1 //===- ScopedHashTable.h - A simple scoped hash table -----------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 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 12 // like this: 13 // 14 // ScopedHashTable<int, int> HT; 15 // { 16 // ScopedHashTableScope<int, int> Scope1(HT); 17 // HT.insert(0, 0); 18 // HT.insert(1, 1); 19 // { 20 // ScopedHashTableScope<int, int> Scope2(HT); 21 // HT.insert(0, 42); 22 // } 23 // } 24 // 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 27 // return 0. 28 // 29 //===----------------------------------------------------------------------===// 30 31 #ifndef LLVM_ADT_SCOPEDHASHTABLE_H 32 #define LLVM_ADT_SCOPEDHASHTABLE_H 33 34 #include "llvm/ADT/DenseMap.h" 35 #include "llvm/ADT/DenseMapInfo.h" 36 #include "llvm/Support/Allocator.h" 37 #include <cassert> 38 #include <new> 39 40 namespace llvm { 41 42 template <typename K, typename V, typename KInfo = DenseMapInfo<K>, 43 typename AllocatorTy = MallocAllocator> 44 class ScopedHashTable; 45 46 template <typename K, typename V> 47 class ScopedHashTableVal { 48 ScopedHashTableVal *NextInScope; 49 ScopedHashTableVal *NextForKey; 50 K Key; 51 V Val; 52 53 ScopedHashTableVal(const K &key, const V &val) : Key(key), Val(val) {} 54 55 public: 56 const K &getKey() const { return Key; } 57 const V &getValue() const { return Val; } 58 V &getValue() { return Val; } 59 60 ScopedHashTableVal *getNextForKey() { return NextForKey; } 61 const ScopedHashTableVal *getNextForKey() const { return NextForKey; } 62 ScopedHashTableVal *getNextInScope() { return NextInScope; } 63 64 template <typename AllocatorTy> 65 static ScopedHashTableVal *Create(ScopedHashTableVal *nextInScope, 66 ScopedHashTableVal *nextForKey, 67 const K &key, const V &val, 68 AllocatorTy &Allocator) { 69 ScopedHashTableVal *New = Allocator.template Allocate<ScopedHashTableVal>(); 70 // Set up the value. 71 new (New) ScopedHashTableVal(key, val); 72 New->NextInScope = nextInScope; 73 New->NextForKey = nextForKey; 74 return New; 75 } 76 77 template <typename AllocatorTy> void Destroy(AllocatorTy &Allocator) { 78 // Free memory referenced by the item. 79 this->~ScopedHashTableVal(); 80 Allocator.Deallocate(this); 81 } 82 }; 83 84 template <typename K, typename V, typename KInfo = DenseMapInfo<K>, 85 typename AllocatorTy = MallocAllocator> 86 class ScopedHashTableScope { 87 /// HT - The hashtable that we are active for. 88 ScopedHashTable<K, V, KInfo, AllocatorTy> &HT; 89 90 /// PrevScope - This is the scope that we are shadowing in HT. 91 ScopedHashTableScope *PrevScope; 92 93 /// LastValInScope - This is the last value that was inserted for this scope 94 /// or null if none have been inserted yet. 95 ScopedHashTableVal<K, V> *LastValInScope; 96 97 public: 98 ScopedHashTableScope(ScopedHashTable<K, V, KInfo, AllocatorTy> &HT); 99 ScopedHashTableScope(ScopedHashTableScope &) = delete; 100 ScopedHashTableScope &operator=(ScopedHashTableScope &) = delete; 101 ~ScopedHashTableScope(); 102 103 ScopedHashTableScope *getParentScope() { return PrevScope; } 104 const ScopedHashTableScope *getParentScope() const { return PrevScope; } 105 106 private: 107 friend class ScopedHashTable<K, V, KInfo, AllocatorTy>; 108 109 ScopedHashTableVal<K, V> *getLastValInScope() { 110 return LastValInScope; 111 } 112 void setLastValInScope(ScopedHashTableVal<K, V> *Val) { 113 LastValInScope = Val; 114 } 115 }; 116 117 template <typename K, typename V, typename KInfo = DenseMapInfo<K>> 118 class ScopedHashTableIterator { 119 ScopedHashTableVal<K, V> *Node; 120 121 public: 122 ScopedHashTableIterator(ScopedHashTableVal<K, V> *node) : Node(node) {} 123 124 V &operator*() const { 125 assert(Node && "Dereference end()"); 126 return Node->getValue(); 127 } 128 V *operator->() const { 129 return &Node->getValue(); 130 } 131 132 bool operator==(const ScopedHashTableIterator &RHS) const { 133 return Node == RHS.Node; 134 } 135 bool operator!