1 //===-- llvm/ADT/FoldingSet.h - Uniquing Hash Set ---------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by James M. Laskey and is distributed under
6 // the University of Illinois Open Source 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"
26 /// This folding set used for two purposes:
27 /// 1. Given information about a node we want to create, look up the unique
28 /// instance of the node in the set. If the node already exists, return
29 /// it, otherwise return the bucket it should be inserted into.
30 /// 2. Given a node that has already been created, remove it from the set.
32 /// This class is implemented as a single-link chained hash table, where the
33 /// "buckets" are actually the nodes themselves (the next pointer is in the
34 /// node). The last node points back to the bucket to simplified node removal.
36 /// Any node that is to be included in the folding set must be a subclass of
37 /// FoldingSetNode. The node class must also define a Profile method used to
38 /// establish the unique bits of data for the node. The Profile method is
39 /// passed a FoldingSetNodeID object which is used to gather the bits. Just
40 /// call one of the Add* functions defined in the FoldingSetImpl::NodeID class.
41 /// NOTE: That the folding set does not own the nodes and it is the
42 /// responsibility of the user to dispose of the nodes.
45 /// class MyNode : public FoldingSetNode {
50 /// MyNode(const char *N, unsigned V) : Name(N), Value(V) {}
52 /// void Profile(FoldingSetNodeID &ID) {
53 /// ID.AddString(Name);
54 /// ID.AddInteger(Value);
59 /// To define the folding set itself use the FoldingSet template;
62 /// FoldingSet<MyNode> MyFoldingSet;
64 /// Four public methods are available to manipulate the folding set;
66 /// 1) If you have an existing node that you want add to the set but unsure
67 /// that the node might already exist then call;
69 /// MyNode *M = MyFoldingSet.GetOrInsertNode(N);
71 /// If The result is equal to the input then the node has been inserted.
72 /// Otherwise, the result is the node existing in the folding set, and the
73 /// input can be discarded (use the result instead.)
75 /// 2) If you are ready to construct a node but want to check if it already
76 /// exists, then call FindNodeOrInsertPos with a FoldingSetNodeID of the bits to
79 /// FoldingSetNodeID ID;
80 /// ID.AddString(Name);
81 /// ID.AddInteger(Value);
82 /// void *InsertPoint;
84 /// MyNode *M = MyFoldingSet.FindNodeOrInsertPos(ID, InsertPoint);
86 /// If found then M with be non-NULL, else InsertPoint will point to where it
87 /// should be inserted using InsertNode.
89 /// 3) If you get a NULL result from FindNodeOrInsertPos then you can as a new
90 /// node with FindNodeOrInsertPos;
92 /// InsertNode(N, InsertPoint);
94 /// 4) Finally, if you want to remove a node from the folding set call;
96 /// bool WasRemoved = RemoveNode(N);
98 /// The result indicates whether the node existed in the folding set.
101 //===----------------------------------------------------------------------===//
102 /// FoldingSetImpl - Implements the folding set functionality. The main
103 /// structure is an array of buckets. Each bucket is indexed by the hash of
104 /// the nodes it contains. The bucket itself points to the nodes contained
105 /// in the bucket via a singly linked list. The last node in the list points
106 /// back to the bucket to facilitate node removal.
108 class FoldingSetImpl {
110 /// Buckets - Array of bucket chains.
114 /// NumBuckets - Length of the Buckets array. Always a power of 2.
118 /// NumNodes - Number of nodes in the folding set. Growth occurs when NumNodes
119 /// is greater than twice the number of buckets.
123 explicit FoldingSetImpl(unsigned Log2InitSize = 6);
124 virtual ~FoldingSetImpl();
126 // Forward declaration.
129 //===--------------------------------------------------------------------===//
130 /// NodeID - This class is used to gather all the unique data bits of a
131 /// node. When all the bits are gathered this class is used to produce a
132 /// hash value for the node.
135 /// Bits - Vector of all the data bits that make the node unique.
136 /// Use a SmallVector to avoid a heap allocation in the common case.
137 SmallVector<unsigned, 32> Bits;
142 /// getRawData - Return the ith entry in the Bits data.
144 unsigned getRawData(unsigned i) const {
148 /// Add* - Add various data types to Bit data.
150 void AddPointer(const void *Ptr);
151 void AddInteger(signed I);
152 void AddInteger(unsigned I);
153 void AddInteger(int64_t I);
154 void AddInteger(uint64_t I);
155 void AddFloat(float F);
156 void AddDouble(double D);
157 void AddAPFloat(const APFloat& apf);
158 void AddString(const std::string &String);
160 /// ComputeHash - Compute a strong hash value for this NodeID, used to
161 /// lookup the node in the FoldingSetImpl.
162 unsigned ComputeHash() const;
164 /// operator== - Used to compare two nodes to each other.
