If you are reported, it means the immigration will start procedures to revoke your PR because you did not meet your residency obligation. They will let you enter and tell you how you can appeal for your PR. You would have to make your appeal within 30 days. Having studied abroad is not really considered a good reason not to meet your residency obligation as they will say you could have studied in Canada so you may lose your appeal.
However, it's not certain that you will be reported. When you enter Canada, they will ask you how long you were outside Canada. When you say you were gone for more than 3 years, they will know that you don't meet the residency obligation so they will pull you out and ask you why you did not meet them. I have seen a post from someone in exactly your situation who told the truth and said he had been outside Canada completing his studies and that he was ready to settle now and the immigration officer told him that he would not like to punish somebody for getting an education and let him in without reporting him. However, there is no guarantee that your immigration officer will say that too.