1. A graphics processing system configured to track per-tile event counts in a tile-based architecture, the graphics processing system comprising: a tiling unit configured to: cause a screen-space pipeline to load a first count value associated with a first cache tile and stored in a first accumulating memory also associated with the first cache tile into a count memory, cause the screen-space pipeline to process a first set of primitives that intersect the first cache tile, cause the screen-space pipeline to store a second count value in a first report memory location, cause the screen-space pipeline to process a second set of primitives that intersect the first cache tile, and cause the screen-space pipeline to store a third count value in the first accumulating memory, wherein at least one primitive in the first set of primitives and at least one primitive in the second set of primitives are configured to cause the screen-space pipeline to detect an event type and increment the count memory.