Abstract: One embodiment of the present invention sets forth a technique for managing buffer table entries in a tile-based architecture. The technique includes binding a plurality of shader registers to a buffer table entry. The technique further includes processing at least one tile by reading a buffer table index stored in the shader register to access the buffer table entry, reading a buffer address stored in the buffer table entry, accessing data associated with the buffer address, and unbinding the shader register from the buffer table entry. The technique further includes determining that none of the shader registers is still bound to the buffer table entry and, in response, causing a release packet to be inserted into an instruction stream. The technique further includes determining that a last tile has been processed and, in response, transmitting the release packet to cause the buffer table entry to be released.

Abstract: One embodiment of the present invention sets forth a graphics processing system configured to track event counts in a tile-based architecture. The graphics processing system includes a screen-space pipeline and a tiling unit. The screen-space pipeline includes a first unit, a count memory associated with the first unit, and an accumulating memory associated with the first unit. The first unit is configured to detect an event type and increment the count memory. The tiling unit is configured to cause the screen-space pipeline to update an external memory address to reflect a first value stored in the count memory when the first unit completes processing of a first set of primitives. The tiling unit is also configured to cause the screen-space pipeline to update the accumulating memory to reflect a second value stored in the count memory when the first unit completes processing of a second set of primitives.

Abstract: A graphics processing pipeline configured for z-cull operations. The graphics processing pipeline comprising a screen-space pipeline and a tiling unit. The screen-space pipeline includes a z-cull unit configured to perform z-culling operations. The tiling unit is configured to determine that a first set of primitives overlaps a first cache tile. The tiling unit is also configured to transmit the first set of primitives to the screen-space pipeline for processing. The tiling unit is further configured to select between processing the first set of primitives in a full-surface z-cull mode or processing the first set of primitives in a partial-surface z-cull mode. The tiling unit is also configured to cause the z-cull unit to process the first set of primitives in the full-surface z-cull mode or to process the first set of primitives in the partial-surface z-cull mode.

Abstract: One embodiment of the present invention includes a technique for processing graphics primitives in a tile-based architecture. The technique includes storing, in a buffer, a first plurality of graphics primitives and a first plurality of state bundles received from a world-space pipeline, and transmitting the first plurality of graphics primitives to a screen-space pipeline for processing while a tiling function is enabled. The technique further includes storing, in the buffer, a second plurality of graphics primitives and a second plurality of state bundles received from the world-space pipeline. The technique further includes determining, based on a first condition, that the tiling function should be disabled and that the second plurality of graphics primitives should be flushed from the buffer, and transmitting the second plurality of graphics primitives to the screen-space pipeline for processing while the tiling function is disabled.

Abstract: One embodiment of the present invention sets forth a technique for parallel distribution of primitives to multiple rasterizers. Multiple, independent geometry units perform geometry processing concurrently on different graphics primitives. A primitive distribution scheme delivers primitives from the multiple geometry units concurrently to multiple rasterizers at rates of multiple primitives per clock. The multiple, independent rasterizer units perform rasterization concurrently on one or more graphics primitives, enabling the rendering of multiple primitives per system clock.

Abstract: One embodiment of the present invention sets forth a technique for computing line stipple using a parallel rasterizer. Stipple phases are computed in parallel for individual line segments of a line strip during the viewport scale, cull, and clipping operations. The line segments are distributed to multiple parallel rasterizers. Each line segment may be sent to only one of the parallel rasterizers. Update phase messages that include an accumulated stipple phase for a batch of line segments are broadcast to all of the multiple parallel rasterizers. The update phase messages are used by the multiple parallel rasterizers to reconstruct the stipple phases for each line segment of a line strip in order to correctly render stippled line strips and produce a continuous stippled line.

Abstract: One embodiment of the present invention sets forth a graphics subsystem configured to implement distributed tiled caching. The graphics subsystem includes one or more world-space pipelines, one or more screen-space pipelines, one or more tiling units, and a crossbar unit. Each world-space pipeline is implemented in a different processing entity and is coupled to a different tiling unit. Each screen-space pipeline is implemented in a different processing entity and is coupled to the crossbar unit. The tiling units are configured to receive primitives from the world-space pipelines, generate cache tile batches based on the primitives, and transmit the primitives to the screen-space pipelines. One advantage of the disclosed approach is that primitives are processed in application-programming-interface order in a highly parallel tiling architecture. Another advantage is that primitives are processed in cache tile order, which reduces memory bandwidth consumption and improves cache memory utilization.

