HP-PA ABI issues - framepointer handling

[Robert Dewar]

<<        If your statement above about unwind conventions refers to the
format of the tables themselves, then I do not know of any GCC target
which matches the native system exception handling tables, unless it just
happens to use GCC's Dwarf-2 tables.
>>

Sorry for the confusion, in providing exception mechanisms for GNAT, we
prefer to follow system conventions for unwinding where possible. We also
prefer to be compatible with what g++ does, it is true that it is not
easy to meet both of these preferences!

For example, on DEC Unix, we use the standard DEC Unwind functions, and
they work just fine for both gcc generated code and DEC compiler generated
code, and do not use dwarf-2 tables, so there is one example at least.

For SGI, we also use the system unwind procedure from SGI, and as far
as I know, that does NOT use dwarf-2.

It's definitely tricky to know what the best way to approach this whole
area is.