int foo() {
    volatile int i = 0;  // force it to be stored to memory
    return i;
}

;;; MSVC -O2
_i$ = -4                                                ; size = 4
int foo(void) PROC                                        ; foo, COMDAT
        push    ecx
        mov     DWORD PTR _i$[esp+4], 0           ; note this is actually [esp+0] ; _i$ = -4
        mov     eax, DWORD PTR _i$[esp+4]
        pop     ecx
        ret     0
int foo(void) ENDP                                        ; foo

;;; MSVC -O0
_i$ = -4                                                ; size = 4
int foo(void) PROC                                        ; foo
        push    ebp
        mov     ebp, esp                     ; make a stack frame
        push    ecx
        mov     DWORD PTR _i$[ebp], 0
        mov     eax, DWORD PTR _i$[ebp]
        mov     esp, ebp
        pop     ebp
        ret     0
int foo(void) ENDP                                        ; foo