判断 Windows操作系统是32位还是64位

function IsWin64: Boolean;
var
  Kernel32Handle: THandle;
  IsWow64Process: function(Handle: Windows.THandle; var Res: Windows.BOOL): Windows.BOOL; stdcall;
  GetNativeSystemInfo: procedure(var lpSystemInfo: TSystemInfo); stdcall;
  isWoW64: Bool;
  SystemInfo: TSystemInfo;
const
  PROCESSOR_ARCHITECTURE_AMD64 = 9;
  PROCESSOR_ARCHITECTURE_IA64 = 6;
begin
  Kernel32Handle := GetModuleHandle('KERNEL32.DLL');
  if Kernel32Handle = 0 then
    Kernel32Handle := LoadLibrary('KERNEL32.DLL');
  if Kernel32Handle <> 0 then
  begin
    IsWOW64Process := GetProcAddress(Kernel32Handle,'IsWow64Process');
    GetNativeSystemInfo := GetProcAddress(Kernel32Handle,'GetNativeSystemInfo');
    if Assigned(IsWow64Process) then
    begin
      IsWow64Process(GetCurrentProcess,isWoW64);
      Result := isWoW64 and Assigned(GetNativeSystemInfo);
      if Result then
      begin
        GetNativeSystemInfo(SystemInfo);
        Result := (SystemInfo.wProcessorArchitecture = PROCESSOR_ARCHITECTURE_AMD64) or
                  (SystemInfo.wProcessorArchitecture = PROCESSOR_ARCHITECTURE_IA64);
      end;
    end
    else Result := False;
  end
  else Result := False;
end;

http://blog.csdn.net/suiyunonghen/article/details/4870219

网上这样的代码和讨论很多，特别是IsWow64Process函数的使用。

忽然想：只有32位的EXE在运行时才需要判断OS是32还是64bit？

如果EXE本身是64bit的，那么运行时根本不用判断了，OS必定是64位的，否则根本不能运行的。

所以，本人感觉网上很多讨论是否有点多余？