PostOrderIterator.h revision 8b6cea1b9595c1ddbb07dbbe8a8af781d78cd51d
1//===- llvm/ADT/PostOrderIterator.h - PostOrder iterator --------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 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. 7// 8//===----------------------------------------------------------------------===// 9// 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. 13// 14//===----------------------------------------------------------------------===// 15 16#ifndef LLVM_ADT_POSTORDERITERATOR_H 17#define LLVM_ADT_POSTORDERITERATOR_H 18 19#include "llvm/ADT/GraphTraits.h" 20#include "llvm/ADT/iterator" 21#include <stack> 22#include <set> 23 24namespace llvm { 25 26template<class SetType, bool External> // Non-external set 27class po_iterator_storage { 28public: 29 SetType Visited; 30}; 31 32template<class SetType> 33class po_iterator_storage<SetType, true> { 34public: 35 po_iterator_storage(SetType &VSet) : Visited(VSet) {} 36 po_iterator_storage(const po_iterator_storage &S) : Visited(S.Visited) {} 37 SetType &Visited; 38}; 39 40template<class GraphT, 41 class SetType = std::set<typename GraphTraits<GraphT>::NodeType*>, 42 bool ExtStorage = false, 43 class GT = GraphTraits<GraphT> > 44class po_iterator : public forward_iterator<typename GT::NodeType, ptrdiff_t>, 45 public po_iterator_storage<SetType, ExtStorage> { 46 typedef forward_iterator<typename GT::NodeType, ptrdiff_t> super; 47 typedef typename GT::NodeType NodeType; 48 typedef typename GT::ChildIteratorType ChildItTy; 49 50 // VisitStack - Used to maintain the ordering. Top = current block 51 // First element is basic block pointer, second is the 'next child' to visit 52 std::stack<std::pair<NodeType *, ChildItTy> > VisitStack; 53 54 void traverseChild() { 55 while (VisitStack.top().second != GT::child_end(VisitStack.top().first)) { 56 NodeType *BB = *VisitStack.top().second++; 57 if (!this->Visited.count(BB)) { // If the block is not visited... 58 this->Visited.insert(BB); 59 VisitStack.push(std::make_pair(BB, GT::child_begin(BB))); 60 } 61 } 62 } 63 64 inline po_iterator(NodeType *BB) { 65 this->Visited.insert(BB); 66 VisitStack.push(std::make_pair(BB, GT::child_begin(BB))); 67 traverseChild(); 68 } 69 inline po_iterator() {} // End is when stack is empty. 70 71 inline po_iterator(NodeType *BB, SetType &S) : 72 po_iterator_storage<SetType, ExtStorage>(&S) { 73 if(!S.count(BB)) { 74 this->Visited.insert(BB); 75 VisitStack.push(std::make_pair(BB, GT::child_begin(BB))); 76 traverseChild(); 77 } 78 } 79 80 inline po_iterator(SetType &S) : 81 po_iterator_storage<SetType, ExtStorage>(&S) { 82 } // End is when stack is empty. 83public: 84 typedef typename super::pointer pointer; 85 typedef po_iterator<GraphT, SetType, ExtStorage, GT> _Self; 86 87 // Provide static "constructors"... 88 static inline _Self begin(GraphT G) { return _Self(GT::getEntryNode(G)); } 89 static inline _Self end (GraphT G) { return _Self(); } 90 91 static inline _Self begin(GraphT G, SetType &S) { 92 return _Self(GT::getEntryNode(G), S); 93 } 94 static inline _Self end (GraphT G, SetType &S) { return _Self(S); } 95 96 inline bool operator==(const _Self& x) const { 97 return VisitStack == x.VisitStack; 98 } 99 inline bool operator!=(const _Self& x) const { return !operator==(x); } 100 101 inline pointer operator*() const { 102 return VisitStack.top().first; 103 } 104 105 // This is a nonstandard operator-> that dereferences the pointer an extra 106 // time... so that you can actually call methods ON the BasicBlock, because 107 // the contained type is a pointer. This allows BBIt->getTerminator() f.e. 108 // 109 inline NodeType *operator->() const { return operator*(); } 110 111 inline _Self& operator++() { // Preincrement 112 VisitStack.pop(); 113 if (!VisitStack.empty()) 114 traverseChild(); 115 return *this; 116 } 117 118 inline _Self operator++(int) { // Postincrement 119 _Self tmp = *this; ++*this; return tmp; 120 } 121}; 122 123// Provide global constructors that automatically figure out correct types... 