FoldingSet.h revision f996831427009c5abe37f0af9d9632ef60f181e2
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 simplify 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 /// clear - Remove all nodes from the folding set. 147 void clear(); 148 149 /// RemoveNode - Remove a node from the folding set, returning true if one 150 /// was removed or false if the node was not in the folding set. 151 bool RemoveNode(Node *N); 152 153 /// GetOrInsertNode - If there is an existing simple Node exactly 154 /// equal to the specified node, return it. Otherwise, insert 'N' and return 155 /// it instead. 156 Node *GetOrInsertNode(Node *N); 157 158 /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists, 159 /// return it. If not, return the insertion token that will make insertion 160 /// faster. 161 Node *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos); 162 163 /// InsertNode - Insert the specified node into the folding set, knowing that 164 /// it is not already in the folding set. InsertPos must be obtained from 165 /// FindNodeOrInsertPos. 166 void InsertNode(Node *N, void *InsertPos); 167 168 /// size - Returns the number of nodes in the folding set. 169 unsigned size() const { return NumNodes; } 170 171 /// empty - Returns true if there are no nodes in the folding set. 172 bool empty() const { return NumNodes == 0; } 173 174private: 175 176 /// GrowHashTable - Double the size of the hash table and rehash everything. 177 /// 178 void GrowHashTable(); 179 180protected: 181 182 /// GetNodeProfile - Instantiations of the FoldingSet template implement 183 /// this function to gather data bits for the given node. 184 virtual void GetNodeProfile(FoldingSetNodeID &ID, Node *N) const = 0; 185}; 186 187//===----------------------------------------------------------------------===// 188/// FoldingSetTrait - This trait class is used to define behavior of how 189/// to "profile" (in the FoldingSet parlance) an object of a given type. 190/// The default behavior is to invoke a 'Profile' method on an object, but 191/// through template specialization the behavior can be tailored for specific 192/// types. Combined with the FoldingSetNodeWrapper classs, one can add objects 193/// to FoldingSets that were not originally designed to have that behavior. 194/// 195template<typename T> struct FoldingSetTrait { 196 static inline void Profile(const T& X, FoldingSetNodeID& ID) { X.Profile(ID);} 197 static inline void Profile(T& X, FoldingSetNodeID& ID) { X.Profile(ID); } 198}; 199 200//===--------------------------------------------------------------------===// 201/// FoldingSetNodeID - This class is used to gather all the unique data bits of 202/// a node. When all the bits are gathered this class is used to produce a 203/// hash value for the node. 204/// 205class FoldingSetNodeID { 206 /// Bits - Vector of all the data bits that make the node unique. 207 /// Use a SmallVector to avoid a heap allocation in the common case. 208 SmallVector<unsigned, 32> Bits; 209 210public: 211 FoldingSetNodeID() {} 212 213 /// getRawData - Return the ith entry in the Bits data. 214 /// 215 unsigned getRawData(unsigned i) const { 216 return Bits[i]; 217 } 218 219 /// Add* - Add various data types to Bit data. 220 /// 221 void AddPointer(const void *Ptr); 222 void AddInteger(signed I); 223 void AddInteger(unsigned I); 224 void AddInteger(long I); 225 void AddInteger(unsigned long I); 226 void AddInteger(long long I); 227 void AddInteger(unsigned long long I); 228 void AddString(const char* String, const char* End); 229 void AddString(const std::string &String); 230 void AddString(const char* String); 231 232 template <typename T> 233 inline void Add(const T& x) { FoldingSetTrait<T>::Profile(x, *this); } 234 235 /// clear - Clear the accumulated profile, allowing this FoldingSetNodeID 236 /// object to be used to compute a new profile. 