//===-- llvm/ADT/FoldingSet.h - Uniquing Hash Set ---------------*- C++ -*-===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file defines a hash set that can be used to remove duplication of nodes // in a graph. This code was originally created by Chris Lattner for use with // SelectionDAGCSEMap, but was isolated to provide use across the llvm code set. // //===----------------------------------------------------------------------===// #ifndef LLVM_ADT_FOLDINGSET_H #define LLVM_ADT_FOLDINGSET_H #include "llvm/System/DataTypes.h" #include "llvm/ADT/SmallVector.h" #include "llvm/ADT/StringRef.h" namespace llvm { class APFloat; class APInt; class BumpPtrAllocator; /// This folding set used for two purposes: /// 1. Given information about a node we want to create, look up the unique /// instance of the node in the set. If the node already exists, return /// it, otherwise return the bucket it should be inserted into. /// 2. Given a node that has already been created, remove it from the set. /// /// This class is implemented as a single-link chained hash table, where the /// "buckets" are actually the nodes themselves (the next pointer is in the /// node). The last node points back to the bucket to simplify node removal. /// /// Any node that is to be included in the folding set must be a subclass of /// FoldingSetNode. The node class must also define a Profile method used to /// establish the unique bits of data for the node. The Profile method is /// passed a FoldingSetNodeID object which is used to gather the bits. Just /// call one of the Add* functions defined in the FoldingSetImpl::NodeID class. /// NOTE: That the folding set does not own the nodes and it is the /// responsibility of the user to dispose of the nodes. /// /// Eg. /// class MyNode : public FoldingSetNode { /// private: /// std::string Name; /// unsigned Value; /// public: /// MyNode(const char *N, unsigned V) : Name(N), Value(V) {} /// ... /// void Profile(FoldingSetNodeID &ID) const { /// ID.AddString(Name); /// ID.AddInteger(Value); /// } /// ... /// }; /// /// To define the folding set itself use the FoldingSet template; /// /// Eg. /// FoldingSet<MyNode> MyFoldingSet; /// /// Four public methods are available to manipulate the folding set; /// /// 1) If you have an existing node that you want add to the set but unsure /// that the node might already exist then call; /// /// MyNode *M = MyFoldingSet.GetOrInsertNode(N); /// /// If The result is equal to the input then the node has been inserted. /// Otherwise, the result is the node existing in the folding set, and the /// input can be discarded (use the result instead.) /// /// 2) If you are ready to construct a node but want to check if it already /// exists, then call FindNodeOrInsertPos with a FoldingSetNodeID of the bits to /// check; /// /// FoldingSetNodeID ID; /// ID.AddString(Name); /// ID.AddInteger(Value); /// void *InsertPoint; /// /// MyNode *M = MyFoldingSet.FindNodeOrInsertPos(ID, InsertPoint); /// /// If found then M with be non-NULL, else InsertPoint will point to where it /// should be inserted using InsertNode. /// /// 3) If you get a NULL result from FindNodeOrInsertPos then you can as a new /// node with FindNodeOrInsertPos; /// /// InsertNode(N, InsertPoint); /// /// 4) Finally, if you want to remove a node from the folding set call; /// /// bool WasRemoved = RemoveNode(N); /// /// The result indicates whether the node existed in the folding set. class FoldingSetNodeID; //===----------------------------------------------------------------------===// /// FoldingSetImpl - Implements the folding set functionality. The main /// structure is an array of buckets. Each bucket is indexed by the hash of /// the nodes it contains. The bucket itself points to the nodes contained /// in the bucket via a singly linked list. The last node in the list points /// back to the bucket to facilitate node removal. /// class FoldingSetImpl { protected: /// Buckets - Array of bucket chains. /// void **Buckets; /// NumBuckets - Length of the Buckets array. Always a power of 2. /// unsigned