-//===-- Support/PostOrderIterator.h - Generic PostOrder iterator -*- C++ -*--=//
+//===- llvm/ADT/PostOrderIterator.h - PostOrder iterator --------*- C++ -*-===//
//
-// This file builds on the Support/GraphTraits.h file to build a generic graph
+// The LLVM Compiler Infrastructure
+//
+// This file 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_SUPPORT_POSTORDER_ITERATOR_H
-#define LLVM_SUPPORT_POSTORDER_ITERATOR_H
+#ifndef LLVM_ADT_POSTORDERITERATOR_H
+#define LLVM_ADT_POSTORDERITERATOR_H
-#include "Support/GraphTraits.h"
-#include <Support/iterator>
-#include <stack>
+#include "llvm/ADT/GraphTraits.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include <set>
+#include <vector>
-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 super::pointer pointer;
+namespace llvm {
+
+// The po_iterator_storage template provides access to the set of already
+// visited nodes during the po_iterator's depth-first traversal.
+//
+// The default implementation simply contains a set of visited nodes, while
+// the Extended=true version uses a reference to an external set.
+//
+// It is possible to prune the depth-first traversal in several ways:
+//
+// - When providing an external set that already contains some graph nodes,
+// those nodes won't be visited again. This is useful for restarting a
+// post-order traversal on a graph with nodes that aren't dominated by a
+// single node.
+//
+// - By providing a custom SetType class, unwanted graph nodes can be excluded
+// by having the insert() function return false. This could for example
+// confine a CFG traversal to blocks in a specific loop.
+//
+// - Finally, by specializing the po_iterator_storage template itself, graph
+// edges can be pruned by returning false in the insertEdge() function. This
+// could be used to remove loop back-edges from the CFG seen by po_iterator.
+//
+// A specialized po_iterator_storage class can observe both the pre-order and
+// the post-order. The insertEdge() function is called in a pre-order, while
+// the finishPostorder() function is called just before the po_iterator moves
+// on to the next node.
+
+/// Default po_iterator_storage implementation with an internal set object.
+template<class SetType, bool External>
+class po_iterator_storage {
+ SetType Visited;
+public:
+ // Return true if edge destination should be visited.
+ template<typename NodeType>
+ bool insertEdge(NodeType *From, NodeType *To) {
+ return Visited.insert(To);
+ }
+
+ // Called after all children of BB have been visited.
+ template<typename NodeType>
+ void finishPostorder(NodeType *BB) {}
+};
+
+/// Specialization of po_iterator_storage that references an external set.
+template<class SetType>
+class po_iterator_storage<SetType, true> {
+ SetType &Visited;
+public:
+ po_iterator_storage(SetType &VSet) : Visited(VSet) {}
+ po_iterator_storage(const po_iterator_storage &S) : Visited(S.Visited) {}
+
+ // Return true if edge destination should be visited, called with From = 0 for
+ // the root node.
+ // Graph edges can be pruned by specializing this function.
+ template<class NodeType>
+ bool insertEdge(NodeType *From, NodeType *To) { return Visited.insert(To); }
+
+ // Called after all children of BB have been visited.
+ template<class NodeType>
+ void finishPostorder(NodeType *BB) {}
+};
+
+template<class GraphT,
+ class SetType = llvm::SmallPtrSet<typename GraphTraits<GraphT>::NodeType*, 8>,
+ bool ExtStorage = false,
+ class GT = GraphTraits<GraphT> >
+class po_iterator : public std::iterator<std::forward_iterator_tag,
+ typename GT::NodeType, ptrdiff_t>,
+ public po_iterator_storage<SetType, ExtStorage> {
+ typedef std::iterator<std::forward_iterator_tag,
+ 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;
+ std::vector<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(make_pair(BB, GT::child_begin(BB)));
+ while (VisitStack.back().second != GT::child_end(VisitStack.back().first)) {
+ NodeType *BB = *VisitStack.back().second++;
+ if (this->insertEdge(VisitStack.back().first, BB)) {
+ // If the block is not visited...
+ VisitStack.push_back(std::make_pair(BB, GT::child_begin(BB)));
}
}
}
inline po_iterator(NodeType *BB) {
- Visited.insert(BB);
- VisitStack.push(make_pair(BB, GT::child_begin(BB)));
+ this->insertEdge((NodeType*)nullptr, BB);
+ VisitStack.push_back(std::make_pair(BB, GT::child_begin(BB)));
traverseChild();
}
- inline po_iterator() { /* End is when stack is empty */ }
+ inline po_iterator() {} // End is when stack is empty.