237 inline void clear() { Bits.clear(); } 238 239 /// ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used 240 /// to lookup the node in the FoldingSetImpl. 241 unsigned ComputeHash() const; 242 243 /// operator== - Used to compare two nodes to each other. 244 /// 245 bool operator==(const FoldingSetNodeID &RHS) const; 246}; 247 248// Convenience type to hide the implementation of the folding set. 249typedef FoldingSetImpl::Node FoldingSetNode; 250template<class T> class FoldingSetIterator; 251template<class T> class FoldingSetBucketIterator; 252 253//===----------------------------------------------------------------------===// 254/// FoldingSet - This template class is used to instantiate a specialized 255/// implementation of the folding set to the node class T. T must be a 256/// subclass of FoldingSetNode and implement a Profile function. 257/// 258template<class T> class FoldingSet : public FoldingSetImpl { 259private: 260 /// GetNodeProfile - Each instantiatation of the FoldingSet needs to provide a 261 /// way to convert nodes into a unique specifier. 262 virtual void GetNodeProfile(FoldingSetNodeID &ID, Node *N) const { 263 T *TN = static_cast<T *>(N); 264 FoldingSetTrait<T>::Profile(*TN,ID); 265 } 266 267public: 268 explicit FoldingSet(unsigned Log2InitSize = 6) 269 : FoldingSetImpl(Log2InitSize) 270 {} 271 272 typedef FoldingSetIterator<T> iterator; 273 iterator begin() { return iterator(Buckets); } 274 iterator end() { return iterator(Buckets+NumBuckets); } 275 276 typedef FoldingSetIterator<const T> const_iterator; 277 const_iterator begin() const { return const_iterator(Buckets); } 278 const_iterator end() const { return const_iterator(Buckets+NumBuckets); } 279 280 typedef FoldingSetBucketIterator<T> bucket_iterator; 281 282 bucket_iterator bucket_begin(unsigned hash) { 283 return bucket_iterator(Buckets + (hash & (NumBuckets-1))); 284 } 285 286 bucket_iterator bucket_end(unsigned hash) { 287 return bucket_iterator(Buckets + (hash & (NumBuckets-1)), true); 288 } 289 290 /// GetOrInsertNode - If there is an existing simple Node exactly 291 /// equal to the specified node, return it. Otherwise, insert 'N' and 292 /// return it instead. 293 T *GetOrInsertNode(Node *N) { 294 return static_cast<T *>(FoldingSetImpl::GetOrInsertNode(N)); 295 } 296 297 /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists, 298 /// return it. If not, return the insertion token that will make insertion 299 /// faster. 300 T *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos) { 301 return static_cast<T *>(FoldingSetImpl::FindNodeOrInsertPos(ID, InsertPos)); 302 } 303}; 304 305//===----------------------------------------------------------------------===// 306/// FoldingSetIteratorImpl - This is the common iterator support shared by all 307/// folding sets, which knows how to walk the folding set hash table. 308class FoldingSetIteratorImpl { 309protected: 310 FoldingSetNode *NodePtr; 311 FoldingSetIteratorImpl(void **Bucket); 312 void advance(); 313 314public: 315 bool operator==(const FoldingSetIteratorImpl &RHS) const { 316 return NodePtr == RHS.NodePtr; 317 } 318 bool operator!=(const FoldingSetIteratorImpl &RHS) const { 319 return NodePtr != RHS.NodePtr; 320 } 321}; 322 323 324template<class T> 325class FoldingSetIterator : public FoldingSetIteratorImpl { 326public: 327 explicit FoldingSetIterator(void **Bucket) : FoldingSetIteratorImpl(Bucket) {} 328 329 T &operator*() const { 330 return *static_cast<T*>(NodePtr); 331 } 332 333 T *operator->() const { 334 return static_cast<T*>(NodePtr); 335 } 336 337 inline FoldingSetIterator& operator++() { // Preincrement 338 advance(); 339 return *this; 340 } 341 FoldingSetIterator operator++(int) { // Postincrement 342 FoldingSetIterator tmp = *this; ++*this; return tmp; 343 } 344}; 345 346//===----------------------------------------------------------------------===// 347/// FoldingSetBucketIteratorImpl - This is the common bucket iterator support 348/// shared by all folding sets, which knows how to walk a particular bucket 349/// of a folding set hash table. 