Re: [patch/rfc/rfa*] Only compare against dummy frame tos when saved

[Kevin Buettner <kevinb@redhat.com>]

On Sep 17,  8:55pm, Andrew Cagney wrote:

> This change does, however, have the potential to break break every 
> target that sets save_dummy_frame_tos().  Going through the list of 
> targets (and treating any with a frame_chain() like the above as ok):
> 
> cris-tdep.c:  ok
> ia64-tdep.c:  ok
> mcore-tdep.c:  *** I suspect it doesn't but should
> mn10300-tdep.c:  *** I suspect it doesn't but should
> rs6000-tdep.c:  ok
> s390-tdep.c:  ok
> xstormy16-tdep.c:  ok (I think).
> 
> I think, for the two *** cases, the code can be tweaked to have 
> frame_chain() return frame->frame.
> 
> Thoughts?  Ok for the targets with maintainers?

I think this change will be okay for ia64 so long as the following
FIXME comment in ia64-tdep.c is fixed:

  /* FIXME: This doesn't belong here!  Instead, SAVE_DUMMY_FRAME_TOS needs
     to be defined to call generic_save_dummy_frame_tos().  But at the
     time of this writing, SAVE_DUMMY_FRAME_TOS wasn't gdbarch'd, so
     I chose to put this call here instead of using the old mechanisms. 
     Once SAVE_DUMMY_FRAME_TOS is gdbarch'd, all we need to do is add the
     line

	set_gdbarch_save_dummy_frame_tos (gdbarch, generic_save_dummy_frame_tos);

     to ia64_gdbarch_init() and remove the line below. */

At the moment, ia64 depends upon ->top being set, but your change will
disable the appropriate test because ia64-tdep.c doesn't (correctly) set
the SAVE_DUMMY_FRAME_TOS method.

I'll try to find a moment or two to give it a try...

Kevin