1 //===- llvm/ADT/PostOrderIterator.h - PostOrder iterator --------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // 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/SmallPtrSet.h"
26 template<class SetType, bool External> // Non-external set
27 class po_iterator_storage {
32 template<class SetType>
33 class po_iterator_storage<SetType, true> {
35 po_iterator_storage(SetType &VSet) : Visited(VSet) {}
36 po_iterator_storage(const po_iterator_storage &S) : Visited(S.Visited) {}
40 template<class GraphT,
41 class SetType = llvm::SmallPtrSet<typename GraphTraits<GraphT>::NodeType*, 8>,
42 bool ExtStorage = false,
43 class GT = GraphTraits<GraphT> >
44 class po_iterator : public std::iterator<std::forward_iterator_tag,
45 typename GT::NodeType, ptrdiff_t>,
46 public po_iterator_storage<SetType, ExtStorage> {
47 typedef std::iterator<std::forward_iterator_tag,
48 typename GT::NodeType, ptrdiff_t> super;
49 typedef typename GT::NodeType NodeType;
50 typedef typename GT::ChildIteratorType ChildItTy;
52 // VisitStack - Used to maintain the ordering. Top = current block
53 // First element is basic block pointer, second is the 'next child' to visit
54 std::vector<std::pair<NodeType *, ChildItTy> > VisitStack;
56 void traverseChild() {
57 while (VisitStack.back().second != GT::child_end(VisitStack.back().first)) {
58 NodeType *BB = *VisitStack.back().second++;
59 if (!this->Visited.count(BB)) { // If the block is not visited...
60 this->Visited.insert(BB);
61 VisitStack.push_back(std::make_pair(BB, GT::child_begin(BB)));
66 inline po_iterator(NodeType *BB) {
67 this->Visited.insert(BB);
68 VisitStack.push_back(std::make_pair(BB, GT::child_begin(BB)));
71 inline po_iterator() {} // End is when stack is empty.
73 inline po_iterator(NodeType *BB, SetType &S) :
74 po_iterator_storage<SetType, ExtStorage>(S) {
76 this->Visited.insert(BB);
77 VisitStack.push_back(std::make_pair(BB, GT::child_begin(BB)));
82 inline po_iterator(SetType &S) :
83 po_iterator_storage<SetType, ExtStorage>(S) {
84 } // End is when stack is empty.
86 typedef typename super::pointer pointer;
87 typedef po_iterator<GraphT, SetType, ExtStorage, GT> _Self;
89 // Provide static "constructors"...
90 static inline _Self begin(GraphT G) { return _Self(GT::getEntryNode(G)); }
91 static inline _Self end (GraphT G) { return _Self(); }
93 static inline _Self begin(GraphT G, SetType &S) {
94 return _Self(GT::getEntryNode(G), S);
96 static inline _Self end (GraphT G, SetType &S) { return _Self(S); }
98 inline bool operator==(const _Self& x) const {
99 return VisitStack == x.VisitStack;
101 inline bool operator!=(const _Self& x) const { return !operator==(x); }
103 inline pointer operator*() const {
104 return VisitStack.back().first;
107 // This is a nonstandard operator-> that dereferences the pointer an extra
108 // time... so that you can actually call methods ON the BasicBlock, because
109 // the contained type is a pointer. This allows BBIt->getTerminator() f.e.
111 inline NodeType *operator->() const { return operator*(); }
113 inline _Self& operator++() { // Preincrement
114 VisitStack.pop_back();
115 if (!VisitStack.empty())
120 inline _Self operator++(int) { // Postincrement
121 _Self tmp = *this; ++*this; return tmp;
125 // Provide global constructors that automatically figure out correct types...
128 po_iterator<T> po_begin(T G) { return po_iterator<T>::begin(G); }
130 po_iterator<T> po_end (T G) { return po_iterator<T>::end(G); }
132 // Provide global definitions of external postorder iterators...
