X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FADT%2FPostOrderIterator.h;h=759a2db24f2a6dae00f9bfa351130c547bfc8179;hb=82c835626fc509771e3927e2ca4886cf0f4245db;hp=47e5b2bd4ad07e469cb074d277bd7c4456f43eb9;hpb=2dac4c1b519feaf1ef63514f07fa16aa5dc7d89a;p=oota-llvm.git

diff --git a/include/llvm/ADT/PostOrderIterator.h b/include/llvm/ADT/PostOrderIterator.h
index 47e5b2bd4ad..759a2db24f2 100644
--- a/include/llvm/ADT/PostOrderIterator.h
+++ b/include/llvm/ADT/PostOrderIterator.h
@@ -18,23 +18,72 @@
 
 #include "llvm/ADT/GraphTraits.h"
 #include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/iterator_range.h"
 #include <set>
 #include <vector>
 
 namespace llvm {
 
-template<class SetType, bool External>   // Non-external set
+// The po_iterator_storage template provides access to the set of already
+// visited nodes during the po_iterator's depth-first traversal.
+//
+// The default implementation simply contains a set of visited nodes, while
+// the Extended=true version uses a reference to an external set.
+//
+// It is possible to prune the depth-first traversal in several ways:
+//
+// - When providing an external set that already contains some graph nodes,
+//   those nodes won't be visited again. This is useful for restarting a
+//   post-order traversal on a graph with nodes that aren't dominated by a
+//   single node.
+//
+// - By providing a custom SetType class, unwanted graph nodes can be excluded
+//   by having the insert() function return false. This could for example
+//   confine a CFG traversal to blocks in a specific loop.
+//
+// - Finally, by specializing the po_iterator_storage template itself, graph
+//   edges can be pruned by returning false in the insertEdge() function. This
+//   could be used to remove loop back-edges from the CFG seen by po_iterator.
+//
+// A specialized po_iterator_storage class can observe both the pre-order and
+// the post-order. The insertEdge() function is called in a pre-order, while
+// the finishPostorder() function is called just before the po_iterator moves
+// on to the next node.
+
+/// Default po_iterator_storage implementation with an internal set object.
+template<class SetType, bool External>
 class po_iterator_storage {
-public:
   SetType Visited;
+public:
+  // Return true if edge destination should be visited.
+  template<typename NodeType>
+  bool insertEdge(NodeType *From, NodeType *To) {
+    return Visited.insert(To).second;
+  }
+
+  // Called after all children of BB have been visited.
+  template<typename NodeType>
+  void finishPostorder(NodeType *BB) {}
 };
 
+/// Specialization of po_iterator_storage that references an external set.
 template<class SetType>
 class po_iterator_storage<SetType, true> {
+  SetType &Visited;
 public:
   po_iterator_storage(SetType &VSet) : Visited(VSet) {}
   po_iterator_storage(const po_iterator_storage &S) : Visited(S.Visited) {}
-  SetType &Visited;
+
+  // Return true if edge destination should be visited, called with From = 0 for
+  // the root node.
+  // Graph edges can be pruned by specializing this function.
+  template <class NodeType> bool insertEdge(NodeType *From, NodeType *To) {
+    return Visited.insert(To).second;
+  }
+
+  // Called after all children of BB have been visited.
+  template<class NodeType>
+  void finishPostorder(NodeType *BB) {}
 };
 
 template<class GraphT,
@@ -56,78 +105,83 @@ class po_iterator : public std::iterator<std::forward_iterator_tag,
   void traverseChild() {
     while (VisitStack.back().second != GT::child_end(VisitStack.back().first)) {
       NodeType *BB = *VisitStack.back().second++;
-      if (!this->Visited.count(BB)) {  // If the block is not visited...
-        this->Visited.insert(BB);
+      if (this->insertEdge(VisitStack.back().first, BB)) {
+        // If the block is not visited...
         VisitStack.push_back(std::make_pair(BB, GT::child_begin(BB)));
       }
     }
   }
 
-  inline po_iterator(NodeType *BB) {
-    this->Visited.insert(BB);
+  po_iterator(NodeType *BB) {
+    this->insertEdge((NodeType*)nullptr, BB);
     VisitStack.push_back(std::make_pair(BB, GT::child_begin(BB)));
     traverseChild();
   }
-  inline po_iterator() {} // End is when stack is empty.
+  po_iterator() {} // End is when stack is empty.
 
