145 lines
4.9 KiB
C++
145 lines
4.9 KiB
C++
//===-- Support/PostOrderIterator.h - Generic PostOrder iterator -*- C++ -*--=//
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//
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// This file builds on the Support/GraphTraits.h file to build a generic graph
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// post order iterator. This should work over any graph type that has a
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// GraphTraits specialization.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_POSTORDER_ITERATOR_H
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#define LLVM_SUPPORT_POSTORDER_ITERATOR_H
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#include "Support/GraphTraits.h"
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#include <iterator>
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#include <stack>
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#include <set>
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template<class GraphT, class GT = GraphTraits<GraphT> >
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class po_iterator : public std::forward_iterator<typename GT::NodeType,
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ptrdiff_t> {
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typedef typename GT::NodeType NodeType;
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typedef typename GT::ChildIteratorType ChildItTy;
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std::set<NodeType *> Visited; // All of the blocks visited so far...
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// VisitStack - Used to maintain the ordering. Top = current block
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// First element is basic block pointer, second is the 'next child' to visit
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std::stack<std::pair<NodeType *, ChildItTy> > VisitStack;
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void traverseChild() {
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while (VisitStack.top().second != GT::child_end(VisitStack.top().first)) {
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NodeType *BB = *VisitStack.top().second++;
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if (!Visited.count(BB)) { // If the block is not visited...
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Visited.insert(BB);
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VisitStack.push(make_pair(BB, GT::child_begin(BB)));
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}
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}
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}
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inline po_iterator(NodeType *BB) {
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Visited.insert(BB);
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VisitStack.push(make_pair(BB, GT::child_begin(BB)));
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traverseChild();
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}
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inline po_iterator() { /* End is when stack is empty */ }
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public:
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typedef po_iterator<GraphT, GT> _Self;
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// Provide static "constructors"...
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static inline _Self begin(GraphT G) { return _Self(GT::getEntryNode(G)); }
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static inline _Self end (GraphT G) { return _Self(); }
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inline bool operator==(const _Self& x) const {
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return VisitStack == x.VisitStack;
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}
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inline bool operator!=(const _Self& x) const { return !operator==(x); }
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inline pointer operator*() const {
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return VisitStack.top().first;
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}
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// This is a nonstandard operator-> that dereferences the pointer an extra
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// time... so that you can actually call methods ON the BasicBlock, because
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// the contained type is a pointer. This allows BBIt->getTerminator() f.e.
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//
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inline NodeType *operator->() const { return operator*(); }
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inline _Self& operator++() { // Preincrement
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VisitStack.pop();
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if (!VisitStack.empty())
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traverseChild();
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return *this;
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}
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inline _Self operator++(int) { // Postincrement
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_Self tmp = *this; ++*this; return tmp;
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}
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};
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// Provide global constructors that automatically figure out correct types...
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//
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template <class T>
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po_iterator<T> po_begin(T G) { return po_iterator<T>::begin(G); }
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template <class T>
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po_iterator<T> po_end (T G) { return po_iterator<T>::end(G); }
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// Provide global definitions of inverse post order iterators...
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template <class T>
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struct ipo_iterator : public po_iterator<Inverse<T> > {
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ipo_iterator(const po_iterator<Inverse<T> > &V) :po_iterator<Inverse<T> >(V){}
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};
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template <class T>
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ipo_iterator<T> ipo_begin(T G, bool Reverse = false) {
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return ipo_iterator<T>::begin(G, Reverse);
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}
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template <class T>
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ipo_iterator<T> ipo_end(T G){
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return ipo_iterator<T>::end(G);
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}
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//===--------------------------------------------------------------------===//
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// Reverse Post Order CFG iterator code
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//===--------------------------------------------------------------------===//
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//
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// This is used to visit basic blocks in a method in reverse post order. This
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// class is awkward to use because I don't know a good incremental algorithm to
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// computer RPO from a graph. Because of this, the construction of the
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// ReversePostOrderTraversal object is expensive (it must walk the entire graph
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// with a postorder iterator to build the data structures). The moral of this
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// story is: Don't create more ReversePostOrderTraversal classes than neccesary.
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//
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// This class should be used like this:
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// {
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// ReversePostOrderTraversal<Method*> RPOT(MethodPtr); // Expensive to create
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// for (rpo_iterator I = RPOT.begin(); I != RPOT.end(); ++I) {
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// ...
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// }
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// for (rpo_iterator I = RPOT.begin(); I != RPOT.end(); ++I) {
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// ...
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// }
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// }
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//
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template<class GraphT, class GT = GraphTraits<GraphT> >
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class ReversePostOrderTraversal {
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typedef typename GT::NodeType NodeType;
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std::vector<NodeType*> Blocks; // Block list in normal PO order
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inline void Initialize(NodeType *BB) {
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copy(po_begin(BB), po_end(BB), back_inserter(Blocks));
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}
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public:
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typedef std::vector<NodeType*>::reverse_iterator rpo_iterator;
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inline ReversePostOrderTraversal(GraphT G) {
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Initialize(GT::getEntryNode(G));
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}
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// Because we want a reverse post order, use reverse iterators from the vector
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inline rpo_iterator begin() { return Blocks.rbegin(); }
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inline rpo_iterator end() { return Blocks.rend(); }
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};
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#endif
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