[PATCH] D144254: [llvm][Uniformity] a phi with an undef argument is not always divergent

[Sameer Sahasrabuddhe via Phabricator via llvm-commits]

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The uniformity analysis treated an undef argument to phi to be distinct from any
other argument, equivalent to calling PHINode::hasConstantValue() instead of
PHINode::hasConstantOrUndefValue(). Such a phi was reported as divergent. This
is different from the older divergence analysis which treats such a phi as
uniform. Fixed uniformity analysis to match the older behaviour.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D144254

Files:
  llvm/include/llvm/ADT/GenericSSAContext.h
  llvm/include/llvm/ADT/GenericUniformityImpl.h
  llvm/include/llvm/CodeGen/MachineSSAContext.h
  llvm/include/llvm/IR/SSAContext.h
  llvm/lib/CodeGen/MachineSSAContext.cpp
  llvm/lib/IR/SSAContext.cpp
  llvm/test/Analysis/DivergenceAnalysis/AMDGPU/phi-undef.ll

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