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/System/DataTypes.h"
20 #include "llvm/ADT/SmallVector.h"
21 #include "llvm/ADT/StringRef.h"
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.
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.
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.
46 /// class MyNode : public FoldingSetNode {
51 /// MyNode(const char *N, unsigned V) : Name(N), Value(V) {}
53 /// void Profile(FoldingSetNodeID &ID) const {
54 /// ID.AddString(Name);
55 /// ID.AddInteger(Value);
60 /// To define the folding set itself use the FoldingSet template;
63 /// FoldingSet<MyNode> MyFoldingSet;
65 /// Four public methods are available to manipulate the folding set;
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;
70 /// MyNode *M = MyFoldingSet.GetOrInsertNode(N);
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.)
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
80 /// FoldingSetNodeID ID;
81 /// ID.AddString(Name);
82 /// ID.AddInteger(Value);
83 /// void *InsertPoint;
85 /// MyNode *M = MyFoldingSet.FindNodeOrInsertPos(ID, InsertPoint);
87 /// If found then M with be non-NULL, else InsertPoint will point to where it
88 /// should be inserted using InsertNode.
90 /// 3) If you get a NULL result from FindNodeOrInsertPos then you can as a new
91 /// node with FindNodeOrInsertPos;
93 /// InsertNode(N, InsertPoint);
95 /// 4) Finally, if you want to remove a node from the folding set call;
97 /// bool WasRemoved = RemoveNode(N);
99 /// The result indicates whether the node existed in the folding set.
101 class FoldingSetNodeID;
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.
110 class FoldingSetImpl {
112 /// Buckets - Array of bucket chains.
116 /// NumBuckets - Length of the Buckets array. Always a power of 2.
120 /// NumNodes - Number of nodes in the folding set. Growth occurs when NumNodes
121 /// is greater than twice the number of buckets.
125 explicit FoldingSetImpl(unsigned Log2InitSize = 6);
126 virtual ~FoldingSetImpl();
128 //===--------------------------------------------------------------------===//
129 /// Node - This class is used to maintain the singly linked bucket list in
134 // NextInFoldingSetBucket - next link in the bucket list.
135 void *NextInFoldingSetBucket;
139 Node() : NextInFoldingSetBucket(0) {}
142 void *getNextInBucket() const { return NextInFoldingSetBucket; }
143 void SetNextInBucket(void *N) { NextInFoldingSetBucket = N; }
146 /// clear - Remove all nodes from the folding set.
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);
153 /// GetOrInsertNode - If there is an existing simple Node exactly
154 /// equal to the specified node, return it. Otherwise, insert 'N' and return
156 Node *GetOrInsertNode(Node *N);
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
161 Node *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos);
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);
168 /// size - Returns the number of nodes in the folding set.
169 unsigned size() const { return NumNodes; }
171 /// empty - Returns true if there are no nodes in the folding set.
172 bool empty() const { return NumNodes == 0; }
176 /// GrowHashTable - Double the size of the hash table and rehash everything.
178 void GrowHashTable();
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;
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.
195 template<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); }
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.
205 class 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;
211 FoldingSetNodeID() {}
213 /// getRawData - Return the ith entry in the Bits data.
215 unsigned getRawData(unsigned i) const {
219 /// Add* - Add various data types to Bit data.
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 AddBoolean(bool B) { AddInteger(B ? 1U : 0U); }
229 void AddString(StringRef String);
231 template <typename T>
232 inline void Add(const T& x) { FoldingSetTrait<T>::Profile(x, *this); }
234 /// clear - Clear the accumulated profile, allowing this FoldingSetNodeID
235 /// object to be used to compute a new profile.
236 inline void clear() { Bits.clear(); }
238 /// ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used
239 /// to lookup the node in the FoldingSetImpl.
240 unsigned ComputeHash() const;
242 /// operator== - Used to compare two nodes to each other.
244 bool operator==(const FoldingSetNodeID &RHS) const;
247 // Convenience type to hide the implementation of the folding set.
248 typedef FoldingSetImpl::Node FoldingSetNode;
249 template<class T> class FoldingSetIterator;
250 template<class T> class FoldingSetBucketIterator;
252 //===----------------------------------------------------------------------===//
253 /// FoldingSet - This template class is used to instantiate a specialized
254 /// implementation of the folding set to the node class T. T must be a
255 /// subclass of FoldingSetNode and implement a Profile function.
257 template<class T> class FoldingSet : public FoldingSetImpl {
259 /// GetNodeProfile - Each instantiatation of the FoldingSet needs to provide a
260 /// way to convert nodes into a unique specifier.
261 virtual void GetNodeProfile(FoldingSetNodeID &ID, Node *N) const {
262 T *TN = static_cast<T *>(N);
263 FoldingSetTrait<T>::Profile(*TN,ID);
267 explicit FoldingSet(unsigned Log2InitSize = 6)
268 : FoldingSetImpl(Log2InitSize)
271 typedef FoldingSetIterator<T> iterator;
272 iterator begin() { return iterator(Buckets); }
273 iterator end() { return iterator(Buckets+NumBuckets); }
275 typedef FoldingSetIterator<const T> const_iterator;
276 const_iterator begin() const { return const_iterator(Buckets); }
277 const_iterator end() const { return const_iterator(Buckets+NumBuckets); }
279 typedef FoldingSetBucketIterator<T> bucket_iterator;
281 bucket_iterator bucket_begin(unsigned hash) {
282 return bucket_iterator(Buckets + (hash & (NumBuckets-1)));
285 bucket_iterator bucket_end(unsigned hash) {
286 return bucket_iterator(Buckets + (hash & (NumBuckets-1)), true);
289 /// GetOrInsertNode - If there is an existing simple Node exactly
290 /// equal to the specified node, return it. Otherwise, insert 'N' and
291 /// return it instead.
