gcc -O2 优化，到底做了什么？ 程序都不能正常运行了。

HMODULE hDll_kernel32 = LoadLibrary("kernel32.dll"); // 加载 kernel32.dll
    if(hDll_kernel32)
    {

        FARPROC proc = GetProcAddress(hDll_kernel32, "SetDllDirectoryA"); //导出 DLL 库函数地址
        if(proc)
        {
            //printf("在 kernel32.dll 找到 SetDllDirectoryA() \n");

            typedef BOOL (*func_SetDllDirectoryA)(LPCSTR);

            func_SetDllDirectoryA _SetDllDirectoryA = (func_SetDllDirectoryA)proc;  //函数指针

            int status = _SetDllDirectoryA(app_folder_path); //将目录添加到用于查找应用程序DLL的搜索路径
            printf("_SetDllDirectoryA()->status:%d\n", status);
        }

        FreeLibrary(hDll_kernel32); //释放
        hDll_kernel32 = NULL;
    }