[llvm] r269235 - SDAG: Have SelectNodeTo replace uses if it CSE's instead of morphing a node

[Justin Bogner via llvm-commits]

Author: bogner
Date: Wed May 11 16:00:33 2016
New Revision: 269235

URL: http://llvm.org/viewvc/llvm-project?rev=269235&view=rev
Log:
SDAG: Have SelectNodeTo replace uses if it CSE's instead of morphing a node

It's awkward to force callers of SelectNodeTo to figure out whether
the node was morphed or CSE'd. Update uses here instead of requiring
callers to (sometimes) do it.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
    llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp?rev=269235&r1=269234&r2=269235&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp Wed May 11 16:00:33 2016
@@ -5942,10 +5942,14 @@ SDNode *SelectionDAG::SelectNodeTo(SDNod
 
 SDNode *SelectionDAG::SelectNodeTo(SDNode *N, unsigned MachineOpc,
                                    SDVTList VTs,ArrayRef<SDValue> Ops) {
-  N = MorphNodeTo(N, ~MachineOpc, VTs, Ops);
+  SDNode *New = MorphNodeTo(N, ~MachineOpc, VTs, Ops);
   // Reset the NodeID to -1.
-  N->setNodeId(-1);
-  return N;
+  New->setNodeId(-1);
+  if (New != N) {
+    ReplaceAllUsesWith(N, New);
+    RemoveDeadNode(N);
+  }
+  return New;
 }
 
 /// UpdadeSDLocOnMergedSDNode - If the opt level is -O0 then it throws away

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp?rev=269235&r1=269234&r2=269235&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp Wed May 11 16:00:33 2016
@@ -2127,12 +2127,7 @@ void SelectionDAGISel::Select_WRITE_REGI
 }
 
 void SelectionDAGISel::Select_UNDEF(SDNode *N) {
-  SDNode *New =
-      CurDAG->SelectNodeTo(N, TargetOpcode::IMPLICIT_DEF, N->getValueType(0));
-  if (New != N) {
-    ReplaceUses(N, New);
-    CurDAG->RemoveDeadNode(N);
-  }
+  CurDAG->SelectNodeTo(N, TargetOpcode::IMPLICIT_DEF, N->getValueType(0));
 }
 
 /// GetVBR - decode a vbr encoding whose top bit is set.