FoldingSet.h revision 167b8bc24d4cc2789c682962b123877a73ad0568
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 class APInt; 26 27/// This folding set used for two purposes: 28/// 1. Given information about a node we want to create, look up the unique 29/// instance of the node in the set. If the node already exists, return 30/// it, otherwise return the bucket it should be inserted into. 31/// 2. Given a node that has already been created, remove it from the set. 32/// 33/// This class is implemented as a single-link chained hash table, where the 34/// "buckets" are actually the nodes themselves (the next pointer is in the 35/// node). The last node points back to the bucket to simplified node removal. 36/// 37/// Any node that is to be included in the folding set must be a subclass of 38/// FoldingSetNode. The node class must also define a Profile method used to 39/// establish the unique bits of data for the node. The Profile method is 40/// passed a FoldingSetNodeID object which is used to gather the bits. Just 41/// call one of the Add* functions defined in the FoldingSetImpl::NodeID class. 42/// NOTE: That the folding set does not own the nodes and it is the 43/// responsibility of the user to dispose of the nodes. 44/// 45/// Eg. 46/// class MyNode : public FoldingSetNode { 47/// private: 48/// std::string Name; 49/// unsigned Value; 50/// public: 51/// MyNode(const char *N, unsigned V) : Name(N), Value(V) {} 52/// ... 53/// void Profile(FoldingSetNodeID &ID) { 54/// ID.AddString(Name); 55/// ID.AddInteger(Value); 56/// } 57/// ... 58/// }; 59/// 60/// To define the folding set itself use the FoldingSet template; 61/// 62/// Eg. 63/// FoldingSet<MyNode> MyFoldingSet; 64/// 65/// Four public methods are available to manipulate the folding set; 66/// 67/// 1) If you have an existing node that you want add to the set but unsure 68/// that the node might already exist then call; 69/// 70/// MyNode *M = MyFoldingSet.GetOrInsertNode(N); 71/// 72/// If The result is equal to the input then the node has been inserted. 73/// Otherwise, the result is the node existing in the folding set, and the 74/// input can be discarded (use the result instead.) 75/// 76/// 2) If you are ready to construct a node but want to check if it already 77/// exists, then call FindNodeOrInsertPos with a FoldingSetNodeID of the bits to 78/// check; 79/// 80/// FoldingSetNodeID ID; 81/// ID.AddString(Name); 82/// ID.AddInteger(Value); 83/// void *InsertPoint; 84/// 85/// MyNode *M = MyFoldingSet.FindNodeOrInsertPos(ID, InsertPoint); 86/// 87/// If found then M with be non-NULL, else InsertPoint will point to where it 88/// should be inserted using InsertNode. 89/// 90/// 3) If you get a NULL result from FindNodeOrInsertPos then you can as a new 91/// node with FindNodeOrInsertPos; 92/// 93/// InsertNode(N, InsertPoint); 94/// 95/// 4) Finally, if you want to remove a node from the folding set call; 96/// 97/// bool WasRemoved = RemoveNode(N); 98/// 99/// The result indicates whether the node existed in the folding set. 100 101class FoldingSetNodeID; 102 103//===----------------------------------------------------------------------===// 104/// FoldingSetImpl - Implements the folding set functionality. The main 105/// structure is an array of buckets. Each bucket is indexed by the hash of 106/// the nodes it contains. The bucket itself points to the nodes contained 107/// in the bucket via a singly linked list. The last node in the list points 108/// back to the bucket to facilitate node removal. 109/// 110class FoldingSetImpl { 111protected: 112 /// Buckets - Array of bucket chains. 113 /// 114 void **Buckets; 115 116 /// NumBuckets - Length of the Buckets array. Always a power of 2. 