[PATCH] D149646: [LLVM][Uniformity] Propagate temporal divergence explicitly

[Sameer Sahasrabuddhe via Phabricator via llvm-commits]

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At a cycle C with divergent exits, UA was using a naive traversal of the exiting
edges to locate blocks that may use values defined inside C. But this traversal
fails when it encounters a cycle. This is now replaced with a much simpler
propagation that iterates over every instruction in C and checks any uses that
are outside C. But such an iteration can be expensive when C is very large; the
original strategy may need to be reconsidered if there is a regression in
compilation times.

Also fixed lit tests that should have originally caught the missed propagation
of temporal divergence.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D149646

Files:
  llvm/include/llvm/ADT/GenericUniformityImpl.h
  llvm/lib/Analysis/UniformityAnalysis.cpp
  llvm/lib/CodeGen/MachineUniformityAnalysis.cpp
  llvm/test/Analysis/UniformityAnalysis/AMDGPU/temporal_diverge.ll

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