FoldingSet.h revision 7ed47a13356daed2a34cd2209a31f92552e3bdd8
1//===-- llvm/ADT/FoldingSet.h - Uniquing Hash Set ---------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file defines a hash set that can be used to remove duplication of nodes 11// in a graph. This code was originally created by Chris Lattner for use with 12// SelectionDAGCSEMap, but was isolated to provide use across the llvm code set. 13// 14//===----------------------------------------------------------------------===// 15 16#ifndef LLVM_ADT_FOLDINGSET_H 17#define LLVM_ADT_FOLDINGSET_H 18 19#include "llvm/Support/DataTypes.h" 20#include "llvm/ADT/SmallVector.h" 21#include <string> 22 23namespace llvm { 24 class APFloat; 25 26/// This folding set used for two purposes: 27/// 1. Given information about a node we want to create, look up the unique 28/// instance of the node in the set. If the node already exists, return 29/// it, otherwise return the bucket it should be inserted into. 30/// 2. Given a node that has already been created, remove it from the set. 31/// 32/// This class is implemented as a single-link chained hash table, where the 33/// "buckets" are actually the nodes themselves (the next pointer is in the 34/// node). The last node points back to the bucket to simplified node removal. 35/// 36/// Any node that is to be included in the folding set must be a subclass of 37/// FoldingSetNode. The node class must also define a Profile method used to 38/// establish the unique bits of data for the node. The Profile method is 39/// passed a FoldingSetNodeID object which is used to gather the bits. Just 40/// call one of the Add* functions defined in the FoldingSetImpl::NodeID class. 41/// NOTE: That the folding set does not own the nodes and it is the 42/// responsibility of the user to dispose of the nodes. 43/// 44/// Eg. 45/// class MyNode : public FoldingSetNode { 46/// private: 47/// std::string Name; 48/// unsigned Value; 49/// public: 50/// MyNode(const char *N, unsigned V) : Name(N), Value(V) {} 51/// ... 52/// void Profile(FoldingSetNodeID &ID) { 53/// ID.AddString(Name); 54/// ID.AddInteger(Value); 55/// } 56/// ... 57/// }; 58/// 59/// To define the folding set itself use the FoldingSet template; 60/// 61/// Eg. 62/// FoldingSet<MyNode> MyFoldingSet; 63/// 64/// Four public methods are available to manipulate the folding set; 65/// 66/// 1) If you have an existing node that you want add to the set but unsure 67/// that the node might already exist then call; 68/// 69/// MyNode *M = MyFoldingSet.GetOrInsertNode(N); 70/// 71/// If The result is equal to the input then the node has been inserted. 72/// Otherwise, the result is the node existing in the folding set, and the 73/// input can be discarded (use the result instead.) 74/// 75/// 2) If you are ready to construct a node but want to check if it already 76/// exists, then call FindNodeOrInsertPos with a FoldingSetNodeID of the bits to 77/// check; 78/// 79/// FoldingSetNodeID ID; 80/// ID.AddString(Name); 81/// ID.AddInteger(Value); 82/// void *InsertPoint; 83/// 84/// MyNode *M = MyFoldingSet.FindNodeOrInsertPos(ID, InsertPoint); 85/// 86/// If found then M with be non-NULL, else InsertPoint will point to where it 87/// should be inserted using InsertNode. 88/// 89/// 3) If you get a NULL result from FindNodeOrInsertPos then you can as a new 90/// node with FindNodeOrInsertPos; 91/// 92/// InsertNode(N, InsertPoint); 93/// 94/// 4) Finally, if you want to remove a node from the folding set call; 95/// 96/// bool WasRemoved = RemoveNode(N); 97/// 98/// The result indicates whether the node existed in the folding set. 99 100 101//===----------------------------------------------------------------------===// 102/// FoldingSetImpl - Implements the folding set functionality. The main 103/// structure is an array of buckets. Each bucket is indexed by the hash of 104/// the nodes it contains. The bucket itself points to the nodes contained 105/// in the bucket via a singly linked list. The last node in the list points 106/// back to the bucket to facilitate node removal. 107/// 108class FoldingSetImpl { 109protected: 110 /// Buckets - Array of bucket chains. 111 /// 112 void **Buckets; 113 114 /// NumBuckets - Length of the Buckets array. Always a power of 2. 115 /// 116 unsigned NumBuckets; 117 118 /// NumNodes - Number of nodes in the folding set. Growth occurs when NumNodes 119 /// is greater than twice the number of buckets. 120 unsigned NumNodes; 121 122public: 123 explicit FoldingSetImpl(unsigned Log2InitSize = 6); 124 virtual ~FoldingSetImpl(); 125 126 // Forward declaration. 127 class Node; 128 129 //===--------------------------------------------------------------------===// 130 /// NodeID - This class is used to gather all the unique data bits of a 131 /// node. When all the bits are gathered this class is used to produce a 132 /// hash value for the node. 133 /// 134 class NodeID { 135 /// Bits - Vector of all the data bits that make the node unique. 136 /// Use a SmallVector to avoid a heap allocation in the common case. 137 SmallVector<unsigned, 32> Bits; 138 139 public: 140 NodeID() {} 141 142 /// getRawData - Return the ith entry in the Bits data. 143 /// 144 unsigned getRawData(unsigned i) const { 145 return Bits[i]; 146 } 147 148 /// Add* - Add various data types to Bit data. 149 /// 150 void AddPointer(const void *Ptr); 151 void AddInteger(signed I); 152 void AddInteger(unsigned I); 153 void AddInteger(int64_t I); 154 void AddInteger(uint64_t I); 155 void AddFloat(float F); 156 void AddDouble(double D); 157 void AddAPFloat(const APFloat& apf); 158 void AddString(const std::string &String); 159 160 /// ComputeHash - Compute a strong hash value for this NodeID, used to 161 /// lookup the node in the FoldingSetImpl. 