117 /// 118 unsigned NumBuckets; 119 120 /// NumNodes - Number of nodes in the folding set. Growth occurs when NumNodes 121 /// is greater than twice the number of buckets. 122 unsigned NumNodes; 123 124public: 125 explicit FoldingSetImpl(unsigned Log2InitSize = 6); 126 virtual ~FoldingSetImpl(); 127 128 //===--------------------------------------------------------------------===// 129 /// Node - This class is used to maintain the singly linked bucket list in 130 /// a folding set. 131 /// 132 class Node { 133 private: 134 // NextInFoldingSetBucket - next link in the bucket list. 135 void *NextInFoldingSetBucket; 136 137 public: 138 139 Node() : NextInFoldingSetBucket(0) {} 140 141 // Accessors 142 void *getNextInBucket() const { return NextInFoldingSetBucket; } 143 void SetNextInBucket(void *N) { NextInFoldingSetBucket = N; } 144 }; 145 146 /// RemoveNode - Remove a node from the folding set, returning true if one 147 /// was removed or false if the node was not in the folding set. 148 bool RemoveNode(Node *N); 149 150 /// GetOrInsertNode - If there is an existing simple Node exactly 151 /// equal to the specified node, return it. Otherwise, insert 'N' and return 152 /// it instead. 153 Node *GetOrInsertNode(Node *N); 154 155 /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists, 156 /// return it. If not, return the insertion token that will make insertion 157 /// faster. 158 Node *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos); 159 160 /// InsertNode - Insert the specified node into the folding set, knowing that 161 /// it is not already in the folding set. InsertPos must be obtained from 162 /// FindNodeOrInsertPos. 163 void InsertNode(Node *N, void *InsertPos); 164 165 /// size - Returns the number of nodes in the folding set. 166 unsigned size() const { return NumNodes; } 167 168private: 169 170 /// GrowHashTable - Double the size of the hash table and rehash everything. 171 /// 172 void GrowHashTable(); 173 174protected: 175 176 /// GetNodeProfile - Instantiations of the FoldingSet template implement 177 /// this function to gather data bits for the given node. 178 virtual void GetNodeProfile(FoldingSetNodeID &ID, Node *N) const = 0; 179}; 180 181//===--------------------------------------------------------------------===// 182/// FoldingSetNodeID - This class is used to gather all the unique data bits of 183/// a node. When all the bits are gathered this class is used to produce a 184/// hash value for the node. 185/// 186class FoldingSetNodeID { 187 /// Bits - Vector of all the data bits that make the node unique. 188 /// Use a SmallVector to avoid a heap allocation in the common case. 189 SmallVector<unsigned, 32> Bits; 190 191public: 192 FoldingSetNodeID() {} 193 194 /// getRawData - Return the ith entry in the Bits data. 195 /// 196 unsigned getRawData(unsigned i) const { 197 return Bits[i]; 198 } 199 200 /// Add* - Add various data types to Bit data. 201 /// 202 void AddPointer(const void *Ptr); 203 void AddInteger(signed I); 204 void AddInteger(unsigned I); 205 void AddInteger(int64_t I); 206 void AddInteger(uint64_t I); 207 void AddFloat(float F); 208 void AddDouble(double D); 209 void AddAPFloat(const APFloat& apf); 210 void AddAPInt(const APInt& api); 211 void AddString(const std::string &String); 212 213 /// clear - Clear the accumulated profile, allowing this FoldingSetNodeID 214 /// object to be used to compute a new profile. 215 inline void clear() { Bits.clear(); } 216 217 /// ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used 218 /// to lookup the node in the FoldingSetImpl. 219 unsigned ComputeHash() const; 220 221 /// operator== - Used to compare two nodes to each other. 