// if a special Identity node in the following pattern is clustered in.
    // That is, an Identity node in the loop cond computation is used to drive
    // const nodes consumed by the loop body.  If this Identity node goes into
    // the same cluster with nodes from the loop body, extra dependency is
    // created between the loop cond and body computations and it hinders the

      return;
    }
    for (Predicate* op : current->GetOperands()) {
      if (visited.insert(op).second) {
        stack.push_back(op);
      }
    }
  }
}

// Creates and owns Predicate instances.  Simplifies predicates as it creates
// them.
class PredicateFactory {
 public:
  Predicate* MakeAndPredicate(absl::Span<Predicate* const> operands) {
    return MakeAndOrImpl(operands, /*is_and=*/true);
  }

  EXPECT_EQ(clusters["B_dev1"], clusters["MatMul1_dev1"]);
}

// TODO(b/117085735): This form of clustering should be prevented.
TEST(XlaCompilationTest, NOT_DontClusterSpreadingNodes) {
  // MatMulSource below creates data for nodes on GPU0 and GPU1 and is placed
  // on GPU0. However, it should not be clustered with the next node on
  // GPU0, because that will prevent the node on GPU1 from beginning its work as