FoldingSet.h revision 1002c0203450620594a85454c6a095ca94b87cb2
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 /// 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/// FoldingSetTrait - This trait class is used to define behavior of how 183/// to "profile" (in the FoldingSet parlance) an object of a given type. 184/// The default behavior is to invoke a 'Profile' method on an object, but 185/// through template specialization the behavior can be tailored for specific 186/// types. Combined with the FoldingSetNodeWrapper classs, one can add objects 187/// to FoldingSets that were not originally designed to have that behavior. 188/// 189template<typename T> struct FoldingSetTrait { 190 static inline void Profile(const T& X, FoldingSetNodeID& ID) { X.Profile(ID);} 191 static inline void Profile(T& X, FoldingSetNodeID& ID) { X.Profile(ID); } 192}; 193 194//===--------------------------------------------------------------------===// 195/// FoldingSetNodeID - This class is used to gather all the unique data bits of 196/// a node. When all the bits are gathered this class is used to produce a 197/// hash value for the node. 198/// 199class FoldingSetNodeID { 200 /// Bits - Vector of all the data bits that make the node unique. 201 /// Use a SmallVector to avoid a heap allocation in the common case. 202 SmallVector<unsigned, 32> Bits; 203 204public: 205 FoldingSetNodeID() {} 206 207 /// getRawData - Return the ith entry in the Bits data. 208 /// 209 unsigned getRawData(unsigned i) const { 210 return Bits[i]; 211 } 212 213 /// Add* - Add various data types to Bit data. 214 /// 215 void AddPointer(const void *Ptr); 216 void AddInteger(signed I); 217 void AddInteger(unsigned I); 218 void AddInteger(int64_t I); 219 void AddInteger(uint64_t I); 220 void AddFloat(float F); 221 void AddDouble(double D); 222 void AddString(const std::string &String); 223 void AddString(const char* String); 224 225 template <typename T> 226 inline void Add(const T& x) { FoldingSetTrait<T>::Profile(x, *this); } 227 228 /// clear - Clear the accumulated profile, allowing this FoldingSetNodeID 229 /// object to be used to compute a new profile. 230 inline void clear() { Bits.clear(); } 231 232 /// ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used 233 /// to lookup the node in the FoldingSetImpl. 234 unsigned ComputeHash() const; 235 236 /// operator== - Used to compare two nodes to each other. 237 /// 238 bool operator==(const FoldingSetNodeID &RHS) const; 239}; 240 241// Convenience type to hide the implementation of the folding set. 242typedef FoldingSetImpl::Node FoldingSetNode; 243template<class T> class FoldingSetIterator; 244template<class T> class FoldingSetBucketIterator; 245 246//===----------------------------------------------------------------------===// 247/// FoldingSet - This template class is used to instantiate a specialized 248/// implementation of the folding set to the node class T. T must be a 249/// subclass of FoldingSetNode and implement a Profile function. 250/// 251template<class T> class FoldingSet : public FoldingSetImpl { 252private: 253 /// GetNodeProfile - Each instantiatation of the FoldingSet needs to provide a 254 /// way to convert nodes into a unique specifier. 255 virtual void GetNodeProfile(FoldingSetNodeID &ID, Node *N) const { 256 T *TN = static_cast<T *>(N); 257 FoldingSetTrait<T>::Profile(*TN,ID); 258 } 259 260public: 261 explicit FoldingSet(unsigned Log2InitSize = 6) 262 : FoldingSetImpl(Log2InitSize) 263 {} 264 265 typedef FoldingSetIterator<T> iterator; 266 iterator begin() { return iterator(Buckets); } 267 iterator end() { return iterator(Buckets+NumBuckets); } 268 269 typedef FoldingSetIterator<const T> const_iterator; 270 const_iterator begin() const { return const_iterator(Buckets); } 271 const_iterator end() const { return const_iterator(Buckets+NumBuckets); } 272 273 typedef FoldingSetBucketIterator<T> bucket_iterator; 274 275 bucket_iterator bucket_begin(unsigned hash) { 276 return bucket_iterator(Buckets + (hash & (NumBuckets-1))); 277 } 278 279 bucket_iterator bucket_end(unsigned hash) { 280 return bucket_iterator(Buckets + (hash & (NumBuckets-1)), true); 281 } 282 283 /// GetOrInsertNode - If there is an existing simple Node exactly 284 /// equal to the specified node, return it. Otherwise, insert 'N' and 285 /// return it instead. 286 T *GetOrInsertNode(Node *N) { 287 return static_cast<T *>(FoldingSetImpl::GetOrInsertNode(N)); 288 } 289 290 /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists, 291 /// return it. If not, return the insertion token that will make insertion 292 /// faster. 