1. A computer-implemented method for rasterizing primitives, comprising: receiving a bounding box that entirely encloses a primitive; determining that the primitive is small based on dimensions of the bounding box; computing per-sample coverage for the small primitive; determining whether at least one sample is covered by the small primitive according to the per-sample coverage; and if at least one sample is covered by the small primitive, then computing coarse raster information for at least one coarse raster tile based on the per-sample coverage; or if no sample is covered by the small primitive, then discarding the small primitive.