It is always recommended to use a shortened URL before posting any link to Facebook either on your homepage or in any page. It is because of the ultimate anti spamming system of Facebook which is operated manually.
Suppose if you post a link to Facebook page and few people report it as a spam or mark it as “used for website promoting” then that link will be immediately banned from Facebook. Then neither you nor anybody else on Facebook can ever use that link. That means they will ban that link for lifetime and then you have to use different URL shortening services to post it again on Facebook.
So it’s better to use a URL shortening service now rather than after get banned from Facebook. You can use some of the most popular URL shortening websites like tinyurl or bit.ly and if possible don’t spam Facebook. 😛