Not a good way.
Suppose you're runnung the t0 onterrupt handler with your flag up. You're nearing the reti instruction. as the last instruction before reti you clear the flag, but suddenly.... x0 makes you go to the high priority handler. The x0 handler doesn't see the flag set, and will think you didn't come out of the t0 handler.
It's a recipe for unexplainable crashes.

Hans