Gary the Dog turnt all the way up at a special Carrie Fisher movie screening Thursday ... and it's the most ADORABLE thing you're going to see all day!!!!!

Gary and his caretaker -- Carrie's former asst. Corby McCoin -- attended the May the 4th showing of "Postcards from the Edge" ... a movie the 'Star Wars' actress famously wrote about her relationship with her late mom, Debbie Reynolds.

But the real action went down outside Angel City Brewery in L.A. -- where Gary put on the cutest little show for his adoring fans. 

Who's a good famous doggy!?! You are!! Yes you are!!!