1 //===- llvm/ADT/PostOrderIterator.h - PostOrder iterator --------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file builds on the ADT/GraphTraits.h file to build a generic graph
11 // post order iterator. This should work over any graph type that has a
12 // GraphTraits specialization.
14 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_ADT_POSTORDERITERATOR_H
17 #define LLVM_ADT_POSTORDERITERATOR_H
19 #include "llvm/ADT/GraphTraits.h"
20 #include "llvm/ADT/iterator"
27 template<class SetType, bool External> // Non-external set
28 class po_iterator_storage {
33 template<class SetType>
34 class po_iterator_storage<SetType, true> {
36 po_iterator_storage(SetType &VSet) : Visited(VSet) {}
37 po_iterator_storage(const po_iterator_storage &S) : Visited(S.Visited) {}
41 template<class GraphT,
42 class SetType = std::set<typename GraphTraits<GraphT>::NodeType*>,
43 bool ExtStorage = false,
44 class GT = GraphTraits<GraphT> >
45 class po_iterator : public forward_iterator<typename GT::NodeType, ptrdiff_t>,
46 public po_iterator_storage<SetType, ExtStorage> {
47 typedef forward_iterator<typename GT::NodeType, ptrdiff_t> super;
48 typedef typename GT::NodeType NodeType;
49 typedef typename GT::ChildIteratorType ChildItTy;
51 // VisitStack - Used to maintain the ordering. Top = current block
52 // First element is basic block pointer, second is the 'next child' to visit
53 std::stack<std::pair<NodeType *, ChildItTy> > VisitStack;
55 void traverseChild() {
56 while (VisitStack.top().second != GT::child_end(VisitStack.top().first)) {
57 NodeType *BB = *VisitStack.top().second++;
58 if (!this->Visited.count(BB)) { // If the block is not visited...
59 this->Visited.insert(BB);
60 VisitStack.push(std::make_pair(BB, GT::child_begin(BB)));
65 inline po_iterator(NodeType *BB) {
66 this->Visited.insert(BB);
67 VisitStack.push(std::make_pair(BB, GT::child_begin(BB)));
70 inline po_iterator() {} // End is when stack is empty.
72 inline po_iterator(NodeType *BB, SetType &S) :
73 po_iterator_storage<SetType, ExtStorage>(&S) {
75 this->Visited.insert(BB);
76 VisitStack.push(std::make_pair(BB, GT::child_begin(BB)));
81 inline po_iterator(SetType &S) :
82 po_iterator_storage<SetType, ExtStorage>(&S) {
83 } // End is when stack is empty.
85 typedef typename super::pointer pointer;
86 typedef po_iterator<GraphT, SetType, ExtStorage, GT> _Self;
88 // Provide static "constructors"...
89 static inline _Self begin(GraphT G) { return _Self(GT::getEntryNode(G)); }
90 static inline _Self end (GraphT G) { return _Self(); }
92 static inline _Self begin(GraphT G, SetType &S) {
93 return _Self(GT::getEntryNode(G), S);
95 static inline _Self end (GraphT G, SetType &S) { return _Self(S); }
97 inline bool operator==(const _Self& x) const {
98 return VisitStack == x.VisitStack;
100 inline bool operator!=(const _Self& x) const { return !operator==(x); }
102 inline pointer operator*() const {
103 return VisitStack.top().first;
106 // This is a nonstandard operator-> that dereferences the pointer an extra
107 // time... so that you can actually call methods ON the BasicBlock, because
108 // the contained type is a pointer. This allows BBIt->getTerminator() f.e.
110 inline NodeType *operator->() const { return operator*(); }
112 inline _Self& operator++() { // Preincrement
114 if (!VisitStack.empty())
119 inline _Self operator++(int) { // Postincrement
120 _Self tmp = *this; ++*this; return tmp;
124 // Provide global constructors that automatically figure out correct types...
127 po_iterator<T> po_begin(T G) { return po_iterator<T>::begin(G); }
129 po_iterator<T> po_end (T G) { return po_iterator<T>::end(G); }
131 // Provide global definitions of external postorder iterators...