-  inline po_iterator(NodeType *BB, SetType &S) :
-    po_iterator_storage<SetType, ExtStorage>(S) {
-    if(!S.count(BB)) {
-      this->Visited.insert(BB);
+  po_iterator(NodeType *BB, SetType &S)
+      : po_iterator_storage<SetType, ExtStorage>(S) {
+    if (this->insertEdge((NodeType*)nullptr, BB)) {
       VisitStack.push_back(std::make_pair(BB, GT::child_begin(BB)));
       traverseChild();
     }
   }
 
-  inline po_iterator(SetType &S) :
-      po_iterator_storage<SetType, ExtStorage>(S) {
+  po_iterator(SetType &S)
+      : po_iterator_storage<SetType, ExtStorage>(S) {
   } // End is when stack is empty.
 public:
   typedef typename super::pointer pointer;
-  typedef po_iterator<GraphT, SetType, ExtStorage, GT> _Self;
 
   // Provide static "constructors"...
-  static inline _Self begin(GraphT G) { return _Self(GT::getEntryNode(G)); }
-  static inline _Self end  (GraphT G) { return _Self(); }
+  static po_iterator begin(GraphT G) {
+    return po_iterator(GT::getEntryNode(G));
+  }
+  static po_iterator end(GraphT G) { return po_iterator(); }
 
-  static inline _Self begin(GraphT G, SetType &S) {
-    return _Self(GT::getEntryNode(G), S);
+  static po_iterator begin(GraphT G, SetType &S) {
+    return po_iterator(GT::getEntryNode(G), S);
   }
-  static inline _Self end  (GraphT G, SetType &S) { return _Self(S); }
+  static po_iterator end(GraphT G, SetType &S) { return po_iterator(S); }
 
-  inline bool operator==(const _Self& x) const {
+  bool operator==(const po_iterator &x) const {
     return VisitStack == x.VisitStack;
   }
-  inline bool operator!=(const _Self& x) const { return !operator==(x); }
+  bool operator!=(const po_iterator &x) const { return !(*this == x); }
 
-  inline pointer operator*() const {
-    return VisitStack.back().first;
-  }
+  pointer operator*() const { return VisitStack.back().first; }
 
   // This is a nonstandard operator-> that dereferences the pointer an extra
   // time... so that you can actually call methods ON the BasicBlock, because
   // the contained type is a pointer.  This allows BBIt->getTerminator() f.e.
   //
-  inline NodeType *operator->() const { return operator*(); }
+  NodeType *operator->() const { return **this; }
 
-  inline _Self& operator++() {   // Preincrement
+  po_iterator &operator++() { // Preincrement
+    this->finishPostorder(VisitStack.back().first);
     VisitStack.pop_back();
     if (!VisitStack.empty())
       traverseChild();
     return *this;
   }
 
-  inline _Self operator++(int) { // Postincrement
-    _Self tmp = *this; ++*this; return tmp;
+  po_iterator operator++(int) { // Postincrement
+    po_iterator tmp = *this;
+    ++*this;
+    return tmp;
   }
 };
 
 // Provide global constructors that automatically figure out correct types...
 //
 template <class T>
-po_iterator<T> po_begin(T G) { return po_iterator<T>::begin(G); }
+po_iterator<T> po_begin(const T &G) { return po_iterator<T>::begin(G); }
 template <class T>
-po_iterator<T> po_end  (T G) { return po_iterator<T>::end(G); }
+po_iterator<T> po_end  (const T &G) { return po_iterator<T>::end(G); }
+
+template <class T> iterator_range<po_iterator<T>> post_order(const T &G) {
+  return make_range(po_begin(G), po_end(G));
+}
 
 // Provide global definitions of external postorder iterators...
 template<class T, class SetType=std::set<typename GraphTraits<T>::NodeType*> >
@@ -146,6 +200,11 @@ po_ext_iterator<T, SetType> po_ext_end(T G, SetType &S) {
   return po_ext_iterator<T, SetType>::end(G, S);
 }
 
