#include "llvm/ADT/GraphTraits.h"
#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/iterator_range.h"
#include <set>
#include <vector>
namespace llvm {
-template<class SetType, bool External> // Non-external set
+// 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 {
-public:
SetType Visited;
+public:
+ // Return true if edge destination should be visited.
+ template<typename NodeType>
+ bool insertEdge(NodeType *From, NodeType *To) {
+ return Visited.insert(To).second;
+ }
+
+ // 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) {}
- SetType &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).second;
+ }
+
+ // Called after all children of BB have been visited.
+ template<class NodeType>
+ void finishPostorder(NodeType *BB) {}
};
template<class GraphT,
void traverseChild() {
while (VisitStack.back().second != GT::child_end(VisitStack.back().first)) {
NodeType *BB = *VisitStack.back().second++;
- if (!this->Visited.count(BB)) { // If the block is not visited...
- this->Visited.insert(BB);
+ 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) {
- this->Visited.insert(BB);
+ po_iterator(NodeType *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.
+ po_iterator() {} // End is when stack is empty.
- inline po_iterator(NodeType *BB, SetType &S) :
- po_iterator_storage<SetType, ExtStorage>(S) {
- if(!S.count(BB)) {
- this->Visited.insert(BB);
+ 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) {
+ po_iterator(SetType &S)
+ : po_iterator_storage<SetType, ExtStorage>(S) {
} // End is when stack is empty.
public:
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(); }
+ static po_iterator begin(GraphT G) {
+ return po_iterator(GT::getEntryNode(G));
+ }
+ static po_iterator end(GraphT G) { return po_iterator(); }
- static inline _Self begin(GraphT G, SetType &S) {
- return _Self(GT::getEntryNode(G), S);
+ static po_iterator begin(GraphT G, SetType &S) {
+ return po_iterator(GT::getEntryNode(G), S);
}
- static inline _Self end (GraphT G, SetType &S) { return _Self(S); }
+ static po_iterator end(GraphT G, SetType &S) { return po_iterator(S); }
- inline bool operator==(const _Self& x) const {
+ bool operator==(const po_iterator &x) const {
return VisitStack == x.VisitStack;
}
- inline bool operator!=(const _Self& x) const { return !operator==(x); }
+ bool operator!=(const po_iterator &x) const { return !(*this == x); }
- inline pointer operator*() const {
- return VisitStack.back().first;
- }
+ pointer operator*() const { return VisitStack.back().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*(); }
+ NodeType *operator->() const { return **this; }
- inline _Self& operator++() { // Preincrement
+ po_iterator &operator++() { // Preincrement
+ this->finishPostorder(VisitStack.back().first);
VisitStack.pop_back();
if (!VisitStack.empty())
traverseChild();
return *this;
}
- inline _Self operator++(int) { // Postincrement
- _Self tmp = *this; ++*this; return tmp;
+ po_iterator operator++(int) { // Postincrement
+ po_iterator 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); }
+po_iterator<T> po_begin(const T &G) { return po_iterator<T>::begin(G); }
template <class T>
-po_iterator<T> po_end (T G) { return po_iterator<T>::end(G); }
+po_iterator<T> po_end (const T &G) { return po_iterator<T>::end(G); }
+
+template <class T> iterator_range<po_iterator<T>> post_order(const T &G) {
+ return make_range(po_begin(G), po_end(G));
+}
// Provide global definitions of external postorder iterators...
template<class T, class SetType=std::set<typename GraphTraits<T>::NodeType*> >
return po_ext_iterator<T, SetType>::end(G, S);
}
+template <class T, class SetType>
+iterator_range<po_ext_iterator<T, SetType>> post_order_ext(const T &G, SetType &S) {
+ return make_range(po_ext_begin(G, S), po_ext_end(G, S));
+}
+
// Provide global definitions of inverse post order iterators...
template <class T,
class SetType = std::set<typename GraphTraits<T>::NodeType*>,
};
template <class T>
-ipo_iterator<T> ipo_begin(T G, bool Reverse = false) {
+ipo_iterator<T> ipo_begin(const T &G, bool Reverse = false) {
return ipo_iterator<T>::begin(G, Reverse);
}
template <class T>
-ipo_iterator<T> ipo_end(T G){
+ipo_iterator<T> ipo_end(const T &G){
return ipo_iterator<T>::end(G);
}
-//Provide global definitions of external inverse postorder iterators...
+template <class T>
+iterator_range<ipo_iterator<T>> inverse_post_order(const T &G, bool Reverse = false) {
+ return make_range(ipo_begin(G, Reverse), ipo_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_iterator<T, SetType, true>(V) {}
ipo_ext_iterator(const po_iterator<Inverse<T>, SetType, true> &V) :
- ipo_iterator<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) {
+ipo_ext_iterator<T, SetType> ipo_ext_begin(const 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) {
+ipo_ext_iterator<T, SetType> ipo_ext_end(const T &G, SetType &S) {
return ipo_ext_iterator<T, SetType>::end(G, S);
}
+template <class T, class SetType>
+iterator_range<ipo_ext_iterator<T, SetType>>
+inverse_post_order_ext(const T &G, SetType &S) {
+ return make_range(ipo_ext_begin(G, S), ipo_ext_end(G, S));
+}
+
//===--------------------------------------------------------------------===//
// Reverse Post Order CFG iterator code
//===--------------------------------------------------------------------===//
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));
+ void Initialize(NodeType *BB) {
+ std::copy(po_begin(BB), po_end(BB), std::back_inserter(Blocks));
}
public:
typedef typename std::vector<NodeType*>::reverse_iterator rpo_iterator;
- inline ReversePostOrderTraversal(GraphT G) {
- Initialize(GT::getEntryNode(G));
- }
+ 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(); }
+ rpo_iterator begin() { return Blocks.rbegin(); }
+ rpo_iterator end() { return Blocks.rend(); }
};
} // End llvm namespace
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