//===- 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 builds on the ADT/GraphTraits.h file to build a generic graph // post order iterator. This should work over any graph type that has a // GraphTraits specialization. // //===----------------------------------------------------------------------===// #ifndef LLVM_ADT_POSTORDERITERATOR_H #define LLVM_ADT_POSTORDERITERATOR_H #include "llvm/ADT/GraphTraits.h" #include "llvm/ADT/iterator" #include <stack> #include <set> 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; 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; 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))); } } } inline po_iterator(NodeType *BB) { Visited.insert(BB); VisitStack.push(std::make_pair(BB, GT::child_begin(BB))); traverseChild(); } inline po_iterator() { /* End is when stack is empty */ } public: typedef typename super::pointer pointer; typedef po_iterator<GraphT, 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 { return VisitStack == x.VisitStack; } inline bool operator!=(const _Self& x) const { return !operator==(x); } inline pointer operator*() const { return VisitStack.top().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*(); } inline _Self& operator++() { // Preincrement VisitStack.pop(); if (!VisitStack.empty()) traverseChild(); return *this; } inline _Self operator++(int) { // Postincrement _Self 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); } template <class T> po_iterator<T> po_end (T G) { return po_iterator<T>::end(G); } // 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> ipo_iterator<T> ipo_begin(T G, bool Reverse = false) { return ipo_iterator<T>::begin(G, Reverse); } template <class T> ipo_iterator<T> ipo_end(T G){ return ipo_iterator<T>::end(G); } //===--------------------------------------------------------------------===// // 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 // 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. // // This class should be used like this: // { // ReversePostOrderTraversal<Function*> RPOT(FuncPtr); // Expensive to create // for (rpo_iterator I = RPOT.begin(); I != RPOT.end(); ++I) { // ... // } // for (rpo_iterator I = RPOT.begin(); I != RPOT.end(); ++I) { // ... // } // } // 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)); } public: typedef typename std::vector<NodeType*>::reverse_iterator rpo_iterator; inline 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(); } }; } // End llvm namespace #endif