[DAG] getNode() - reuse result type instead of calling getValueType again. NFC. (#159381)

We have assertions above confirming VT == N1.getValueType() for INSERT_VECTOR_ELT nodes.

Author: RKSimon

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -8247,8 +8247,8 @@ SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT,
     // INSERT_VECTOR_ELT into out-of-bounds element is an UNDEF, except
     // for scalable vectors where we will generate appropriate code to
     // deal with out-of-bounds cases correctly.
-    if (N3C && N1.getValueType().isFixedLengthVector() &&
-        N3C->getZExtValue() >= N1.getValueType().getVectorNumElements())
+    if (N3C && VT.isFixedLengthVector() &&
+        N3C->getZExtValue() >= VT.getVectorNumElements())
       return getUNDEF(VT);
 
     // Undefined index can be assumed out-of-bounds, so that's UNDEF too.