Register DAGUpdateListeners with SelectionDAG.

Instead of passing listener pointers to RAUW, let SelectionDAG itself
keep a linked list of interested listeners.

This makes it possible to have multiple listeners active at once, like
RAUWUpdateListener was already doing. It also makes it possible to
register listeners up the call stack without controlling all RAUW calls
below.

DAGUpdateListener uses an RAII pattern to add itself to the SelectionDAG
list of active listeners.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155248 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 87 insertions, 119 deletions

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 0914c66..1ed1ee7 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -328,15 +328,12 @@ namespace {
 class WorkListRemover : public SelectionDAG::DAGUpdateListener {
   DAGCombiner &DC;
 public:
-  explicit WorkListRemover(DAGCombiner &dc) : DC(dc) {}
+  explicit WorkListRemover(DAGCombiner &dc)
+    : SelectionDAG::DAGUpdateListener(dc.getDAG()), DC(dc) {}
 
   virtual void NodeDeleted(SDNode *N, SDNode *E) {
     DC.removeFromWorkList(N);
   }
-
-  virtual void NodeUpdated(SDNode *N) {
-    // Ignore updates.
-  }
 };
 }
 
@@ -619,8 +616,7 @@ SDValue DAGCombiner::CombineTo(SDNode *N, const SDValue *To, unsigned NumTo,
                   N->getValueType(i) == To[i].getValueType()) &&
                  "Cannot combine value to value of different type!"));
   WorkListRemover DeadNodes(*this);
-  DAG.ReplaceAllUsesWith(N, To, &DeadNodes);
-
+  DAG.ReplaceAllUsesWith(N, To);
   if (AddTo) {
     // Push the new nodes and any users onto the worklist
     for (unsigned i = 0, e = NumTo; i != e; ++i) {
@@ -650,7 +646,7 @@ CommitTargetLoweringOpt(const TargetLowering::TargetLoweringOpt &TLO) {
   // Replace all uses.  If any nodes become isomorphic to other nodes and
   // are deleted, make sure to remove them from our worklist.
   WorkListRemover DeadNodes(*this);
-  DAG.ReplaceAllUsesOfValueWith(TLO.Old, TLO.New, &DeadNodes);
+  DAG.ReplaceAllUsesOfValueWith(TLO.Old, TLO.New);
 
   // Push the new node and any (possibly new) users onto the worklist.
   AddToWorkList(TLO.New.getNode());
@@ -707,9 +703,8 @@ void DAGCombiner::ReplaceLoadWithPromotedLoad(SDNode *Load, SDNode *ExtLoad) {
         Trunc.getNode()->dump(&DAG);
         dbgs() << '\n');
   WorkListRemover DeadNodes(*this);
-  DAG.ReplaceAllUsesOfValueWith(SDValue(Load, 0), Trunc, &DeadNodes);
-  DAG.ReplaceAllUsesOfValueWith(SDValue(Load, 1), SDValue(ExtLoad, 1),
-                                &DeadNodes);
+  DAG.ReplaceAllUsesOfValueWith(SDValue(Load, 0), Trunc);
+  DAG.ReplaceAllUsesOfValueWith(SDValue(Load, 1), SDValue(ExtLoad, 1));
   removeFromWorkList(Load);
   DAG.DeleteNode(Load);
   AddToWorkList(Trunc.getNode());
@@ -961,8 +956,8 @@ bool DAGCombiner::PromoteLoad(SDValue Op) {
           Result.getNode()->dump(&DAG);
           dbgs() << '\n');
     WorkListRemover DeadNodes(*this);
-    DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result, &DeadNodes);
-    DAG.ReplaceAllUsesOfValueWith(SDValue(N, 1), NewLD.getValue(1), &DeadNodes);
+    DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result);
+    DAG.ReplaceAllUsesOfValueWith(SDValue(N, 1), NewLD.getValue(1));
     removeFromWorkList(N);
     DAG.DeleteNode(N);
     AddToWorkList(Result.getNode());
@@ -1047,12 +1042,12 @@ void DAGCombiner::Run(CombineLevel AtLevel) {
     DAG.TransferDbgValues(SDValue(N, 0), RV);
     WorkListRemover DeadNodes(*this);
     if (N->getNumValues() == RV.getNode()->getNumValues())
-      DAG.ReplaceAllUsesWith(N, RV.getNode(), &DeadNodes);
+      DAG.ReplaceAllUsesWith(N, RV.getNode());
     else {
       assert(N->getValueType(0) == RV.getValueType() &&
              N->getNumValues() == 1 && "Type mismatch");
       SDValue OpV = RV;
-      DAG.ReplaceAllUsesWith(N, &OpV, &DeadNodes);
+      DAG.ReplaceAllUsesWith(N, &OpV);
     }
 