NumBuckets; /// NumNodes - Number of nodes in the folding set. Growth occurs when NumNodes /// is greater than twice the number of buckets. unsigned NumNodes; public: explicit FoldingSetImpl(unsigned Log2InitSize = 6); virtual ~FoldingSetImpl(); //===--------------------------------------------------------------------===// /// Node - This class is used to maintain the singly linked bucket list in /// a folding set. /// class Node { private: // NextInFoldingSetBucket - next link in the bucket list. void *NextInFoldingSetBucket; public: Node() : NextInFoldingSetBucket(0) {} // Accessors void *getNextInBucket() const { return NextInFoldingSetBucket; } void SetNextInBucket(void *N) { NextInFoldingSetBucket = N; } }; /// clear - Remove all nodes from the folding set. void clear(); /// RemoveNode - Remove a node from the folding set, returning true if one /// was removed or false if the node was not in the folding set. bool RemoveNode(Node *N); /// GetOrInsertNode - If there is an existing simple Node exactly /// equal to the specified node, return it. Otherwise, insert 'N' and return /// it instead. Node *GetOrInsertNode(Node *N); /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists, /// return it. If not, return the insertion token that will make insertion /// faster. Node *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos); /// InsertNode - Insert the specified node into the folding set, knowing that /// it is not already in the folding set. InsertPos must be obtained from /// FindNodeOrInsertPos. void InsertNode(Node *N, void *InsertPos); /// size - Returns the number of nodes in the folding set. unsigned size() const { return NumNodes; } /// empty - Returns true if there are no nodes in the folding set. bool empty() const { return NumNodes == 0; } private: /// GrowHashTable - Double the size of the hash table and rehash everything. /// void GrowHashTable(); protected: /// GetNodeProfile - Instantiations of the FoldingSet template implement /// this function to gather data bits for the given node. virtual void GetNodeProfile(FoldingSetNodeID &ID, Node *N) const = 0; }; //===----------------------------------------------------------------------===// /// FoldingSetTrait - This trait class is used to define behavior of how /// to "profile" (in the FoldingSet parlance) an object of a given type. /// The default behavior is to invoke a 'Profile' method on an object, but /// through template specialization the behavior can be tailored for specific /// types. Combined with the FoldingSetNodeWrapper classs, one can add objects /// to FoldingSets that were not originally designed to have that behavior. /// template<typename T> struct FoldingSetTrait { static inline void Profile(const T& X, FoldingSetNodeID& ID) { X.Profile(ID);} static inline void Profile(T& X, FoldingSetNodeID& ID) { X.Profile(ID); } }; //===--------------------------------------------------------------------===// /// FoldingSetNodeIDRef - This class describes a reference to an interned /// FoldingSetNodeID, which can be a useful to store node id data rather /// than using plain FoldingSetNodeIDs, since the 32-element SmallVector /// is often much larger than necessary, and the possibility of heap /// allocation means it requires a non-trivial destructor call. class FoldingSetNodeIDRef { unsigned* Data; size_t Size; public: FoldingSetNodeIDRef() : Data(0), Size(0) {} FoldingSetNodeIDRef(unsigned *D, size_t S) : Data(D), Size(S) {} unsigned *getData() const { return Data; } size_t getSize() const { return Size; } }; //===--------------------------------------------------------------------===// /// FoldingSetNodeID - This class is used to gather all the unique data bits of /// a node. When all the bits are gathered this class is used to produce a /// hash value for the node. /// class FoldingSetNodeID { /// Bits - Vector of all the data bits that make the node unique. /// Use a SmallVector to avoid a heap allocation in the common case. SmallVector<unsigned, 32> Bits; public: FoldingSetNodeID() {} FoldingSetNodeID(FoldingSetNodeIDRef Ref) : Bits(Ref.getData(), Ref.getData() + Ref.getSize()) {} /// Add* - Add various data types to Bit data. /// void AddPointer(const void *Ptr); void AddInteger(signed I); void AddInteger(unsigned I); void AddInteger(long I); void AddInteger(unsigned long I); void AddInteger(long long I); void AddInteger(unsigned long long I); void AddBoolean(bool B) { AddInteger(B ? 