Change the Dominators recalculate() function to only rely on GraphTraits

This is a patch by Guoping Long!

As part of utilizing LLVM Dominator computation in Clang, made two changes to LLVM dominators tree implementation:

 - (1) Change the recalculate() template function to only rely on GraphTraits.
 - (2) Add a size() method to GraphTraits template class to query the number of nodes in the graph.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@145837 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ADT/GraphTraits.h

@@ -43,9 +43,12 @@ struct GraphTraits {
   // typedef  ...iterator nodes_iterator;
   // static nodes_iterator nodes_begin(GraphType *G)
   // static nodes_iterator nodes_end  (GraphType *G)
-  //
   //    nodes_iterator/begin/end - Allow iteration over all nodes in the graph
 
+  // static unsigned       size       (GraphType *G)
+  //    Return total number of nodes in the graph
+  //
+
 
   // If anyone tries to use this class without having an appropriate
   // specialization, make an error.  If you get this error, it's because you

include/llvm/Analysis/DominatorInternals.h

@@ -171,7 +171,7 @@ void Calculate(DominatorTreeBase<typename GraphTraits<NodeT>::NodeType>& DT,
 
   // it might be that some blocks did not get a DFS number (e.g., blocks of 
   // infinite loops). In these cases an artificial exit node is required.
-  MultipleRoots |= (DT.isPostDominator() && N != F.size());
+  MultipleRoots |= (DT.isPostDominator() && N != GraphTraits<FuncT*>::size(&F));
 
   // When naively implemented, the Lengauer-Tarjan algorithm requires a separate
   // bucket for each vertex. However, this is unnecessary, because each vertex

include/llvm/Analysis/Dominators.h

@@ -653,21 +653,24 @@ public:
   /// recalculate - compute a dominator tree for the given function
   template<class FT>
   void recalculate(FT& F) {
+    typedef GraphTraits<FT*> TraitsTy;
     reset();
     this->Vertex.push_back(0);
 
     if (!this->IsPostDominators) {
       // Initialize root
-      this->Roots.push_back(&F.front());
-      this->IDoms[&F.front()] = 0;
-      this->DomTreeNodes[&F.front()] = 0;
+      NodeT *entry = TraitsTy::getEntryNode(&F);
+      this->Roots.push_back(entry);
+      this->IDoms[entry] = 0;
+      this->DomTreeNodes[entry] = 0;
 
       Calculate<FT, NodeT*>(*this, F);
     } else {
       // Initialize the roots list
-      for (typename FT::iterator I = F.begin(), E = F.end(); I != E; ++I) {
-        if (std::distance(GraphTraits<FT*>::child_begin(I),
-                          GraphTraits<FT*>::child_end(I)) == 0)
+      for (typename TraitsTy::nodes_iterator I = TraitsTy::nodes_begin(&F),
+                                        E = TraitsTy::nodes_end(&F); I != E; ++I) {
+        if (std::distance(TraitsTy::child_begin(I),
+                          TraitsTy::child_end(I)) == 0)
           addRoot(I);
 
         // Prepopulate maps so that we don't get iterator invalidation issues later.

include/llvm/CodeGen/MachineFunction.h

@@ -437,6 +437,7 @@ template <> struct GraphTraits<MachineFunction*> :
   typedef MachineFunction::iterator nodes_iterator;
   static nodes_iterator nodes_begin(MachineFunction *F) { return F->begin(); }
   static nodes_iterator nodes_end  (MachineFunction *F) { return F->end(); }
+  static unsigned       size       (MachineFunction *F) { return F->size(); }
 };
 template <> struct GraphTraits<const MachineFunction*> :
   public GraphTraits<const MachineBasicBlock*> {
@@ -452,6 +453,9 @@ template <> struct GraphTraits<const MachineFunction*> :
   static nodes_iterator nodes_end  (const MachineFunction *F) {
     return F->end();
   }
+  static unsigned       size       (const MachineFunction *F)  {
+    return F->size();
+  }
 };
 
 

include/llvm/Support/CFG.h

@@ -314,6 +314,7 @@ template <> struct GraphTraits<Function*> : public GraphTraits<BasicBlock*> {
   typedef Function::iterator nodes_iterator;
   static nodes_iterator nodes_begin(Function *F) { return F->begin(); }
   static nodes_iterator nodes_end  (Function *F) { return F->end(); }
+  static unsigned       size       (Function *F) { return F->size(); }
 };
 template <> struct GraphTraits<const Function*> :
   public GraphTraits<const BasicBlock*> {
@@ -323,6 +324,7 @@ template <> struct GraphTraits<const Function*> :
   typedef Function::const_iterator nodes_iterator;
   static nodes_iterator nodes_begin(const Function *F) { return F->begin(); }
   static nodes_iterator nodes_end  (const Function *F) { return F->end(); }
+  static unsigned       size       (const Function *F) { return F->size(); }
 };