1 //===- ScopedHashTable.h - A simple scoped hash table ---------------------===//
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 implements an efficient scoped hash table, which is useful for
11 // things like dominator-based optimizations. This allows clients to do things
14 // ScopedHashTable<int, int> HT;
16 // ScopedHashTableScope<int, int> Scope1(HT);
20 // ScopedHashTableScope<int, int> Scope2(HT);
25 // Looking up the value for "0" in the Scope2 block will return 42. Looking
26 // up the value for 0 before 42 is inserted or after Scope2 is popped will
29 //===----------------------------------------------------------------------===//
31 #ifndef LLVM_ADT_SCOPEDHASHTABLE_H
32 #define LLVM_ADT_SCOPEDHASHTABLE_H
34 #include "llvm/ADT/DenseMap.h"
35 #include "llvm/Support/Allocator.h"
39 template <typename K, typename V, typename KInfo = DenseMapInfo<K>,
40 typename AllocatorTy = MallocAllocator>
41 class ScopedHashTable;
43 template <typename K, typename V>
44 class ScopedHashTableVal {
45 ScopedHashTableVal *NextInScope;
46 ScopedHashTableVal *NextForKey;
49 ScopedHashTableVal(const K &key, const V &val) : Key(key), Val(val) {}
52 const K &getKey() const { return Key; }
53 const V &getValue() const { return Val; }
54 V &getValue() { return Val; }
56 ScopedHashTableVal *getNextForKey() { return NextForKey; }
57 const ScopedHashTableVal *getNextForKey() const { return NextForKey; }
58 ScopedHashTableVal *getNextInScope() { return NextInScope; }
60 template <typename AllocatorTy>
61 static ScopedHashTableVal *Create(ScopedHashTableVal *nextInScope,
62 ScopedHashTableVal *nextForKey,
63 const K &key, const V &val,
64 AllocatorTy &Allocator) {
65 ScopedHashTableVal *New = Allocator.template Allocate<ScopedHashTableVal>();
67 new (New) ScopedHashTableVal(key, val);
68 New->NextInScope = nextInScope;
69 New->NextForKey = nextForKey;
73 template <typename AllocatorTy>
74 void Destroy(AllocatorTy &Allocator) {
75 // Free memory referenced by the item.
76 this->~ScopedHashTableVal();
77 Allocator.Deallocate(this);
81 template <typename K, typename V, typename KInfo = DenseMapInfo<K>,
82 typename AllocatorTy = MallocAllocator>
83 class ScopedHashTableScope {
84 /// HT - The hashtable that we are active for.
85 ScopedHashTable<K, V, KInfo, AllocatorTy> &HT;
87 /// PrevScope - This is the scope that we are shadowing in HT.
88 ScopedHashTableScope *PrevScope;
90 /// LastValInScope - This is the last value that was inserted for this scope
91 /// or null if none have been inserted yet.
92 ScopedHashTableVal<K, V> *LastValInScope;
93 void operator=(ScopedHashTableScope&) LLVM_DELETED_FUNCTION;
94 ScopedHashTableScope(ScopedHashTableScope&) LLVM_DELETED_FUNCTION;
96 ScopedHashTableScope(ScopedHashTable<K, V, KInfo, AllocatorTy> &HT);
97 ~ScopedHashTableScope();
99 ScopedHashTableScope *getParentScope() { return PrevScope; }
100 const ScopedHashTableScope *getParentScope() const { return PrevScope; }
103 friend class ScopedHashTable<K, V, KInfo, AllocatorTy>;
104 ScopedHashTableVal<K, V> *getLastValInScope() {
105 return LastValInScope;
107 void setLastValInScope(ScopedHashTableVal<K, V> *Val) {
108 LastValInScope = Val;
113 template <typename K, typename V, typename KInfo = DenseMapInfo<K> >
114 class ScopedHashTableIterator {
115 ScopedHashTableVal<K, V> *Node;
117 ScopedHashTableIterator(ScopedHashTableVal<K, V> *node) : Node(node) {}
119 V &operator*() const {
120 assert(Node && "Dereference end()");
121 return Node->getValue();
123 V *operator->() const {
124 return &Node->getValue();
127 bool operator==(const ScopedHashTableIterator &RHS) const {
128 return Node == RHS.Node;
130 bool operator!=(const ScopedHashTableIterator &RHS) const {
131 return Node != RHS.Node;
134 inline ScopedHashTableIterator& operator++() { // Preincrement
135 assert(Node && "incrementing past end()");
136 Node = Node->getNextForKey();
139 ScopedHashTableIterator operator++(int) { // Postincrement
140 ScopedHashTableIterator tmp = *this; ++*this; return tmp;
145 template <typename K, typename V, typename KInfo, typename AllocatorTy>
146 class ScopedHashTable {
148 /// ScopeTy - This is a helpful typedef that allows clients to get easy access
149 /// to the name of the scope for this hash table.
