Exception handling, dynamic linking and weak symbol tricks

[Melissa O'Neill]

I wrote:
> the new
> > ``__throw'' method for exception handling does not appear to be
> > compatible with dynamic linking at all (at least in its current
> > incarnation), since seems to assume that frame information will be
> > statically determined.

... Mike Stump replied:
> Not compatible?  [...]  I think the underlying scheme was designed to
> support dynamic loading and unloading of code.

I overstated the case when I said ``not compatible''. I think the
underlying scheme can support dynamic loading and unloading of code,
but parts of the current realization (especially on systems without gnu
ld, where collect2 gets used to handle frame table initialization) seem
to assume that there is a single exceptions table that is statically
determined.

The internals of exception handling and the mechanisms of dynamic linking
are not my fields of expertise. But, after happening to stare at
gthr-posix.h and frame.c for a while, I had some nagging worries, so it
sensible to raise the issue here. If my worries are unfounded, so much
the better.

    Melissa.