exception handling predicament

[David Miller]

From: Jakub Jelinek <jakub@redhat.com>
Date: Fri, 19 Aug 2011 20:22:08 +0200

> GCC doesn't have a -fasynchronous-exceptions option which would
> consider every single insn to be able to trap (and I think it would be hard
> to implement it).

I don't think GCC should implement this, but why would it be so hard?

All we care about is the scope of the __cleanup__ variable, and the
basic blocks encompasing that is very well defined.

Otherwise GCC couldn't properly implement the execution of the cleanup
when the variable goes out of scope.  It basically has to know this
information already.