Convert push_back loops into append calls.

No functionality change intended.

llvm-svn: 230849
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 6129401..8722c62 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -11465,14 +11465,12 @@
       unsigned NumElts = OpVT.getVectorNumElements();
 
       if (ISD::UNDEF == Op.getOpcode())
-        for (unsigned i = 0; i != NumElts; ++i)
-          Opnds.push_back(DAG.getUNDEF(MinVT));
+        Opnds.append(NumElts, DAG.getUNDEF(MinVT));
 
       if (ISD::BUILD_VECTOR == Op.getOpcode()) {
         if (SVT.isFloatingPoint()) {
           assert(SVT == OpVT.getScalarType() && "Concat vector type mismatch");
-          for (unsigned i = 0; i != NumElts; ++i)
-            Opnds.push_back(Op.getOperand(i));
+          Opnds.append(Op->op_begin(), Op->op_begin() + NumElts);
         } else {
           for (unsigned i = 0; i != NumElts; ++i)
             Opnds.push_back(