Re: [RFA/RFC] dwarf2-frame read_reg

[Michael Snyder <msnyder at redhat dot com>]

Mark Kettenis wrote:
> > Date: Tue, 11 Apr 2006 21:42:01 -0700
> > From: "Jim Blandy" <jimb@red-bean.com>
> >
> > On 4/11/06, Michael Snyder <msnyder@redhat.com> wrote:
> >
> > > I want you guys to vett this change.  I was getting wrong results
> > > on a target where sizeof (SP) != sizeof (void *).  The local func
> > > read_reg was calling extract_unsigned_integer with the wrong size.
> >
> > Well, extract_typed_address requires the type of the register to be
> > some sort of pointer.  read_reg is given as a callback to the Dwarf
> > expression evaluator in dwarf2expr.c, so it could be handed any
> > register at all.
> >
> > How about unpack_long (buf, register_type (gdbarch, regnum))? 
> > Definitely regression-test this on several platforms...
>
>
> This is likely to be wrong for platforms where addresses are signed.
>
> Michael, what kind of funny target is this?  It has a stack pointer
> register, but its size is different from the size of pointers?

Yep, the reg size is 3 bytes.  When it's pushed onto the stack,
it occupies 3 bytes of memory.  Funky, huh?  The cpu can only
reach 24 bits worth of address space.