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"
26 class BumpPtrAllocator;
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 /// InsertNode - Insert the specified node into the folding set, knowing that
170 /// it is not already in the folding set.
171 void InsertNode(Node *N) {
172 Node *Inserted = GetOrInsertNode(N);
174 assert(Inserted == N && "Node already inserted!");
177 /// size - Returns the number of nodes in the folding set.
178 unsigned size() const { return NumNodes; }
180 /// empty - Returns true if there are no nodes in the folding set.
181 bool empty() const { return NumNodes == 0; }
185 /// GrowHashTable - Double the size of the hash table and rehash everything.
187 void GrowHashTable();
191 /// GetNodeProfile - Instantiations of the FoldingSet template implement
192 /// this function to gather data bits for the given node.
193 virtual void GetNodeProfile(FoldingSetNodeID &ID, Node *N) const = 0;
196 //===----------------------------------------------------------------------===//
197 /// FoldingSetTrait - This trait class is used to define behavior of how
198 /// to "profile" (in the FoldingSet parlance) an object of a given type.
199 /// The default behavior is to invoke a 'Profile' method on an object, but
200 /// through template specialization the behavior can be tailored for specific
201 /// types. Combined with the FoldingSetNodeWrapper class, one can add objects
202 /// to FoldingSets that were not originally designed to have that behavior.
204 template<typename T> struct FoldingSetTrait {
205 static inline void Profile(const T& X, FoldingSetNodeID& ID) { X.Profile(ID);}
206 static inline void Profile(T& X, FoldingSetNodeID& ID) { X.Profile(ID); }
207 template <typename Ctx>
208 static inline void Profile(T &X, FoldingSetNodeID &ID, Ctx Context) {
209 X.Profile(ID, Context);
213 //===--------------------------------------------------------------------===//
214 /// FoldingSetNodeIDRef - This class describes a reference to an interned
215 /// FoldingSetNodeID, which can be a useful to store node id data rather
216 /// than using plain FoldingSetNodeIDs, since the 32-element SmallVector
217 /// is often much larger than necessary, and the possibility of heap
218 /// allocation means it requires a non-trivial destructor call.
219 class FoldingSetNodeIDRef {
223 FoldingSetNodeIDRef() : Data(0), Size(0) {}
224 FoldingSetNodeIDRef(unsigned *D, size_t S) : Data(D), Size(S) {}
226 unsigned *getData() const { return Data; }
227 size_t getSize() const { return Size; }
230 //===--------------------------------------------------------------------===//
231 /// FoldingSetNodeID - This class is used to gather all the unique data bits of
232 /// a node. When all the bits are gathered this class is used to produce a
233 /// hash value for the node.
235 class FoldingSetNodeID {
236 /// Bits - Vector of all the data bits that make the node unique.
237 /// Use a SmallVector to avoid a heap allocation in the common case.
238 SmallVector<unsigned, 32> Bits;
241 FoldingSetNodeID() {}
243 FoldingSetNodeID(FoldingSetNodeIDRef Ref)
244 : Bits(Ref.getData(), Ref.getData() + Ref.getSize()) {}
246 /// Add* - Add various data types to Bit data.
248 void AddPointer(const void *Ptr);
249 void AddInteger(signed I);
250 void AddInteger(unsigned I);
251 void AddInteger(long I);
252 void AddInteger(unsigned long I);
253 void AddInteger(long long I);
254 void AddInteger(unsigned long long I);
255 void AddBoolean(bool B) { AddInteger(B ? 1U : 0U); }
256 void AddString(StringRef String);
258 template <typename T>
259 inline void Add(const T& x) { FoldingSetTrait<T>::Profile(x, *this); }
261 /// clear - Clear the accumulated profile, allowing this FoldingSetNodeID
262 /// object to be used to compute a new profile.
263 inline void clear() { Bits.clear(); }
265 /// ComputeHash - Compute a strong hash value for this FoldingSetNodeID, used
266 /// to lookup the node in the FoldingSetImpl.
267 unsigned ComputeHash() const;
269 /// operator== - Used to compare two nodes to each other.
271 bool operator==(const FoldingSetNodeID &RHS) const;
273 /// Intern - Copy this node's data to a memory region allocated from the
274 /// given allocator and return a FoldingSetNodeIDRef describing the
276 FoldingSetNodeIDRef Intern(BumpPtrAllocator &Allocator) const;
279 // Convenience type to hide the implementation of the folding set.
280 typedef FoldingSetImpl::Node FoldingSetNode;
281 template<class T> class FoldingSetIterator;
282 template<class T> class FoldingSetBucketIterator;
284 //===----------------------------------------------------------------------===//
285 /// FoldingSet - This template class is used to instantiate a specialized
286 /// implementation of the folding set to the node class T. T must be a
287 /// subclass of FoldingSetNode and implement a Profile function.
