diff --git a/net_link.cc b/net_link.cc
index 056ad089b..3cd433039 100644
--- a/net_link.cc
+++ b/net_link.cc
@@ -476,16 +476,20 @@ const Link* Nexus::first_nlink() const
       else return 0;
 }
 
-ivl_nexus_t Nexus::t_cookie() const
+/*
+ * The t_cookie can be set exactly once. This attaches an ivl_nexus_t
+ * object to the Nexus, and causes the Link list to be marked up for
+ * efficient use by the code generator. The change is to give all the
+ * links a valid nexus_ pointer. This breaks most of the other
+ * methods, but they are not used during code generation.
+*/
+void Nexus::t_cookie(ivl_nexus_t val) const
 {
-      return t_cookie_;
-}
-
-ivl_nexus_t Nexus::t_cookie(ivl_nexus_t val)const
-{
-      ivl_nexus_t tmp = t_cookie_;
+      assert(val && !t_cookie_);
       t_cookie_ = val;
-      return tmp;
+
+      for (Link*cur = list_->next_ ; cur->nexus_ == 0 ; cur = cur->next_)
+	    cur->nexus_ = const_cast<Nexus*> (this);
 }
 
 unsigned Nexus::vector_width() const
diff --git a/netlist.cc b/netlist.cc
index add9690f0..ea6618db5 100644
--- a/netlist.cc
+++ b/netlist.cc
@@ -491,9 +491,9 @@ const Link& NetDelaySrc::condit_pin() const
 NetNet::NetNet(NetScope*s, perm_string n, Type t, unsigned npins)
 : NetObj(s, n, 1),
     type_(t), port_type_(NOT_A_PORT), data_type_(IVL_VT_NO_TYPE),
-    signed_(false), isint_(false), is_scalar_(false),
+    signed_(false), isint_(false), is_scalar_(false), local_flag_(false),
     discipline_(0), msb_(npins-1), lsb_(0), dimensions_(0),
-    s0_(0), e0_(0), local_flag_(false), eref_count_(0), lref_count_(0)
+    s0_(0), e0_(0), eref_count_(0), lref_count_(0)
 {
       assert(s);
       assert(npins>0);
@@ -544,9 +544,10 @@ NetNet::NetNet(NetScope*s, perm_string n, Type t,
 	       long ms, long ls)
 : NetObj(s, n, 1), type_(t),
     port_type_(NOT_A_PORT), data_type_(IVL_VT_NO_TYPE), signed_(false),
-    isint_(false), is_scalar_(false), discipline_(0), msb_(ms), lsb_(ls),
+    isint_(false), is_scalar_(false), local_flag_(false), discipline_(0),
+    msb_(ms), lsb_(ls),
     dimensions_(0), s0_(0), e0_(0),
-    local_flag_(false), eref_count_(0), lref_count_(0)
+    eref_count_(0), lref_count_(0)
 {
       assert(s);
 
@@ -595,9 +596,10 @@ NetNet::NetNet(NetScope*s, perm_string n, Type t,
 : NetObj(s, n, calculate_count(array_s, array_e)),
     type_(t), port_type_(NOT_A_PORT),
     data_type_(IVL_VT_NO_TYPE), signed_(false), isint_(false),
-    is_scalar_(false), discipline_(0), msb_(ms), lsb_(ls),
+    is_scalar_(false), local_flag_(false), discipline_(0),
+    msb_(ms), lsb_(ls),
     dimensions_(1), s0_(array_s), e0_(array_e),
-    local_flag_(false), eref_count_(0), lref_count_(0)
+    eref_count_(0), lref_count_(0)
 {
       ivl_assert(*this, s);
       if (pin_count() == 0) {
diff --git a/netlist.h b/netlist.h
index 0a09755ab..5bc381fb9 100644
--- a/netlist.h
+++ b/netlist.h
@@ -322,9 +322,12 @@ class NetBranch  : public NetPins, public IslandBranch {
  * the first. The last link also has a non-nil nexus_ pointer back to
  * this nexus.
  *
- * The t_cookie() is a void* that targets can use to store information
- * in a Nexus. ivl guarantees that the t_cookie will be 0 when the
- * target is invoked.
+ * The t_cookie() is an ivl_nexus_t that the code generator uses to
+ * store data in the nexus. When a Nexus is created, this cookie is
+ * set to nil. The code generator may set the cookie once. This locks
+ * the nexus, and rewrites the Link list to be optimal for the code
+ * generator. In the process, *all* of the other methods are no longer
+ * functional.
  */
 class Nexus {
 
@@ -373,8 +376,10 @@ class Nexus {
 	   the value that has been driven. */
       verinum::V driven_value() const;
 
-      ivl_nexus_t t_cookie() const;
-      ivl_nexus_t t_cookie(ivl_nexus_t) const;
+	/* The code generator sets an ivl_nexus_t to attach code
+	   generation details to the nexus. */
+      ivl_nexus_t t_cookie() const { return t_cookie_; }
+      void t_cookie(ivl_nexus_t) const;
 
     private:
       Link*list_;
@@ -662,19 +667,19 @@ class NetNet  : public NetObj {
       void initialize_value_and_dir(verinum::V init_value, Link::DIR dir);
 
     private:
-      Type   type_;
-      PortType port_type_;
-      ivl_variable_type_t data_type_;
-      bool signed_;
-      bool isint_;		// original type of integer
-      bool is_scalar_;
+      Type   type_    : 5;
+      PortType port_type_ : 3;
+      ivl_variable_type_t data_type_ : 3;
+      bool signed_    : 1;
+      bool isint_     : 1;		// original type of integer
+      bool is_scalar_ : 1;
+      bool local_flag_: 1;
       ivl_discipline_t discipline_;
 
       long msb_, lsb_;
       const unsigned dimensions_;
       long s0_, e0_;
 
-      bool local_flag_;
       unsigned eref_count_;
       unsigned lref_count_;