Use range based for loop. NFCI.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@288671 91177308-0d34-0410-b5e6-96231b3b80d8

Author: RKSimon

lib/Target/X86/X86ISelLowering.cpp

@@ -27396,13 +27396,10 @@ static SDValue combineShuffleOfConcatUndef(SDNode *N, SelectionDAG &DAG,
   // index, but elements from the second source no longer need to skip an undef.
   SmallVector<int, 8> Mask;
   int NumElts = VT.getVectorNumElements();
-  for (int i = 0; i < NumElts; ++i) {
-    int Elt = cast<ShuffleVectorSDNode>(N)->getMaskElt(i);
-    if (Elt < NumElts)
-      Mask.push_back(Elt);
-    else
-      Mask.push_back(Elt - NumElts / 2);
-  }
+
+  ShuffleVectorSDNode *SVOp = cast<ShuffleVectorSDNode>(N);
+  for (int Elt : SVOp->getMask())
+    Mask.push_back(Elt < NumElts ? Elt : (Elt - NumElts / 2));
 
   SDLoc DL(N);
   SDValue Concat = DAG.getNode(ISD::CONCAT_VECTORS, DL, VT, N0.getOperand(0),