292 T *GetOrInsertNode(Node *N) {
293 return static_cast<T *>(FoldingSetImpl::GetOrInsertNode(N));
296 /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists,
297 /// return it. If not, return the insertion token that will make insertion
299 T *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos) {
300 return static_cast<T *>(FoldingSetImpl::FindNodeOrInsertPos(ID, InsertPos));
304 //===----------------------------------------------------------------------===//
305 /// FoldingSetIteratorImpl - This is the common iterator support shared by all
306 /// folding sets, which knows how to walk the folding set hash table.
307 class FoldingSetIteratorImpl {
309 FoldingSetNode *NodePtr;
310 FoldingSetIteratorImpl(void **Bucket);
314 bool operator==(const FoldingSetIteratorImpl &RHS) const {
315 return NodePtr == RHS.NodePtr;
317 bool operator!=(const FoldingSetIteratorImpl &RHS) const {
318 return NodePtr != RHS.NodePtr;
324 class FoldingSetIterator : public FoldingSetIteratorImpl {
326 explicit FoldingSetIterator(void **Bucket) : FoldingSetIteratorImpl(Bucket) {}
328 T &operator*() const {
329 return *static_cast<T*>(NodePtr);
332 T *operator->() const {
333 return static_cast<T*>(NodePtr);
336 inline FoldingSetIterator& operator++() { // Preincrement
340 FoldingSetIterator operator++(int) { // Postincrement
341 FoldingSetIterator tmp = *this; ++*this; return tmp;
345 //===----------------------------------------------------------------------===//
346 /// FoldingSetBucketIteratorImpl - This is the common bucket iterator support
347 /// shared by all folding sets, which knows how to walk a particular bucket
348 /// of a folding set hash table.
350 class FoldingSetBucketIteratorImpl {
354 explicit FoldingSetBucketIteratorImpl(void **Bucket);
356 FoldingSetBucketIteratorImpl(void **Bucket, bool)
360 void *Probe = static_cast<FoldingSetNode*>(Ptr)->getNextInBucket();
361 uintptr_t x = reinterpret_cast<uintptr_t>(Probe) & ~0x1;
362 Ptr = reinterpret_cast<void*>(x);
366 bool operator==(const FoldingSetBucketIteratorImpl &RHS) const {
367 return Ptr == RHS.Ptr;
369 bool operator!=(const FoldingSetBucketIteratorImpl &RHS) const {
370 return Ptr != RHS.Ptr;
376 class FoldingSetBucketIterator : public FoldingSetBucketIteratorImpl {
378 explicit FoldingSetBucketIterator(void **Bucket) :
379 FoldingSetBucketIteratorImpl(Bucket) {}
381 FoldingSetBucketIterator(void **Bucket, bool) :
382 FoldingSetBucketIteratorImpl(Bucket, true) {}
384 T& operator*() const { return *static_cast<T*>(Ptr); }
385 T* operator->() const { return static_cast<T*>(Ptr); }
387 inline FoldingSetBucketIterator& operator++() { // Preincrement
391 FoldingSetBucketIterator operator++(int) { // Postincrement
392 FoldingSetBucketIterator tmp = *this; ++*this; return tmp;
396 //===----------------------------------------------------------------------===//
397 /// FoldingSetNodeWrapper - This template class is used to "wrap" arbitrary
398 /// types in an enclosing object so that they can be inserted into FoldingSets.
399 template <typename T>
400 class FoldingSetNodeWrapper : public FoldingSetNode {
403 explicit FoldingSetNodeWrapper(const T& x) : data(x) {}
404 virtual ~FoldingSetNodeWrapper() {}
406 template<typename A1>
407 explicit FoldingSetNodeWrapper(const A1& a1)
410 template <typename A1, typename A2>
411 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2)
414 template <typename A1, typename A2, typename A3>
415 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3)
418 template <typename A1, typename A2, typename A3, typename A4>
419 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3,
421 : data(a1,a2,a3,a4) {}
423 template <typename A1, typename A2, typename A3, typename A4, typename A5>
424 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3,
425 const A4& a4, const A5& a5)
426 : data(a1,a2,a3,a4,a5) {}
429 void Profile(FoldingSetNodeID& ID) { FoldingSetTrait<T>::Profile(data, ID); }
431 T& getValue() { return data; }
432 const T& getValue() const { return data; }
434 operator T&() { return data; }
435 operator const T&() const { return data; }
438 //===----------------------------------------------------------------------===//
439 /// FastFoldingSetNode - This is a subclass of FoldingSetNode which stores
440 /// a FoldingSetNodeID value rather than requiring the node to recompute it
441 /// each time it is needed. This trades space for speed (which can be
442 /// significant if the ID is long), and it also permits nodes to drop
443 /// information that would otherwise only be required for recomputing an ID.
444 class FastFoldingSetNode : public FoldingSetNode {
445 FoldingSetNodeID FastID;
447 explicit FastFoldingSetNode(const FoldingSetNodeID &ID) : FastID(ID) {}
449 void Profile(FoldingSetNodeID& ID) { ID = FastID; }
452 //===----------------------------------------------------------------------===//
453 // Partial specializations of FoldingSetTrait.
455 template<typename T> struct FoldingSetTrait<T*> {
456 static inline void Profile(const T* X, FoldingSetNodeID& ID) {
459 static inline void Profile(T* X, FoldingSetNodeID& ID) {
464 template<typename T> struct FoldingSetTrait<const T*> {
465 static inline void Profile(const T* X, FoldingSetNodeID& ID) {
470 } // End of namespace llvm.