293 T *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos) { 294 return static_cast<T *>(FoldingSetImpl::FindNodeOrInsertPos(ID, InsertPos)); 295 } 296}; 297 298//===----------------------------------------------------------------------===// 299/// FoldingSetIteratorImpl - This is the common iterator support shared by all 300/// folding sets, which knows how to walk the folding set hash table. 301class FoldingSetIteratorImpl { 302protected: 303 FoldingSetNode *NodePtr; 304 FoldingSetIteratorImpl(void **Bucket); 305 void advance(); 306 307public: 308 bool operator==(const FoldingSetIteratorImpl &RHS) const { 309 return NodePtr == RHS.NodePtr; 310 } 311 bool operator!=(const FoldingSetIteratorImpl &RHS) const { 312 return NodePtr != RHS.NodePtr; 313 } 314}; 315 316 317template<class T> 318class FoldingSetIterator : public FoldingSetIteratorImpl { 319public: 320 explicit FoldingSetIterator(void **Bucket) : FoldingSetIteratorImpl(Bucket) {} 321 322 T &operator*() const { 323 return *static_cast<T*>(NodePtr); 324 } 325 326 T *operator->() const { 327 return static_cast<T*>(NodePtr); 328 } 329 330 inline FoldingSetIterator& operator++() { // Preincrement 331 advance(); 332 return *this; 333 } 334 FoldingSetIterator operator++(int) { // Postincrement 335 FoldingSetIterator tmp = *this; ++*this; return tmp; 336 } 337}; 338 339//===----------------------------------------------------------------------===// 340/// FoldingSetBucketIteratorImpl - This is the common bucket iterator support 341/// shared by all folding sets, which knows how to walk a particular bucket 342/// of a folding set hash table. 343 344class FoldingSetBucketIteratorImpl { 345protected: 346 void *Ptr; 347 348 explicit FoldingSetBucketIteratorImpl(void **Bucket); 349 350 FoldingSetBucketIteratorImpl(void **Bucket, bool) 351 : Ptr(reinterpret_cast<void*>(Bucket)) {} 352 353 void advance() { 354 void *Probe = static_cast<FoldingSetNode*>(Ptr)->getNextInBucket(); 355 uintptr_t x = reinterpret_cast<uintptr_t>(Probe) & ~0x1; 356 Ptr = reinterpret_cast<void*>(x); 357 } 358 359public: 360 bool operator==(const FoldingSetBucketIteratorImpl &RHS) const { 361 return Ptr == RHS.Ptr; 362 } 363 bool operator!=(const FoldingSetBucketIteratorImpl &RHS) const { 364 return Ptr != RHS.Ptr; 365 } 366}; 367 368 369template<class T> 370class FoldingSetBucketIterator : public FoldingSetBucketIteratorImpl { 371public: 372 explicit FoldingSetBucketIterator(void **Bucket) : 373 FoldingSetBucketIteratorImpl(Bucket) {} 374 375 FoldingSetBucketIterator(void **Bucket, bool) : 376 FoldingSetBucketIteratorImpl(Bucket, true) {} 377 378 T& operator*() const { return *static_cast<T*>(Ptr); } 379 T* operator->() const { return static_cast<T*>(Ptr); } 380 381 inline FoldingSetBucketIterator& operator++() { // Preincrement 382 advance(); 383 return *this; 384 } 385 FoldingSetBucketIterator operator++(int) { // Postincrement 386 FoldingSetBucketIterator tmp = *this; ++*this; return tmp; 387 } 388}; 389 390//===----------------------------------------------------------------------===// 391/// FoldingSetNodeWrapper - This template class is used to "wrap" arbitrary 392/// types in an enclosing object so that they can be inserted into FoldingSets. 393template <typename T> 394class FoldingSetNodeWrapper : public FoldingSetNode { 395 T data; 396public: 397 explicit FoldingSetNodeWrapper(const T& x) : data(x) {} 398 virtual ~FoldingSetNodeWrapper() {} 399 400 template<typename A1> 401 explicit FoldingSetNodeWrapper(const A1& a1) 402 : data(a1) {} 403 404 template <typename A1, typename A2> 405 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2) 406 : data(a1,a2) {} 407 408 template <typename A1, typename A2, typename A3> 409 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3) 410 : data(a1,a2,a3) {} 411 412 template <typename A1, typename A2, typename A3, typename A4> 413 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3, 414 const A4& a4) 415 : data(a1,a2,a3,a4) {} 416 417 template <typename A1, typename A2, typename A3, typename A4, typename A5> 418 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3, 419 const A4& a4, const A5& a5) 420 : data(a1,a2,a3,a4,a5) {} 421 422 423 void Profile(FoldingSetNodeID& ID) { FoldingSetTrait<T>::Profile(data, ID); } 424 425 T& getValue() { return data; } 426 const T& getValue() const { return data; } 427 428 operator T&() { return data; } 429 operator const T&() const { return data; } 430}; 431 432//===----------------------------------------------------------------------===// 433// Partial specializations of FoldingSetTrait. 434 435template<typename T> struct FoldingSetTrait<T*> { 436 static inline void Profile(const T* X, FoldingSetNodeID& ID) { 437 ID.AddPointer(X); 438 } 439 static inline void Profile(T* X, FoldingSetNodeID& ID) { 440 ID.AddPointer(X); 441 } 442}; 443 444} // End of namespace llvm. 445 446 447#endif 448 449