150 typedef ScopedHashTableScope<K, V, KInfo, AllocatorTy> ScopeTy;
152 typedef ScopedHashTableVal<K, V> ValTy;
153 DenseMap<K, ValTy*, KInfo> TopLevelMap;
156 AllocatorTy Allocator;
158 ScopedHashTable(const ScopedHashTable&); // NOT YET IMPLEMENTED
159 void operator=(const ScopedHashTable&); // NOT YET IMPLEMENTED
160 friend class ScopedHashTableScope<K, V, KInfo, AllocatorTy>;
162 ScopedHashTable() : CurScope(nullptr) {}
163 ScopedHashTable(AllocatorTy A) : CurScope(0), Allocator(A) {}
165 assert(!CurScope && TopLevelMap.empty() && "Scope imbalance!");
169 /// Access to the allocator.
170 AllocatorTy &getAllocator() { return Allocator; }
171 const AllocatorTy &getAllocator() const { return Allocator; }
173 bool count(const K &Key) const {
174 return TopLevelMap.count(Key);
177 V lookup(const K &Key) {
178 typename DenseMap<K, ValTy*, KInfo>::iterator I = TopLevelMap.find(Key);
179 if (I != TopLevelMap.end())
180 return I->second->getValue();
185 void insert(const K &Key, const V &Val) {
186 insertIntoScope(CurScope, Key, Val);
189 typedef ScopedHashTableIterator<K, V, KInfo> iterator;
191 iterator end() { return iterator(0); }
193 iterator begin(const K &Key) {
194 typename DenseMap<K, ValTy*, KInfo>::iterator I =
195 TopLevelMap.find(Key);
196 if (I == TopLevelMap.end()) return end();
197 return iterator(I->second);
200 ScopeTy *getCurScope() { return CurScope; }
201 const ScopeTy *getCurScope() const { return CurScope; }
203 /// insertIntoScope - This inserts the specified key/value at the specified
204 /// (possibly not the current) scope. While it is ok to insert into a scope
205 /// that isn't the current one, it isn't ok to insert *underneath* an existing
206 /// value of the specified key.
207 void insertIntoScope(ScopeTy *S, const K &Key, const V &Val) {
208 assert(S && "No scope active!");
209 ScopedHashTableVal<K, V> *&KeyEntry = TopLevelMap[Key];
210 KeyEntry = ValTy::Create(S->getLastValInScope(), KeyEntry, Key, Val,
212 S->setLastValInScope(KeyEntry);
216 /// ScopedHashTableScope ctor - Install this as the current scope for the hash
218 template <typename K, typename V, typename KInfo, typename Allocator>
219 ScopedHashTableScope<K, V, KInfo, Allocator>::
220 ScopedHashTableScope(ScopedHashTable<K, V, KInfo, Allocator> &ht) : HT(ht) {
221 PrevScope = HT.CurScope;
223 LastValInScope = nullptr;
226 template <typename K, typename V, typename KInfo, typename Allocator>
227 ScopedHashTableScope<K, V, KInfo, Allocator>::~ScopedHashTableScope() {
228 assert(HT.CurScope == this && "Scope imbalance!");
229 HT.CurScope = PrevScope;
231 // Pop and delete all values corresponding to this scope.
232 while (ScopedHashTableVal<K, V> *ThisEntry = LastValInScope) {
233 // Pop this value out of the TopLevelMap.
234 if (!ThisEntry->getNextForKey()) {
235 assert(HT.TopLevelMap[ThisEntry->getKey()] == ThisEntry &&
237 HT.TopLevelMap.erase(ThisEntry->getKey());
239 ScopedHashTableVal<K, V> *&KeyEntry = HT.TopLevelMap[ThisEntry->getKey()];
240 assert(KeyEntry == ThisEntry && "Scope imbalance!");
241 KeyEntry = ThisEntry->getNextForKey();
244 // Pop this value out of the scope.
245 LastValInScope = ThisEntry->getNextInScope();
247 // Delete this entry.
248 ThisEntry->Destroy(HT.getAllocator());
252 } // end namespace llvm