     // Push the new node and any users onto the worklist
@@ -1327,8 +1322,7 @@ SDValue DAGCombiner::visitMERGE_VALUES(SDNode *N) {
   // uses remain, to ensure that the node can be safely deleted.
   do {
     for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
-      DAG.ReplaceAllUsesOfValueWith(SDValue(N, i), N->getOperand(i),
-                                    &DeadNodes);
+      DAG.ReplaceAllUsesOfValueWith(SDValue(N, i), N->getOperand(i));
   } while (!N->use_empty());
   removeFromWorkList(N);
   DAG.DeleteNode(N);
@@ -5041,8 +5035,7 @@ SDValue DAGCombiner::ReduceLoadWidth(SDNode *N) {
 
   // Replace the old load's chain with the new load's chain.
   WorkListRemover DeadNodes(*this);
-  DAG.ReplaceAllUsesOfValueWith(N0.getValue(1), Load.getValue(1),
-                                &DeadNodes);
+  DAG.ReplaceAllUsesOfValueWith(N0.getValue(1), Load.getValue(1));
 
   // Shift the result left, if we've swallowed a left shift.
   SDValue Result = Load;
@@ -6185,7 +6178,7 @@ SDValue DAGCombiner::visitBRCOND(SDNode *N) {
           }
           // Replace the uses of SRL with SETCC
           WorkListRemover DeadNodes(*this);
-          DAG.ReplaceAllUsesOfValueWith(N1, SetCC, &DeadNodes);
+          DAG.ReplaceAllUsesOfValueWith(N1, SetCC);
           removeFromWorkList(N1.getNode());
           DAG.DeleteNode(N1.getNode());
           return SDValue(N, 0);   // Return N so it doesn't get rechecked!
@@ -6214,7 +6207,7 @@ SDValue DAGCombiner::visitBRCOND(SDNode *N) {
               Tmp.getNode()->dump(&DAG);
               dbgs() << '\n');
         WorkListRemover DeadNodes(*this);
-        DAG.ReplaceAllUsesOfValueWith(N1, Tmp, &DeadNodes);
+        DAG.ReplaceAllUsesOfValueWith(N1, Tmp);
         removeFromWorkList(TheXor);
         DAG.DeleteNode(TheXor);
         return DAG.getNode(ISD::BRCOND, N->getDebugLoc(),
@@ -6240,7 +6233,7 @@ SDValue DAGCombiner::visitBRCOND(SDNode *N) {
                                    Equal ? ISD::SETEQ : ISD::SETNE);
       // Replace the uses of XOR with SETCC
       WorkListRemover DeadNodes(*this);
-      DAG.ReplaceAllUsesOfValueWith(N1, SetCC, &DeadNodes);
+      DAG.ReplaceAllUsesOfValueWith(N1, SetCC);
       removeFromWorkList(N1.getNode());
       DAG.DeleteNode(N1.getNode());
       return DAG.getNode(ISD::BRCOND, N->getDebugLoc(),
@@ -6431,21 +6424,17 @@ bool DAGCombiner::CombineToPreIndexedLoadStore(SDNode *N) {
         dbgs() << '\n');
   WorkListRemover DeadNodes(*this);
   if (isLoad) {
-    DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result.getValue(0),
-                                  &DeadNodes);
-    DAG.ReplaceAllUsesOfValueWith(SDValue(N, 1), Result.getValue(2),
-                                  &DeadNodes);
+    DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result.getValue(0));
+    DAG.ReplaceAllUsesOfValueWith(SDValue(N, 1), Result.getValue(2));
   } else {
-    DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result.getValue(1),
-                                  &DeadNodes);
+    DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result.getValue(1));
   }
 
   // Finally, since the node is now dead, remove it from the graph.
   DAG.DeleteNode(N);
 
   // Replace the uses of Ptr with uses of the updated base value.
-  DAG.ReplaceAllUsesOfValueWith(Ptr, Result.getValue(isLoad ? 1 : 0),
-                                &DeadNodes);
+  DAG.ReplaceAllUsesOfValueWith(Ptr, Result.getValue(isLoad ? 1 : 0));
   removeFromWorkList(Ptr.getNode());
   DAG.DeleteNode(Ptr.getNode());
 
