FoldingSet.h revision 1d3b26ac023b519077811e55f3f9e56de9c2e6f7
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#include <iterator> 23 24namespace llvm { 25 class APFloat; 26 class APInt; 27 28/// This folding set used for two purposes: 29/// 1. Given information about a node we want to create, look up the unique 30/// instance of the node in the set. If the node already exists, return 31/// it, otherwise return the bucket it should be inserted into. 32/// 2. Given a node that has already been created, remove it from the set. 33/// 34/// This class is implemented as a single-link chained hash table, where the 35/// "buckets" are actually the nodes themselves (the next pointer is in the 36/// node). The last node points back to the bucket to simplify node removal. 37/// 38/// Any node that is to be included in the folding set must be a subclass of 39/// FoldingSetNode. The node class must also define a Profile method used to 40/// establish the unique bits of data for the node. The Profile method is 41/// passed a FoldingSetNodeID object which is used to gather the bits. Just 42/// call one of the Add* functions defined in the FoldingSetImpl::NodeID class. 43/// NOTE: That the folding set does not own the nodes and it is the 44/// responsibility of the user to dispose of the nodes. 45/// 46/// Eg. 47/// class MyNode : public FoldingSetNode { 48/// private: 49/// std::string Name; 50/// unsigned Value; 51/// public: 52/// MyNode(const char *N, unsigned V) : Name(N), Value(V) {} 53/// ... 54/// void Profile(FoldingSetNodeID &ID) const { 55/// ID.AddString(Name); 56/// ID.AddInteger(Value); 57/// } 58/// ... 59/// }; 60/// 61/// To define the folding set itself use the FoldingSet template; 62/// 63/// Eg. 64/// FoldingSet<MyNode> MyFoldingSet; 65/// 66/// Four public methods are available to manipulate the folding set; 67/// 68/// 1) If you have an existing node that you want add to the set but unsure 69/// that the node might already exist then call; 70/// 71/// MyNode *M = MyFoldingSet.GetOrInsertNode(N); 72/// 73/// If The result is equal to the input then the node has been inserted. 74/// Otherwise, the result is the node existing in the folding set, and the 75/// input can be discarded (use the result instead.) 76/// 77/// 2) If you are ready to construct a node but want to check if it already 78/// exists, then call FindNodeOrInsertPos with a FoldingSetNodeID of the bits to 79/// check; 80/// 81/// FoldingSetNodeID ID; 82/// ID.AddString(Name); 83/// ID.AddInteger(Value); 84/// void *InsertPoint; 85/// 86/// MyNode *M = MyFoldingSet.FindNodeOrInsertPos(ID, InsertPoint); 87/// 88/// If found then M with be non-NULL, else InsertPoint will point to where it 89/// should be inserted using InsertNode. 90/// 91/// 3) If you get a NULL result from FindNodeOrInsertPos then you can as a new 92/// node with FindNodeOrInsertPos; 93/// 94/// InsertNode(N, InsertPoint); 95/// 96/// 4) Finally, if you want to remove a node from the folding set call; 97/// 98/// bool WasRemoved = RemoveNode(N); 99/// 100/// The result indicates whether the node existed in the folding set. 101 102class FoldingSetNodeID; 103 104//===----------------------------------------------------------------------===// 105/// FoldingSetImpl - Implements the folding set functionality. The main 106/// structure is an array of buckets. Each bucket is indexed by the hash of 107/// the nodes it contains. The bucket itself points to the nodes contained 108/// in the bucket via a singly linked list. The last node in the list points 109/// back to the bucket to facilitate node removal. 110/// 111class FoldingSetImpl { 112protected: 113 /// Buckets - Array of bucket chains. 114 /// 115 void **Buckets; 116 117 /// NumBuckets - Length of the Buckets array. Always a power of 2. 118 /// 119 unsigned NumBuckets; 120 121 /// NumNodes - Number of nodes in the folding set. Growth occurs when NumNodes 122 /// is greater than twice the number of buckets. 