Revising salary after rolling out offer - What are the different options for a company?

I would like to discuss a case that happened with a company. A candidate was offered x amount of salary, but after reconsideration it was found that salary offered is high. The candidate has accepted the offer and also resigned from previous company. What are the different options for a company?

In my opinion, the employer cannot roll back the offer. When an offer of a party is accepted by the other, it becomes a promise. The employer has to consider the follow up action taken by the employee and the negative impact of the proposed roll back of the offer would cause on his career.
If the already offered salary is actually very higher than the industry norms and made in haste, the alternative is to freeze it for some time or add some feasible additional responsibility to his job profile with the consent of the prospective employee.