I'm thinking something like the SV finder from perl-src/sv.c might do the trick...

    for (sva = PL_sv_arenaroot; sva; sva = (SV*)SvANY(sva)) {
        svend = &sva[SvREFCNT(sva)];

        for (sv = sva + 1; sv < svend; ++sv) {
            if (SvROK(sv)) {
                // find addr
            }
        }
    }
[download]

Am I way off?