@@ -6559,13 +6548,10 @@ bool DAGCombiner::CombineToPostIndexedLoadStore(SDNode *N) {
               dbgs() << '\n');
         WorkListRemover DeadNodes(*this);
         if (isLoad) {
-          DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result.getValue(0),
-                                        &DeadNodes);
-          DAG.ReplaceAllUsesOfValueWith(SDValue(N, 1), Result.getValue(2),
-                                        &DeadNodes);
+          DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result.getValue(0));
+          DAG.ReplaceAllUsesOfValueWith(SDValue(N, 1), Result.getValue(2));
         } else {
-          DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result.getValue(1),
-                                        &DeadNodes);
+          DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result.getValue(1));
         }
 
         // Finally, since the node is now dead, remove it from the graph.
@@ -6573,8 +6559,7 @@ bool DAGCombiner::CombineToPostIndexedLoadStore(SDNode *N) {
 
         // Replace the uses of Use with uses of the updated base value.
         DAG.ReplaceAllUsesOfValueWith(SDValue(Op, 0),
-                                      Result.getValue(isLoad ? 1 : 0),
-                                      &DeadNodes);
+                                      Result.getValue(isLoad ? 1 : 0));
         removeFromWorkList(Op);
         DAG.DeleteNode(Op);
         return true;
@@ -6609,7 +6594,7 @@ SDValue DAGCombiner::visitLOAD(SDNode *N) {
               Chain.getNode()->dump(&DAG);
               dbgs() << "\n");
         WorkListRemover DeadNodes(*this);
-        DAG.ReplaceAllUsesOfValueWith(SDValue(N, 1), Chain, &DeadNodes);
+        DAG.ReplaceAllUsesOfValueWith(SDValue(N, 1), Chain);
 
         if (N->use_empty()) {
           removeFromWorkList(N);
@@ -6629,11 +6614,10 @@ SDValue DAGCombiner::visitLOAD(SDNode *N) {
               Undef.getNode()->dump(&DAG);
               dbgs() << " and 2 other values\n");
         WorkListRemover DeadNodes(*this);
-        DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Undef, &DeadNodes);
+        DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Undef);
         DAG.ReplaceAllUsesOfValueWith(SDValue(N, 1),
-                                      DAG.getUNDEF(N->getValueType(1)),
-                                      &DeadNodes);
-        DAG.ReplaceAllUsesOfValueWith(SDValue(N, 2), Chain, &DeadNodes);
+                                      DAG.getUNDEF(N->getValueType(1)));
+        DAG.ReplaceAllUsesOfValueWith(SDValue(N, 2), Chain);
         removeFromWorkList(N);
         DAG.DeleteNode(N);
         return SDValue(N, 0);   // Return N so it doesn't get rechecked!
@@ -6955,8 +6939,7 @@ SDValue DAGCombiner::ReduceLoadOpStoreWidth(SDNode *N) {
       AddToWorkList(NewLD.getNode());
       AddToWorkList(NewVal.getNode());
       WorkListRemover DeadNodes(*this);
-      DAG.ReplaceAllUsesOfValueWith(N0.getValue(1), NewLD.getValue(1),
-                                    &DeadNodes);
+      DAG.ReplaceAllUsesOfValueWith(N0.getValue(1), NewLD.getValue(1));
       ++OpsNarrowed;
       return NewST;
     }
@@ -7013,8 +6996,7 @@ SDValue DAGCombiner::TransformFPLoadStorePair(SDNode *N) {
     AddToWorkList(NewLD.getNode());
     AddToWorkList(NewST.getNode());
     WorkListRemover DeadNodes(*this);
-    DAG.ReplaceAllUsesOfValueWith(Value.getValue(1), NewLD.getValue(1),
-                                  &DeadNodes);
+    DAG.ReplaceAllUsesOfValueWith(Value.getValue(1), NewLD.getValue(1));
     ++LdStFP2Int;
     return NewST;
   }
@@ -7472,7 +7454,7 @@ SDValue DAGCombiner::visitEXTRACT_VECTOR_ELT(SDNode *N) {
     WorkListRemover DeadNodes(*this);
     SDValue From[] = { SDValue(N, 0), SDValue(LN0,1) };
     SDValue To[] = { Load, Chain };
-    DAG.ReplaceAllUsesOfValuesWith(From, To, 2, &DeadNodes);
+    DAG.ReplaceAllUsesOfValuesWith(From, To, 2);
     // Since we're explcitly calling ReplaceAllUses, add the new node to the
     // worklist explicitly as well.
     AddToWorkList(Load.getNode());
diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index a96a997..32973cc 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -150,21 +150,21 @@ public:
   // Node replacement helpers
   void ReplacedNode(SDNode *N) {
     if (N->use_empty()) {
-      DAG.RemoveDeadNode(N, this);
+      DAG.RemoveDeadNode(N);
     } else {
       ForgetNode(N);
     }
   }
   void ReplaceNode(SDNode *Old, SDNode *New) {
-    DAG.ReplaceAllUsesWith(Old, New, this);
+    DAG.ReplaceAllUsesWith(Old, New);
     ReplacedNode(Old);
   }
   void ReplaceNode(SDValue Old, SDValue New) {
-    DAG.ReplaceAllUsesWith(Old, New, this);
+    DAG.ReplaceAllUsesWith(Old, New);
     ReplacedNode(Old.getNode());
   }
   void ReplaceNode(SDNode *Old, const SDValue *New) {
-    DAG.ReplaceAllUsesWith(Old, New, this);
+    DAG.ReplaceAllUsesWith(Old, New);
     ReplacedNode(Old);
   }
 };
@@ -203,7 +203,8 @@ SelectionDAGLegalize::ShuffleWithNarrowerEltType(EVT NVT, EVT VT,  DebugLoc dl,
 }
 
