http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44107
--- Comment #22 from David Fang <fang at csl dot cornell.edu> --- Do one of these apple libunwind sources (0.30, 0.35.1) correspond to what's bundled in libgcc_s in darwin8,9,10? http://opensource.apple.com/tarballs/libunwind/