Yes, if you need your AGI from last year to file your taxes and don't have your 1040, but do have your 8879 form for 2016, you can use line 1. The form 8879 is the IRS e-file Signature Authorization and gets the information from your 1040.
Your AGI is found on your 1040:
Form 1040 – Line 37
Form 1040A – Line 21
Form 1040EZ – Line 4
Form 1040NR – Line
36