 SelectionDAGLegalize::SelectionDAGLegalize(SelectionDAG &dag)
-  : TM(dag.getTarget()), TLI(dag.getTargetLoweringInfo()),
+  : SelectionDAG::DAGUpdateListener(dag),
+    TM(dag.getTarget()), TLI(dag.getTargetLoweringInfo()),
     DAG(dag) {
 }
 
@@ -851,7 +852,7 @@ void SelectionDAGLegalize::LegalizeOp(SDNode *Node) {
 
     SDNode *NewNode = DAG.UpdateNodeOperands(Node, Ops.data(), Ops.size());
     if (NewNode != Node) {
-      DAG.ReplaceAllUsesWith(Node, NewNode, this);
+      DAG.ReplaceAllUsesWith(Node, NewNode);
       for (unsigned i = 0, e = Node->getNumValues(); i != e; ++i)
         DAG.TransferDbgValues(SDValue(Node, i), SDValue(NewNode, i));
       ReplacedNode(Node);
@@ -873,7 +874,7 @@ void SelectionDAGLegalize::LegalizeOp(SDNode *Node) {
             ResultVals.push_back(Tmp1.getValue(i));
         }
         if (Tmp1.getNode() != Node || Tmp1.getResNo() != 0) {
-          DAG.ReplaceAllUsesWith(Node, ResultVals.data(), this);
+          DAG.ReplaceAllUsesWith(Node, ResultVals.data());
           for (unsigned i = 0, e = Node->getNumValues(); i != e; ++i)
             DAG.TransferDbgValues(SDValue(Node, i), ResultVals[i]);
           ReplacedNode(Node);
diff --git a/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp b/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
index 439aa4d..324ddc9 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
@@ -628,7 +628,8 @@ namespace {
   public:
     explicit NodeUpdateListener(DAGTypeLegalizer &dtl,
                                 SmallSetVector<SDNode*, 16> &nta)
-      : DTL(dtl), NodesToAnalyze(nta) {}
+      : SelectionDAG::DAGUpdateListener(dtl.getDAG()),
+        DTL(dtl), NodesToAnalyze(nta) {}
 
     virtual void NodeDeleted(SDNode *N, SDNode *E) {
       assert(N->getNodeId() != DAGTypeLegalizer::ReadyToProcess &&
@@ -680,7 +681,7 @@ void DAGTypeLegalizer::ReplaceValueWith(SDValue From, SDValue To) {
   SmallSetVector<SDNode*, 16> NodesToAnalyze;
   NodeUpdateListener NUL(*this, NodesToAnalyze);
   do {
-    DAG.ReplaceAllUsesOfValueWith(From, To, &NUL);
+    DAG.ReplaceAllUsesOfValueWith(From, To);
 