1U : 0U); } void AddString(StringRef String); template <typename T> inline void Add(const T& x) { FoldingSetTrait<T>::Profile(x, *this); } /// clear - Clear the accumulated profile, allowing this FoldingSetNodeID /// object to be used to compute a new profile. inline void clear() { Bits.clear(); } /// ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used /// to lookup the node in the FoldingSetImpl. unsigned ComputeHash() const; /// operator== - Used to compare two nodes to each other. /// bool operator==(const FoldingSetNodeID &RHS) const; /// Intern - Copy this node's data to a memory region allocated from the /// given allocator and return a FoldingSetNodeIDRef describing the /// interned data. FoldingSetNodeIDRef Intern(BumpPtrAllocator &Allocator) const; }; // Convenience type to hide the implementation of the folding set. typedef FoldingSetImpl::Node FoldingSetNode; template<class T> class FoldingSetIterator; template<class T> class FoldingSetBucketIterator; //===----------------------------------------------------------------------===// /// FoldingSet - This template class is used to instantiate a specialized /// implementation of the folding set to the node class T. T must be a /// subclass of FoldingSetNode and implement a Profile function. /// template<class T> class FoldingSet : public FoldingSetImpl { private: /// GetNodeProfile - Each instantiatation of the FoldingSet needs to provide a /// way to convert nodes into a unique specifier. virtual void GetNodeProfile(FoldingSetNodeID &ID, Node *N) const { T *TN = static_cast<T *>(N); FoldingSetTrait<T>::Profile(*TN,ID); } public: explicit FoldingSet(unsigned Log2InitSize = 6) : FoldingSetImpl(Log2InitSize) {} typedef FoldingSetIterator<T> iterator; iterator begin() { return iterator(Buckets); } iterator end() { return iterator(Buckets+NumBuckets); } typedef FoldingSetIterator<const T> const_iterator; const_iterator begin() const { return const_iterator(Buckets); } const_iterator end() const { return const_iterator(Buckets+NumBuckets); } typedef FoldingSetBucketIterator<T> bucket_iterator; bucket_iterator bucket_begin(unsigned hash) { return bucket_iterator(Buckets + (hash & (NumBuckets-1))); } bucket_iterator bucket_end(unsigned hash) { return bucket_iterator(Buckets + (hash & (NumBuckets-1)), true); } /// GetOrInsertNode - If there is an existing simple Node exactly /// equal to the specified node, return it. Otherwise, insert 'N' and /// return it instead. T *GetOrInsertNode(Node *N) { return static_cast<T *>(FoldingSetImpl::GetOrInsertNode(N)); } /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists, /// return it. If not, return the insertion token that will make insertion /// faster. T *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos) { return static_cast<T *>(FoldingSetImpl::FindNodeOrInsertPos(ID, InsertPos)); } }; //===----------------------------------------------------------------------===// /// FoldingSetIteratorImpl - This is the common iterator support shared by all /// folding sets, which knows how to walk the folding set hash table. class FoldingSetIteratorImpl { protected: FoldingSetNode *NodePtr; FoldingSetIteratorImpl(void **Bucket); void advance(); public: bool operator==(const FoldingSetIteratorImpl &RHS) const { return NodePtr == RHS.NodePtr; } bool operator!