+
+ inline po_iterator(NodeType *BB, SetType &S) :
+ po_iterator_storage<SetType, ExtStorage>(S) {
+ if (this->insertEdge((NodeType*)nullptr, BB)) {
+ VisitStack.push_back(std::make_pair(BB, GT::child_begin(BB)));
+ traverseChild();
+ }
+ }
+
+ inline po_iterator(SetType &S) :
+ po_iterator_storage<SetType, ExtStorage>(S) {
+ } // End is when stack is empty.
public:
- typedef po_iterator<GraphT, GT> _Self;
+ typedef typename super::pointer pointer;
+ typedef po_iterator<GraphT, SetType, ExtStorage, 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 {
+ static inline _Self begin(GraphT G, SetType &S) {
+ return _Self(GT::getEntryNode(G), S);
+ }
+ static inline _Self end (GraphT G, SetType &S) { return _Self(S); }
+
+ 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;
+ inline pointer operator*() const {
+ return VisitStack.back().first;
}
// This is a nonstandard operator-> that dereferences the pointer an extra
inline NodeType *operator->() const { return operator*(); }
inline _Self& operator++() { // Preincrement
- VisitStack.pop();
+ this->finishPostorder(VisitStack.back().first);
+ VisitStack.pop_back();
if (!VisitStack.empty())
traverseChild();
- return *this;
+ return *this;
}
inline _Self operator++(int) { // Postincrement
- _Self tmp = *this; ++*this; return tmp;
+ _Self tmp = *this; ++*this; return tmp;
}
};
template <class T>
po_iterator<T> po_end (T G) { return po_iterator<T>::end(G); }
+// Provide global definitions of external postorder iterators...
+template<class T, class SetType=std::set<typename GraphTraits<T>::NodeType*> >
+struct po_ext_iterator : public po_iterator<T, SetType, true> {
+ po_ext_iterator(const po_iterator<T, SetType, true> &V) :
+ po_iterator<T, SetType, true>(V) {}
+};
+
+template<class T, class SetType>
+po_ext_iterator<T, SetType> po_ext_begin(T G, SetType &S) {
+ return po_ext_iterator<T, SetType>::begin(G, S);
+}
+
+template<class T, class SetType>
+po_ext_iterator<T, SetType> po_ext_end(T G, SetType &S) {
+ return po_ext_iterator<T, SetType>::end(G, S);
+}
+
// 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,
+ class SetType = std::set<typename GraphTraits<T>::NodeType*>,
+ bool External = false>
+struct ipo_iterator : public po_iterator<Inverse<T>, SetType, External > {
+ ipo_iterator(const po_iterator<Inverse<T>, SetType, External> &V) :
+ po_iterator<Inverse<T>, SetType, External> (V) {}
};
template <class T>
return ipo_iterator<T>::end(G);
}
+// Provide global definitions of external inverse postorder iterators...
+template <class T,
+ class SetType = std::set<typename GraphTraits<T>::NodeType*> >
+struct ipo_ext_iterator : public ipo_iterator<T, SetType, true> {
+ ipo_ext_iterator(const ipo_iterator<T, SetType, true> &V) :
+ ipo_iterator<T, SetType, true>(V) {}
+ ipo_ext_iterator(const po_iterator<Inverse<T>, SetType, true> &V) :
+ ipo_iterator<T, SetType, true>(V) {}
+};
+
+template <class T, class SetType>
+ipo_ext_iterator<T, SetType> ipo_ext_begin(T G, SetType &S) {
+ return ipo_ext_iterator<T, SetType>::begin(G, S);
+}
+
+template <class T, class SetType>
+ipo_ext_iterator<T, SetType> ipo_ext_end(T G, SetType &S) {
+ return ipo_ext_iterator<T, SetType>::end(G, S);
+}
//===--------------------------------------------------------------------===//
// 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
+// 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 neccesary.
+// story is: Don't create more ReversePostOrderTraversal classes than necessary.
//
// This class should be used like this:
// {
-// ReversePostOrderTraversal<Method*> RPOT(MethodPtr); // Expensive to create
+// ReversePostOrderTraversal<Function*> RPOT(FuncPtr); // Expensive to create
// for (rpo_iterator I = RPOT.begin(); I != RPOT.end(); ++I) {
// ...
// }
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));
+ std::copy(po_begin(BB), po_end(BB), std::back_inserter(Blocks));
}
public:
typedef typename std::vector<NodeType*>::reverse_iterator rpo_iterator;
inline rpo_iterator end() { return Blocks.rend(); }
};
+} // End llvm namespace
+
#endif
projects / oota-llvm.git / blobdiff