------- Comment #13 from rguenth at gcc dot gnu dot org 2010-09-02 09:07
-------
(In reply to comment #11)
> (In reply to comment #10)
> > typedef my_unaligned_aliasing_uint32 uint32
> > __attribute__((aligned(1),may_alias));
> >
> > inline __attribute__((__always_inline__)) uint32 READ_UINT32(const void
> > *ptr)
> > {
> > return *(const my_unaligned_aliasing_uint32 *)ptr;
> > }
>
> It does not:
> READ_UINT32:
> j $31
> lw $2,0($4)
>
> The aligned attribute is ignored there I think.
It is if the target is STRICT_ALIGNMENT (which of course is a bug, but
well ... and I happen to have a fix as well)
> memcpy produces:
> lbu $2,3($4)
> lbu $6,0($4)
> lbu $5,1($4)
> lbu $3,2($4)
> addiu $sp,$sp,-16
> sb $6,0($sp)
> sb $5,1($sp)
> sb $3,2($sp)
> sb $2,3($sp)
> lw $2,0($sp)
> j $31
> addiu $sp,$sp,16
>
> Which is bad and could be improved by using lwl/lwr. I will file a bug about
> that.
>
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45462