     // The old node may still be present in a map like ExpandedIntegers or
     // PromotedIntegers.  Inform maps about the replacement.
@@ -709,7 +710,7 @@ void DAGTypeLegalizer::ReplaceValueWith(SDValue From, SDValue To) {
           SDValue NewVal(M, i);
           if (M->getNodeId() == Processed)
             RemapValue(NewVal);
-          DAG.ReplaceAllUsesOfValueWith(OldVal, NewVal, &NUL);
+          DAG.ReplaceAllUsesOfValueWith(OldVal, NewVal);
           // OldVal may be a target of the ReplacedValues map which was marked
           // NewNode to force reanalysis because it was updated.  Ensure that
           // anything that ReplacedValues mapped to OldVal will now be mapped
diff --git a/lib/CodeGen/SelectionDAG/LegalizeTypes.h b/lib/CodeGen/SelectionDAG/LegalizeTypes.h
index e866445..ca17450 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeTypes.h
+++ b/lib/CodeGen/SelectionDAG/LegalizeTypes.h
@@ -135,6 +135,8 @@ public:
       ReplacedValues[SDValue(Old, i)] = SDValue(New, i);
   }
 
+  SelectionDAG &getDAG() const { return DAG; }
+
 private:
   SDNode *AnalyzeNewNode(SDNode *N);
   void AnalyzeNewValue(SDValue &Val);
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 92671d1..0f2a5df 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -71,7 +71,9 @@ static const fltSemantics *EVTToAPFloatSemantics(EVT VT) {
   }
 }
 
-SelectionDAG::DAGUpdateListener::~DAGUpdateListener() {}
+// Default null implementations of the callbacks.
+void SelectionDAG::DAGUpdateListener::NodeDeleted(SDNode*, SDNode*) {}
+void SelectionDAG::DAGUpdateListener::NodeUpdated(SDNode*) {}
 
 //===----------------------------------------------------------------------===//
 //                              ConstantFPSDNode Class
@@ -544,16 +546,15 @@ void SelectionDAG::RemoveDeadNodes() {
 
 /// RemoveDeadNodes - This method deletes the unreachable nodes in the
 /// given list, and any nodes that become unreachable as a result.
-void SelectionDAG::RemoveDeadNodes(SmallVectorImpl<SDNode *> &DeadNodes,
-                                   DAGUpdateListener *UpdateListener) {
+void SelectionDAG::RemoveDeadNodes(SmallVectorImpl<SDNode *> &DeadNodes) {
 
   // Process the worklist, deleting the nodes and adding their uses to the
   // worklist.
   while (!DeadNodes.empty()) {
     SDNode *N = DeadNodes.pop_back_val();
 
-    if (UpdateListener)
-      UpdateListener->NodeDeleted(N, 0);
+    for (DAGUpdateListener *DUL = UpdateListeners; DUL; DUL = DUL->Next)
+      DUL->NodeDeleted(N, 0);
 
     // Take the node out of the appropriate CSE map.
     RemoveNodeFromCSEMaps(N);
@@ -574,7 +575,7 @@ void SelectionDAG::RemoveDeadNodes(SmallVectorImpl<SDNode *> &DeadNodes,
   }
 }
 
-void SelectionDAG::RemoveDeadNode(SDNode *N, DAGUpdateListener *UpdateListener){
+void SelectionDAG::RemoveDeadNode(SDNode *N){
   SmallVector<SDNode*, 16> DeadNodes(1, N);
 
   // Create a dummy node that adds a reference to the root node, preventing
@@ -582,7 +583,7 @@ void SelectionDAG::RemoveDeadNode(SDNode *N, DAGUpdateListener *UpdateListener){
   // dead node.)
   HandleSDNode Dummy(getRoot());
 
-  RemoveDeadNodes(DeadNodes, UpdateListener);
+  RemoveDeadNodes(DeadNodes);
 }
 
 void SelectionDAG::DeleteNode(SDNode *N) {
@@ -684,8 +685,7 @@ bool SelectionDAG::RemoveNodeFromCSEMaps(SDNode *N) {
 /// node. This transfer can potentially trigger recursive merging.
 ///
 void
-SelectionDAG::AddModifiedNodeToCSEMaps(SDNode *N,
-                                       DAGUpdateListener *UpdateListener) {
+SelectionDAG::AddModifiedNodeToCSEMaps(SDNode *N) {
   // For node types that aren't CSE'd, just act as if no identical node
   // already exists.
   if (!doNotCSE(N)) {
@@ -694,20 +694,19 @@ SelectionDAG::AddModifiedNodeToCSEMaps(SDNode *N,
       // If there was already an existing matching node, use ReplaceAllUsesWith
       // to replace the dead one with the existing one.  This can cause
       // recursive merging of other unrelated nodes down the line.
-      ReplaceAllUsesWith(N, Existing, UpdateListener);
+      ReplaceAllUsesWith(N, Existing);
 
