[SDAG] Fix CombineTo ordering in visitZERO_EXTEND and visitSIGN_EXTEND

Reorder CombineTo Calls to prevent references to stale/deleted SDNodes which caused undue assertions.

Reviewers: dbabokin

Subscribers: aemerson, rengolin, llvm-commits

Differential Revision: https://reviews.llvm.org/D31625

llvm-svn: 304460

1 files changed, 8 insertions, 15 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index b1df262a184..fb51a4eb142 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -7227,12 +7227,11 @@ SDValue DAGCombiner::visitSIGN_EXTEND(SDNode *N) {
       SDValue ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, DL, VT, LN0->getChain(),
                                        LN0->getBasePtr(), N0.getValueType(),
                                        LN0->getMemOperand());
-      CombineTo(N, ExtLoad);
       SDValue Trunc = DAG.getNode(ISD::TRUNCATE, SDLoc(N0),
                                   N0.getValueType(), ExtLoad);
-      CombineTo(N0.getNode(), Trunc, ExtLoad.getValue(1));
       ExtendSetCCUses(SetCCs, Trunc, ExtLoad, DL, ISD::SIGN_EXTEND);
-      return SDValue(N, 0);   // Return N so it doesn't get rechecked!
+      CombineTo(N0.getNode(), Trunc, ExtLoad.getValue(1));
+      return CombineTo(N, ExtLoad); // Return N so it doesn't get rechecked!
     }
   }
 
@@ -7288,10 +7287,9 @@ SDValue DAGCombiner::visitSIGN_EXTEND(SDNode *N) {
         SDValue Trunc = DAG.getNode(ISD::TRUNCATE,
                                     SDLoc(N0.getOperand(0)),
                                     N0.getOperand(0).getValueType(), ExtLoad);
-        CombineTo(N, And);
-        CombineTo(N0.getOperand(0).getNode(), Trunc, ExtLoad.getValue(1));
         ExtendSetCCUses(SetCCs, Trunc, ExtLoad, DL, ISD::SIGN_EXTEND);
-        return SDValue(N, 0);   // Return N so it doesn't get rechecked!
+        CombineTo(N0.getOperand(0).getNode(), Trunc, ExtLoad.getValue(1));
+        return CombineTo(N, And); // Return N so it doesn't get rechecked!
       }
     }
   }
@@ -7530,12 +7528,9 @@ SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {
 
       SDValue Trunc = DAG.getNode(ISD::TRUNCATE, SDLoc(N0),
                                   N0.getValueType(), ExtLoad);
+      ExtendSetCCUses(SetCCs, Trunc, ExtLoad, SDLoc(N), ISD::ZERO_EXTEND);
       CombineTo(N0.getNode(), Trunc, ExtLoad.getValue(1));
-
-      ExtendSetCCUses(SetCCs, Trunc, ExtLoad, SDLoc(N),
-                      ISD::ZERO_EXTEND);
-      CombineTo(N, ExtLoad);
-      return SDValue(N, 0);   // Return N so it doesn't get rechecked!
+      return CombineTo(N, ExtLoad); // Return N so it doesn't get rechecked!
     }
   }
 
@@ -7585,11 +7580,9 @@ SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {
         SDValue Trunc = DAG.getNode(ISD::TRUNCATE,
                                     SDLoc(N0.getOperand(0)),
                                     N0.getOperand(0).getValueType(), ExtLoad);
-        CombineTo(N, And);
+        ExtendSetCCUses(SetCCs, Trunc, ExtLoad, DL, ISD::ZERO_EXTEND);
         CombineTo(N0.getOperand(0).getNode(), Trunc, ExtLoad.getValue(1));
-        ExtendSetCCUses(SetCCs, Trunc, ExtLoad, DL,
-                        ISD::ZERO_EXTEND);
-        return SDValue(N, 0);   // Return N so it doesn't get rechecked!
+        return CombineTo(N, And); // Return N so it doesn't get rechecked!
       }
     }
   }