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archived-llvm/lib/Target/AMDGPU
Neil Henning b461f4de29 [AMDGPU] Add an AMDGPU specific atomic optimizer.
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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@343973 91177308-0d34-0410-b5e6-96231b3b80d8
2018-10-08 15:49:19 +00:00
..
2018-04-30 19:08:16 +00:00
2016-11-10 16:02:37 +00:00