222 /// 223 bool operator==(const FoldingSetNodeID &RHS) const; 224}; 225 226// Convenience type to hide the implementation of the folding set. 227typedef FoldingSetImpl::Node FoldingSetNode; 228template<class T> class FoldingSetIterator; 229template<class T> class FoldingSetBucketIterator; 230 231//===----------------------------------------------------------------------===// 232/// FoldingSetTrait - This trait class is used to define behavior of how 233/// to "profile" (in the FoldingSet parlance) an object of a given type. 234/// The default behavior is to invoke a 'Profile' method on an object, but 235/// through template specialization the behavior can be tailored for specific 236/// types. Combined with the FoldingSetNodeWrapper classs, one can add objects 237/// to FoldingSets that were not originally designed to have that behavior. 238/// 239template<typename T> struct FoldingSetTrait { 240 static inline void Profile(const T& X, FoldingSetNodeID& ID) { X.Profile(ID);} 241 static inline void Profile(T& X, FoldingSetNodeID& ID) { X.Profile(ID); } 242}; 243 244//===----------------------------------------------------------------------===// 245/// FoldingSet - This template class is used to instantiate a specialized 246/// implementation of the folding set to the node class T. T must be a 247/// subclass of FoldingSetNode and implement a Profile function. 248/// 249template<class T> class FoldingSet : public FoldingSetImpl { 250private: 251 /// GetNodeProfile - Each instantiatation of the FoldingSet needs to provide a 252 /// way to convert nodes into a unique specifier. 253 virtual void GetNodeProfile(FoldingSetNodeID &ID, Node *N) const { 254 T *TN = static_cast<T *>(N); 255 FoldingSetTrait<T>::Profile(*TN,ID); 256 } 257 258public: 259 explicit FoldingSet(unsigned Log2InitSize = 6) 260 : FoldingSetImpl(Log2InitSize) 261 {} 262 263 typedef FoldingSetIterator<T> iterator; 264 iterator begin() { return iterator(Buckets); } 265 iterator end() { return iterator(Buckets+NumBuckets); } 266 267 typedef FoldingSetIterator<const T> const_iterator; 268 const_iterator begin() const { return const_iterator(Buckets); } 269 const_iterator end() const { return const_iterator(Buckets+NumBuckets); } 270 271 typedef FoldingSetBucketIterator<T> bucket_iterator; 272 273 bucket_iterator bucket_begin(unsigned hash) { 274 return bucket_iterator(Buckets + (hash & (NumBuckets-1))); 275 } 276 277 bucket_iterator bucket_end(unsigned hash) { 278 return bucket_iterator(Buckets + (hash & (NumBuckets-1)), true); 279 } 280 281 /// GetOrInsertNode - If there is an existing simple Node exactly 282 /// equal to the specified node, return it. Otherwise, insert 'N' and 283 /// return it instead. 284 T *GetOrInsertNode(Node *N) { 285 return static_cast<T *>(FoldingSetImpl::GetOrInsertNode(N)); 286 } 287 288 /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists, 289 /// return it. If not, return the insertion token that will make insertion 290 /// faster. 291 T *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos) { 292 return static_cast<T *>(FoldingSetImpl::FindNodeOrInsertPos(ID, InsertPos)); 293 } 294}; 295 296//===----------------------------------------------------------------------===// 297/// FoldingSetIteratorImpl - This is the common iterator support shared by all 298/// folding sets, which knows how to walk the folding set hash table. 299class FoldingSetIteratorImpl { 300protected: 301 FoldingSetNode *NodePtr; 302 FoldingSetIteratorImpl(void **Bucket); 303 void advance(); 304 305public: 306 bool operator==(const FoldingSetIteratorImpl &RHS) const { 307 return NodePtr == RHS.NodePtr; 308 } 309 bool operator!