Daniel Berlin <dberlin@xxxxxxxxxxx> writes:
> On Thu, 2005-08-25 at 21:24 -0700, Steve Zook wrote:
> > Using m68k-elf-gcc with either revision 3.3.3 or 3.4.4, I compile the
> > following test program (as a C++ program) at -O2 to an object file:
> >
> >
> > struct sA { unsigned volatile const B;
> > unsigned volatile C;
> > unsigned const D;
> > unsigned E; };
> > void Function( sA & A ) { A.B; A.C; A.D; A.E; }
> >
> >
> > The object file I get looks like (edited for brevity):
> >
> > .globl _Z8FunctionR2sA
> > .type _Z8FunctionR2sA, @function
> > _Z8FunctionR2sA:
> > link.w %a6,#0
> > move.l 8(%a6),%a0 | A, A
>
> This is a load of A.B. It's the first member of the structure, and
> thus, is at offset 0, and is also known as "A".
No, that's a load of the address of A--i.e., loading the argument into
a register. On the m68k arguments are passed on the stack. To
actually load A.B, rather than just the address of A.B, would require
a following
move.l 0(%a0),....
Ian
