Some assembly benchmarks for C++

I'm rather curious about C++ to be honest...I've never dealt with a programming language without a common object model before (yes, I love Java and D).

So, I tried my hand at a few things. First, I wanted to check some properties of the mythical vtable. So what I do is I create a toy object by creating a file test.cpp and a header Object.hpp. The header is:

#include < iostream >
using namespace std;

class Object
{
public:
      Object() { }
      ~Object() { }

      int getAddress()
      {
            return (int)(this);
      }
      void address()
      {
            cout << "Object @" << getAddress() << endl;
      }
      void stat()
      {
            address();
            cout << "Size of object: " << sizeof(this) << endl;
      }
};

And then the test.cpp file I don't change that much:

#include "Object.hpp"

int main()
{
      Object* o = new Object();
      o->stat();
      return 0;
}

The number of lines of assembly for this, by using the command:

$ g++ -S test.cpp

Then opening test.s is 376 lines. This is the control.

Spice Things Up

The next thing I try is to make all the methods and constructors/destructors virtual. I don't know how, if at all, this would change anything. Mind you, I have not taken a formal course on C++ so I don't know what happens if I change anything.

I then found out, by means of a compiler error, that I cannot make constructors virtual. I decided to make the destructor non-virtual also.

The resulting assembly file is 414 lines long. So adding the virtual qualifier bloats the program.

I assume that this is because of the vtable in some manner, but I do not know for certain.

I am ashamed to admit it, but I am going to brush up on the vtable with Wikipedia. I'll probably write about it next...or else I'll write about object oriented C.