program ObjTest;
uses Windows;

type T_TEST = Class
  function add(a,b: Integer):Integer;
end;

function T_TEST.add(a,b: Integer):Integer;
begin
  MessageBox(0, 'test', 'test',0);
  Result:=a+b;
end;

var obj: T_TEST;
begin
  obj:=T_TEST.Create;
  obj.add(2,3);
  obj.add(3,4);
  obj.Free;
end.

mov ecx, 00000004
mov edx, 00000003
mov eax, ebx
call 00403620
...
00403620: 
  push ebx
  push esi
  mov esi, ecx
  mov ebx, edx
  push 00
  push 00403640; "test"
  push 00403640; "test"
  push 00
  call User32!MessageBoxA
  lea eax, [ebx+esi]
  pop esi
  pop ebx
  ret