289 template<class T> class FoldingSet : public FoldingSetImpl {
291 /// GetNodeProfile - Each instantiatation of the FoldingSet needs to provide a
292 /// way to convert nodes into a unique specifier.
293 virtual void GetNodeProfile(FoldingSetNodeID &ID, Node *N) const {
294 T *TN = static_cast<T *>(N);
295 FoldingSetTrait<T>::Profile(*TN,ID);
299 explicit FoldingSet(unsigned Log2InitSize = 6)
300 : FoldingSetImpl(Log2InitSize)
303 typedef FoldingSetIterator<T> iterator;
304 iterator begin() { return iterator(Buckets); }
305 iterator end() { return iterator(Buckets+NumBuckets); }
307 typedef FoldingSetIterator<const T> const_iterator;
308 const_iterator begin() const { return const_iterator(Buckets); }
309 const_iterator end() const { return const_iterator(Buckets+NumBuckets); }
311 typedef FoldingSetBucketIterator<T> bucket_iterator;
313 bucket_iterator bucket_begin(unsigned hash) {
314 return bucket_iterator(Buckets + (hash & (NumBuckets-1)));
317 bucket_iterator bucket_end(unsigned hash) {
318 return bucket_iterator(Buckets + (hash & (NumBuckets-1)), true);
321 /// GetOrInsertNode - If there is an existing simple Node exactly
322 /// equal to the specified node, return it. Otherwise, insert 'N' and
323 /// return it instead.
324 T *GetOrInsertNode(Node *N) {
325 return static_cast<T *>(FoldingSetImpl::GetOrInsertNode(N));
328 /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists,
329 /// return it. If not, return the insertion token that will make insertion
331 T *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos) {
332 return static_cast<T *>(FoldingSetImpl::FindNodeOrInsertPos(ID, InsertPos));
336 //===----------------------------------------------------------------------===//
337 /// ContextualFoldingSet - This template class is a further refinement
338 /// of FoldingSet which provides a context argument when calling
339 /// Profile on its nodes. Currently, that argument is fixed at
340 /// initialization time.
342 /// T must be a subclass of FoldingSetNode and implement a Profile
343 /// function with signature
344 /// void Profile(llvm::FoldingSetNodeID &, Ctx);
345 template <class T, class Ctx>
346 class ContextualFoldingSet : public FoldingSetImpl {
347 // Unfortunately, this can't derive from FoldingSet<T> because the
348 // construction vtable for FoldingSet<T> requires
349 // FoldingSet<T>::GetNodeProfile to be instantiated, which in turn
350 // requires a single-argument T::Profile().
355 /// GetNodeProfile - Each instantiatation of the FoldingSet needs to provide a
356 /// way to convert nodes into a unique specifier.
357 virtual void GetNodeProfile(FoldingSetNodeID &ID,
358 FoldingSetImpl::Node *N) const {
359 T *TN = static_cast<T *>(N);
361 // We must use explicit template arguments in case Ctx is a
363 FoldingSetTrait<T>::template Profile<Ctx>(*TN, ID, Context);
367 explicit ContextualFoldingSet(Ctx Context, unsigned Log2InitSize = 6)
368 : FoldingSetImpl(Log2InitSize), Context(Context)
371 Ctx getContext() const { return Context; }
374 typedef FoldingSetIterator<T> iterator;
375 iterator begin() { return iterator(Buckets); }
376 iterator end() { return iterator(Buckets+NumBuckets); }
378 typedef FoldingSetIterator<const T> const_iterator;
379 const_iterator begin() const { return const_iterator(Buckets); }
380 const_iterator end() const { return const_iterator(Buckets+NumBuckets); }
382 typedef FoldingSetBucketIterator<T> bucket_iterator;
384 bucket_iterator bucket_begin(unsigned hash) {
385 return bucket_iterator(Buckets + (hash & (NumBuckets-1)));
388 bucket_iterator bucket_end(unsigned hash) {
389 return bucket_iterator(Buckets + (hash & (NumBuckets-1)), true);
392 /// GetOrInsertNode - If there is an existing simple Node exactly
393 /// equal to the specified node, return it. Otherwise, insert 'N'
394 /// and return it instead.
395 T *GetOrInsertNode(Node *N) {
396 return static_cast<T *>(FoldingSetImpl::GetOrInsertNode(N));
399 /// FindNodeOrInsertPos - Look up the node specified by ID. If it
400 /// exists, return it. If not, return the insertion token that will
401 /// make insertion faster.
402 T *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos) {
403 return static_cast<T *>(FoldingSetImpl::FindNodeOrInsertPos(ID, InsertPos));
407 //===----------------------------------------------------------------------===//
408 /// FoldingSetIteratorImpl - This is the common iterator support shared by all
409 /// folding sets, which knows how to walk the folding set hash table.
