[rfc] frame->frame => frame->addr && frame->base()

[Andrew Cagney <ac131313@cygnus.com>]

Hello,

This comes from DanielB's and my discussion about dwarf2 CFA and 
dwarf2's frame_base vs GDB's frame->frame.

An executive summary is that the two dwarf2 frame concepts (CFA and 
frame_base) do not go into one GDB frame (frame->frame).

Because of this, I'd like to propose that the frame object have both:

struct frame_info
{
  ...

// An ISA/ABI specific address within the ``specified frame'' that is 
constant throughout the lifetime of the frame.  This address is used by 
GDB as a handle to identify this frame.  This field must be initialized 
as part of the creation of a frame object.  (see dwarf2 CFA)

CORE_ADDR addr;

// High level language concept of the base address of a frame.  Often 
refered to as ``frame_base'' or ``frame pointer''.  This value should 
only be computed on-demand.  It is strongly recommended, though, that 
implementations cache the computed value in the frame cache.  The method 
is initialized as part of the frame objects creation.  The default 
method returns frame->addr.  (see dwarf2 DW_AT_frame_base)

CORE_ADDR (*base) (struct frame_info *frame);

...
}


Thoughts?

Andrew