[PATCH] D71539: [SCEV] Look through trivial PHIs.

[Martin Storsjö via Phabricator via llvm-commits]

mstorsjo added a comment.

This commit (recommitted in the final form in 20d798bd47ec5191de1b2a8a031da06a04e612e1 <https://reviews.llvm.org/rG20d798bd47ec5191de1b2a8a031da06a04e612e1>) seems to be triggering failed asserts - see https://github.com/llvm/llvm-project/issues/57825 for details. Reposting the essential details here too:

  $ cat repro.c
  double *a;
  double b, c;
  int d, e;
  long f;
  void g() {
    d = 1;
    for (; d >= 0; d--) {
      e = 0;
      for (; e < f; e++) {
        c = *(&b + e);
        *a = *(&b + d + e) = c;
        a++;
      }
    }
  }
  $ clang -target aarch64-windows-msvc -c repro.c -O2
  clang: ../lib/Analysis/ScalarEvolution.cpp:768: llvm::Optional<int> CompareSCEVComplexity(llvm::EquivalenceClasses<const llvm::SCEV*>&, llvm::EquivalenceClasses<const llvm::Value*>&, const llvm::LoopInfo*, const llvm::SCEV*, const llvm::SCEV*, llvm::DominatorTree&, unsigned int): Assertion `DT.dominates(RHead, LHead) && "No dominance between recurrences used by one SCEV?"' failed.


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