=(const ScopedHashTableIterator &RHS) const { 136 return Node != RHS.Node; 137 } 138 139 inline ScopedHashTableIterator& operator++() { // Preincrement 140 assert(Node && "incrementing past end()"); 141 Node = Node->getNextForKey(); 142 return *this; 143 } 144 ScopedHashTableIterator operator++(int) { // Postincrement 145 ScopedHashTableIterator tmp = *this; ++*this; return tmp; 146 } 147 }; 148 149 template <typename K, typename V, typename KInfo, typename AllocatorTy> 150 class ScopedHashTable { 151 public: 152 /// ScopeTy - This is a helpful typedef that allows clients to get easy access 153 /// to the name of the scope for this hash table. 154 typedef ScopedHashTableScope<K, V, KInfo, AllocatorTy> ScopeTy; 155 typedef unsigned size_type; 156 157 private: 158 friend class ScopedHashTableScope<K, V, KInfo, AllocatorTy>; 159 160 typedef ScopedHashTableVal<K, V> ValTy; 161 DenseMap<K, ValTy*, KInfo> TopLevelMap; 162 ScopeTy *CurScope = nullptr; 163 164 AllocatorTy Allocator; 165 166 public: 167 ScopedHashTable() = default; 168 ScopedHashTable(AllocatorTy A) : CurScope(0), Allocator(A) {} 169 ScopedHashTable(const ScopedHashTable &) = delete; 170 ScopedHashTable &operator=(const ScopedHashTable &) = delete; 171 172 ~ScopedHashTable() { 173 assert(!CurScope && TopLevelMap.empty() && "Scope imbalance!"); 174 } 175 176 /// Access to the allocator. 177 AllocatorTy &getAllocator() { return Allocator; } 178 const AllocatorTy &getAllocator() const { return Allocator; } 179 180 /// Return 1 if the specified key is in the table, 0 otherwise. 181 size_type count(const K &Key) const { 182 return TopLevelMap.count(Key); 183 } 184 185 V lookup(const K &Key) const { 186 auto I = TopLevelMap.find(Key); 187 if (I != TopLevelMap.end()) 188 return I->second->getValue(); 189 190 return V(); 191 } 192 193 void insert(const K &Key, const V &Val) { 194 insertIntoScope(CurScope, Key, Val); 195 } 196 197 typedef ScopedHashTableIterator<K, V, KInfo> iterator; 198 199 iterator end() { return iterator(0); } 200 201 iterator begin(const K &Key) { 202 typename DenseMap<K, ValTy*, KInfo>::iterator I = 203 TopLevelMap.find(Key); 204 if (I == TopLevelMap.end()) return end(); 205 return iterator(I->second); 206 } 207 208 ScopeTy *getCurScope() { return CurScope; } 209 const ScopeTy *getCurScope() const { return CurScope; } 210 211 /// insertIntoScope - This inserts the specified key/value at the specified 212 /// (possibly not the current) scope. While it is ok to insert into a scope 213 /// that isn't the current one, it isn't ok to insert *underneath* an existing 214 /// value of the specified key. 215 void insertIntoScope(ScopeTy *S, const K &Key, const V &Val) { 216 assert(S && "No scope active!"); 217 ScopedHashTableVal<K, V> *&KeyEntry = TopLevelMap[Key]; 218 KeyEntry = ValTy::Create(S->getLastValInScope(), KeyEntry, Key, Val, 219 Allocator); 220 S->setLastValInScope(KeyEntry); 221 } 222 }; 223 224 /// ScopedHashTableScope ctor - Install this as the current scope for the hash 225 /// table. 226 template <typename K, typename V, typename KInfo, typename Allocator> 227 ScopedHashTableScope<K, V, KInfo, Allocator>:: 228 ScopedHashTableScope(ScopedHashTable<K, V, KInfo, Allocator> &ht) : HT(ht) { 229 PrevScope = HT.CurScope; 230 HT.CurScope = this; 231 LastValInScope = nullptr; 232 } 233 234 template <typename K, typename V, typename KInfo, typename Allocator> 235 ScopedHashTableScope<K, V, KInfo, Allocator>::~ScopedHashTableScope() { 236 assert(HT.CurScope == this && "Scope imbalance!"); 237 HT.CurScope = PrevScope; 238 239 // Pop and delete all values corresponding to this scope. 240 while (ScopedHashTableVal<K, V> *ThisEntry = LastValInScope) { 241 // Pop this value out of the TopLevelMap. 242 if (!ThisEntry->getNextForKey()) { 243 assert(HT.TopLevelMap[ThisEntry->getKey()] == ThisEntry && 244 "Scope imbalance!"); 245 HT.TopLevelMap.erase(ThisEntry->getKey()); 246 } else { 247 ScopedHashTableVal<K, V> *&KeyEntry = HT.TopLevelMap[ThisEntry->getKey()]; 248 assert(KeyEntry == ThisEntry && "Scope imbalance!"); 249 KeyEntry = ThisEntry->getNextForKey(); 250 } 251 252 // Pop this value out of the scope. 253 LastValInScope = ThisEntry->getNextInScope(); 254 255 // Delete this entry. 256 ThisEntry->Destroy(HT.getAllocator()); 257 } 258 } 259 260 } // end namespace llvm 261 262 #endif // LLVM_ADT_SCOPEDHASHTABLE_H 263