// Returns constraints on the operands specified by the clustering policy if the
// operation can be clustered (constraints could be empty). Otherwise return
// empty optional.
static std::optional<ValuesConstraintSet> CanBeClustered(
    Operation *op, const ClusteringPolicySet &policies,
    const std::function<bool(Operation *op)> &filter) {
  // Check that op has no side effects. This guarantees that we will not