X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FADT%2FPostOrderIterator.h;h=7f6350e4443e1567cc712b1e8b6d872bd9bb207a;hb=e19f11215d8fa29635b28317dd1cfd1915d048d4;hp=961be340f7166d40f971e9da296bd4e357029386;hpb=c72c617a4ea3784c9a9f634478dc405ef6b2866b;p=oota-llvm.git

diff --git a/include/llvm/ADT/PostOrderIterator.h b/include/llvm/ADT/PostOrderIterator.h
index 961be340f71..7f6350e4443 100644
--- a/include/llvm/ADT/PostOrderIterator.h
+++ b/include/llvm/ADT/PostOrderIterator.h
@@ -1,10 +1,10 @@
 //===- llvm/ADT/PostOrderIterator.h - PostOrder iterator --------*- C++ -*-===//
-// 
+//
 //                     The LLVM Compiler Infrastructure
 //
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
-// 
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
 //===----------------------------------------------------------------------===//
 //
 // This file builds on the ADT/GraphTraits.h file to build a generic graph
@@ -17,54 +17,137 @@
 #define LLVM_ADT_POSTORDERITERATOR_H
 
 #include "llvm/ADT/GraphTraits.h"
-#include "llvm/ADT/iterator"
-#include <stack>
+#include "llvm/ADT/SmallPtrSet.h"
 #include <set>
+#include <vector>
 
 namespace llvm {
 
-template<class GraphT, class GT = GraphTraits<GraphT> >
-class po_iterator : public forward_iterator<typename GT::NodeType, ptrdiff_t> {
-  typedef forward_iterator<typename GT::NodeType, ptrdiff_t> super;
+// 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 {
+  SetType Visited;
+public:
+  // Return true if edge destination should be visited.
+  template<typename NodeType>
+  bool insertEdge(NodeType *From, NodeType *To) {
+    return Visited.insert(To);
+  }
+
+  // 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) {}
+
+  // 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); }
+
+  // Called after all children of BB have been visited.
+  template<class NodeType>
+  void finishPostorder(NodeType *BB) {}
+};
+
+template<class GraphT,
+  class SetType = llvm::SmallPtrSet<typename GraphTraits<GraphT>::NodeType*, 8>,
+  bool ExtStorage = false,
+  class GT = GraphTraits<GraphT> >
+class po_iterator : public std::iterator<std::forward_iterator_tag,
+                                         typename GT::NodeType, ptrdiff_t>,
+                    public po_iterator_storage<SetType, ExtStorage> {
+  typedef std::iterator<std::forward_iterator_tag,
+                        typename GT::NodeType, ptrdiff_t> super;
   typedef typename GT::NodeType          NodeType;
   typedef typename GT::ChildIteratorType ChildItTy;
 
-  std::set<NodeType *> Visited;    // All of the blocks visited so far...
   // VisitStack - Used to maintain the ordering.  Top = current block
   // First element is basic block pointer, second is the 'next child' to visit
-  std::stack<std::pair<NodeType *, ChildItTy> > VisitStack;
+  std::vector<std::pair<NodeType *, ChildItTy> > VisitStack;
 
   void traverseChild() {
-    while (VisitStack.top().second != GT::child_end(VisitStack.top().first)) {
-      NodeType *BB = *VisitStack.top().second++;
-      if (!Visited.count(BB)) {  // If the block is not visited...
-	Visited.insert(BB);
-	VisitStack.push(std::make_pair(BB, GT::child_begin(BB)));
+    while (VisitStack.back().second != GT::child_end(VisitStack.back().first)) {
+      NodeType *BB = *VisitStack.back().second++;
+      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) {
-    Visited.insert(BB);
-    VisitStack.push(std::make_pair(BB, GT::child_begin(BB)));
+    this->insertEdge((NodeType*)0, BB);
+    VisitStack.push_back(std::make_pair(BB, GT::child_begin(BB)));
     traverseChild();
   }
-  inline po_iterator() { /* End is when stack is empty */ }
+  inline po_iterator() {} // End is when stack is empty.
+
+  inline po_iterator(NodeType *BB, SetType &S) :
+    po_iterator_storage<SetType, ExtStorage>(S) {
+    if (this->insertEdge((NodeType*)0, BB)) {
+      VisitStack.push_back(std::make_pair(BB, GT::child_begin(BB)));
+      traverseChild();
+    }
+  }
+
+  inline 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, GT> _Self;
+  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(); }
 
