Re: frame->unwind->this_base()

[Andrew Cagney <ac131313@redhat.com>]

> 
> So in this case should we be hooking the get_frame_base() call to
> return the computed DW_AT_frame_base?  [...]  And what happens if we don't have DWARF-2
> information?

At the start I wrote:

 > For dwarf2 frames, it would return, DW_AT_frame_base.  For prologue 
frames, it would return an attempt at an equivalent value.  Hopefully it 
wouldn't be called for other frame types :-).

A better question is, what about other debug types?  The definition of 
the frame-base is dependant on the debug info.

Dig dig.  Other debug info (e.g., LOC_LOCAL) depends on 
FRAME_LOCALS_ADDRESS().  So to take this a step further, it is a merged 
FRAME_LOCALS_ADDRESS() + get_frame_base() that is needs to become per frame.

 > If so, we're going to need to go
 > through all the uses and computations of the frame base in all targets
 > for consistency.

All existing calls to get_frame_base() in core-gdb need to be audited 
anyway :-(  This is so that breakage such as VALUE_FRAME() can finally 
be laid to rest (see "frame.h", "frame ID" for why get_frame_base() 
isn't up to the task).

Andrew