You should have the total gross pay you received since the start of the year. It should also state the total tax and PRSI paid. Also it should include your personal details particularly the correct PPS Number.
If you paid into a pension direct from your salary, it is quite likely that this is not reflected in your gross amount. When I get my annual P60, the total gross pay stated is the actual gross pay minus the pension contributions made through the year. I guess it would be the same for a P45. On the other hand, depending on your length of service at the company, you may be re-imbursed all your pension contributions when you leave within a certain time. For example if I have paid less than 2 years of contributions when/if I leave my current employer, I will get it all back.