message: Do not hoist nodes that modify frame info.
diff: @@ -1541,7 +1541,7 @@ class HoistCWiseUnaryChainsStage : public ArithmeticOptimizerStage {
  const ChainLinkSet& ops) const {
  if (ops.empty()) return true;
  const NodeDef* op0 = ops.begin()->node;
  - if (!IsUnaryElementWise(*op0)) return false;
  + if (ModifiesFrameInfo(*op0) || !IsUnaryElementWise(*op0)) return false;
  for (const auto& link : ops) {
  const NodeDef* op = link.node;
  if (op->device() != root_node.device() || op->op() != op0->op() ||
  