__do_global_dtors_aux and __do_global_ctors_aux

Question

I disassembled a simple program written in C++ and there are these two function names. I guess that ctor means constructor and dtor means destructor, and word global maybe m

Answer 1

They are auxiliary functions added by the compiler to construct and destroy static objects.

e.g.

std::vector some_global;

int main() { return 0; }

some_global needs to be actually constructed (and destructed) somewhere, and C++ guarantees that construction happens before main. One way to do this is to emit a function that happens before main, which constructs global objects, and another function that happens after main to destroy them.

If you stuck a breakpoint inside the std::vector constructor and ran this program, the stack trace would show you the function that it was being initialised from.