Re: [PATCH/RFC] Per-architecture DWARF CFI register state initialization hooks

[Ulrich Weigand <weigand at i1 dot informatik dot uni-erlangen dot de>]

Daniel Jacobowitz wrote:

> On Mon, Feb 16, 2004 at 02:27:24AM +0100, Ulrich Weigand wrote:
> > +void
> > +dwarf2_frame_set_init_reg (struct gdbarch *gdbarch,
> > +                          void (*init_reg) (struct gdbarch *, int,
> > +                                            struct dwarf2_frame_state_reg *))
> 
> > Unfortunately this now crashes on s390, because the 
> > dwarf2_frame_init routine is called from within
> > _initialize_dwarf2_frame, while the s390 backend calls
> > dwarf2_frame_set_init_reg from within _initialize_s390_tdep.
> 
> Er, how?  You shouldn't have a gdbarch in _initialize_s390_tdep.  You
> don't have one until s390_gdbarch_init.

Sorry, my analysis wasn't completely correct.  What actually happens
is an init-order problem during the initialization of the gdbarch
in initialize_current_architecture.  The problem is that I call
dwarf2_frame_set_init_reg from within the s390_gdbarch_init routine
(which I gather is the right place?), and at this point in time,
the gdbarch_data call in dwarf2_frame_set_init_reg returns NULL
because the gdbarch hasn't finished initialization yet:

gdbarch_data (struct gdbarch *gdbarch, struct gdbarch_data *data)
{
  gdb_assert (data->index < gdbarch->nr_data);
  /* The data-pointer isn't initialized, call init() to get a value but
     only if the architecture initializaiton has completed.  Otherwise
     punt - hope that the caller knows what they are doing.  */
  if (gdbarch->data[data->index] == NULL
      && gdbarch->initialized_p)

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  weigand@informatik.uni-erlangen.de