FoldingSet.h revision 69e3bd10ecc36f7551b822a09d311fec08254cc0
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 AddFloat(float F);
229  void AddDouble(double D);
230  void AddString(const std::string &String);
231  void AddString(const char* String);
232
233  template <typename T>
234  inline void Add(const T& x) { FoldingSetTrait<T>::Profile(x, *this); }
235
236  /// clear - Clear the accumulated profile, allowing this FoldingSetNodeID
237  ///  object to be used to compute a new profile.
238  inline void clear() { Bits.clear(); }
239
240  /// ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used
241  ///  to lookup the node in the FoldingSetImpl.
242  unsigned ComputeHash() const;
243
244  /// operator== - Used to compare two nodes to each other.
245  ///
246  bool operator==(const FoldingSetNodeID &RHS) const;
247};
248
249// Convenience type to hide the implementation of the folding set.
250typedef FoldingSetImpl::Node FoldingSetNode;
251template<class T> class FoldingSetIterator;
252template<class T> class FoldingSetBucketIterator;
253
254//===----------------------------------------------------------------------===//
255/// FoldingSet - This template class is used to instantiate a specialized
256/// implementation of the folding set to the node class T.  T must be a
257/// subclass of FoldingSetNode and implement a Profile function.
258///
259template<class T> class FoldingSet : public FoldingSetImpl {
260private:
261  /// GetNodeProfile - Each instantiatation of the FoldingSet needs to provide a
262  /// way to convert nodes into a unique specifier.
263  virtual void GetNodeProfile(FoldingSetNodeID &ID, Node *N) const {
264    T *TN = static_cast<T *>(N);
265    FoldingSetTrait<T>::Profile(*TN,ID);
266  }
267
268public:
269  explicit FoldingSet(unsigned Log2InitSize = 6)
270  : FoldingSetImpl(Log2InitSize)
271  {}
272
273  typedef FoldingSetIterator<T> iterator;
274  iterator begin() { return iterator(Buckets); }
275  iterator end() { return iterator(Buckets+NumBuckets); }
276
277  typedef FoldingSetIterator<const T> const_iterator;
278  const_iterator begin() const { return const_iterator(Buckets); }
279  const_iterator end() const { return const_iterator(Buckets+NumBuckets); }
280
281  typedef FoldingSetBucketIterator<T> bucket_iterator;
282
283  bucket_iterator bucket_begin(unsigned hash) {
284    return bucket_iterator(Buckets + (hash & (NumBuckets-1)));
285  }
286
287  bucket_iterator bucket_end(unsigned hash) {
288    return bucket_iterator(Buckets + (hash & (NumBuckets-1)), true);
289  }
290
291  /// GetOrInsertNode - If there is an existing simple Node exactly
292  /// equal to the specified node, return it.  Otherwise, insert 'N' and
293  /// return it instead.
294  T *GetOrInsertNode(Node *N) {
295    return static_cast<T *>(FoldingSetImpl::GetOrInsertNode(N));
296  }
297
298  /// FindNodeOrInsertPos - Look up the node specified by ID.  If it exists,
299  /// return it.  If not, return the insertion token that will make insertion
300  /// faster.
301  T *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos) {
302    return static_cast<T *>(FoldingSetImpl::FindNodeOrInsertPos(ID, InsertPos));
303  }
304};
305
306//===----------------------------------------------------------------------===//
307/// FoldingSetIteratorImpl - This is the common iterator support shared by all
308/// folding sets, which knows how to walk the folding set hash table.
309class FoldingSetIteratorImpl {
310protected:
311  FoldingSetNode *NodePtr;
312  FoldingSetIteratorImpl(void **Bucket);
313  void advance();
314
315public:
316  bool operator==(const FoldingSetIteratorImpl &RHS) const {
317    return NodePtr == RHS.NodePtr;
318  }
319  bool operator!=(const FoldingSetIteratorImpl &RHS) const {
320    return NodePtr != RHS.NodePtr;
321  }
322};
323
324
325template<class T>
326class FoldingSetIterator : public FoldingSetIteratorImpl {
327public:
328  explicit FoldingSetIterator(void **Bucket) : FoldingSetIteratorImpl(Bucket) {}
329
330  T &operator*() const {
331    return *static_cast<T*>(NodePtr);
332  }
333
334  T *operator->() const {
335    return static_cast<T*>(NodePtr);
336  }
337
338  inline FoldingSetIterator& operator++() {          // Preincrement
339    advance();
340    return *this;
341  }
342  FoldingSetIterator operator++(int) {        // Postincrement
343    FoldingSetIterator tmp = *this; ++*this; return tmp;
344  }
345};
346
347//===----------------------------------------------------------------------===//
348/// FoldingSetBucketIteratorImpl - This is the common bucket iterator support
349///  shared by all folding sets, which knows how to walk a particular bucket
350///  of a folding set hash table.