410 class FoldingSetIteratorImpl {
412 FoldingSetNode *NodePtr;
413 FoldingSetIteratorImpl(void **Bucket);
417 bool operator==(const FoldingSetIteratorImpl &RHS) const {
418 return NodePtr == RHS.NodePtr;
420 bool operator!=(const FoldingSetIteratorImpl &RHS) const {
421 return NodePtr != RHS.NodePtr;
427 class FoldingSetIterator : public FoldingSetIteratorImpl {
429 explicit FoldingSetIterator(void **Bucket) : FoldingSetIteratorImpl(Bucket) {}
431 T &operator*() const {
432 return *static_cast<T*>(NodePtr);
435 T *operator->() const {
436 return static_cast<T*>(NodePtr);
439 inline FoldingSetIterator& operator++() { // Preincrement
443 FoldingSetIterator operator++(int) { // Postincrement
444 FoldingSetIterator tmp = *this; ++*this; return tmp;
448 //===----------------------------------------------------------------------===//
449 /// FoldingSetBucketIteratorImpl - This is the common bucket iterator support
450 /// shared by all folding sets, which knows how to walk a particular bucket
451 /// of a folding set hash table.
453 class FoldingSetBucketIteratorImpl {
457 explicit FoldingSetBucketIteratorImpl(void **Bucket);
459 FoldingSetBucketIteratorImpl(void **Bucket, bool)
463 void *Probe = static_cast<FoldingSetNode*>(Ptr)->getNextInBucket();
464 uintptr_t x = reinterpret_cast<uintptr_t>(Probe) & ~0x1;
465 Ptr = reinterpret_cast<void*>(x);
469 bool operator==(const FoldingSetBucketIteratorImpl &RHS) const {
470 return Ptr == RHS.Ptr;
472 bool operator!=(const FoldingSetBucketIteratorImpl &RHS) const {
473 return Ptr != RHS.Ptr;
479 class FoldingSetBucketIterator : public FoldingSetBucketIteratorImpl {
481 explicit FoldingSetBucketIterator(void **Bucket) :
482 FoldingSetBucketIteratorImpl(Bucket) {}
484 FoldingSetBucketIterator(void **Bucket, bool) :
485 FoldingSetBucketIteratorImpl(Bucket, true) {}
487 T& operator*() const { return *static_cast<T*>(Ptr); }
488 T* operator->() const { return static_cast<T*>(Ptr); }
490 inline FoldingSetBucketIterator& operator++() { // Preincrement
494 FoldingSetBucketIterator operator++(int) { // Postincrement
495 FoldingSetBucketIterator tmp = *this; ++*this; return tmp;
499 //===----------------------------------------------------------------------===//
500 /// FoldingSetNodeWrapper - This template class is used to "wrap" arbitrary
501 /// types in an enclosing object so that they can be inserted into FoldingSets.
502 template <typename T>
503 class FoldingSetNodeWrapper : public FoldingSetNode {
506 explicit FoldingSetNodeWrapper(const T& x) : data(x) {}
507 virtual ~FoldingSetNodeWrapper() {}
509 template<typename A1>
510 explicit FoldingSetNodeWrapper(const A1& a1)
513 template <typename A1, typename A2>
514 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2)
517 template <typename A1, typename A2, typename A3>
518 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3)
521 template <typename A1, typename A2, typename A3, typename A4>
522 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3,
524 : data(a1,a2,a3,a4) {}
526 template <typename A1, typename A2, typename A3, typename A4, typename A5>
527 explicit FoldingSetNodeWrapper(const A1& a1, const A2& a2, const A3& a3,
528 const A4& a4, const A5& a5)
529 : data(a1,a2,a3,a4,a5) {}
532 void Profile(FoldingSetNodeID& ID) { FoldingSetTrait<T>::Profile(data, ID); }
534 T& getValue() { return data; }
535 const T& getValue() const { return data; }
537 operator T&() { return data; }
538 operator const T&() const { return data; }
541 //===----------------------------------------------------------------------===//
542 /// FastFoldingSetNode - This is a subclass of FoldingSetNode which stores
543 /// a FoldingSetNodeID value rather than requiring the node to recompute it
544 /// each time it is needed. This trades space for speed (which can be
545 /// significant if the ID is long), and it also permits nodes to drop
546 /// information that would otherwise only be required for recomputing an ID.
547 class FastFoldingSetNode : public FoldingSetNode {
548 FoldingSetNodeID FastID;
550 explicit FastFoldingSetNode(const FoldingSetNodeID &ID) : FastID(ID) {}
552 void Profile(FoldingSetNodeID& ID) { ID = FastID; }
555 //===----------------------------------------------------------------------===//
556 // Partial specializations of FoldingSetTrait.
558 template<typename T> struct FoldingSetTrait<T*> {
559 static inline void Profile(const T* X, FoldingSetNodeID& ID) {
562 static inline void Profile(T* X, FoldingSetNodeID& ID) {
567 template<typename T> struct FoldingSetTrait<const T*> {
568 static inline void Profile(const T* X, FoldingSetNodeID& ID) {
573 } // End of namespace llvm.