-      // N is now dead.  Inform the listener if it exists and delete it.
-      if (UpdateListener)
-        UpdateListener->NodeDeleted(N, Existing);
+      // N is now dead. Inform the listeners and delete it.
+      for (DAGUpdateListener *DUL = UpdateListeners; DUL; DUL = DUL->Next)
+        DUL->NodeDeleted(N, Existing);
       DeleteNodeNotInCSEMaps(N);
       return;
     }
   }
 
-  // If the node doesn't already exist, we updated it.  Inform a listener if
-  // it exists.
-  if (UpdateListener)
-    UpdateListener->NodeUpdated(N);
+  // If the node doesn't already exist, we updated it.  Inform listeners.
+  for (DAGUpdateListener *DUL = UpdateListeners; DUL; DUL = DUL->Next)
+    DUL->NodeUpdated(N);
 }
 
 /// FindModifiedNodeSlot - Find a slot for the specified node if its operands
@@ -855,7 +854,7 @@ unsigned SelectionDAG::getEVTAlignment(EVT VT) const {
 SelectionDAG::SelectionDAG(const TargetMachine &tm, CodeGenOpt::Level OL)
   : TM(tm), TLI(*tm.getTargetLowering()), TSI(*tm.getSelectionDAGInfo()),
     OptLevel(OL), EntryNode(ISD::EntryToken, DebugLoc(), getVTList(MVT::Other)),
-    Root(getEntryNode()), Ordering(0) {
+    Root(getEntryNode()), Ordering(0), UpdateListeners(0) {
   AllNodes.push_back(&EntryNode);
   Ordering = new SDNodeOrdering();
   DbgInfo = new SDDbgInfo();
@@ -867,6 +866,7 @@ void SelectionDAG::init(MachineFunction &mf) {
 }
 
 SelectionDAG::~SelectionDAG() {
+  assert(!UpdateListeners && "Dangling registered DAGUpdateListeners");
   allnodes_clear();
   delete Ordering;
   delete DbgInfo;
@@ -5237,11 +5237,7 @@ namespace {
 /// pointed to by a use iterator is deleted, increment the use iterator
 /// so that it doesn't dangle.
 ///
-/// This class also manages a "downlink" DAGUpdateListener, to forward
-/// messages to ReplaceAllUsesWith's callers.
-///
 class RAUWUpdateListener : public SelectionDAG::DAGUpdateListener {
-  SelectionDAG::DAGUpdateListener *DownLink;
   SDNode::use_iterator &UI;
   SDNode::use_iterator &UE;
 
@@ -5249,21 +5245,13 @@ class RAUWUpdateListener : public SelectionDAG::DAGUpdateListener {
     // Increment the iterator as needed.
     while (UI != UE && N == *UI)
       ++UI;
-
-    // Then forward the message.
-    if (DownLink) DownLink->NodeDeleted(N, E);
-  }
-
-  virtual void NodeUpdated(SDNode *N) {
-    // Just forward the message.
-    if (DownLink) DownLink->NodeUpdated(N);
   }
 
 public:
-  RAUWUpdateListener(SelectionDAG::DAGUpdateListener *dl,
+  RAUWUpdateListener(SelectionDAG &d,
                      SDNode::use_iterator &ui,
                      SDNode::use_iterator &ue)
-    : DownLink(dl), UI(ui), UE(ue) {}
+    : SelectionDAG::DAGUpdateListener(d), UI(ui), UE(ue) {}
 };
 
 }
@@ -5273,8 +5261,7 @@ public:
 ///
 /// This version assumes From has a single result value.
 ///
-void SelectionDAG::ReplaceAllUsesWith(SDValue FromN, SDValue To,
-                                      DAGUpdateListener *UpdateListener) {
+void SelectionDAG::ReplaceAllUsesWith(SDValue FromN, SDValue To) {
   SDNode *From = FromN.getNode();
   assert(From->getNumValues() == 1 && FromN.getResNo() == 0 &&
          "Cannot replace with this method!");
@@ -5288,7 +5275,7 @@ void SelectionDAG::ReplaceAllUsesWith(SDValue FromN, SDValue To,
   // is replaced by To, we don't want to replace of all its users with To
   // too. See PR3018 for more info.
   SDNode::use_iterator UI = From->use_begin(), UE = From->use_end();
-  RAUWUpdateListener Listener(UpdateListener, UI, UE);
+  RAUWUpdateListener Listener(*this, UI, UE);
   while (UI != UE) {
     SDNode *User = *UI;
 
@@ -5307,7 +5294,7 @@ void SelectionDAG::ReplaceAllUsesWith(SDValue FromN, SDValue To,
 