+template <class T, class SetType>
+iterator_range<po_ext_iterator<T, SetType>> post_order_ext(const T &G, SetType &S) {
+  return make_range(po_ext_begin(G, S), po_ext_end(G, S));
+}
+
 // Provide global definitions of inverse post order iterators...
 template <class T,
           class SetType = std::set<typename GraphTraits<T>::NodeType*>,
@@ -156,35 +215,46 @@ struct ipo_iterator : public po_iterator<Inverse<T>, SetType, External > {
 };
 
 template <class T>
-ipo_iterator<T> ipo_begin(T G, bool Reverse = false) {
+ipo_iterator<T> ipo_begin(const T &G, bool Reverse = false) {
   return ipo_iterator<T>::begin(G, Reverse);
 }
 
 template <class T>
-ipo_iterator<T> ipo_end(T G){
+ipo_iterator<T> ipo_end(const T &G){
   return ipo_iterator<T>::end(G);
 }
 
-//Provide global definitions of external inverse postorder iterators...
+template <class T>
+iterator_range<ipo_iterator<T>> inverse_post_order(const T &G, bool Reverse = false) {
+  return make_range(ipo_begin(G, Reverse), ipo_end(G));
+}
+
+// Provide global definitions of external inverse postorder iterators...
 template <class T,
           class SetType = std::set<typename GraphTraits<T>::NodeType*> >
 struct ipo_ext_iterator : public ipo_iterator<T, SetType, true> {
   ipo_ext_iterator(const ipo_iterator<T, SetType, true> &V) :
-    ipo_iterator<T, SetType, true>(&V) {}
+    ipo_iterator<T, SetType, true>(V) {}
   ipo_ext_iterator(const po_iterator<Inverse<T>, SetType, true> &V) :
-    ipo_iterator<T, SetType, true>(&V) {}
+    ipo_iterator<T, SetType, true>(V) {}
 };
 
 template <class T, class SetType>
-ipo_ext_iterator<T, SetType> ipo_ext_begin(T G, SetType &S) {
+ipo_ext_iterator<T, SetType> ipo_ext_begin(const T &G, SetType &S) {
   return ipo_ext_iterator<T, SetType>::begin(G, S);
 }
 
 template <class T, class SetType>
-ipo_ext_iterator<T, SetType> ipo_ext_end(T G, SetType &S) {
+ipo_ext_iterator<T, SetType> ipo_ext_end(const T &G, SetType &S) {
   return ipo_ext_iterator<T, SetType>::end(G, S);
 }
 
+template <class T, class SetType>
+iterator_range<ipo_ext_iterator<T, SetType>>
+inverse_post_order_ext(const T &G, SetType &S) {
+  return make_range(ipo_ext_begin(G, S), ipo_ext_end(G, S));
+}
+
 //===--------------------------------------------------------------------===//
 // Reverse Post Order CFG iterator code
 //===--------------------------------------------------------------------===//
@@ -212,19 +282,17 @@ template<class GraphT, class GT = GraphTraits<GraphT> >
 class ReversePostOrderTraversal {
   typedef typename GT::NodeType NodeType;
   std::vector<NodeType*> Blocks;       // Block list in normal PO order
-  inline void Initialize(NodeType *BB) {
-    copy(po_begin(BB), po_end(BB), back_inserter(Blocks));
+  void Initialize(NodeType *BB) {
+    std::copy(po_begin(BB), po_end(BB), std::back_inserter(Blocks));
   }
 public:
   typedef typename std::vector<NodeType*>::reverse_iterator rpo_iterator;
 
-  inline ReversePostOrderTraversal(GraphT G) {
-    Initialize(GT::getEntryNode(G));
-  }
+  ReversePostOrderTraversal(GraphT G) { Initialize(GT::getEntryNode(G)); }
 
   // Because we want a reverse post order, use reverse iterators from the vector
-  inline rpo_iterator begin() { return Blocks.rbegin(); }
-  inline rpo_iterator end()   { return Blocks.rend(); }
+  rpo_iterator begin() { return Blocks.rbegin(); }
+  rpo_iterator end() { return Blocks.rend(); }
 };
 
 } // End llvm namespace