[DAG] canCreateUndefOrPoison - merge INSERT_VECTOR_ELT/EXTRACT_VECTOR_ELT cases. NFC.

The only difference is the operand index for the element index variable.

Author: RKSimon

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -5241,17 +5241,12 @@ bool SelectionDAG::canCreateUndefOrPoison(SDValue Op, const APInt &DemandedElts,
     // Check if we demand any upper (undef) elements.
     return !PoisonOnly && DemandedElts.ugt(1);
 
+  case ISD::INSERT_VECTOR_ELT:
   case ISD::EXTRACT_VECTOR_ELT: {
     // Ensure that the element index is in bounds.
     EVT VecVT = Op.getOperand(0).getValueType();
-    KnownBits KnownIdx = computeKnownBits(Op.getOperand(1), Depth + 1);
-    return KnownIdx.getMaxValue().uge(VecVT.getVectorMinNumElements());
-  }
-
-  case ISD::INSERT_VECTOR_ELT:{
-    // Ensure that the element index is in bounds.
-    EVT VecVT = Op.getOperand(0).getValueType();
-    KnownBits KnownIdx = computeKnownBits(Op.getOperand(2), Depth + 1);
+    SDValue Idx = Op.getOperand(Opcode == ISD::INSERT_VECTOR_ELT ? 2 : 1);
+    KnownBits KnownIdx = computeKnownBits(Idx, Depth + 1);
     return KnownIdx.getMaxValue().uge(VecVT.getVectorMinNumElements());
   }