wtf.cpp

struct A { int v; };
struct B { int v; };
struct C { int v; };
struct Ar { int& v; };
struct Br { int& v; };
struct Cr { int& v; };

void add_ref(A& a, B& b, C& c) {
	a.v += c.v;
	b.v += c.v;
}
void add_obj(const Ar a, const Br b, const Cr c) {
	a.v += c.v;
	b.v += c.v;
}

#include <ctime>

int main() {
	time((time_t*)add_ref);
	time((time_t*)add_obj);
	
	return 0;
}


DISASSEMBLY:

void add_ref(A& a, B& b, C& c) {
01361002  in          al,dx  
	a.v += c.v;
01361003  mov         edx,dword ptr [c]  
01361006  mov         eax,dword ptr [a]  
01361009  mov         ecx,dword ptr [edx]  
0136100B  add         dword ptr [eax],ecx  
	b.v += c.v;
0136100D  mov         eax,dword ptr [b]  
01361010  mov         ecx,dword ptr [edx]  
01361012  add         dword ptr [eax],ecx  
}
01361014  pop         ebp  
01361015  ret  

void add_obj(const Ar a, const Br b, const Cr c) {
01361020  push        ebp  
01361021  mov         ebp,esp  
	a.v += c.v;
01361023  mov         eax,dword ptr [c]
01361026  mov         ecx,dword ptr [eax]  
01361028  mov         eax,dword ptr [a]  
0136102B  add         dword ptr [eax],ecx  
	b.v += c.v;
0136102D  mov         eax,dword ptr [c]  // WTF?
01361030  mov         ecx,dword ptr [eax]  
01361032  mov         eax,dword ptr [b]  
01361035  add         dword ptr [eax],ecx  
}
01361037  pop         ebp  
01361038  ret