350 351class FoldingSetBucketIteratorImpl { 352protected: 353 void *Ptr; 354 355 explicit FoldingSetBucketIteratorImpl(void **Bucket); 356 357 FoldingSetBucketIteratorImpl(void **Bucket, bool) 358 : Ptr(Bucket) {} 359 360 void advance() { 361 void *Probe = static_cast<FoldingSetNode*>(Ptr)->getNextInBucket(); 362 uintptr_t x = reinterpret_cast<uintptr_t>(Probe) & ~0x1; 363 Ptr = reinterpret_cast<void*>(x); 364 } 365 366public: 367 bool operator==(const FoldingSetBucketIteratorImpl &RHS) const { 368 return Ptr == RHS.Ptr; 369 } 370 bool operator!=(const FoldingSetBucketIteratorImpl &RHS) const { 371 return Ptr != RHS.Ptr; 372 } 373}; 374 375 376template<class T> 377class FoldingSetBucketIterator : public FoldingSetBucketIteratorImpl { 378public: 379 explicit FoldingSetBucketIterator(void **Bucket) : 380 FoldingSetBucketIteratorImpl(Bucket) {} 381 382 FoldingSetBucketIterator(void **Bucket, bool) : 383 FoldingSetBucketIteratorImpl(Bucket, true) {} 384 385 T& operator*() const { return *static_cast<T*>(Ptr); } 386 T* operator->() const { return static_cast<T*>(Ptr); } 387 388 inline FoldingSetBucketIterator& operator++() { // Preincrement 389 advance(); 390 return *this; 391 } 392 FoldingSetBucketIterator operator++(int) { // Postincrement 393 FoldingSetBucketIterator tmp = *this; ++*this; return tmp; 394 } 395}; 396 397//===----------------------------------------------------------------------===// 398/// FoldingSetNodeWrapper - This template class is used to "wrap" arbitrary 399/// types in an enclosing object so that they can be inserted into FoldingSets. 400template <typename T> 401class FoldingSetNodeWrapper : public FoldingSetNode { 402 T data; 403public: 404 explicit FoldingSetNodeWrapper(const T& x) : data(x) {} 405 virtual ~FoldingSetNodeWrapper() {} 406 407 template<typename A1> 408 explicit FoldingSetNodeWrapper(const A1& a1) 409 : data(a1) {} 410 411 template <typename A1, typename A2> 412 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2) 413 : data(a1,a2) {} 414 415 template <typename A1, typename A2, typename A3> 416 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3) 417 : data(a1,a2,a3) {} 418 419 template <typename A1, typename A2, typename A3, typename A4> 420 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3, 421 const A4& a4) 422 : data(a1,a2,a3,a4) {} 423 424 template <typename A1, typename A2, typename A3, typename A4, typename A5> 425 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3, 426 const A4& a4, const A5& a5) 427 : data(a1,a2,a3,a4,a5) {} 428 429 430 void Profile(FoldingSetNodeID& ID) { FoldingSetTrait<T>::Profile(data, ID); } 431 432 T& getValue() { return data; } 433 const T& getValue() const { return data; } 434 435 operator T&() { return data; } 436 operator const T&() const { return data; } 437}; 438 439//===----------------------------------------------------------------------===// 440// Partial specializations of FoldingSetTrait. 441 442template<typename T> struct FoldingSetTrait<T*> { 443 static inline void Profile(const T* X, FoldingSetNodeID& ID) { 444 ID.AddPointer(X); 445 } 446 static inline void Profile(T* X, FoldingSetNodeID& ID) { 447 ID.AddPointer(X); 448 } 449}; 450 451template<typename T> struct FoldingSetTrait<const T*> { 452 static inline void Profile(const T* X, FoldingSetNodeID& ID) { 453 ID.AddPointer(X); 454 } 455}; 456 457} // End of namespace llvm. 458 459#endif 460