[PATCH] D128251: [SCCP] Only handle unknown lattice values in resolvedUndefsIn()

[Nikita Popov via Phabricator via llvm-commits]

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This is a minor refinement of resolvedUndefsIn(), mostly for clarity. If the value of an instruction is `undef`, then that's already a legal final result -- we can safely rauw such an instruction with `undef`. We only need to mark `unknown` values as overdefined, as that's the result we get for an instruction that has not been processed because it has an undef operand.

Depends on D126962 <https://reviews.llvm.org/D126962>.


https://reviews.llvm.org/D128251

Files:
  llvm/lib/Transforms/Utils/SCCPSolver.cpp
  llvm/test/Transforms/SCCP/PR26044.ll
  llvm/test/Transforms/SCCP/ipsccp-phi-one-pred-dead.ll

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