Re: GNAT exception traceback

[kenner@lab.ultra.nyu.edu (Richard Kenner)]

In article <33A6A725.3BD0@no.such.com> Spam Hater <no.such.user@no.such.com> writes:
>gcc C has a builtin function (macro?) for the return address.
>Someone sent me C that uses this in a loop to get a stack trace.
>Note the parameter to __builtin_frame_address - if I remember 
>right, this allows you to say how high up the stack you want 
>to go.

That's right, but many (if not most) implementations of this builtin
are incorrect for non-zero operands.  As you point out, implementing this
function for arbitrary values is equivalent to knowing how to do a full
traceback, which is a very hard task.  These builtins dated back to CISC
days when this was straightforward.

In GCC 2.8.0, these functions will be involved in part of an exception
system that has at least some of this capability, but they are not
recommended for use by programmers with other than an argument of
zero.  They were never documented.