     // Now that we have modified User, add it back to the CSE maps.  If it
     // already exists there, recursively merge the results together.
-    AddModifiedNodeToCSEMaps(User, &Listener);
+    AddModifiedNodeToCSEMaps(User);
   }
 
   // If we just RAUW'd the root, take note.
@@ -5321,8 +5308,7 @@ void SelectionDAG::ReplaceAllUsesWith(SDValue FromN, SDValue To,
 /// This version assumes that for each value of From, there is a
 /// corresponding value in To in the same position with the same type.
 ///
-void SelectionDAG::ReplaceAllUsesWith(SDNode *From, SDNode *To,
-                                      DAGUpdateListener *UpdateListener) {
+void SelectionDAG::ReplaceAllUsesWith(SDNode *From, SDNode *To) {
 #ifndef NDEBUG
   for (unsigned i = 0, e = From->getNumValues(); i != e; ++i)
     assert((!From->hasAnyUseOfValue(i) ||
@@ -5337,7 +5323,7 @@ void SelectionDAG::ReplaceAllUsesWith(SDNode *From, SDNode *To,
   // Iterate over just the existing users of From. See the comments in
   // the ReplaceAllUsesWith above.
   SDNode::use_iterator UI = From->use_begin(), UE = From->use_end();
-  RAUWUpdateListener Listener(UpdateListener, UI, UE);
+  RAUWUpdateListener Listener(*this, UI, UE);
   while (UI != UE) {
     SDNode *User = *UI;
 
@@ -5356,7 +5342,7 @@ void SelectionDAG::ReplaceAllUsesWith(SDNode *From, SDNode *To,
 
     // Now that we have modified User, add it back to the CSE maps.  If it
     // already exists there, recursively merge the results together.
-    AddModifiedNodeToCSEMaps(User, &Listener);
+    AddModifiedNodeToCSEMaps(User);
   }
 
   // If we just RAUW'd the root, take note.
@@ -5369,16 +5355,14 @@ void SelectionDAG::ReplaceAllUsesWith(SDNode *From, SDNode *To,
 ///
 /// This version can replace From with any result values.  To must match the
 /// number and types of values returned by From.
-void SelectionDAG::ReplaceAllUsesWith(SDNode *From,
-                                      const SDValue *To,
-                                      DAGUpdateListener *UpdateListener) {
+void SelectionDAG::ReplaceAllUsesWith(SDNode *From, const SDValue *To) {
   if (From->getNumValues() == 1)  // Handle the simple case efficiently.
-    return ReplaceAllUsesWith(SDValue(From, 0), To[0], UpdateListener);
+    return ReplaceAllUsesWith(SDValue(From, 0), To[0]);
 
   // Iterate over just the existing users of From. See the comments in
   // the ReplaceAllUsesWith above.
   SDNode::use_iterator UI = From->use_begin(), UE = From->use_end();
-  RAUWUpdateListener Listener(UpdateListener, UI, UE);
+  RAUWUpdateListener Listener(*this, UI, UE);
   while (UI != UE) {
     SDNode *User = *UI;
 
@@ -5398,7 +5382,7 @@ void SelectionDAG::ReplaceAllUsesWith(SDNode *From,
 
     // Now that we have modified User, add it back to the CSE maps.  If it
     // already exists there, recursively merge the results together.
-    AddModifiedNodeToCSEMaps(User, &Listener);
+    AddModifiedNodeToCSEMaps(User);
   }
 
   // If we just RAUW'd the root, take note.
@@ -5409,14 +5393,13 @@ void SelectionDAG::ReplaceAllUsesWith(SDNode *From,
 /// ReplaceAllUsesOfValueWith - Replace any uses of From with To, leaving
 /// uses of other values produced by From.getNode() alone.  The Deleted
 /// vector is handled the same way as for ReplaceAllUsesWith.
-void SelectionDAG::ReplaceAllUsesOfValueWith(SDValue From, SDValue To,
-                                             DAGUpdateListener *UpdateListener){
+void SelectionDAG::ReplaceAllUsesOfValueWith(SDValue From, SDValue To){
   // Handle the really simple, really trivial case efficiently.
   if (From == To) return;
 
   // Handle the simple, trivial, case efficiently.
   if (From.getNode()->getNumValues() == 1) {
-    ReplaceAllUsesWith(From, To, UpdateListener);
+    ReplaceAllUsesWith(From, To);
     return;
   }
 
