FoldingSet.h revision 27dba671c3f158a33c8cbdf5196a6fd16489be03
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 "llvm/ADT/StringRef.h" 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(StringRef 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/// FastFoldingSetNode - This is a subclass of FoldingSetNode which stores 441/// a FoldingSetNodeID value rather than requiring the node to recompute it 442/// each time it is needed. This trades space for speed (which can be 443/// significant if the ID is long), and it also permits nodes to drop 444/// information that would otherwise only be required for recomputing an ID. 445class FastFoldingSetNode : public FoldingSetNode { 446 FoldingSetNodeID FastID; 447protected: 448 explicit FastFoldingSetNode(const FoldingSetNodeID &ID) : FastID(ID) {} 449public: 450 void Profile(FoldingSetNodeID& ID) { ID = FastID; } 451}; 452 453//===----------------------------------------------------------------------===// 454// Partial specializations of FoldingSetTrait. 455 456template<typename T> struct FoldingSetTrait<T*> { 457 static inline void Profile(const T* X, FoldingSetNodeID& ID) { 458 ID.AddPointer(X); 459 } 460 static inline void Profile(T* X, FoldingSetNodeID& ID) { 461 ID.AddPointer(X); 462 } 463}; 464 465template<typename T> struct FoldingSetTrait<const T*> { 466 static inline void Profile(const T* X, FoldingSetNodeID& ID) { 467 ID.AddPointer(X); 468 } 469}; 470 471} // End of namespace llvm. 472 473#endif 474