Paolo Carlini wrote:
I think you should consider also the option of having less stuff
exported from libsupc++: if you somehow manage to have the different
code paths in the headers
That's impossible without exposing unwind-cxx.h to the public, and
that's a can of worms I don't even want to look at, much less open. The
reference counting must act on the count in the __cxa_exception_header
object, and that structure is strictly internal.
The problem is that the core exception mechanism
(__gxx_exception_cleanup, to be specific) needs the atomic instruction.
This means that if the target doesn't have support for it, you'd need a
different libsupc++. You can't have the same libsupc++ for i386 and i486
if one has exception_ptr and the other doesn't. Doing this thing
conditionally is just not possible, in my opinion.
Meanwhile, I'm looking at the __exchange_and_add implementation. This is
quite a hack: it's implemented in a "header" file in
config/cpu/<arch>/atomicity.h, but then src/Makefile.am creates a
symlink in the target directory that it calls atomicity.cc, and compiles
that.
I think that hack could be simply moved to libsupc++/Makefile.am, though.
Sebastian