Abstract: One embodiment of the present invention sets forth a technique for managing buffer entries in a tile-based architecture. The technique includes receiving a first plurality of graphics primitives and a first buffer address at which attributes associated with the first plurality of graphics primitives are stored. The technique further includes, for each tile included in a plurality of tiles, transmitting the first plurality of graphics primitives and the first buffer address to a screen space pipeline and receiving an acknowledgement from the screen space pipeline indicating that processing the first plurality of graphics primitives has completed. The technique further includes determining that processing the first plurality of graphics primitives has completed for a last tile included in the plurality of tiles and that the acknowledgement has been received for each tile included in the plurality of tiles, and, in response, releasing a buffer entry associated with the first buffer address.

Abstract: One embodiment of the present invention sets forth a technique for redistributing geometric primitives generated by tessellation and geometry shaders for processing by multiple graphics pipelines. Geometric primitives that are generated in a first processing cycle are collected and redistributed more evenly and in smaller tasks to the multiple graphics pipelines for vertex processing in a second processing cycle. The smaller tasks do not exceed the resource limits of a graphics pipeline and the per-vertex processing workloads of the graphics pipelines in the second cycle are balanced and make full use of resources. Therefore, the performance of the tessellation and geometry shaders is improved.

Abstract: A graphics processing unit includes a set of geometry processing units each configured to process graphics primitives in parallel with one another. A given geometry processing unit generates one or more graphics primitives or geometry objects and buffers the associated vertex data locally. The geometry processing unit also buffers different sets of indices to those vertices, where each such set represents a different graphics primitive or geometry object. The geometry processing units may then stream the buffered vertices and indices to global buffers in parallel with one another. A stream output synchronization unit coordinates the parallel streaming of vertices and indices by providing each geometry processing unit with a different base address within a global vertex buffer where vertices may be written. The stream output synchronization unit also provides each geometry processing unit with a different base address within a global index buffer where indices may be written.

Abstract: One embodiment of the present invention sets forth a graphics subsystem. The graphics subsystem includes a first tiling unit associated with a first set of raster tiles and a crossbar unit. The crossbar unit is configured to transmit a first set of primitives to the first tiling unit and to transmit a first cache invalidate command to the first tiling unit. The first tiling unit is configured to determine that a second bounding box associated with primitives included in the first set of primitives overlaps a first cache tile and that the first bounding box overlaps the first cache tile. The first tiling unit is further configured to transmit the primitives and the first cache invalidate command to a first screen-space pipeline associated with the first tiling unit for processing. The screen-space pipeline processes the cache invalidate command to invalidate cache lines specified by the cache invalidate command.

Abstract: A tessellation pipeline includes an alpha phase and a beta phase. The alpha phase includes pre-tessellation processing stages, while the beta phase includes post-tessellation processing stages. A processing unit configured to implement a processing stage in the alpha phase stores input graphics data within a buffer and then copies over that buffer with output graphics data, thereby conserving memory resources. The processing unit may also copy output graphics data directly to a level 2 (L2) cache for beta phase processing by other tessellation pipelines, thereby avoiding the need for fixed function copy-out hardware.

Abstract: One embodiment of the present invention includes a method for generating accumulated bounding boxes for graphics primitives. The method includes generating a first bounding box associated with a first graphics primitive. The method further includes, for each graphics primitive included in a first set of one or more additional graphics primitives, determining that the graphics primitive is within a threshold distance of the first bounding box, and adding the graphics primitive to the first bounding box. The method further includes determining not to add a second graphics primitive to the first bounding box. The method further includes generating a second bounding box associated with the second graphics primitive. Finally, the method includes transmitting the first bounding box to a tiling unit via a crossbar. One advantage of the disclosed embodiments is that multiple bounding boxes are combined to generate an accumulated bounding box that is then transferred across the crossbar.

