Re: [patch/rfc] Add a sentinel frame

[Andrew Cagney <ac131313@redhat.com>]

> +struct frame_id
> +generic_unwind_dummy_id (struct gdbarch *gdbarch, struct frame_info *frame)
> +{
> +  static struct frame_id id;
> +
> +  id.base = dummy_frame_stack->top;
> +  id.pc = frame->pc;
> +
> +  return id;
> +}
> +

No.  That would make unwind dummy id's implementation circular.  The 
ID's value is needed to find the correct dummy frame in the 
dummy_frame_stack.

This method needs to unwind register value's from the NEXT_FRAME and 
then use that to determine the dummy frame's ID.  The d10v's 
implementation (not yet committed) looks like:

/* Assuming NEXT_FRAME->prev is a dummy, return the frame ID of that
    dummy frame.  The frame ID's base needs to match the TOS value
    saved by save_dummy_frame_tos(), and the PC match the dummy frame's
    breakpoint.  */

static struct frame_id
d10v_unwind_dummy_id (struct gdbarch *gdbarch, struct frame_info 
*next_frame)
{
   ULONGEST base;
   struct frame_id id;
   id.pc = frame_pc_unwind (next_frame);
   frame_unwind_unsigned_register (next_frame, SP_REGNUM, &base);
   id.base = d10v_make_daddr (base);
   return id;
}

Andrew