British singer Charli XCX and producer Sophie shut down Hype Hotel at South by Southwest on Thursday at 1 a.m. One of those people has had more effect on the other.

Much like AlunaGeorge at the same venue in the same time slot on Wednesday, this set was a pure turn-up. Charli stayed silhouetted against harsh white light and oppressive fog, her high ponytail whipping on beat. On her two full-length albums, “True Romance” and “Sucker,” the singer struck variations on the brat-pop genre. But new EP “Vroom Vroom,” produced by Sophie (aka Samuel Long), bears a repititious anti-structure and doom-saturated atmosphere that peels away from Charli’s earlier work at record speeds.

(Eric Webb/American-Statesman)

Anyone showing up to Hype Hotel hoping for a straightforward song or two should have just cashed in those free drink tickets and paid closer attention to the Sophie half of the bill.  It was a seamless set hype-raising, PC glitches and twisty bass. Get outta here with that “verse-bridge-chorus” nonsense. The night put a distinctly 2016 spin on the idea of a medley — Charli’s “Doing It” and Sophie’s “Just Like We Never Said Goodbye” reared their heads.

But if you’re the SXSW trend-hunting type, it’s fun to speculate about what it means that the biggest radio pop star playing Hype Hotel this year showed up to a discovery festival in full rave mode.