1 //===-- llvm/ADT/FoldingSet.h - Uniquing Hash Set ---------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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.
14 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_ADT_FOLDINGSET_H
17 #define LLVM_ADT_FOLDINGSET_H
19 #include "llvm/Support/DataTypes.h"
20 #include "llvm/ADT/SmallVector.h"
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.
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.
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.
47 /// class MyNode : public FoldingSetNode {
52 /// MyNode(const char *N, unsigned V) : Name(N), Value(V) {}
54 /// void Profile(FoldingSetNodeID &ID) const {
55 /// ID.AddString(Name);
56 /// ID.AddInteger(Value);
61 /// To define the folding set itself use the FoldingSet template;
64 /// FoldingSet<MyNode> MyFoldingSet;
66 /// Four public methods are available to manipulate the folding set;
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;
71 /// MyNode *M = MyFoldingSet.GetOrInsertNode(N);
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.)
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
81 /// FoldingSetNodeID ID;
82 /// ID.AddString(Name);
83 /// ID.AddInteger(Value);
84 /// void *InsertPoint;
86 /// MyNode *M = MyFoldingSet.FindNodeOrInsertPos(ID, InsertPoint);
88 /// If found then M with be non-NULL, else InsertPoint will point to where it
89 /// should be inserted using InsertNode.
91 /// 3) If you get a NULL result from FindNodeOrInsertPos then you can as a new
92 /// node with FindNodeOrInsertPos;
94 /// InsertNode(N, InsertPoint);
96 /// 4) Finally, if you want to remove a node from the folding set call;
98 /// bool WasRemoved = RemoveNode(N);
100 /// The result indicates whether the node existed in the folding set.
102 class FoldingSetNodeID;
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.
111 class FoldingSetImpl {
113 /// Buckets - Array of bucket chains.
117 /// NumBuckets - Length of the Buckets array. Always a power of 2.
121 /// NumNodes - Number of nodes in the folding set. Growth occurs when NumNodes
122 /// is greater than twice the number of buckets.
126 explicit FoldingSetImpl(unsigned Log2InitSize = 6);
127 virtual ~FoldingSetImpl();
129 //===--------------------------------------------------------------------===//
130 /// Node - This class is used to maintain the singly linked bucket list in
135 // NextInFoldingSetBucket - next link in the bucket list.
136 void *NextInFoldingSetBucket;
140 Node() : NextInFoldingSetBucket(0) {}
143 void *getNextInBucket() const { return NextInFoldingSetBucket; }
144 void SetNextInBucket(void *N) { NextInFoldingSetBucket = N; }
147 /// clear - Remove all nodes from the folding set.
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);
154 /// GetOrInsertNode - If there is an existing simple Node exactly
155 /// equal to the specified node, return it. Otherwise, insert 'N' and return
157 Node *GetOrInsertNode(Node *N);
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
162 Node *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos);
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);
169 /// size - Returns the number of nodes in the folding set.
170 unsigned size() const { return NumNodes; }
172 /// empty - Returns true if there are no nodes in the folding set.
173 bool empty() const { return NumNodes == 0; }
177 /// GrowHashTable - Double the size of the hash table and rehash everything.
179 void GrowHashTable();
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;
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.
196 template<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); }
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.
206 class 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;
212 FoldingSetNodeID() {}
214 /// getRawData - Return the ith entry in the Bits data.
216 unsigned getRawData(unsigned i) const {
220 /// Add* - Add various data types to Bit data.
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);
234 template <typename T>
235 inline void Add(const T& x) { FoldingSetTrait<T>::Profile(x, *this); }
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(); }
241 /// ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used
242 /// to lookup the node in the FoldingSetImpl.
243 unsigned ComputeHash() const;
245 /// operator== - Used to compare two nodes to each other.
247 bool operator==(const FoldingSetNodeID &RHS) const;
250 // Convenience type to hide the implementation of the folding set.
251 typedef FoldingSetImpl::Node FoldingSetNode;
252 template<class T> class FoldingSetIterator;
253 template<class T> class FoldingSetBucketIterator;
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.
