http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51784
--- Comment #17 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-01-14 00:38:18 UTC --- Sounds like i?86-darwin target bug. The %ebx value is wrong, should be 0x2929 instead (i.e. the point after call __x86.get_pc_thunk.bx in x, but most probably is the point after call __x86.get_pc_thunk.bx in y instead. Seems on Darwin %ebx (or whatever the PIC register is) contains the address after the call to the get_pc_thunk, and thus each function has it different and therefore non-local goto on i?86-darwin must restore %ebx, but clearly it doesn't. On i?86-linux this bug doesn't exist, because %ebx there is the address of _GLOBAL_OFFSET_TABLE_ - nonlocal goto is only possible within the same CU and thus will have the same _GOT_ value, so nothing needs to be restored. Similarly on x86_64-linux, where there is no PIC pointer, but %rip addressing is used. Doesn't look like a regression to me though, if the above is the case, then probably darwin never supported nonlocal gotos in pic code (which is the default there).
