Hi Geoff, Richard et al., Looks like there's a problem with the support for static constructor priorities when targeting Darwin.
This manifests under AddressSanitizer (gcc/asan.c), which inserts an additional static constructor with priority equal to MAX_RESERVED_INIT_PRIORITY-1 per each module - however the constructor ends up being the last one in the __mod_init_func section, which leads to crashes (see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55617) Looking at gcc/config/darwin.c I suspect that this is because machopic_asm_out_constructor() just emits a pointer into __mod_init_func for each constructor irrespective of its priority. This might be fine if the constructors are created by a single compiler pass (at least non-ASan builds behave correctly - maybe someone else takes care of the priorities), but everything stops working if another pass tries to add its own constructor. As a proof of concept I've modified gcc/config/darwin.c to save the constructors in machopic_asm_out_constructor() and emit them in reversed order in darwin_file_end() (see http://gcc.gnu.org/bugzilla/attachment.cgi?id=29309&action=diff) - this really changes the order of constructors and makes small ASan tests pass, but this solution is far from a complete one. Is my understanding of the current problem with machopic_asm_out_constructor() correct? If so, any chance it can be fixed? Thanks, Alexander Potapenko Software Engineer Google Moscow