162 unsigned ComputeHash() const; 163 164 /// operator== - Used to compare two nodes to each other. 165 /// 166 bool operator==(const NodeID &RHS) const; 167 }; 168 169 //===--------------------------------------------------------------------===// 170 /// Node - This class is used to maintain the singly linked bucket list in 171 /// a folding set. 172 /// 173 class Node { 174 private: 175 // NextInFoldingSetBucket - next link in the bucket list. 176 void *NextInFoldingSetBucket; 177 178 public: 179 180 Node() : NextInFoldingSetBucket(0) {} 181 182 // Accessors 183 void *getNextInBucket() const { return NextInFoldingSetBucket; } 184 void SetNextInBucket(void *N) { NextInFoldingSetBucket = N; } 185 }; 186 187 /// RemoveNode - Remove a node from the folding set, returning true if one 188 /// was removed or false if the node was not in the folding set. 189 bool RemoveNode(Node *N); 190 191 /// GetOrInsertNode - If there is an existing simple Node exactly 192 /// equal to the specified node, return it. Otherwise, insert 'N' and return 193 /// it instead. 194 Node *GetOrInsertNode(Node *N); 195 196 /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists, 197 /// return it. If not, return the insertion token that will make insertion 198 /// faster. 199 Node *FindNodeOrInsertPos(const NodeID &ID, void *&InsertPos); 200 201 /// InsertNode - Insert the specified node into the folding set, knowing that 202 /// it is not already in the folding set. InsertPos must be obtained from 203 /// FindNodeOrInsertPos. 204 void InsertNode(Node *N, void *InsertPos); 205 206 /// size - Returns the number of nodes in the folding set. 207 unsigned size() const { return NumNodes; } 208 209private: 210 211 /// GrowHashTable - Double the size of the hash table and rehash everything. 212 /// 213 void GrowHashTable(); 214 215protected: 216 217 /// GetNodeProfile - Instantiations of the FoldingSet template implement 218 /// this function to gather data bits for the given node. 219 virtual void GetNodeProfile(NodeID &ID, Node *N) const = 0; 220}; 221 222// Convenience types to hide the implementation of the folding set. 223typedef FoldingSetImpl::Node FoldingSetNode; 224typedef FoldingSetImpl::NodeID FoldingSetNodeID; 225 226template<class T> class FoldingSetIterator; 227 228//===----------------------------------------------------------------------===// 229/// FoldingSet - This template class is used to instantiate a specialized 230/// implementation of the folding set to the node class T. T must be a 231/// subclass of FoldingSetNode and implement a Profile function. 232/// 233template<class T> class FoldingSet : public FoldingSetImpl { 234private: 235 /// GetNodeProfile - Each instantiatation of the FoldingSet needs to provide a 236 /// way to convert nodes into a unique specifier. 237 virtual void GetNodeProfile(NodeID &ID, Node *N) const { 238 T *TN = static_cast<T *>(N); 239 TN->Profile(ID); 240 } 241 242public: 243 explicit FoldingSet(unsigned Log2InitSize = 6) 244 : FoldingSetImpl(Log2InitSize) 245 {} 246 247 typedef FoldingSetIterator<T> iterator; 248 iterator begin() { return iterator(Buckets); } 249 iterator end() { return iterator(Buckets+NumBuckets); } 250 251 typedef FoldingSetIterator<const T> const_iterator; 252 const_iterator begin() const { return const_iterator(Buckets); } 253 const_iterator end() const { return const_iterator(Buckets+NumBuckets); } 254 255 /// GetOrInsertNode - If there is an existing simple Node exactly 256 /// equal to the specified node, return it. Otherwise, insert 'N' and 257 /// return it instead. 258 T *GetOrInsertNode(Node *N) { 259 return static_cast<T *>(FoldingSetImpl::GetOrInsertNode(N)); 260 } 261 262 /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists, 263 /// return it. If not, return the insertion token that will make insertion 264 /// faster. 265 T *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos) { 266 return static_cast<T *>(FoldingSetImpl::FindNodeOrInsertPos(ID, InsertPos)); 267 } 268}; 269 270//===----------------------------------------------------------------------===// 271/// FoldingSetIteratorImpl - This is the common iterator support shared by all 272/// folding sets, which knows how to walk the folding set hash table. 273class FoldingSetIteratorImpl { 274protected: 275 FoldingSetNode *NodePtr; 276 FoldingSetIteratorImpl(void **Bucket); 277 void advance(); 278 279public: 280 bool operator==(const FoldingSetIteratorImpl &RHS) const { 281 return NodePtr == RHS.NodePtr; 282 } 283 bool operator!=(const FoldingSetIteratorImpl &RHS) const { 284 return NodePtr != RHS.NodePtr; 285 } 286}; 287 288 289template<class T> 290class FoldingSetIterator : public FoldingSetIteratorImpl { 291public: 292 FoldingSetIterator(void **Bucket) : FoldingSetIteratorImpl(Bucket) {} 293 294 T &operator*() const { 295 return *static_cast<T*>(NodePtr); 296 } 297 298 T *operator->() const { 299 return static_cast<T*>(NodePtr); 300 } 301 302 inline FoldingSetIterator& operator++() { // Preincrement 303 advance(); 304 return *this; 305 } 306 FoldingSetIterator operator++(int) { // Postincrement 307 FoldingSetIterator tmp = *this; ++*this; return tmp; 308 } 309}; 310 311} // End of namespace llvm. 312 313 314#endif 315 316