On Sun, Mar 16, 2003 at 05:04:36PM -0500, Andrew Cagney wrote:
At present there is a per-frame ID method since different frames
determine their ID using different techniques. The ID (which identifies
a given frame instance) includes a base and pc/func value.
GDB's frame code also makes available the get_frame_base() method.
While the default implementation returns get_frame_id().base, I think
there is going to need to be a per-frame frame->unwind->this_base method.
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 :-).
It might even be reasonable for a prologue based unwinder to error out
when asked for the frame's base before the stack frame has been created.
Thoughts?
I should note that dwarf2expr.c contains code that tries to
locally/directly evaluate the frame base. I think that should instead
do a get_frame_base() call.
There's no guarantee right now that the DW_AT_frame_base agrees with
the frame's base. I don't even think it's necessary that they be the
same.