diff --git a/src/V3Graph.cpp b/src/V3Graph.cpp
index 208386338..eb66cd934 100644
--- a/src/V3Graph.cpp
+++ b/src/V3Graph.cpp
@@ -140,6 +140,14 @@ V3GraphEdge::V3GraphEdge(V3Graph* graphp,
     inPushBack();
 }
 
+V3GraphEdge* V3GraphEdge::relinkFromp(V3GraphVertex* newFromp) {
+    V3GraphEdge *oldNxt = outNextp();
+    m_outs.unlink(m_fromp->m_outs, this);
+    m_fromp = newFromp;
+    outPushBack();
+    return oldNxt;
+}
+
 void V3GraphEdge::unlinkDelete() {
     // Unlink from side
     m_outs.unlink(m_fromp->m_outs, this);
diff --git a/src/V3Graph.h b/src/V3Graph.h
index fd6e22a9b..b307c5c58 100644
--- a/src/V3Graph.h
+++ b/src/V3Graph.h
@@ -242,6 +242,7 @@ public:
 	return top()->sortCmp(rhsp->top());
     }
     void	unlinkDelete();
+    V3GraphEdge* relinkFromp(V3GraphVertex* newFromp);
     // ACCESSORS
     int		weight() const { return m_weight; }
     void	weight(int weight) { m_weight=weight; }
diff --git a/src/V3Hashed.cpp b/src/V3Hashed.cpp
index 1086f41fe..fe220023c 100644
--- a/src/V3Hashed.cpp
+++ b/src/V3Hashed.cpp
@@ -105,12 +105,16 @@ public:
 //######################################################################
 // Hashed class functions
 
-void V3Hashed::hashAndInsert(AstNode* nodep) {
+V3Hashed::iterator V3Hashed::hashAndInsert(AstNode* nodep) {
+    hash(nodep);
+    return m_hashMmap.insert(make_pair(nodeHash(nodep), nodep));
+}
+
+void V3Hashed::hash(AstNode* nodep) {
     UINFO(8,"   hashI "<<nodep<<endl);
     if (!nodep->user4p()) {
 	HashedVisitor visitor (nodep);
     }
-    m_hashMmap.insert(make_pair(nodeHash(nodep), nodep));
 }
 
 bool V3Hashed::sameNodes(AstNode* node1p, AstNode* node2p) {
@@ -189,3 +193,16 @@ V3Hashed::iterator V3Hashed::findDuplicate(AstNode* nodep) {
     return end();
 }
 
+V3Hashed::iterator V3Hashed::findDuplicate(AstNode* nodep, V3HashedUserCheck* checkp) {
+    UINFO(8,"   findD "<<nodep<<endl);
+    if (!nodep->user4p()) nodep->v3fatalSrc("Called findDuplicate on non-hashed node");
+    pair <HashMmap::iterator,HashMmap::iterator> eqrange = mmap().equal_range(nodeHash(nodep));
+    for (HashMmap::iterator eqit = eqrange.first; eqit != eqrange.second; ++eqit) {
+	AstNode* node2p = eqit->second;
+	if (nodep != node2p && checkp->check(nodep,node2p) && sameNodes(nodep, node2p)) {
+	    return eqit;
+	}
+    }
+    return end();
+}
+
diff --git a/src/V3Hashed.h b/src/V3Hashed.h
index 68b2392bc..4c4038d1b 100644
--- a/src/V3Hashed.h
+++ b/src/V3Hashed.h
@@ -45,6 +45,11 @@ public:
 
 //============================================================================
 
+struct V3HashedUserCheck {
+    // Functor for V3Hashed::findDuplicate
+    virtual bool check(AstNode*,AstNode*) =0;
+};
+
 class V3Hashed : public VHashedBase {
     // NODE STATE
     //  AstNode::user4()	-> V3Hash.  Hash value of this node (hash of 0 is illegal)
@@ -70,10 +75,12 @@ public:
 
     // METHODS
     void clear() { m_hashMmap.clear(); AstNode::user4ClearTree(); }
-    void hashAndInsert(AstNode* nodep);	// Hash the node, and insert into map
+    iterator hashAndInsert(AstNode* nodep);	// Hash the node, and insert into map. Return iterator to inserted
+    void hash(AstNode* nodep);	// Only hash the node
     bool sameNodes(AstNode* node1p, AstNode* node2p);	// After hashing, and tell if identical
     void erase(iterator it);		// Remove node from structures
     iterator findDuplicate(AstNode* nodep);	// Return duplicate in hash, if any
+    iterator findDuplicate(AstNode* nodep, V3HashedUserCheck* checkp);	// Extra user checks for sameness
     AstNode* iteratorNodep(iterator it) { return it->second; }
     void dumpFile(const string& filename, bool tree);
     void dumpFilePrefixed(const string& nameComment, bool tree=false);