Index: llvm/trunk/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
+++ llvm/trunk/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
@@ -1010,6 +1010,34 @@
     computeLatency(LoadSU);
   }
 
+  bool isNewN = true;
+  SUnit *NewSU;
+  // This can only happen when isNewLoad is false.
+  if (N->getNodeId() != -1) {
+    NewSU = &SUnits[N->getNodeId()];
+    // If NewSU has already been scheduled, we need to clone it, but this
+    // negates the benefit to unfolding so just return SU.
+    if (NewSU->isScheduled)
+      return SU;
+    isNewN = false;
+  } else {
+    NewSU = CreateNewSUnit(N);
+    N->setNodeId(NewSU->NodeNum);
+
+    const MCInstrDesc &MCID = TII->get(N->getMachineOpcode());
+    for (unsigned i = 0; i != MCID.getNumOperands(); ++i) {
+      if (MCID.getOperandConstraint(i, MCOI::TIED_TO) != -1) {
+        NewSU->isTwoAddress = true;
+        break;
+      }
+    }
+    if (MCID.isCommutable())
+      NewSU->isCommutable = true;
+
+    InitNumRegDefsLeft(NewSU);
+    computeLatency(NewSU);
+  }
+
   LLVM_DEBUG(dbgs() << "Unfolding SU #" << SU->NodeNum << "\n");
 
   // Now that we are committed to unfolding replace DAG Uses.
@@ -1018,23 +1046,6 @@
   DAG->ReplaceAllUsesOfValueWith(SDValue(SU->getNode(), OldNumVals - 1),
                                  SDValue(LoadNode, 1));
 
-  SUnit *NewSU = CreateNewSUnit(N);
-  assert(N->getNodeId() == -1 && "Node already inserted!");
-  N->setNodeId(NewSU->NodeNum);
-
-  const MCInstrDesc &MCID = TII->get(N->getMachineOpcode());
-  for (unsigned i = 0; i != MCID.getNumOperands(); ++i) {
-    if (MCID.getOperandConstraint(i, MCOI::TIED_TO) != -1) {
-      NewSU->isTwoAddress = true;
-      break;
-    }
-  }
-  if (MCID.isCommutable())
-    NewSU->isCommutable = true;
-
-  InitNumRegDefsLeft(NewSU);
-  computeLatency(NewSU);
-
   // Record all the edges to and from the old SU, by category.
   SmallVector<SDep, 4> ChainPreds;
   SmallVector<SDep, 4> ChainSuccs;
@@ -1100,7 +1111,8 @@
 
   if (isNewLoad)
     AvailableQueue->addNode(LoadSU);
-  AvailableQueue->addNode(NewSU);
+  if (isNewN)
+    AvailableQueue->addNode(NewSU);
 
   ++NumUnfolds;
 
Index: llvm/trunk/test/CodeGen/X86/pr37916.ll
===================================================================
--- llvm/trunk/test/CodeGen/X86/pr37916.ll
+++ llvm/trunk/test/CodeGen/X86/pr37916.ll
@@ -0,0 +1,44 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=i386-unknown-linux-gnu %s -o - | FileCheck %s
+
+@f = external local_unnamed_addr global i64*, align 4
+@a = external global i64, align 8
+
+define void @fn1() local_unnamed_addr {
+; CHECK-LABEL: fn1:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    .p2align 4, 0x90
+; CHECK-NEXT:  .LBB0_1: # %if.end
+; CHECK-NEXT:    # =>This Inner Loop Header: Depth=1
+; CHECK-NEXT:    movl a+4, %eax
+; CHECK-NEXT:    orl a, %eax
+; CHECK-NEXT:    movl $a, f
+; CHECK-NEXT:    je .LBB0_3
+; CHECK-NEXT:  # %bb.2: # %if.end
+; CHECK-NEXT:    # in Loop: Header=BB0_1 Depth=1
+; CHECK-NEXT:    jne .LBB0_1
+; CHECK-NEXT:  .LBB0_3: # %cond.false
+entry:
+  br label %if.end
+
+if.end:                                           ; preds = %cond.end, %entry
+  br label %if.then7
+
+if.then7:                                         ; preds = %if.end
+  store i64* @a, i64** @f, align 4
+  %0 = load i64*, i64** @f, align 4
+  %1 = load i64, i64* %0, align 4
+  %tobool12 = icmp ne i64 %1, 0
+  %2 = load i64, i64* @a, align 8
+  %tobool13 = icmp ne i64 %2, 0
+  %3 = and i1 %tobool12, %tobool13
+  %tobool14.demorgan = and i1 %tobool12, %tobool13
+  br i1 %tobool14.demorgan, label %cond.end, label %cond.false
+
+cond.false:                                       ; preds = %if.then7
+  unreachable
+
+cond.end:                                         ; preds = %if.then7
+  %conv17 = sext i1 %3 to i8
+  br label %if.end
+}