@@ -5424,7 +5407,7 @@ void SelectionDAG::ReplaceAllUsesOfValueWith(SDValue From, SDValue To,
   // the ReplaceAllUsesWith above.
   SDNode::use_iterator UI = From.getNode()->use_begin(),
                        UE = From.getNode()->use_end();
-  RAUWUpdateListener Listener(UpdateListener, UI, UE);
+  RAUWUpdateListener Listener(*this, UI, UE);
   while (UI != UE) {
     SDNode *User = *UI;
     bool UserRemovedFromCSEMaps = false;
@@ -5460,7 +5443,7 @@ void SelectionDAG::ReplaceAllUsesOfValueWith(SDValue From, SDValue To,
 
     // Now that we have modified User, add it back to the CSE maps.  If it
     // already exists there, recursively merge the results together.
-    AddModifiedNodeToCSEMaps(User, &Listener);
+    AddModifiedNodeToCSEMaps(User);
   }
 
   // If we just RAUW'd the root, take note.
@@ -5489,11 +5472,10 @@ namespace {
 /// handled the same way as for ReplaceAllUsesWith.
 void SelectionDAG::ReplaceAllUsesOfValuesWith(const SDValue *From,
                                               const SDValue *To,
-                                              unsigned Num,
-                                              DAGUpdateListener *UpdateListener){
+                                              unsigned Num){
   // Handle the simple, trivial case efficiently.
   if (Num == 1)
-    return ReplaceAllUsesOfValueWith(*From, *To, UpdateListener);
+    return ReplaceAllUsesOfValueWith(*From, *To);
 
   // Read up all the uses and make records of them. This helps
   // processing new uses that are introduced during the
@@ -5538,7 +5520,7 @@ void SelectionDAG::ReplaceAllUsesOfValuesWith(const SDValue *From,
 
     // Now that we have modified User, add it back to the CSE maps.  If it
     // already exists there, recursively merge the results together.
-    AddModifiedNodeToCSEMaps(User, UpdateListener);
+    AddModifiedNodeToCSEMaps(User);
   }
 }
 
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 605509b..aa2b843 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -749,8 +749,8 @@ void SelectionDAGISel::DoInstructionSelection() {
       // If after the replacement this node is not used any more,
       // remove this dead node.
       if (Node->use_empty()) { // Don't delete EntryToken, etc.
-        ISelUpdater ISU(ISelPosition);
-        CurDAG->RemoveDeadNode(Node, &ISU);
+        ISelUpdater ISU(*CurDAG, ISelPosition);
+        CurDAG->RemoveDeadNode(Node);
       }
     }
 
@@ -1680,7 +1680,7 @@ UpdateChainsAndGlue(SDNode *NodeToMatch, SDValue InputChain,
                     bool isMorphNodeTo) {
   SmallVector<SDNode*, 4> NowDeadNodes;
 
-  ISelUpdater ISU(ISelPosition);
+  ISelUpdater ISU(*CurDAG, ISelPosition);
 
   // Now that all the normal results are replaced, we replace the chain and
   // glue results if present.
@@ -1705,7 +1705,7 @@ UpdateChainsAndGlue(SDNode *NodeToMatch, SDValue InputChain,
       if (ChainVal.getValueType() == MVT::Glue)
         ChainVal = ChainVal.getValue(ChainVal->getNumValues()-2);
       assert(ChainVal.getValueType() == MVT::Other && "Not a chain?");
-      CurDAG->ReplaceAllUsesOfValueWith(ChainVal, InputChain, &ISU);
+      CurDAG->ReplaceAllUsesOfValueWith(ChainVal, InputChain);
 
       // If the node became dead and we haven't already seen it, delete it.
       if (ChainNode->use_empty() &&
@@ -1728,7 +1728,7 @@ UpdateChainsAndGlue(SDNode *NodeToMatch, SDValue InputChain,
       assert(FRN->getValueType(FRN->getNumValues()-1) == MVT::Glue &&
              "Doesn't have a glue result");
       CurDAG->ReplaceAllUsesOfValueWith(SDValue(FRN, FRN->getNumValues()-1),
-                                        InputGlue, &ISU);
+                                        InputGlue);
 
       // If the node became dead and we haven't already seen it, delete it.
       if (FRN->use_empty() &&
@@ -1738,7 +1738,7 @@ UpdateChainsAndGlue(SDNode *NodeToMatch, SDValue InputChain,
   }
 
   if (!NowDeadNodes.empty())
-    CurDAG->RemoveDeadNodes(NowDeadNodes, &ISU);
+    CurDAG->RemoveDeadNodes(NowDeadNodes);
 
   DEBUG(errs() << "ISEL: Match complete!\n");
 }