123 unsigned NumNodes; 124 125public: 126 explicit FoldingSetImpl(unsigned Log2InitSize = 6); 127 virtual ~FoldingSetImpl(); 128 129 //===--------------------------------------------------------------------===// 130 /// Node - This class is used to maintain the singly linked bucket list in 131 /// a folding set. 132 /// 133 class Node { 134 private: 135 // NextInFoldingSetBucket - next link in the bucket list. 136 void *NextInFoldingSetBucket; 137 138 public: 139 140 Node() : NextInFoldingSetBucket(0) {} 141 142 // Accessors 143 void *getNextInBucket() const { return NextInFoldingSetBucket; } 144 void SetNextInBucket(void *N) { NextInFoldingSetBucket = N; } 145 }; 146 147 /// clear - Remove all nodes from the folding set. 148 void clear(); 149 150 /// RemoveNode - Remove a node from the folding set, returning true if one 151 /// was removed or false if the node was not in the folding set. 152 bool RemoveNode(Node *N); 153 154 /// GetOrInsertNode - If there is an existing simple Node exactly 155 /// equal to the specified node, return it. Otherwise, insert 'N' and return 156 /// it instead. 157 Node *GetOrInsertNode(Node *N); 158 159 /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists, 160 /// return it. If not, return the insertion token that will make insertion 161 /// faster. 162 Node *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos); 163 164 /// InsertNode - Insert the specified node into the folding set, knowing that 165 /// it is not already in the folding set. InsertPos must be obtained from 166 /// FindNodeOrInsertPos. 167 void InsertNode(Node *N, void *InsertPos); 168 169 /// size - Returns the number of nodes in the folding set. 170 unsigned size() const { return NumNodes; } 171 172 /// empty - Returns true if there are no nodes in the folding set. 173 bool empty() const { return NumNodes == 0; } 174 175private: 176 177 /// GrowHashTable - Double the size of the hash table and rehash everything. 178 /// 179 void GrowHashTable(); 180 181protected: 182 183 /// GetNodeProfile - Instantiations of the FoldingSet template implement 184 /// this function to gather data bits for the given node. 185 virtual void GetNodeProfile(FoldingSetNodeID &ID, Node *N) const = 0; 186}; 187 188//===----------------------------------------------------------------------===// 189/// FoldingSetTrait - This trait class is used to define behavior of how 190/// to "profile" (in the FoldingSet parlance) an object of a given type. 191/// The default behavior is to invoke a 'Profile' method on an object, but 192/// through template specialization the behavior can be tailored for specific 193/// types. Combined with the FoldingSetNodeWrapper classs, one can add objects 194/// to FoldingSets that were not originally designed to have that behavior. 195/// 196template<typename T> struct FoldingSetTrait { 197 static inline void Profile(const T& X, FoldingSetNodeID& ID) { X.Profile(ID);} 198 static inline void Profile(T& X, FoldingSetNodeID& ID) { X.Profile(ID); } 199}; 200 201//===--------------------------------------------------------------------===// 202/// FoldingSetNodeID - This class is used to gather all the unique data bits of 203/// a node. When all the bits are gathered this class is used to produce a 204/// hash value for the node. 205/// 206class FoldingSetNodeID { 207 /// Bits - Vector of all the data bits that make the node unique. 208 /// Use a SmallVector to avoid a heap allocation in the common case. 209 SmallVector<unsigned, 32> Bits; 210 211public: 212 FoldingSetNodeID() {} 213 214 /// getRawData - Return the ith entry in the Bits data. 215 /// 216 unsigned getRawData(unsigned i) const { 217 return Bits[i]; 218 } 219 220 /// Add* - Add various data types to Bit data. 221 /// 222 void AddPointer(const void *Ptr); 223 void AddInteger(signed I); 224 void AddInteger(unsigned I); 225 void AddInteger(long I); 226 void AddInteger(unsigned long I); 227 void AddInteger(long long I); 228 void AddInteger(unsigned long long I); 229 void AddBoolean(bool B) { AddInteger(B ? 