DirectedGraph: Add a constructor that takes a list of Nodes.

[jreiffers]

Summary

This makes it possible to efficiently build a graph without repeatedly iterating
over the list of nodes.

[bkramer]

Test case maybe?

llvm/include/llvm/ADT/DirectedGraph.h

186

Make it explicit

[jreiffers]

Add test.

[jreiffers]

Thanks, PTAL!

[jreiffers]

Fix test.

llvm/include/llvm/ADT/DirectedGraph.h

 
 /// Directed graph
 ///
 /// The graph is represented by a table of nodes.
 /// Each node contains a (possibly empty) list of outgoing edges.
 /// Each edge contains the target node it connects to.
 template <class NodeType, class EdgeType> class DirectedGraph {
 protected:
-  using NodeListTy = SmallVector<NodeType *, 10>;
   using EdgeListTy = SmallVector<EdgeType *, 10>;
 public:
+  using NodeListTy = SmallVector<NodeType *, 10>;
   using iterator = typename NodeListTy::iterator;
   using const_iterator = typename NodeListTy::const_iterator;
   using DGraphType = DirectedGraph<NodeType, EdgeType>;
 
   DirectedGraph() = default;
   explicit DirectedGraph(NodeType &N) : Nodes() { addNode(N); }
   DirectedGraph(const DGraphType &G) : Nodes(G.Nodes) {}
   DirectedGraph(DGraphType &&RHS) : Nodes(std::move(RHS.Nodes)) {}
+  DirectedGraph(NodeListTy Nodes) : Nodes(std::move(Nodes)) {}
   DGraphType &operator=(const DGraphType &G) {
     Nodes = G.Nodes;
     return *this;
   }
   DGraphType &operator=(const DGraphType &&G) {
     Nodes = std::move(G.Nodes);
     return *this;
   }