X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FADT%2FPostOrderIterator.h;h=7f6350e4443e1567cc712b1e8b6d872bd9bb207a;hb=5d37976090df34f003e5128e39593b763be0ca71;hp=97831a232dfd0510811ca2099537a0453f97bdb6;hpb=9769ab22265b313171d201b5928688524a01bd87;p=oota-llvm.git diff --git a/include/llvm/ADT/PostOrderIterator.h b/include/llvm/ADT/PostOrderIterator.h index 97831a232df..7f6350e4443 100644 --- a/include/llvm/ADT/PostOrderIterator.h +++ b/include/llvm/ADT/PostOrderIterator.h @@ -2,8 +2,8 @@ // // 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 is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // @@ -17,54 +17,137 @@ #define LLVM_ADT_POSTORDERITERATOR_H #include "llvm/ADT/GraphTraits.h" -#include "llvm/ADT/iterator" -#include +#include "llvm/ADT/SmallPtrSet.h" #include +#include namespace llvm { -template > -class po_iterator : public forward_iterator { - typedef forward_iterator super; +// 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 po_iterator_storage { + SetType Visited; +public: + // Return true if edge destination should be visited. + template + bool insertEdge(NodeType *From, NodeType *To) { + return Visited.insert(To); + } + + // Called after all children of BB have been visited. + template + void finishPostorder(NodeType *BB) {} +}; + +/// Specialization of po_iterator_storage that references an external set. +template +class po_iterator_storage { + 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 + bool insertEdge(NodeType *From, NodeType *To) { return Visited.insert(To); } + + // Called after all children of BB have been visited. + template + void finishPostorder(NodeType *BB) {} +}; + +template::NodeType*, 8>, + bool ExtStorage = false, + class GT = GraphTraits > +class po_iterator : public std::iterator, + public po_iterator_storage { + typedef std::iterator super; typedef typename GT::NodeType NodeType; typedef typename GT::ChildIteratorType ChildItTy; - std::set 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 > VisitStack; + std::vector > 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))); + 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(std::make_pair(BB, GT::child_begin(BB))); + this->insertEdge((NodeType*)0, 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(S) { + if (this->insertEdge((NodeType*)0, BB)) { + VisitStack.push_back(std::make_pair(BB, GT::child_begin(BB))); + traverseChild(); + } + } + + inline po_iterator(SetType &S) : + po_iterator_storage(S) { + } // End is when stack is empty. public: typedef typename super::pointer pointer; - typedef po_iterator _Self; + typedef po_iterator _Self; // Provide static "constructors"... static inline _Self begin(GraphT G) { return _Self(GT::getEntryNode(G)); } static inline _Self end (GraphT G) { return _Self(); } + 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; + return VisitStack.back().first; } // This is a nonstandard operator-> that dereferences the pointer an extra @@ -74,7 +157,8 @@ public: 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; @@ -92,10 +176,30 @@ po_iterator po_begin(T G) { return po_iterator::begin(G); } template po_iterator po_end (T G) { return po_iterator::end(G); } +// Provide global definitions of external postorder iterators... +template::NodeType*> > +struct po_ext_iterator : public po_iterator { + po_ext_iterator(const po_iterator &V) : + po_iterator(V) {} +}; + +template +po_ext_iterator po_ext_begin(T G, SetType &S) { + return po_ext_iterator::begin(G, S); +} + +template +po_ext_iterator po_ext_end(T G, SetType &S) { + return po_ext_iterator::end(G, S); +} + // Provide global definitions of inverse post order iterators... -template -struct ipo_iterator : public po_iterator > { - ipo_iterator(const po_iterator > &V) :po_iterator >(V){} +template ::NodeType*>, + bool External = false> +struct ipo_iterator : public po_iterator, SetType, External > { + ipo_iterator(const po_iterator, SetType, External> &V) : + po_iterator, SetType, External> (V) {} }; template @@ -108,6 +212,25 @@ ipo_iterator ipo_end(T G){ return ipo_iterator::end(G); } +// Provide global definitions of external inverse postorder iterators... +template ::NodeType*> > +struct ipo_ext_iterator : public ipo_iterator { + ipo_ext_iterator(const ipo_iterator &V) : + ipo_iterator(V) {} + ipo_ext_iterator(const po_iterator, SetType, true> &V) : + ipo_iterator(V) {} +}; + +template +ipo_ext_iterator ipo_ext_begin(T G, SetType &S) { + return ipo_ext_iterator::begin(G, S); +} + +template +ipo_ext_iterator ipo_ext_end(T G, SetType &S) { + return ipo_ext_iterator::end(G, S); +} //===--------------------------------------------------------------------===// // Reverse Post Order CFG iterator code