132 template<class T, class SetType=std::set<typename GraphTraits<T>::NodeType*> >
133 struct po_ext_iterator : public po_iterator<T, SetType, true> {
134 po_ext_iterator(const po_iterator<T, SetType, true> &V) :
135 po_iterator<T, SetType, true>(V) {}
138 template<class T, class SetType>
139 po_ext_iterator<T, SetType> po_ext_begin(T G, SetType &S) {
140 return po_ext_iterator<T, SetType>::begin(G, S);
143 template<class T, class SetType>
144 po_ext_iterator<T, SetType> po_ext_end(T G, SetType &S) {
145 return po_ext_iterator<T, SetType>::end(G, S);
148 // Provide global definitions of inverse post order iterators...
150 class SetType = std::set<typename GraphTraits<T>::NodeType*>,
151 bool External = false>
152 struct ipo_iterator : public po_iterator<Inverse<T>, SetType, External > {
153 ipo_iterator(const po_iterator<Inverse<T>, SetType, External> &V) :
154 po_iterator<Inverse<T>, SetType, External> (V) {}
158 ipo_iterator<T> ipo_begin(T G, bool Reverse = false) {
159 return ipo_iterator<T>::begin(G, Reverse);
163 ipo_iterator<T> ipo_end(T G){
164 return ipo_iterator<T>::end(G);
167 //Provide global definitions of external inverse postorder iterators...
168 template <class T, class SetType = std::set<typename GraphTraits<T>::NodeType*> >
169 struct ipo_ext_iterator : public ipo_iterator<T, SetType, true> {
170 ipo_ext_iterator(const ipo_iterator<T, SetType, true> &V) :
171 ipo_iterator<T, SetType, true>(&V) {}
172 ipo_ext_iterator(const po_iterator<Inverse<T>, SetType, true> &V) :
173 ipo_iterator<T, SetType, true>(&V) {}
176 template <class T, class SetType>
177 ipo_ext_iterator<T, SetType> ipo_ext_begin(T G, SetType &S) {
178 return ipo_ext_iterator<T, SetType>::begin(G, S);
181 template <class T, class SetType>
182 ipo_ext_iterator<T, SetType> ipo_ext_end(T G, SetType &S) {
183 return ipo_ext_iterator<T, SetType>::end(G, S);
186 //===--------------------------------------------------------------------===//
187 // Reverse Post Order CFG iterator code
188 //===--------------------------------------------------------------------===//
190 // This is used to visit basic blocks in a method in reverse post order. This
191 // class is awkward to use because I don't know a good incremental algorithm to
192 // computer RPO from a graph. Because of this, the construction of the
193 // ReversePostOrderTraversal object is expensive (it must walk the entire graph
194 // with a postorder iterator to build the data structures). The moral of this
195 // story is: Don't create more ReversePostOrderTraversal classes than necessary.
197 // This class should be used like this:
199 // ReversePostOrderTraversal<Function*> RPOT(FuncPtr); // Expensive to create
200 // for (rpo_iterator I = RPOT.begin(); I != RPOT.end(); ++I) {
203 // for (rpo_iterator I = RPOT.begin(); I != RPOT.end(); ++I) {
209 template<class GraphT, class GT = GraphTraits<GraphT> >
210 class ReversePostOrderTraversal {
211 typedef typename GT::NodeType NodeType;
212 std::vector<NodeType*> Blocks; // Block list in normal PO order
213 inline void Initialize(NodeType *BB) {
214 copy(po_begin(BB), po_end(BB), back_inserter(Blocks));
217 typedef typename std::vector<NodeType*>::reverse_iterator rpo_iterator;
219 inline ReversePostOrderTraversal(GraphT G) {
220 Initialize(GT::getEntryNode(G));
223 // Because we want a reverse post order, use reverse iterators from the vector
224 inline rpo_iterator begin() { return Blocks.rbegin(); }
225 inline rpo_iterator end() { return Blocks.rend(); }
228 } // End llvm namespace