrote:
> S. Couture & K. Musgrove wrote:
> > This seem to be a bug, the code generated is byte access only.
> > # cat test.c
> > struct a_packed{
> >    int data;
> > } __attribute__((packed));
> > struct a_unpacked{
> >    int data;
> > };
> > void test_packed(int in)
> > {     struct a_packed * ptr;
> >    ptr->data = in;
> > }
> > void test_unpacked(int in)
> > {     struct a_unpacked * ptr;
> >    ptr->data = in;
> > }
> The compiler cannot assume anything about alignment of a packed 
> structure and therefore cannot assume that "ptr->data" as at a 
> byte-aligned address.
Thanks altough the same compiler using -te600 generates dword access for 
both packed and unpacked and I am not aware of any limitation in the 
e500 architecture wrt to unaligned access.  This has serious performance 
implications for e500 users.