Index: lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -1153,8 +1153,10 @@
     }
     switch (Action) {
     case TargetLowering::Legal:
+      DEBUG(dbgs() << "Legal node: nothing to do\n");
       return;
     case TargetLowering::Custom: {
+      DEBUG(dbgs() << "Trying custom legalization\n");
       // FIXME: The handling for custom lowering with multiple results is
       // a complete mess.
       if (SDValue Res = TLI.LowerOperation(SDValue(Node, 0), DAG)) {
@@ -1162,6 +1164,7 @@
           return;
 
         if (Node->getNumValues() == 1) {
+          DEBUG(dbgs() << "Successfully custom legalized node\n");
           // We can just directly replace this node with the lowered value.
           ReplaceNode(SDValue(Node, 0), Res);
           return;
@@ -1170,9 +1173,11 @@
         SmallVector<SDValue, 8> ResultVals;
         for (unsigned i = 0, e = Node->getNumValues(); i != e; ++i)
           ResultVals.push_back(Res.getValue(i));
+        DEBUG(dbgs() << "Successfully custom legalized node\n");
         ReplaceNode(Node, ResultVals.data());
         return;
       }
+      DEBUG(dbgs() << "Could not custom legalize node\n");
       LLVM_FALLTHROUGH;
     }
     case TargetLowering::Expand:
@@ -1998,10 +2003,19 @@
 
   std::pair<SDValue, SDValue> CallInfo = TLI.LowerCallTo(CLI);
 
-  if (!CallInfo.second.getNode())
+  if (!CallInfo.second.getNode()) {
+    DEBUG(
+      dbgs() << "Created tailcall: ";
+      DAG.getRoot().dump();
+    );
     // It's a tailcall, return the chain (which is the DAG root).
     return DAG.getRoot();
+  }
 
+  DEBUG(
+    dbgs() << "Created libcall: ";
+    CallInfo.first.dump();
+  );
   return CallInfo.first;
 }
 
@@ -2801,6 +2815,7 @@
 }
 
 bool SelectionDAGLegalize::ExpandNode(SDNode *Node) {
+  DEBUG(dbgs() << "Trying to expand node\n");
   SmallVector<SDValue, 8> Results;
   SDLoc dl(Node);
   SDValue Tmp1, Tmp2, Tmp3, Tmp4;
@@ -3870,14 +3885,18 @@
   }
 
   // Replace the original node with the legalized result.
-  if (Results.empty())
+  if (Results.empty()) {
+    DEBUG(dbgs() << "Cannot expand node\n");
     return false;
+  }
 
+  DEBUG(dbgs() << "Succesfully expanded node\n");
   ReplaceNode(Node, Results.data());
   return true;
 }
 
 void SelectionDAGLegalize::ConvertNodeToLibcall(SDNode *Node) {
+  DEBUG(dbgs() << "Trying to create a libcall\n");
   SmallVector<SDValue, 8> Results;
   SDLoc dl(Node);
   SDValue Tmp1, Tmp2, Tmp3, Tmp4;
@@ -4132,8 +4151,11 @@
   }
 
   // Replace the original node with the legalized result.
-  if (!Results.empty())
+  if (!Results.empty()) {
+    DEBUG(dbgs() << "Successfully created libcall\n");
     ReplaceNode(Node, Results.data());
+  } else
+    DEBUG(dbgs() << "Could not create libcall\n");
 }
 
 // Determine the vector type to use in place of an original scalar element when
@@ -4147,6 +4169,7 @@
 }
 
 void SelectionDAGLegalize::PromoteNode(SDNode *Node) {
+  DEBUG(dbgs() << "Trying to promote node\n");
   SmallVector<SDValue, 8> Results;
   MVT OVT = Node->getSimpleValueType(0);
   if (Node->getOpcode() == ISD::UINT_TO_FP ||
@@ -4585,8 +4608,11 @@
   }
 
   // Replace the original node with the legalized result.
-  if (!Results.empty())
+  if (!Results.empty()) {
+    DEBUG(dbgs() << "Successfully promoted node\n");
     ReplaceNode(Node, Results.data());
+  } else
+    DEBUG(dbgs() << "Could not promote node\n");
 }
 
 /// This is the entry point for the file.