Output capture_enter_outer = ops::internal::Enter(
      root.WithOpName("capture_enter_outer"), captured, "outer_loop",
      ops::internal::Enter::Attrs().IsConstant(true));
  Output capture_enter_inner = ops::internal::Enter(
      root.WithOpName("capture_enter_inner"), capture_enter_outer, "inner_loop",
      ops::internal::Enter::Attrs().IsConstant(true));

  Node* node = options.FinalizeBuilder(&node_builder);
  // Add any Enter nodes required to bring the constant to the correct control
  // flow frame.
  while (!control_flow_info[src_node->id()].frame_name.empty()) {
    NodeDebugInfo debug_info(*src_node);
    NodeBuilder enter_builder(options.GetNameForOp("Enter"), "Enter",
                              options.op_registry(), &debug_info);

  auto a = ops::Placeholder(root.WithOpName("A"), DT_FLOAT);
  auto b = ops::Placeholder(root.WithOpName("B"), DT_FLOAT);
  auto c = ops::Add(root.WithOpName("C"), a, b);
  auto enter = ops::internal::Enter(root, c, "aframe");
  auto next_iter = ops::NextIteration(root, enter);
  auto exit = ops::internal::Exit(root, next_iter);
  auto d = ops::Add(root.WithOpName("D"), c, exit);

  std::unique_ptr<Graph> graph(new Graph(OpRegistry::Global()));

	// termination complete.
	n := work.cycles.Load()
	gcWaitOnMark(n)

	// We're now in sweep N or later. Trigger GC cycle N+1, which
	// will first finish sweep N if necessary and then enter sweep
	// termination N+1.
	gcStart(gcTrigger{kind: gcTriggerCycle, n: n + 1})

	// Wait for mark termination N+1 to complete.
	gcWaitOnMark(n + 1)

	// Finish sweep N+1 before returning. We do this both to

    self.symbols = []
    self.enter_scope()
    self.scf_scope = 0
    # reserved key words
    self.insert_symbol('len', 'len', TFRTypes.PY_BUILTIN_FUNC)

  def enter_scope(self, scf_scope=False):
    """Enter a new scope - at function level."""
    self.symbols.append({'types': {}, 'symbols': {}})
    self.curr_table = self.symbols[len(self.symbols) - 1]
    if scf_scope:
      self.scf_scope += 1

  ASSERT_TRUE(GetFunctionDef(func_, &fdef));
  VerifyFDefInputs(fdef, M({{"feed1"}, {"feed2"}}));
  VerifyFDefOutputs(fdef, M({{"test_loop_exit"}}));
  VerifyFDefEdges(fdef,
                  {{"feed1", "test_loop/Enter:0"},
                   {"test_loop/Enter:output:0", "test_loop/Merge:0"},
                   {"test_loop/Merge:output:0", "test_loop/Switch:0"},
                   {"test_loop/Switch:output_false:0", "test_loop/Exit:0"},

	wantNoneReg(ctxt, ins, "rs3", ins.rs3)
}

func validateRaw(ctxt *obj.Link, ins *instruction) {
	// Treat the raw value specially as a 32-bit unsigned integer.
	// Nobody wants to enter negative machine code.
	if ins.imm < 0 || 1<<32 <= ins.imm {
		ctxt.Diag("%v: immediate %d in raw position cannot be larger than 32 bits", ins.as, ins.imm)
	}
}

         ...

//
// We first do an optimistic analysis and, if it does not converge, we then fall
// back to a pessimistic analysis.  The optimistic analysis assigns the same
// symbolic predicate to all the merge nodes whose preceding enter nodes have
// the same frame name on the first iteration.  On the second iteration, if all
// the merge nodes are pattern matched into the same AndRecurrence predicate

	})
	if labels != nil {
		labels[0] = ourg.labels
	}
	ourg.goroutineProfiled.Store(goroutineProfileSatisfied)
	goroutineProfile.offset.Store(1)

	// Prepare for all other goroutines to enter the profile. Aside from ourg,
	// every goroutine struct in the allgs list has its goroutineProfiled field
	// cleared. Any goroutine created from this point on (while