summaryrefslogtreecommitdiffstats
path: root/llvm/lib/Target/AMDGPU/AMDGPUAtomicOptimizer.cpp
Commit message (Collapse)AuthorAgeFilesLines
* Update the file headers across all of the LLVM projects in the monorepoChandler Carruth2019-01-191-4/+3
| | | | | | | | | | | | | | | | | to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
* [AMDGPU] Fix the new atomic optimizer in pixel shaders.Neil Henning2018-11-051-2/+39
| | | | | | | | | | | | | | | | | The new atomic optimizer I previously added in D51969 did not work correctly when a pixel shader was using derivatives, and had helper lanes active. To fix this we add an llvm.amdgcn.ps.live call that guards a branch around the entire atomic operation - ensuring that all helper lanes are inactive within the wavefront when we compute our atomic results. I've added a test case that can cause derivatives, and exposes the problem. Differential Revision: https://reviews.llvm.org/D53930 llvm-svn: 346128
* [AMDGPU] Add an AMDGPU specific atomic optimizer.Neil Henning2018-10-081-0/+421
This commit adds a new IR level pass to the AMDGPU backend to perform atomic optimizations. It works by: - Running through a function and finding atomicrmw add/sub or uses of the atomic buffer intrinsics for add/sub. - If all arguments except the value to be added/subtracted are uniform, record the value to be optimized. - Run through the atomic operations we can optimize and, depending on whether the value is uniform/divergent use wavefront wide operations (DPP in the divergent case) to calculate the total amount to be atomically added/subtracted. - Then let only a single lane of each wavefront perform the atomic operation, reducing the total number of atomic operations in flight. - Lastly we recombine the result from the single lane to each lane of the wavefront, and calculate our individual lanes offset into the final result. Differential Revision: https://reviews.llvm.org/D51969 llvm-svn: 343973
OpenPOWER on IntegriCloud