1U : 0U); } 230 void AddString(const char* String, const char* End); 231 void AddString(const std::string &String); 232 void AddString(const char* String); 233 234 template <typename T> 235 inline void Add(const T& x) { FoldingSetTrait<T>::Profile(x, *this); } 236 237 /// clear - Clear the accumulated profile, allowing this FoldingSetNodeID 238 /// object to be used to compute a new profile. 239 inline void clear() { Bits.clear(); } 240 241 /// ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used 242 /// to lookup the node in the FoldingSetImpl. 243 unsigned ComputeHash() const; 244 245 /// operator== - Used to compare two nodes to each other. 246 /// 247 bool operator==(const FoldingSetNodeID &RHS) const; 248}; 249 250// Convenience type to hide the implementation of the folding set. 251typedef FoldingSetImpl::Node FoldingSetNode; 252template<class T> class FoldingSetIterator; 253template<class T> class FoldingSetBucketIterator; 254 255//===----------------------------------------------------------------------===// 256/// FoldingSet - This template class is used to instantiate a specialized 257/// implementation of the folding set to the node class T. T must be a 258/// subclass of FoldingSetNode and implement a Profile function. 259/// 260template<class T> class FoldingSet : public FoldingSetImpl { 261private: 262 /// GetNodeProfile - Each instantiatation of the FoldingSet needs to provide a 263 /// way to convert nodes into a unique specifier. 264 virtual void GetNodeProfile(FoldingSetNodeID &ID, Node *N) const { 265 T *TN = static_cast<T *>(N); 266 FoldingSetTrait<T>::Profile(*TN,ID); 267 } 268 269public: 270 explicit FoldingSet(unsigned Log2InitSize = 6) 271 : FoldingSetImpl(Log2InitSize) 272 {} 273 274 typedef FoldingSetIterator<T> iterator; 275 iterator begin() { return iterator(Buckets); } 276 iterator end() { return iterator(Buckets+NumBuckets); } 277 278 typedef FoldingSetIterator<const T> const_iterator; 279 const_iterator begin() const { return const_iterator(Buckets); } 280 const_iterator end() const { return const_iterator(Buckets+NumBuckets); } 281 282 typedef FoldingSetBucketIterator<T> bucket_iterator; 283 284 bucket_iterator bucket_begin(unsigned hash) { 285 return bucket_iterator(Buckets + (hash & (NumBuckets-1))); 286 } 287 288 bucket_iterator bucket_end(unsigned hash) { 289 return bucket_iterator(Buckets + (hash & (NumBuckets-1)), true); 290 } 291 292 /// GetOrInsertNode - If there is an existing simple Node exactly 293 /// equal to the specified node, return it. Otherwise, insert 'N' and 294 /// return it instead. 295 T *GetOrInsertNode(Node *N) { 296 return static_cast<T *>(FoldingSetImpl::GetOrInsertNode(N)); 297 } 298 299 /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists, 300 /// return it. If not, return the insertion token that will make insertion 301 /// faster. 302 T *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos) { 303 return static_cast<T *>(FoldingSetImpl::FindNodeOrInsertPos(ID, InsertPos)); 304 } 305}; 306 307//===----------------------------------------------------------------------===// 308/// FoldingSetIteratorImpl - This is the common iterator support shared by all 309/// folding sets, which knows how to walk the folding set hash table. 310class FoldingSetIteratorImpl { 311protected: 312 FoldingSetNode *NodePtr; 313 FoldingSetIteratorImpl(void **Bucket); 314 void advance(); 315 316public: 317 bool operator==(const FoldingSetIteratorImpl &RHS) const { 318 return NodePtr == RHS.NodePtr; 319 } 320 bool operator!