260 template<class T> class FoldingSet : public FoldingSetImpl {
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);
270 explicit FoldingSet(unsigned Log2InitSize = 6)
271 : FoldingSetImpl(Log2InitSize)
274 typedef FoldingSetIterator<T> iterator;
275 iterator begin() { return iterator(Buckets); }
276 iterator end() { return iterator(Buckets+NumBuckets); }
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); }
282 typedef FoldingSetBucketIterator<T> bucket_iterator;
284 bucket_iterator bucket_begin(unsigned hash) {
285 return bucket_iterator(Buckets + (hash & (NumBuckets-1)));
288 bucket_iterator bucket_end(unsigned hash) {
289 return bucket_iterator(Buckets + (hash & (NumBuckets-1)), true);
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));
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
302 T *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos) {
303 return static_cast<T *>(FoldingSetImpl::FindNodeOrInsertPos(ID, InsertPos));
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.
310 class FoldingSetIteratorImpl {
312 FoldingSetNode *NodePtr;
313 FoldingSetIteratorImpl(void **Bucket);
317 bool operator==(const FoldingSetIteratorImpl &RHS) const {
318 return NodePtr == RHS.NodePtr;
320 bool operator!=(const FoldingSetIteratorImpl &RHS) const {
321 return NodePtr != RHS.NodePtr;
327 class FoldingSetIterator : public FoldingSetIteratorImpl {
329 explicit FoldingSetIterator(void **Bucket) : FoldingSetIteratorImpl(Bucket) {}
331 T &operator*() const {
332 return *static_cast<T*>(NodePtr);
335 T *operator->() const {
336 return static_cast<T*>(NodePtr);
339 inline FoldingSetIterator& operator++() { // Preincrement
343 FoldingSetIterator operator++(int) { // Postincrement
344 FoldingSetIterator tmp = *this; ++*this; return tmp;
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.
353 class FoldingSetBucketIteratorImpl {
357 explicit FoldingSetBucketIteratorImpl(void **Bucket);
359 FoldingSetBucketIteratorImpl(void **Bucket, bool)
363 void *Probe = static_cast<FoldingSetNode*>(Ptr)->getNextInBucket();
364 uintptr_t x = reinterpret_cast<uintptr_t>(Probe) & ~0x1;
365 Ptr = reinterpret_cast<void*>(x);
369 bool operator==(const FoldingSetBucketIteratorImpl &RHS) const {
370 return Ptr == RHS.Ptr;
372 bool operator!=(const FoldingSetBucketIteratorImpl &RHS) const {
373 return Ptr != RHS.Ptr;
379 class FoldingSetBucketIterator : public FoldingSetBucketIteratorImpl {
381 explicit FoldingSetBucketIterator(void **Bucket) :
382 FoldingSetBucketIteratorImpl(Bucket) {}
384 FoldingSetBucketIterator(void **Bucket, bool) :
385 FoldingSetBucketIteratorImpl(Bucket, true) {}
387 T& operator*() const { return *static_cast<T*>(Ptr); }
388 T* operator->() const { return static_cast<T*>(Ptr); }
390 inline FoldingSetBucketIterator& operator++() { // Preincrement
394 FoldingSetBucketIterator operator++(int) { // Postincrement
395 FoldingSetBucketIterator tmp = *this; ++*this; return tmp;
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.
402 template <typename T>
403 class FoldingSetNodeWrapper : public FoldingSetNode {
406 explicit FoldingSetNodeWrapper(const T& x) : data(x) {}
407 virtual ~FoldingSetNodeWrapper() {}
409 template<typename A1>
410 explicit FoldingSetNodeWrapper(const A1& a1)
413 template <typename A1, typename A2>
414 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2)
417 template <typename A1, typename A2, typename A3>
418 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3)
421 template <typename A1, typename A2, typename A3, typename A4>
422 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3,
424 : data(a1,a2,a3,a4) {}
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) {}
432 void Profile(FoldingSetNodeID& ID) { FoldingSetTrait<T>::Profile(data, ID); }
434 T& getValue() { return data; }
435 const T& getValue() const { return data; }
437 operator T&() { return data; }
438 operator const T&() const { return data; }
441 //===----------------------------------------------------------------------===//
442 // Partial specializations of FoldingSetTrait.
444 template<typename T> struct FoldingSetTrait<T*> {
445 static inline void Profile(const T* X, FoldingSetNodeID& ID) {
448 static inline void Profile(T* X, FoldingSetNodeID& ID) {
453 template<typename T> struct FoldingSetTrait<const T*> {
454 static inline void Profile(const T* X, FoldingSetNodeID& ID) {
459 } // End of namespace llvm.