[llvm] r353338 - [DAG] Immediately cleanup unused nodes from extend-based combines.

[Nirav Dave via llvm-commits]

Author: niravd
Date: Wed Feb  6 12:12:03 2019
New Revision: 353338

URL: http://llvm.org/viewvc/llvm-project?rev=353338&view=rev
Log:
[DAG] Immediately cleanup unused nodes from extend-based combines.

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

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=353338&r1=353337&r2=353338&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Wed Feb  6 12:12:03 2019
@@ -8543,19 +8543,21 @@ static SDValue tryToFoldExtOfExtload(Sel
                                                    : ISD::isZEXTLoad(N0Node);
   if ((!isAExtLoad && !ISD::isEXTLoad(N0Node)) ||
       !ISD::isUNINDEXEDLoad(N0Node) || !N0.hasOneUse())
-    return {};
+    return SDValue();
 
   LoadSDNode *LN0 = cast<LoadSDNode>(N0);
   EVT MemVT = LN0->getMemoryVT();
   if ((LegalOperations || LN0->isVolatile() || VT.isVector()) &&
       !TLI.isLoadExtLegal(ExtLoadType, VT, MemVT))
-    return {};
+    return SDValue();
 
   SDValue ExtLoad =
       DAG.getExtLoad(ExtLoadType, SDLoc(LN0), VT, LN0->getChain(),
                      LN0->getBasePtr(), MemVT, LN0->getMemOperand());
   Combiner.CombineTo(N, ExtLoad);
   DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
+  if (LN0->use_empty())
+    Combiner.recursivelyDeleteUnusedNodes(LN0);
   return SDValue(N, 0); // Return N so it doesn't get rechecked!
 }
 
@@ -8593,6 +8595,7 @@ static SDValue tryToFoldExtOfLoad(Select
   Combiner.CombineTo(N, ExtLoad);
   if (NoReplaceTrunc) {
     DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
+    Combiner.recursivelyDeleteUnusedNodes(LN0);
   } else {
     SDValue Trunc =
         DAG.getNode(ISD::TRUNCATE, SDLoc(N0), N0.getValueType(), ExtLoad);
@@ -9196,6 +9199,7 @@ SDValue DAGCombiner::visitANY_EXTEND(SDN
       CombineTo(N, ExtLoad);
       if (NoReplaceTrunc) {
         DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
+        recursivelyDeleteUnusedNodes(LN0);
       } else {
         SDValue Trunc = DAG.getNode(ISD::TRUNCATE, SDLoc(N0),
                                     N0.getValueType(), ExtLoad);
@@ -9219,6 +9223,7 @@ SDValue DAGCombiner::visitANY_EXTEND(SDN
                                        MemVT, LN0->getMemOperand());
       CombineTo(N, ExtLoad);
       DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
+      recursivelyDeleteUnusedNodes(LN0);
       return SDValue(N, 0);   // Return N so it doesn't get rechecked!
     }
   }