=(const FoldingSetIteratorImpl &RHS) const { 321 return NodePtr != RHS.NodePtr; 322 } 323}; 324 325 326template<class T> 327class FoldingSetIterator : public FoldingSetIteratorImpl { 328public: 329 explicit FoldingSetIterator(void **Bucket) : FoldingSetIteratorImpl(Bucket) {} 330 331 T &operator*() const { 332 return *static_cast<T*>(NodePtr); 333 } 334 335 T *operator->() const { 336 return static_cast<T*>(NodePtr); 337 } 338 339 inline FoldingSetIterator& operator++() { // Preincrement 340 advance(); 341 return *this; 342 } 343 FoldingSetIterator operator++(int) { // Postincrement 344 FoldingSetIterator tmp = *this; ++*this; return tmp; 345 } 346}; 347 348//===----------------------------------------------------------------------===// 349/// FoldingSetBucketIteratorImpl - This is the common bucket iterator support 350/// shared by all folding sets, which knows how to walk a particular bucket 351/// of a folding set hash table. 352 353class FoldingSetBucketIteratorImpl { 354protected: 355 void *Ptr; 356 357 explicit FoldingSetBucketIteratorImpl(void **Bucket); 358 359 FoldingSetBucketIteratorImpl(void **Bucket, bool) 360 : Ptr(Bucket) {} 361 362 void advance() { 363 void *Probe = static_cast<FoldingSetNode*>(Ptr)->getNextInBucket(); 364 uintptr_t x = reinterpret_cast<uintptr_t>(Probe) & ~0x1; 365 Ptr = reinterpret_cast<void*>(x); 366 } 367 368public: 369 bool operator==(const FoldingSetBucketIteratorImpl &RHS) const { 370 return Ptr == RHS.Ptr; 371 } 372 bool operator!=(const FoldingSetBucketIteratorImpl &RHS) const { 373 return Ptr != RHS.Ptr; 374 } 375}; 376 377 378template<class T> 379class FoldingSetBucketIterator : public FoldingSetBucketIteratorImpl { 380public: 381 explicit FoldingSetBucketIterator(void **Bucket) : 382 FoldingSetBucketIteratorImpl(Bucket) {} 383 384 FoldingSetBucketIterator(void **Bucket, bool) : 385 FoldingSetBucketIteratorImpl(Bucket, true) {} 386 387 T& operator*() const { return *static_cast<T*>(Ptr); } 388 T* operator->() const { return static_cast<T*>(Ptr); } 389 390 inline FoldingSetBucketIterator& operator++() { // Preincrement 391 advance(); 392 return *this; 393 } 394 FoldingSetBucketIterator operator++(int) { // Postincrement 395 FoldingSetBucketIterator tmp = *this; ++*this; return tmp; 396 } 397}; 398 399//===----------------------------------------------------------------------===// 400/// FoldingSetNodeWrapper - This template class is used to "wrap" arbitrary 401/// types in an enclosing object so that they can be inserted into FoldingSets. 402template <typename T> 403class FoldingSetNodeWrapper : public FoldingSetNode { 404 T data; 405public: 406 explicit FoldingSetNodeWrapper(const T& x) : data(x) {} 407 virtual ~FoldingSetNodeWrapper() {} 408 409 template<typename A1> 410 explicit FoldingSetNodeWrapper(const A1& a1) 411 : data(a1) {} 412 413 template <typename A1, typename A2> 414 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2) 415 : data(a1,a2) {} 416 417 template <typename A1, typename A2, typename A3> 418 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3) 419 : data(a1,a2,a3) {} 420 421 template <typename A1, typename A2, typename A3, typename A4> 422 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3, 423 const A4& a4) 424 : data(a1,a2,a3,a4) {} 425 426 template <typename A1, typename A2, typename A3, typename A4, typename A5> 427 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3, 428 const A4& a4, const A5& a5) 429 : data(a1,a2,a3,a4,a5) {} 430 431 432 void Profile(FoldingSetNodeID& ID) { FoldingSetTrait<T>::Profile(data, ID); } 433 434 T& getValue() { return data; } 435 const T& getValue() const { return data; } 436 437 operator T&() { return data; } 438 operator const T&() const { return data; } 439}; 440 441//===----------------------------------------------------------------------===// 442// Partial specializations of FoldingSetTrait. 443 444template<typename T> struct FoldingSetTrait<T*> { 445 static inline void Profile(const T* X, FoldingSetNodeID& ID) { 446 ID.AddPointer(X); 447 } 448 static inline void Profile(T* X, FoldingSetNodeID& ID) { 449 ID.AddPointer(X); 450 } 451}; 452 453template<typename T> struct FoldingSetTrait<const T*> { 454 static inline void Profile(const T* X, FoldingSetNodeID& ID) { 455 ID.AddPointer(X); 456 } 457}; 458 459} // End of namespace llvm. 460 461#endif 462