diff --git a/llvm/lib/CodeGen/ComplexDeinterleavingPass.cpp b/llvm/lib/CodeGen/ComplexDeinterleavingPass.cpp
--- a/llvm/lib/CodeGen/ComplexDeinterleavingPass.cpp
+++ b/llvm/lib/CodeGen/ComplexDeinterleavingPass.cpp
@@ -271,8 +271,6 @@
   bool identifyNodes(Instruction *RootI);
 
   /// Perform the actual replacement of the underlying instruction graph.
-  /// Returns false if the deinterleaving operation should be cancelled for the
-  /// current graph.
   void replaceNodes();
 };
 
@@ -598,8 +596,16 @@
        Rotation == ComplexDeinterleavingRotation::Rotation_270)
           ? CommonOperand
           : nullptr);
-  NodePtr CNode = identifyNodeWithImplicitAdd(
-      cast<Instruction>(CR), cast<Instruction>(CI), PartialMatch);
+
+  auto *CRInst = dyn_cast<Instruction>(CR);
+  auto *CIInst = dyn_cast<Instruction>(CI);
+
+  if (!CRInst || !CIInst) {
+    LLVM_DEBUG(dbgs() << "  - Common operands are not instructions.\n");
+    return nullptr;
+  }
+
+  NodePtr CNode = identifyNodeWithImplicitAdd(CRInst, CIInst, PartialMatch);
   if (!CNode) {
     LLVM_DEBUG(dbgs() << "  - No cnode identified\n");
     return nullptr;
@@ -633,20 +639,21 @@
 ComplexDeinterleavingGraph::identifyAdd(Instruction *Real, Instruction *Imag) {
   LLVM_DEBUG(dbgs() << "identifyAdd " << *Real << " / " << *Imag << "\n");
 
-  // Determine rotation
-  ComplexDeinterleavingRotation Rotation;
-  if ((Real->getOpcode() == Instruction::FSub &&
-       Imag->getOpcode() == Instruction::FAdd) ||
-      (Real->getOpcode() == Instruction::Sub &&
-       Imag->getOpcode() == Instruction::Add))
-    Rotation = ComplexDeinterleavingRotation::Rotation_90;
-  else if ((Real->getOpcode() == Instruction::FAdd &&
-            Imag->getOpcode() == Instruction::FSub) ||
-           (Real->getOpcode() == Instruction::Add &&
-            Imag->getOpcode() == Instruction::Sub))
-    Rotation = ComplexDeinterleavingRotation::Rotation_270;
-  else {
-    LLVM_DEBUG(dbgs() << " - Unhandled case, rotation is not assigned.\n");
+  unsigned RotKey = 0;
+  RotKey |= Real->getOpcode() == Instruction::FSub ||
+            Real->getOpcode() == Instruction::Sub;
+  RotKey |= ((Imag->getOpcode() == Instruction::FSub ||
+              Imag->getOpcode() == Instruction::Sub)
+             << 1);
+  if ((RotKey & 2) == 2)
+    RotKey ^= 1;
+
+  ComplexDeinterleavingRotation Rotation =
+      (ComplexDeinterleavingRotation)RotKey;
+
+  if (Rotation == llvm::ComplexDeinterleavingRotation::Rotation_0 ||
+      Rotation == llvm::ComplexDeinterleavingRotation::Rotation_180) {
+    LLVM_DEBUG(dbgs() << " - Unsupported rotation.\n");
     return nullptr;
   }
 
@@ -832,7 +839,8 @@
   // Check all instructions have internal uses
   for (const auto &Node : CompositeNodes) {
     if (!Node->hasAllInternalUses(AllInstructions)) {
-      LLVM_DEBUG(dbgs() << "  - Invalid internal uses\n");
+      LLVM_DEBUG(dbgs() << "  - Invalid internal uses in " << Node.get()
+                        << "\n");
       return false;
     }
   }
@@ -845,12 +853,14 @@
     return Node->ReplacementNode;
 
   Value *Input0 = replaceNode(Node->Operands[0]);
-  Value *Input1 = replaceNode(Node->Operands[1]);
+  Value *Input1 =
+      Node->Operands.size() > 1 ? replaceNode(Node->Operands[1]) : nullptr;
   Value *Accumulator =
       Node->Operands.size() > 2 ? replaceNode(Node->Operands[2]) : nullptr;
 
-  assert(Input0->getType() == Input1->getType() &&
-         "Node inputs need to be of the same type");
+  if (Input1)
+    assert(Input0->getType() == Input1->getType() &&
+           "Node inputs need to be of the same type");
 
   Node->ReplacementNode = TL->createComplexDeinterleavingIR(
       Node->Real, Node->Operation, Node->Rotation, Input0, Input1, Accumulator);