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fe7eef8441
Previously, we used a bitmask stored in the primitive visibility state to determine which alpha batchers a primitive should be added to, based on dirty regions. The problem with this is that we had a limited number of bits that could store visibility. If we overflowed that, all primitives that touched any dirty rect would get added to the final bit group. This was a performance cost in this edge case, but didn't affect the correctness of rendering. However, in future we'll have alpha tiles behind and in front of compositor surfaces, if the compositor surface itself is not opaque. This means we'll have more tiles that we need to add prims to, and we must ensure the dirty rect tracking only adds prims to tiles that the prim definitely belongs to. This patch removes the bitmask, and instead stores a rect that the prim occupies, which is intersected with the dirty rect for the specific alpha batcher. No extra space in consumed in the visibility state enum, as there was already padding in the Detailed enum kind. There is a slight extra cost in terms of the comparison for dirty primitives, but this is mitigated by the ability to early out during Coarse -> Detailed prim visibility. Long term, we want to change how tiles store this information so that an index buffer is stored of dirty prims, negating the need to walk the entire picture tree during batching. Differential Revision: https://phabricator.services.mozilla.com/D109023