[SDAG] MorphNodeTo recursively deletes dead operands of the old

fromulation of the node, which isn't really the desired behavior from
within the combiner or legalizer, but is necessary within ISel. I've
added a hopefully helpful comment and fixed the only two places where
this took place.

Yet another step toward the combiner and legalizer not needing to use
update listeners with virtual calls to manage the worklists behind
legalization and combining.

llvm-svn: 214574

2 files changed, 9 insertions, 9 deletions

diff --git a/llvm/lib/Target/Mips/MipsSEISelLowering.cpp b/llvm/lib/Target/Mips/MipsSEISelLowering.cpp
index 16b414e8856..515b8ac87c6 100644
--- a/llvm/lib/Target/Mips/MipsSEISelLowering.cpp
+++ b/llvm/lib/Target/Mips/MipsSEISelLowering.cpp
@@ -578,10 +578,9 @@ static SDValue performANDCombine(SDNode *N, SelectionDAG &DAG,
     if ((Op0Opcode == MipsISD::VEXTRACT_ZEXT_ELT && Log2 >= ExtendTySize) ||
         Log2 == ExtendTySize) {
       SDValue Ops[] = { Op0->getOperand(0), Op0->getOperand(1), Op0Op2 };
-      DAG.MorphNodeTo(Op0.getNode(), MipsISD::VEXTRACT_ZEXT_ELT,
-                      Op0->getVTList(),
-                      makeArrayRef(Ops, Op0->getNumOperands()));
-      return Op0;
+      return DAG.getNode(MipsISD::VEXTRACT_ZEXT_ELT, SDLoc(Op0),
+                         Op0->getVTList(),
+                         makeArrayRef(Ops, Op0->getNumOperands()));
     }
   }
 
@@ -923,10 +922,9 @@ static SDValue performSRACombine(SDNode *N, SelectionDAG &DAG,
            TotalBits <= 32)) {
         SDValue Ops[] = { Op0Op0->getOperand(0), Op0Op0->getOperand(1),
                           Op0Op0->getOperand(2) };
-        DAG.MorphNodeTo(Op0Op0.getNode(), MipsISD::VEXTRACT_SEXT_ELT,
-                        Op0Op0->getVTList(),
-                        makeArrayRef(Ops, Op0Op0->getNumOperands()));
-        return Op0Op0;
+        return DAG.getNode(MipsISD::VEXTRACT_SEXT_ELT, SDLoc(Op0Op0),
+                           Op0Op0->getVTList(),
+                           makeArrayRef(Ops, Op0Op0->getNumOperands()));
       }
     }
   }
diff --git a/llvm/lib/Target/R600/SIISelLowering.cpp b/llvm/lib/Target/R600/SIISelLowering.cpp
index dc26a82e19d..36afe5792a3 100644
--- a/llvm/lib/Target/R600/SIISelLowering.cpp
+++ b/llvm/lib/Target/R600/SIISelLowering.cpp
@@ -774,7 +774,9 @@ SDValue SITargetLowering::LowerBRCOND(SDValue BRCOND,
       BR->getOperand(0),
       BRCOND.getOperand(2)
     };
-    DAG.MorphNodeTo(BR, ISD::BR, BR->getVTList(), Ops);
+    SDValue NewBR = DAG.getNode(ISD::BR, DL, BR->getVTList(), Ops);
+    DAG.ReplaceAllUsesWith(BR, NewBR.getNode());
+    BR = NewBR.getNode();
   }
 
   SDValue Chain = SDValue(Result, Result->getNumValues() - 1);