Carrie and Gary Fisher at Cannes. (Alberto Pizzolo/AFP Getty Images)

CANNES — Not content with stealing the show at the “Star Wars: The Force Awakens” press tour and last month’s White House Correspondents Dinner, Carrie Fisher’s French bulldog Gary Fisher took Cannes by storm on Saturday night, patiently posing for the paparazzi on the red carpet before the world premiere of “Bright Lights: Starring Carrie Fisher and Debbie Reynolds,” a documentary about his human mom and grandmother.

The next day, Gary was relaxing at the Majestic Hotel, where he shared a bowl of vanilla ice cream with Fisher, who chatted with a reporter while taking turns spooning the delicacy into the dog’s mouth, then hers (with the same spoon). “They say ice cream and something else, I think it’s peanut butter, are the things for depression,” said Fisher, who has been diagnosed with bipolar disorder. Visibly tired after a day of doing press, she added, “I feel like I’ve drained my personality out of a hole.”

Still, Fisher was happy about how “Bright Lights” had been received the night before; the film received enthusiastic reviews as an intimate, sometimes painfully honest examination of fame, family, aging and mother-daughter dynamics that, in Fisher and Reynolds’s case, haven’t always been smooth. She wanted to make the film, she said, because Reynolds – who still performs her nightclub act when she’s up to it – had begun to decline, physically and cognitively.

“I didn’t know how much longer she would be performing,” Fisher explained. “It’s the thing that gives her life, but it was also pulling it out of her, because she’d perform and then she’d have to recover. But this is someone who wants to go back and do it now. She became very ill and now she’s bouncing back. At 84, she’s going to be at the South Point [Hotel and Casino in Las Vegas].” Although Fisher applauds her mother’s passion to perform, it’s not one she shares. “She automatically says, ‘And then you’ll come too.’ And I say, ‘Wait a minute. You said you want that, I don’t [want] it.’ ”

An homage to the end of an era in Hollywood, “Bright Lights” is full of storied glamour and scandal – including the episode when Fisher’s father, Eddie, left Reynolds for family friend and neighbor Elizabeth Taylor. The intention, according to Fisher, was to reveal Reynolds as the person behind the persona so carefully constructed and managed by MGM, with whom she made her breakout movie, “Singin’ In the Rain,” at 19. But getting her to drop her movie-star habits wasn’t always easy.

Fisher Stevens, who co-directed “Bright Lights” with Alexis Bloom, noted that the veteran actress’s instinct was to play to the audience. “We’d have to teach her” not to look at her daughter instead of the camera, Stevens said, adding that there moments when she would ask for her lines. Her only condition, he added, was a small one. “Debbie wouldn’t shoot without her wig,” he said.

“Bright Lights: Starring Carrie Fisher and Debbie Reynolds” will appear on HBO early next year.