=(const FoldingSetIteratorImpl &RHS) const { return NodePtr != RHS.NodePtr; } }; template<class T> class FoldingSetIterator : public FoldingSetIteratorImpl { public: explicit FoldingSetIterator(void **Bucket) : FoldingSetIteratorImpl(Bucket) {} T &operator*() const { return *static_cast<T*>(NodePtr); } T *operator->() const { return static_cast<T*>(NodePtr); } inline FoldingSetIterator& operator++() { // Preincrement advance(); return *this; } FoldingSetIterator operator++(int) { // Postincrement FoldingSetIterator tmp = *this; ++*this; return tmp; } }; //===----------------------------------------------------------------------===// /// FoldingSetBucketIteratorImpl - This is the common bucket iterator support /// shared by all folding sets, which knows how to walk a particular bucket /// of a folding set hash table. class FoldingSetBucketIteratorImpl { protected: void *Ptr; explicit FoldingSetBucketIteratorImpl(void **Bucket); FoldingSetBucketIteratorImpl(void **Bucket, bool) : Ptr(Bucket) {} void advance() { void *Probe = static_cast<FoldingSetNode*>(Ptr)->getNextInBucket(); uintptr_t x = reinterpret_cast<uintptr_t>(Probe) & ~0x1; Ptr = reinterpret_cast<void*>(x); } public: bool operator==(const FoldingSetBucketIteratorImpl &RHS) const { return Ptr == RHS.Ptr; } bool operator!=(const FoldingSetBucketIteratorImpl &RHS) const { return Ptr != RHS.Ptr; } }; template<class T> class FoldingSetBucketIterator : public FoldingSetBucketIteratorImpl { public: explicit FoldingSetBucketIterator(void **Bucket) : FoldingSetBucketIteratorImpl(Bucket) {} FoldingSetBucketIterator(void **Bucket, bool) : FoldingSetBucketIteratorImpl(Bucket, true) {} T& operator*() const { return *static_cast<T*>(Ptr); } T* operator->() const { return static_cast<T*>(Ptr); } inline FoldingSetBucketIterator& operator++() { // Preincrement advance(); return *this; } FoldingSetBucketIterator operator++(int) { // Postincrement FoldingSetBucketIterator tmp = *this; ++*this; return tmp; } }; //===----------------------------------------------------------------------===// /// FoldingSetNodeWrapper - This template class is used to "wrap" arbitrary /// types in an enclosing object so that they can be inserted into FoldingSets. template <typename T> class FoldingSetNodeWrapper : public FoldingSetNode { T data; public: explicit FoldingSetNodeWrapper(const T& x) : data(x) {} virtual ~FoldingSetNodeWrapper() {} template<typename A1> explicit FoldingSetNodeWrapper(const A1& a1) : data(a1) {} template <typename A1, typename A2> explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2) : data(a1,a2) {} template <typename A1, typename A2, typename A3> explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3) : data(a1,a2,a3) {} template <typename A1, typename A2, typename A3, typename A4> explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3, const A4& a4) : data(a1,a2,a3,a4) {} template <typename A1, typename A2, typename A3, typename A4, typename A5> explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3, const A4& a4, const A5& a5) : data(a1,a2,a3,a4,a5) {} void Profile(FoldingSetNodeID& ID) { FoldingSetTrait<T>::Profile(data, ID); } T& getValue() { return data; } const T& getValue() const { return data; } operator T&() { return data; } operator const T&() const { return data; } }; //===----------------------------------------------------------------------===// /// FastFoldingSetNode - This is a subclass of FoldingSetNode which stores /// a FoldingSetNodeID value rather than requiring the node to recompute it /// each time it is needed. This trades space for speed (which can be /// significant if the ID is long), and it also permits nodes to drop /// information that would otherwise only be required for recomputing an ID. class FastFoldingSetNode : public FoldingSetNode { FoldingSetNodeID FastID; protected: explicit FastFoldingSetNode(const FoldingSetNodeID &ID) : FastID(ID) {} public: void Profile(FoldingSetNodeID& ID) { ID = FastID; } }; //===----------------------------------------------------------------------===// // Partial specializations of FoldingSetTrait. template<typename T> struct FoldingSetTrait<T*> { static inline void Profile(const T* X, FoldingSetNodeID& ID) { ID.AddPointer(X); } static inline void Profile(T* X, FoldingSetNodeID& ID) { ID.AddPointer(X); } }; template<typename T> struct FoldingSetTrait<const T*> { static inline void Profile(const T* X, FoldingSetNodeID& ID) { ID.AddPointer(X); } }; } // End of namespace llvm. #endif