------- Comment #13 from rguenth at gcc dot gnu dot org 2010-09-16 13:39
(In reply to comment #12)
> (In reply to comment #4)
> > Created an attachment (id=21809)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21809&action=view) 
> > patch to fix "half STRICT_ALIGNMENT" targets memcpy folding
> > Might need this patch to fix as well. i?86 / x86_64 isn't really
> > !STRICT_ALIGNMENT.
> We need a HARD_ALIGNMENT which depends on type for x86.
With that patch the assignment generated from memcpy doesn't need more
that int alignment, but still cfgexpand.c sets DECL_ALIGN of the
decl to 128 so expand uses aligned instructions.
cfgexpand.c should not increase alignment and not set 'needs stack
alignment' then, based on your comment #10. So this _is_ about
stack alignment (but maybe not exclusively).