On Tue, Nov 12, 2013 at 01:42:00PM -0800, Mike Stump wrote:
> On Nov 12, 2013, at 1:16 PM, Jakub Jelinek <ja...@redhat.com> wrote:
> > On Tue, Nov 12, 2013 at 01:11:04PM -0800, Mike Stump wrote:
> >> Alignments are stored in a byte, large alignments don't actually work
> >> nicely. This caps the alignment to 128, as most ports would define
> >> BIGGEST_ALIGNMENT to be smaller than this. The competing change would to
> >> be to make it a short, but, I'd be happy to punt that until such time as
> >> someone actually needs that.
> >>
> >> Ports break down this way currently:
> >>
> >> 12 #define BIGGEST_ALIGNMENT 64
> >> 10 #define BIGGEST_ALIGNMENT 32
> >> 6 #define BIGGEST_ALIGNMENT 128
> >> 3 #define BIGGEST_ALIGNMENT 8
> >> 8 #define BIGGEST_ALIGNMENT 16
> >
> > You are missing i386 that has BIGGEST_ALIGNMENT 512 (or less, depending on
> > compiler options). So this doesn't look right.
>
> And yet alignments for modes with sizes like 256 won't work and i386 has no
> mode with alignment bigger than 128 in this table.
Well, BIGGEST_ALIGNMENT is in bits, while mode_base_align seems to be in bytes
it
seems:
unsigned int
get_mode_alignment (enum machine_mode mode)
{
return MIN (BIGGEST_ALIGNMENT, MAX (1, mode_base_align[mode]*BITS_PER_UNIT));
}
So, supposedly it works up to 1024 bit alignment right now.
Jakub