Abstract: One embodiment of the present invention includes a method for performing a multi-pass tiling test. The method includes combining a plurality of bounding boxes to generate a coarse bounding box. The method further includes identifying a first cache tile associated with a render surface and determining that the coarse bounding box intersects the first cache tile. The method further includes comparing each bounding box included in the plurality of bounding boxes against the first cache tile to determine that a first set of one or more bounding boxes included in the plurality of bounding boxes intersects the first cache tile. Finally, the method includes, for each bounding box included in the first set of one or more bounding boxes, processing one or more graphics primitives associated with the bounding box. One advantage of the disclosed technique is that the number of intersection calculations performed for each cache tile is reduced.

Abstract: A graphics processing system configured to track per-tile event counts in a tile-based architecture. A tiling unit in the graphics processing system is configured to cause a screen-space pipeline to load a count value associated with a first cache tile into a count memory and to cause the screen-space pipeline to process a first set of primitives that intersect the first cache tile. The tiling unit is further configured to cause the screen-space pipeline to store a second count value in a report memory location. The tiling unit is also configured to cause the screen-space pipeline to process a second set of primitives that intersect the first cache tile and to cause the screen-space pipeline to store a third count value in the first accumulating memory. Conditional rendering operations may be performed on a per-cache tile basis, based on the per-tile event count.

Abstract: A graphics processing unit includes a set of geometry processing units each configured to process graphics primitives in parallel with one another. A given geometry processing unit generates one or more graphics primitives or geometry objects and buffers the associated vertex data locally. The geometry processing unit also buffers different sets of indices to those vertices, where each such set represents a different graphics primitive or geometry object. The geometry processing units may then stream the buffered vertices and indices to global buffers in parallel with one another. A stream output synchronization unit coordinates the parallel streaming of vertices and indices by providing each geometry processing unit with a different base address within a global vertex buffer where vertices may be written. The stream output synchronization unit also provides each geometry processing unit with a different base address within a global index buffer where indices may be written.

Abstract: A tessellation pipeline includes an alpha phase and a beta phase. The alpha phase includes pre-tessellation processing stages, while the beta phase includes post-tessellation processing stages. A processing unit configured to implement a processing stage in the alpha phase stores input graphics data within a buffer and then copies over that buffer with output graphics data, thereby conserving memory resources. The processing unit may also copy output graphics data directly to a level 2 (L2) cache for beta phase processing by other tessellation pipelines, thereby avoiding the need for fixed function copy-out hardware.

Abstract: One embodiment of the present invention includes a method for processing graphics objects. The method includes receiving a first draw-call and a second draw-call. The method also includes dividing the first draw-call into a first set of sub-draw-calls and the second draw-call into a second set of sub-draw-calls. The method further includes identifying a first screen tile. The method also includes identifying a first group of sub-draw-calls included in the first set of sub-draw-calls that overlap the first screen tile and a second group of sub-draw-calls included in the second set of sub-draw-calls that overlap the second screen tile. The method further includes causing the first group of sub-draw-calls and the second group of sub-draw-calls to be processed together.

Abstract: One embodiment of the present invention sets forth a method for analyzing the performance of a graphics processing pipeline. A first workload and a second workload are combined together in a pipeline to generate a combined workload. The first workload is associated with a first instance and the second workload is associated with a second instance. A first and second initial event are generated for the combined workload, indicating that the first and second workloads have begun processing at a first position in the graphics processing pipeline. A first and second final event are generated, indicating that the first and second workloads have finished processing at a second position in the graphics processing pipeline.

Abstract: One embodiment of the present invention includes a technique for processing graphics primitives in a tile-based architecture. The technique includes storing, in a buffer, a first plurality of graphics primitives and a first plurality of state bundles received from a world-space pipeline, and transmitting the first plurality of graphics primitives to a screen-space pipeline for processing while a tiling function is enabled. The technique further includes storing, in the buffer, a second plurality of graphics primitives and a second plurality of state bundles received from the world-space pipeline. The technique further includes determining, based on a first condition, that the tiling function should be disabled and that the second plurality of graphics primitives should be flushed from the buffer, and transmitting the second plurality of graphics primitives to the screen-space pipeline for processing while the tiling function is disabled.