124// 125template <class T> 126po_iterator<T> po_begin(T G) { return po_iterator<T>::begin(G); } 127template <class T> 128po_iterator<T> po_end (T G) { return po_iterator<T>::end(G); } 129 130// Provide global definitions of external postorder iterators... 131template<class T, class SetType=std::set<typename GraphTraits<T>::NodeType*> > 132struct po_ext_iterator : public po_iterator<T, SetType, true> { 133 po_ext_iterator(const po_iterator<T, SetType, true> &V) : 134 po_iterator<T, SetType, true>(V) {} 135}; 136 137template<class T, class SetType> 138po_ext_iterator<T, SetType> po_ext_begin(T G, SetType &S) { 139 return po_ext_iterator<T, SetType>::begin(G, S); 140} 141 142template<class T, class SetType> 143po_ext_iterator<T, SetType> po_ext_end(T G, SetType &S) { 144 return po_ext_iterator<T, SetType>::end(G, S); 145} 146 147// Provide global definitions of inverse post order iterators... 148template <class T, 149 class SetType = std::set<typename GraphTraits<T>::NoddeType*>, 150 bool External = false> 151struct ipo_iterator : public po_iterator<Inverse<T>, SetType, External > { 152 ipo_iterator(const po_iterator<Inverse<T>, SetType, External> &V) : 153 po_iterator<Inverse<T>, SetType, External> (V) {} 154}; 155 156template <class T> 157ipo_iterator<T> ipo_begin(T G, bool Reverse = false) { 158 return ipo_iterator<T>::begin(G, Reverse); 159} 160 161template <class T> 162ipo_iterator<T> ipo_end(T G){ 163 return ipo_iterator<T>::end(G); 164} 165 166//Provide global definitions of external inverse postorder iterators... 167template <class T, class SetType = std::set<typename GraphTraits<T>::NodeType*> > 168struct ipo_ext_iterator : public ipo_iterator<T, SetType, true> { 169 ipo_ext_iterator(const ipo_iterator<T, SetType, true> &V) : 170 ipo_iterator<T, SetType, true>(&V) {} 171 ipo_ext_iterator(const po_iterator<Inverse<T>, SetType, true> &V) : 172 ipo_iterator<T, SetType, true>(&V) {} 173}; 174 175template <class T, class SetType> 176ipo_ext_iterator<T, SetType> ipo_ext_begin(T G, SetType &S) { 177 return ipo_ext_iterator<T, SetType>::begin(G, S); 178} 179 180template <class T, class SetType> 181ipo_ext_iterator<T, SetType> ipo_ext_end(T G, SetType &S) { 182 return ipo_ext_iterator<T, SetType>::end(G, S); 183} 184 185//===--------------------------------------------------------------------===// 186// Reverse Post Order CFG iterator code 187//===--------------------------------------------------------------------===// 188// 189// This is used to visit basic blocks in a method in reverse post order. This 190// class is awkward to use because I don't know a good incremental algorithm to 191// computer RPO from a graph. Because of this, the construction of the 192// ReversePostOrderTraversal object is expensive (it must walk the entire graph 193// with a postorder iterator to build the data structures). The moral of this 194// story is: Don't create more ReversePostOrderTraversal classes than necessary. 195// 196// This class should be used like this: 197// { 198// ReversePostOrderTraversal<Function*> RPOT(FuncPtr); // Expensive to create 199// for (rpo_iterator I = RPOT.begin(); I != RPOT.end(); ++I) { 200// ... 201// } 202// for (rpo_iterator I = RPOT.begin(); I != RPOT.end(); ++I) { 203// ... 204// } 205// } 206// 207 208template<class GraphT, class GT = GraphTraits<GraphT> > 209class ReversePostOrderTraversal { 210 typedef typename GT::NodeType NodeType; 211 std::vector<NodeType*> Blocks; // Block list in normal PO order 212 inline void Initialize(NodeType *BB) { 213 copy(po_begin(BB), po_end(BB), back_inserter(Blocks)); 214 } 215public: 216 typedef typename std::vector<NodeType*>::reverse_iterator rpo_iterator; 217 218 inline ReversePostOrderTraversal(GraphT G) { 219 Initialize(GT::getEntryNode(G)); 220 } 221 222 // Because we want a reverse post order, use reverse iterators from the vector 223 inline rpo_iterator begin() { return Blocks.rbegin(); } 224 inline rpo_iterator end() { return Blocks.rend(); } 225}; 226 227} // End llvm namespace 228 229#endif 230