Nobody hit on what I thin is the real reason in this case. He simply needed an exact number of syllables in the words of the line for it to fit in time with the music.

Musical and theatrical arts frequently employ bad grammar. This is done with intent in order to replicate the voices of ordinary people and to produce desired artistic effects.

Tbh Lucio you’d have to ask Bruno Mars! As you say, it’s grammatically wrong. Maybe he wanted a one syllable word instead of two syllables (given) There are so many songs that corrupt correct English, so sadly music isn’t necessarily the best way of learning grammar.

Yes, technically it should be 'given'. But using the past simple form instead of the past participle is a really common feature of many English dialects. Also bear in mind that 'should have given' is four syllables while 'should have gave' is three. Maybe 'should have given' wouldn't scan.

Hello Lucio You have to take into account that Bruno was using 'American slang' which is characterized by misuse of tenses and other prepositions. "should have given you all my hours" is grammatically correct, but according to the language pattern he was using he was correct