351
352class FoldingSetBucketIteratorImpl {
353protected:
354  void *Ptr;
355
356  explicit FoldingSetBucketIteratorImpl(void **Bucket);
357
358  FoldingSetBucketIteratorImpl(void **Bucket, bool)
359    : Ptr(Bucket) {}
360
361  void advance() {
362    void *Probe = static_cast<FoldingSetNode*>(Ptr)->getNextInBucket();
363    uintptr_t x = reinterpret_cast<uintptr_t>(Probe) & ~0x1;
364    Ptr = reinterpret_cast<void*>(x);
365  }
366
367public:
368  bool operator==(const FoldingSetBucketIteratorImpl &RHS) const {
369    return Ptr == RHS.Ptr;
370  }
371  bool operator!=(const FoldingSetBucketIteratorImpl &RHS) const {
372    return Ptr != RHS.Ptr;
373  }
374};
375
376
377template<class T>
378class FoldingSetBucketIterator : public FoldingSetBucketIteratorImpl {
379public:
380  explicit FoldingSetBucketIterator(void **Bucket) :
381    FoldingSetBucketIteratorImpl(Bucket) {}
382
383  FoldingSetBucketIterator(void **Bucket, bool) :
384    FoldingSetBucketIteratorImpl(Bucket, true) {}
385
386  T& operator*() const { return *static_cast<T*>(Ptr); }
387  T* operator->() const { return static_cast<T*>(Ptr); }
388
389  inline FoldingSetBucketIterator& operator++() { // Preincrement
390    advance();
391    return *this;
392  }
393  FoldingSetBucketIterator operator++(int) {      // Postincrement
394    FoldingSetBucketIterator tmp = *this; ++*this; return tmp;
395  }
396};
397
398//===----------------------------------------------------------------------===//
399/// FoldingSetNodeWrapper - This template class is used to "wrap" arbitrary
400/// types in an enclosing object so that they can be inserted into FoldingSets.
401template <typename T>
402class FoldingSetNodeWrapper : public FoldingSetNode {
403  T data;
404public:
405  explicit FoldingSetNodeWrapper(const T& x) : data(x) {}
406  virtual ~FoldingSetNodeWrapper() {}
407
408  template<typename A1>
409  explicit FoldingSetNodeWrapper(const A1& a1)
410    : data(a1) {}
411
412  template <typename A1, typename A2>
413  explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2)
414    : data(a1,a2) {}
415
416  template <typename A1, typename A2, typename A3>
417  explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3)
418    : data(a1,a2,a3) {}
419
420  template <typename A1, typename A2, typename A3, typename A4>
421  explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3,
422                                 const A4& a4)
423    : data(a1,a2,a3,a4) {}
424
425  template <typename A1, typename A2, typename A3, typename A4, typename A5>
426  explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3,
427                                 const A4& a4, const A5& a5)
428  : data(a1,a2,a3,a4,a5) {}
429
430
431  void Profile(FoldingSetNodeID& ID) { FoldingSetTrait<T>::Profile(data, ID); }
432
433  T& getValue() { return data; }
434  const T& getValue() const { return data; }
435
436  operator T&() { return data; }
437  operator const T&() const { return data; }
438};
439
440//===----------------------------------------------------------------------===//
441// Partial specializations of FoldingSetTrait.
442
443template<typename T> struct FoldingSetTrait<T*> {
444  static inline void Profile(const T* X, FoldingSetNodeID& ID) {
445    ID.AddPointer(X);
446  }
447  static inline void Profile(T* X, FoldingSetNodeID& ID) {
448    ID.AddPointer(X);
449  }
450};
451
452template<typename T> struct FoldingSetTrait<const T*> {
453  static inline void Profile(const T* X, FoldingSetNodeID& ID) {
454    ID.AddPointer(X);
455  }
456};
457
458} // End of namespace llvm.
459
460
461#endif
462
463