triangle symbol in xilinx schematic view
It probably just means it's an input. The picture below is how I normally see this in Altium. Pins 19 and 22 are inputs because of the inward arrow, and the others are either input or output because of both arrows. I'd normally expect it to be part of the component though, rather than something you add on the schematic. That's the confusing part.

It also looks a bit like a buffer symbol, so it could be just to signify that this one is the line that is buffered by the chip, and not the DIVCLK line.