Hi Eljay - __m128 is typedef'd to: typedef int __m128 __attribute__ ((__mode__(__V4SF__))); I was under the impression (from the info page for gcc) that this mode also implies the aligned attribute? If that's not true, then that could be my problem... Brian On Tue, 15 Feb 2005 06:27:01 -0600, Eljay Love-Jensen <eljay@xxxxxxxxx> wrote: > Hi Brian, > > How are you making sure that your foo in... > > _m128 foo = bar; > > ...which is allocated on the stack is 16-byte aligned? > > What happens when you do this... > > _m128 foo __attribute__((aligned(16))) = bar; > > ...? > > Or do you have the __attribute__((aligned(16))) in your class? > > --Eljay > >