-  inline bool operator==(const _Self& x) const { 
+  static inline _Self begin(GraphT G, SetType &S) {
+    return _Self(GT::getEntryNode(G), S);
+  }
+  static inline _Self end  (GraphT G, SetType &S) { return _Self(S); }
+
+  inline bool operator==(const _Self& x) const {
     return VisitStack == x.VisitStack;
   }
   inline bool operator!=(const _Self& x) const { return !operator==(x); }
 
-  inline pointer operator*() const { 
-    return VisitStack.top().first;
+  inline pointer operator*() const {
+    return VisitStack.back().first;
   }
 
   // This is a nonstandard operator-> that dereferences the pointer an extra
@@ -74,14 +157,15 @@ public:
   inline NodeType *operator->() const { return operator*(); }
 
   inline _Self& operator++() {   // Preincrement
-    VisitStack.pop();
+    this->finishPostorder(VisitStack.back().first);
+    VisitStack.pop_back();
     if (!VisitStack.empty())
       traverseChild();
-    return *this; 
+    return *this;
   }
 
   inline _Self operator++(int) { // Postincrement
-    _Self tmp = *this; ++*this; return tmp; 
+    _Self tmp = *this; ++*this; return tmp;
   }
 };
 
@@ -92,10 +176,30 @@ po_iterator<T> po_begin(T G) { return po_iterator<T>::begin(G); }
 template <class T>
 po_iterator<T> po_end  (T G) { return po_iterator<T>::end(G); }
 
+// Provide global definitions of external postorder iterators...
+template<class T, class SetType=std::set<typename GraphTraits<T>::NodeType*> >
+struct po_ext_iterator : public po_iterator<T, SetType, true> {
+  po_ext_iterator(const po_iterator<T, SetType, true> &V) :
+  po_iterator<T, SetType, true>(V) {}
+};
+
+template<class T, class SetType>
+po_ext_iterator<T, SetType> po_ext_begin(T G, SetType &S) {
+  return po_ext_iterator<T, SetType>::begin(G, S);
+}
+
+template<class T, class SetType>
+po_ext_iterator<T, SetType> po_ext_end(T G, SetType &S) {
+  return po_ext_iterator<T, SetType>::end(G, S);
+}
+
 // Provide global definitions of inverse post order iterators...
-template <class T>
-struct ipo_iterator : public po_iterator<Inverse<T> > {
-  ipo_iterator(const po_iterator<Inverse<T> > &V) :po_iterator<Inverse<T> >(V){}
+template <class T,
+          class SetType = std::set<typename GraphTraits<T>::NodeType*>,
+          bool External = false>
+struct ipo_iterator : public po_iterator<Inverse<T>, SetType, External > {
+  ipo_iterator(const po_iterator<Inverse<T>, SetType, External> &V) :
+     po_iterator<Inverse<T>, SetType, External> (V) {}
 };
 
 template <class T>
@@ -108,14 +212,33 @@ ipo_iterator<T> ipo_end(T G){
   return ipo_iterator<T>::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_ext_iterator(const po_iterator<Inverse<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) {
+  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) {
+  return ipo_ext_iterator<T, SetType>::end(G, S);
+}
 
 //===--------------------------------------------------------------------===//
 // Reverse Post Order CFG iterator code
 //===--------------------------------------------------------------------===//
-// 
+//
 // This is used to visit basic blocks in a method in reverse post order.  This
 // class is awkward to use because I don't know a good incremental algorithm to
-// computer RPO from a graph.  Because of this, the construction of the 
+// computer RPO from a graph.  Because of this, the construction of the
 // ReversePostOrderTraversal object is expensive (it must walk the entire graph
 // with a postorder iterator to build the data structures).  The moral of this
 // story is: Don't create more ReversePostOrderTraversal classes than necessary.