=(const FoldingSetIteratorImpl &RHS) const { 310 return NodePtr != RHS.NodePtr; 311 } 312}; 313 314 315template<class T> 316class FoldingSetIterator : public FoldingSetIteratorImpl { 317public: 318 FoldingSetIterator(void **Bucket) : FoldingSetIteratorImpl(Bucket) {} 319 320 T &operator*() const { 321 return *static_cast<T*>(NodePtr); 322 } 323 324 T *operator->() const { 325 return static_cast<T*>(NodePtr); 326 } 327 328 inline FoldingSetIterator& operator++() { // Preincrement 329 advance(); 330 return *this; 331 } 332 FoldingSetIterator operator++(int) { // Postincrement 333 FoldingSetIterator tmp = *this; ++*this; return tmp; 334 } 335}; 336 337//===----------------------------------------------------------------------===// 338/// FoldingSetBucketIteratorImpl - This is the common bucket iterator support 339/// shared by all folding sets, which knows how to walk a particular bucket 340/// of a folding set hash table. 341 342class FoldingSetBucketIteratorImpl { 343protected: 344 void *Ptr; 345 346 FoldingSetBucketIteratorImpl(void **Bucket); 347 348 FoldingSetBucketIteratorImpl(void **Bucket, bool) 349 : Ptr(reinterpret_cast<void*>(Bucket)) {} 350 351 void advance() { 352 void *Probe = static_cast<FoldingSetNode*>(Ptr)->getNextInBucket(); 353 uintptr_t x = reinterpret_cast<uintptr_t>(Probe) & ~0x1; 354 Ptr = reinterpret_cast<void*>(x); 355 } 356 357public: 358 bool operator==(const FoldingSetBucketIteratorImpl &RHS) const { 359 return Ptr == RHS.Ptr; 360 } 361 bool operator!=(const FoldingSetBucketIteratorImpl &RHS) const { 362 return Ptr != RHS.Ptr; 363 } 364}; 365 366 367template<class T> 368class FoldingSetBucketIterator : public FoldingSetBucketIteratorImpl { 369public: 370 FoldingSetBucketIterator(void **Bucket) : 371 FoldingSetBucketIteratorImpl(Bucket) {} 372 373 FoldingSetBucketIterator(void **Bucket, bool) : 374 FoldingSetBucketIteratorImpl(Bucket, true) {} 375 376 T& operator*() const { return *static_cast<T*>(Ptr); } 377 T* operator->() const { return static_cast<T*>(Ptr); } 378 379 inline FoldingSetBucketIterator& operator++() { // Preincrement 380 advance(); 381 return *this; 382 } 383 FoldingSetBucketIterator operator++(int) { // Postincrement 384 FoldingSetBucketIterator tmp = *this; ++*this; return tmp; 385 } 386}; 387 388//===----------------------------------------------------------------------===// 389/// FoldingSetNodeWrapper - This template class is used to "wrap" arbitrary 390/// types in an enclosing object so that they can be inserted into FoldingSets. 391template <typename T> 392class FoldingSetNodeWrapper : public FoldingSetNode { 393 T data; 394public: 395 FoldingSetNodeWrapper(const T& x) : data(x) {} 396 virtual ~FoldingSetNodeWrapper() {} 397 398 template<typename A1> 399 explicit FoldingSetNodeWrapper(const A1& a1) 400 : data(a1) {} 401 402 template <typename A1, typename A2> 403 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2) 404 : data(a1,a2) {} 405 406 template <typename A1, typename A2, typename A3> 407 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3) 408 : data(a1,a2,a3) {} 409 410 template <typename A1, typename A2, typename A3, typename A4> 411 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3, 412 const A4& a4) 413 : data(a1,a2,a3,a4) {} 414 415 template <typename A1, typename A2, typename A3, typename A4, typename A5> 416 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3, 417 const A4& a4, const A5& a5) 418 : data(a1,a2,a3,a4,a5) {} 419 420 421 void Profile(FoldingSetNodeID& ID) { FoldingSetTrait<T>::Profile(data, ID); } 422 423 T& getValue() { return data; } 424 const T& getValue() const { return data; } 425 426 operator T&() { return data; } 427 operator const T&() const { return data; } 428}; 429 430} // End of namespace llvm. 431 432 433#endif 434 435