[PUSHED] [PATCH] S390: Add use of unavailable-stack frame ID

[Andreas Arnez <arnez@linux.vnet.ibm.com>]

Pushed.

On Mon, Mar 07 2016, Andreas Arnez wrote:

> When determining the frame ID of an inline frame, GDB currently asserts
> that a valid ID of the underlying real frame is found, and that it does
> not match outer_frame_id.  From inline_frame_this_id():
>
>   /* For now, require we don't match outer_frame_id either (see
>      comment above).  */
>   gdb_assert (!frame_id_eq (*this_id, outer_frame_id));
>
> However, this assertion may fail when the real frame's unwinder can not
> determine the frame ID.  This happened on an s390x target with a binary
> that lacked call frame information and also confused the prologue
> analyzer, because then s390_frame_this_id() left the frame ID at its
> default.
>
> To fix this, this change enhances s390_frame_this_id such that an
> unavailable-stack frame ID is built if no frame base can be determined
> but the function address is available.
>
> gdb/ChangeLog:
>
> 	* s390-linux-tdep.c (s390_prologue_frame_unwind_cache): Store
> 	frame func's PC in info->func before any other failure can occur.
> 	(s390_frame_this_id): Use frame_id_build_unavailable_stack if
> 	info->func has been filled out.

-- 
Andreas Arnez