166 bool operator==(const NodeID &RHS) const;
169 //===--------------------------------------------------------------------===//
170 /// Node - This class is used to maintain the singly linked bucket list in
175 // NextInFoldingSetBucket - next link in the bucket list.
176 void *NextInFoldingSetBucket;
180 Node() : NextInFoldingSetBucket(0) {}
183 void *getNextInBucket() const { return NextInFoldingSetBucket; }
184 void SetNextInBucket(void *N) { NextInFoldingSetBucket = N; }
187 /// RemoveNode - Remove a node from the folding set, returning true if one
188 /// was removed or false if the node was not in the folding set.
189 bool RemoveNode(Node *N);
191 /// GetOrInsertNode - If there is an existing simple Node exactly
192 /// equal to the specified node, return it. Otherwise, insert 'N' and return
194 Node *GetOrInsertNode(Node *N);
196 /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists,
197 /// return it. If not, return the insertion token that will make insertion
199 Node *FindNodeOrInsertPos(const NodeID &ID, void *&InsertPos);
201 /// InsertNode - Insert the specified node into the folding set, knowing that
202 /// it is not already in the folding set. InsertPos must be obtained from
203 /// FindNodeOrInsertPos.
204 void InsertNode(Node *N, void *InsertPos);
208 /// GrowHashTable - Double the size of the hash table and rehash everything.
210 void GrowHashTable();
214 /// GetNodeProfile - Instantiations of the FoldingSet template implement
215 /// this function to gather data bits for the given node.
216 virtual void GetNodeProfile(NodeID &ID, Node *N) const = 0;
219 // Convenience types to hide the implementation of the folding set.
220 typedef FoldingSetImpl::Node FoldingSetNode;
221 typedef FoldingSetImpl::NodeID FoldingSetNodeID;
223 template<class T> class FoldingSetIterator;
225 //===----------------------------------------------------------------------===//
226 /// FoldingSet - This template class is used to instantiate a specialized
227 /// implementation of the folding set to the node class T. T must be a
228 /// subclass of FoldingSetNode and implement a Profile function.
230 template<class T> class FoldingSet : public FoldingSetImpl {
232 /// GetNodeProfile - Each instantiatation of the FoldingSet needs to provide a
233 /// way to convert nodes into a unique specifier.
234 virtual void GetNodeProfile(NodeID &ID, Node *N) const {
235 T *TN = static_cast<T *>(N);
240 explicit FoldingSet(unsigned Log2InitSize = 6)
241 : FoldingSetImpl(Log2InitSize)
244 typedef FoldingSetIterator<T> iterator;
245 iterator begin() { return iterator(Buckets); }
246 iterator end() { return iterator(Buckets+NumBuckets); }
248 typedef FoldingSetIterator<const T> const_iterator;
249 const_iterator begin() const { return const_iterator(Buckets); }
250 const_iterator end() const { return const_iterator(Buckets+NumBuckets); }
252 /// GetOrInsertNode - If there is an existing simple Node exactly
253 /// equal to the specified node, return it. Otherwise, insert 'N' and
254 /// return it instead.
255 T *GetOrInsertNode(Node *N) {
256 return static_cast<T *>(FoldingSetImpl::GetOrInsertNode(N));
259 /// FindNodeOrInsertPos - Look up the node specified by ID. If it exists,
260 /// return it. If not, return the insertion token that will make insertion
262 T *FindNodeOrInsertPos(const FoldingSetNodeID &ID, void *&InsertPos) {
263 return static_cast<T *>(FoldingSetImpl::FindNodeOrInsertPos(ID, InsertPos));
267 //===----------------------------------------------------------------------===//
268 /// FoldingSetIteratorImpl - This is the common iterator support shared by all
269 /// folding sets, which knows how to walk the folding set hash table.
270 class FoldingSetIteratorImpl {
272 FoldingSetNode *NodePtr;
273 FoldingSetIteratorImpl(void **Bucket);
277 bool operator==(const FoldingSetIteratorImpl &RHS) const {
278 return NodePtr == RHS.NodePtr;
280 bool operator!=(const FoldingSetIteratorImpl &RHS) const {
281 return NodePtr != RHS.NodePtr;
287 class FoldingSetIterator : public FoldingSetIteratorImpl {
289 FoldingSetIterator(void **Bucket) : FoldingSetIteratorImpl(Bucket) {}
291 T &operator*() const {
292 return *static_cast<T*>(NodePtr);
295 T *operator->() const {
296 return static_cast<T*>(NodePtr);
299 inline FoldingSetIterator& operator++() { // Preincrement
303 FoldingSetIterator operator++(int) { // Postincrement
304 FoldingSetIterator tmp = *this; ++*this; return tmp;
308 } // End of namespace llvm.