LLVM  4.0.0
ScopedHashTable.h
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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>
45 
46 template <typename K, typename V>
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>
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>
87  /// HT - The hashtable that we are active for.
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:
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>>
120 
121 public:
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.
155  typedef unsigned size_type;
156 
157 private:
158  friend class ScopedHashTableScope<K, V, KInfo, AllocatorTy>;
159 
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 
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) {
186  typename DenseMap<K, ValTy*, KInfo>::iterator 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 
198 
199  iterator end() { return iterator(0); }
200 
201  iterator begin(const K &Key) {
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>
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>
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
ScopedHashTableVal * getNextInScope()
ScopedHashTableIterator operator++(int)
void insertIntoScope(ScopeTy *S, const K &Key, const V &Val)
insertIntoScope - This inserts the specified key/value at the specified (possibly not the current) sc...
const V & getValue() const
bool operator!=(const ScopedHashTableIterator &RHS) const
This file defines the MallocAllocator and BumpPtrAllocator interfaces.
static ScopedHashTableVal * Create(ScopedHashTableVal *nextInScope, ScopedHashTableVal *nextForKey, const K &key, const V &val, AllocatorTy &Allocator)
bool operator==(const ScopedHashTableIterator &RHS) const
ScopedHashTableScope< K, V, KInfo, AllocatorTy > ScopeTy
ScopeTy - This is a helpful typedef that allows clients to get easy access to the name of the scope f...
V lookup(const K &Key)
size_type count(const K &Key) const
Return 1 if the specified key is in the table, 0 otherwise.
ScopedHashTableScope * getParentScope()
ScopedHashTable & operator=(const ScopedHashTable &)=delete
const ScopedHashTableVal * getNextForKey() const
Greedy Register Allocator
const K & getKey() const
AllocatorTy & getAllocator()
Access to the allocator.
ScopedHashTableVal * getNextForKey()
const ScopeTy * getCurScope() const
const AllocatorTy & getAllocator() const
ScopedHashTable(AllocatorTy A)
void insert(const K &Key, const V &Val)
iterator begin(const K &Key)
ScopedHashTableIterator & operator++()
#define I(x, y, z)
Definition: MD5.cpp:54
ScopedHashTableScope & operator=(ScopedHashTableScope &)=delete
ScopedHashTableScope(ScopedHashTable< K, V, KInfo, AllocatorTy > &HT)
ScopedHashTableIterator(ScopedHashTableVal< K, V > *node)
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
void Destroy(AllocatorTy &Allocator)
ScopedHashTableIterator< K, V, KInfo > iterator
static GCRegistry::Add< ErlangGC > A("erlang","erlang-compatible garbage collector")
const ScopedHashTableScope * getParentScope() const