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

1 files changed, 46 insertions, 29 deletions

diff --git a/include/llvm/CodeGen/SelectionDAG.h b/include/llvm/CodeGen/SelectionDAG.h
index 6a7a87e866..a5a912ac33 100644
--- a/include/llvm/CodeGen/SelectionDAG.h
+++ b/include/llvm/CodeGen/SelectionDAG.h
@@ -177,6 +177,44 @@ class SelectionDAG {
   /// DbgInfo - Tracks dbg_value information through SDISel.
   SDDbgInfo *DbgInfo;
 
+public:
+  /// DAGUpdateListener - Clients of various APIs that cause global effects on
+  /// the DAG can optionally implement this interface.  This allows the clients
+  /// to handle the various sorts of updates that happen.
+  ///
+  /// A DAGUpdateListener automatically registers itself with DAG when it is
+  /// constructed, and removes itself when destroyed in RAII fashion.
+  struct DAGUpdateListener {
+    DAGUpdateListener *const Next;
+    SelectionDAG &DAG;
+
+    explicit DAGUpdateListener(SelectionDAG &D)
+      : Next(D.UpdateListeners), DAG(D) {
+      DAG.UpdateListeners = this;
+    }
+
+    virtual ~DAGUpdateListener() {
+      assert(DAG.UpdateListeners == this &&
+             "DAGUpdateListeners must be destroyed in LIFO order");
+      DAG.UpdateListeners = Next;
+    }
+
+    /// NodeDeleted - The node N that was deleted and, if E is not null, an
+    /// equivalent node E that replaced it.
+    virtual void NodeDeleted(SDNode *N, SDNode *E);
+
+    /// NodeUpdated - The node N that was updated.
+    virtual void NodeUpdated(SDNode *N);
+  };
+
+private:
+  /// DAGUpdateListener is a friend so it can manipulate the listener stack.
+  friend struct DAGUpdateListener;
+
+  /// UpdateListeners - Linked list of registered DAGUpdateListener instances.
+  /// This stack is maintained by DAGUpdateListener RAII.
+  DAGUpdateListener *UpdateListeners;
+
   /// setGraphColorHelper - Implementation of setSubgraphColor.
   /// Return whether we had to truncate the search.
   ///
@@ -817,30 +855,14 @@ public:
   SDDbgValue *getDbgValue(MDNode *MDPtr, unsigned FI, uint64_t Off,
                           DebugLoc DL, unsigned O);
 
-  /// DAGUpdateListener - Clients of various APIs that cause global effects on
-  /// the DAG can optionally implement this interface.  This allows the clients
-  /// to handle the various sorts of updates that happen.
-  class DAGUpdateListener {
-  public:
-    virtual ~DAGUpdateListener();
-
-    /// NodeDeleted - The node N that was deleted and, if E is not null, an
-    /// equivalent node E that replaced it.
-    virtual void NodeDeleted(SDNode *N, SDNode *E) = 0;
-
-    /// NodeUpdated - The node N that was updated.
-    virtual void NodeUpdated(SDNode *N) = 0;
-  };
-
   /// RemoveDeadNode - Remove the specified node from the system. If any of its
   /// operands then becomes dead, remove them as well. Inform UpdateListener
   /// for each node deleted.
-  void RemoveDeadNode(SDNode *N, DAGUpdateListener *UpdateListener = 0);
+  void RemoveDeadNode(SDNode *N);
 
   /// RemoveDeadNodes - This method deletes the unreachable nodes in the
   /// given list, and any nodes that become unreachable as a result.
-  void RemoveDeadNodes(SmallVectorImpl<SDNode *> &DeadNodes,
-                       DAGUpdateListener *UpdateListener = 0);
+  void RemoveDeadNodes(SmallVectorImpl<SDNode *> &DeadNodes);
 
   /// ReplaceAllUsesWith - Modify anything using 'From' to use 'To' instead.
   /// This can cause recursive merging of nodes in the DAG.  Use the first
@@ -857,24 +879,19 @@ public:
   /// to be given new uses. These new uses of From are left in place, and
   /// not automatically transferred to To.
   ///
-  void ReplaceAllUsesWith(SDValue From, SDValue Op,
-                          DAGUpdateListener *UpdateListener = 0);
-  void ReplaceAllUsesWith(SDNode *From, SDNode *To,
-                          DAGUpdateListener *UpdateListener = 0);
-  void ReplaceAllUsesWith(SDNode *From, const SDValue *To,
-                          DAGUpdateListener *UpdateListener = 0);
+  void ReplaceAllUsesWith(SDValue From, SDValue Op);
+  void ReplaceAllUsesWith(SDNode *From, SDNode *To);
+  void ReplaceAllUsesWith(SDNode *From, const SDValue *To);
 
   /// ReplaceAllUsesOfValueWith - Replace any uses of From with To, leaving
   /// uses of other values produced by From.Val alone.
-  void ReplaceAllUsesOfValueWith(SDValue From, SDValue To,
-                                 DAGUpdateListener *UpdateListener = 0);
+  void ReplaceAllUsesOfValueWith(SDValue From, SDValue To);
 
   /// ReplaceAllUsesOfValuesWith - Like ReplaceAllUsesOfValueWith, but
   /// for multiple values at once. This correctly handles the case where
   /// there is an overlap between the From values and the To values.
   void ReplaceAllUsesOfValuesWith(const SDValue *From, const SDValue *To,
-                                  unsigned Num,
-                                  DAGUpdateListener *UpdateListener = 0);
+                                  unsigned Num);
 
   /// AssignTopologicalOrder - Topological-sort the AllNodes list and a
   /// assign a unique node id for each node in the DAG based on their
@@ -1031,7 +1048,7 @@ public:
 
 private:
   bool RemoveNodeFromCSEMaps(SDNode *N);
-  void AddModifiedNodeToCSEMaps(SDNode *N, DAGUpdateListener *UpdateListener);
+  void AddModifiedNodeToCSEMaps(SDNode *N);
   SDNode *FindModifiedNodeSlot(SDNode *N, SDValue Op, void *&InsertPos);
   SDNode *FindModifiedNodeSlot(SDNode *N, SDValue Op1, SDValue Op2,
                                void *&InsertPos);