[DAG] visitINSERT_VECTOR_ELT - move mergeInsertEltWithShuffle / combineInsertEltToShuffle folds after canonicalization

Noticed while triaging D127115 regressions - there's no need to attempt these costly folds until after the easy canonicalization cases have been addressed

Author: RKSimon

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -20149,12 +20149,6 @@ SDValue DAGCombiner::visitINSERT_VECTOR_ELT(SDNode *N) {
   // We must know which element is being inserted for folds below here.
   unsigned Elt = IndexC->getZExtValue();
 
-  if (SDValue Shuf = mergeInsertEltWithShuffle(N, Elt))
-    return Shuf;
-
-  if (SDValue Shuf = combineInsertEltToShuffle(N, Elt))
-    return Shuf;
-
   // Handle <1 x ???> vector insertion special cases.
   if (NumElts == 1) {
     // insert_vector_elt(x, extract_vector_elt(y, 0), 0) -> y
@@ -20184,6 +20178,12 @@ SDValue DAGCombiner::visitINSERT_VECTOR_ELT(SDNode *N) {
     }
   }
 
+  if (SDValue Shuf = mergeInsertEltWithShuffle(N, Elt))
+    return Shuf;
+
+  if (SDValue Shuf = combineInsertEltToShuffle(N, Elt))
+    return Shuf;
+
   // Attempt to convert an insert_vector_elt chain into a legal build_vector.
   if (!LegalOperations || TLI.isOperationLegal(ISD::BUILD_VECTOR, VT)) {
     // vXi1 vector - we don't need to recurse.