133 template<class T, class SetType=std::set<typename GraphTraits<T>::NodeType*> >
134 struct po_ext_iterator : public po_iterator<T, SetType, true> {
135 po_ext_iterator(const po_iterator<T, SetType, true> &V) :
136 po_iterator<T, SetType, true>(V) {}
139 template<class T, class SetType>
140 po_ext_iterator<T, SetType> po_ext_begin(T G, SetType &S) {
141 return po_ext_iterator<T, SetType>::begin(G, S);
144 template<class T, class SetType>
145 po_ext_iterator<T, SetType> po_ext_end(T G, SetType &S) {
146 return po_ext_iterator<T, SetType>::end(G, S);
149 // Provide global definitions of inverse post order iterators...
151 class SetType = std::set<typename GraphTraits<T>::NodeType*>,
152 bool External = false>
153 struct ipo_iterator : public po_iterator<Inverse<T>, SetType, External > {
154 ipo_iterator(const po_iterator<Inverse<T>, SetType, External> &V) :
155 po_iterator<Inverse<T>, SetType, External> (V) {}
159 ipo_iterator<T> ipo_begin(T G, bool Reverse = false) {
160 return ipo_iterator<T>::begin(G, Reverse);
164 ipo_iterator<T> ipo_end(T G){
165 return ipo_iterator<T>::end(G);
168 //Provide global definitions of external inverse postorder iterators...
170 class SetType = std::set<typename GraphTraits<T>::NodeType*> >
171 struct ipo_ext_iterator : public ipo_iterator<T, SetType, true> {
172 ipo_ext_iterator(const ipo_iterator<T, SetType, true> &V) :
173 ipo_iterator<T, SetType, true>(&V) {}
174 ipo_ext_iterator(const po_iterator<Inverse<T>, SetType, true> &V) :
175 ipo_iterator<T, SetType, true>(&V) {}
178 template <class T, class SetType>
179 ipo_ext_iterator<T, SetType> ipo_ext_begin(T G, SetType &S) {
180 return ipo_ext_iterator<T, SetType>::begin(G, S);
183 template <class T, class SetType>
184 ipo_ext_iterator<T, SetType> ipo_ext_end(T G, SetType &S) {
185 return ipo_ext_iterator<T, SetType>::end(G, S);
188 //===--------------------------------------------------------------------===//
189 // Reverse Post Order CFG iterator code
190 //===--------------------------------------------------------------------===//
192 // This is used to visit basic blocks in a method in reverse post order. This
193 // class is awkward to use because I don't know a good incremental algorithm to
194 // computer RPO from a graph. Because of this, the construction of the
195 // ReversePostOrderTraversal object is expensive (it must walk the entire graph
196 // with a postorder iterator to build the data structures). The moral of this
197 // story is: Don't create more ReversePostOrderTraversal classes than necessary.
199 // This class should be used like this:
201 // ReversePostOrderTraversal<Function*> RPOT(FuncPtr); // Expensive to create
202 // for (rpo_iterator I = RPOT.begin(); I != RPOT.end(); ++I) {
205 // for (rpo_iterator I = RPOT.begin(); I != RPOT.end(); ++I) {
211 template<class GraphT, class GT = GraphTraits<GraphT> >
212 class ReversePostOrderTraversal {
213 typedef typename GT::NodeType NodeType;
214 std::vector<NodeType*> Blocks; // Block list in normal PO order
215 inline void Initialize(NodeType *BB) {
216 copy(po_begin(BB), po_end(BB), back_inserter(Blocks));
219 typedef typename std::vector<NodeType*>::reverse_iterator rpo_iterator;
221 inline ReversePostOrderTraversal(GraphT G) {
222 Initialize(GT::getEntryNode(G));
225 // Because we want a reverse post order, use reverse iterators from the vector
226 inline rpo_iterator begin() { return Blocks.rbegin(); }
227 inline rpo_iterator end() { return Blocks.rend(); }
230 } // End llvm namespace