[all-commits] [llvm/llvm-project] f1c18a: [NewGVN] do phi(undef, x) -> x only if x is not po...

[Nuno Lopes via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: f1c18acb07aa40f42b87b70462a6d1ab77a4825c
      https://github.com/llvm/llvm-project/commit/f1c18acb07aa40f42b87b70462a6d1ab77a4825c
  Author: Nuno Lopes <nuno.lopes at tecnico.ulisboa.pt>
  Date:   2022-01-29 (Sat, 29 Jan 2022)

  Changed paths:
    M llvm/lib/Transforms/Scalar/NewGVN.cpp
    M llvm/test/Transforms/NewGVN/completeness.ll
    M llvm/test/Transforms/NewGVN/phi-edge-handling.ll
    M llvm/test/Transforms/NewGVN/pr31682.ll
    M llvm/test/Transforms/NewGVN/pr32403.ll
    M llvm/test/Transforms/NewGVN/pr32838.ll
    M llvm/test/Transforms/NewGVN/pr34135.ll

  Log Message:
  -----------
  [NewGVN] do phi(undef, x) -> x only if x is not poison

phi([undef, A], [x, B]) -> x is only correct x is guaranteed to be
a non-poison value.
Otherwise we would be changing an undef to poison in the branch A.

Differential Revision: https://reviews.llvm.org/D117907