PHP 5.4.x 安装dedecms最新版后台登陆 网页一片空白

最新版本的PHP 5.4.x的环境安装了dedecms v57 sp1 UTF-8，结果后台登陆提交了用户名和密码之后，居然一片空白。
仔细跟代码，才发现是两个地方导致的 因为PHP新版本的几个函数不存在了。

session_register

session_unregister

文件/include/userlogin.class.php

/**
*  保持用户的会话状态
*
* @access    public
* @return    int    成功返回 1 ，失败返回 -1
*/
function keepUser()
{
if($this->userID != '' && $this->userType != '')
{
global $admincachefile,$adminstyle;
if(empty($adminstyle)) $adminstyle = 'dedecms';

if(function_exists("session_register")) $session_register = true;

if($session_register) @session_register($this->keepUserIDTag);
$_SESSION[$this->keepUserIDTag] = $this->userID;

if($session_register) @session_register($this->keepUserTypeTag);
$_SESSION[$this->keepUserTypeTag] = $this->userType;

if($session_register) @session_register($this->keepUserChannelTag);
$_SESSION[$this->keepUserChannelTag] = $this->userChannel;

if($session_register) @session_register($this->keepUserNameTag);
$_SESSION[$this->keepUserNameTag] = $this->userName;

if($session_register) @session_register($this->keepUserPurviewTag);
$_SESSION[$this->keepUserPurviewTag] = $this->userPurview;

if($session_register) @session_register($this->keepAdminStyleTag);
$_SESSION[$this->keepAdminStyleTag] = $adminstyle;

PutCookie('DedeUserID', $this->userID, 3600 * 24, '/');
PutCookie('DedeLoginTime', time(), 3600 * 24, '/');

$this->ReWriteAdminChannel();

return 1;
}
else
{
return -1;
}
}

//
/**
*  结束用户的会话状态
*
* @access    public
* @return    void
*/
function exitUser()
{
ClearMyAddon();
if(function_exists("session_unregister"))
{
@session_unregister($this->keepUserIDTag);
@session_unregister($this->keepUserTypeTag);
@session_unregister($this->keepUserChannelTag);
@session_unregister($this->keepUserNameTag);
@session_unregister($this->keepUserPurviewTag);
}
DropCookie('dedeAdmindir');
DropCookie('DedeUserID');
DropCookie('DedeLoginTime');
$_SESSION = array();
}