LLVM  10.0.0svn
ScopedHashTable.h
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1 //===- ScopedHashTable.h - A simple scoped hash table -----------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements an efficient scoped hash table, which is useful for
10 // things like dominator-based optimizations. This allows clients to do things
11 // like this:
12 //
13 // ScopedHashTable<int, int> HT;
14 // {
15 // ScopedHashTableScope<int, int> Scope1(HT);
16 // HT.insert(0, 0);
17 // HT.insert(1, 1);
18 // {
19 // ScopedHashTableScope<int, int> Scope2(HT);
20 // HT.insert(0, 42);
21 // }
22 // }
23 //
24 // Looking up the value for "0" in the Scope2 block will return 42. Looking
25 // up the value for 0 before 42 is inserted or after Scope2 is popped will
26 // return 0.
27 //
28 //===----------------------------------------------------------------------===//
29 
30 #ifndef LLVM_ADT_SCOPEDHASHTABLE_H
31 #define LLVM_ADT_SCOPEDHASHTABLE_H
32 
33 #include "llvm/ADT/DenseMap.h"
34 #include "llvm/ADT/DenseMapInfo.h"
35 #include "llvm/Support/Allocator.h"
36 #include <cassert>
37 #include <new>
38 
39 namespace llvm {
40 
41 template <typename K, typename V, typename KInfo = DenseMapInfo<K>,
42  typename AllocatorTy = MallocAllocator>
44 
45 template <typename K, typename V>
47  ScopedHashTableVal *NextInScope;
48  ScopedHashTableVal *NextForKey;
49  K Key;
50  V Val;
51 
52  ScopedHashTableVal(const K &key, const V &val) : Key(key), Val(val) {}
53 
54 public:
55  const K &getKey() const { return Key; }
56  const V &getValue() const { return Val; }
57  V &getValue() { return Val; }
58 
59  ScopedHashTableVal *getNextForKey() { return NextForKey; }
60  const ScopedHashTableVal *getNextForKey() const { return NextForKey; }
61  ScopedHashTableVal *getNextInScope() { return NextInScope; }
62 
63  template <typename AllocatorTy>
65  ScopedHashTableVal *nextForKey,
66  const K &key, const V &val,
67  AllocatorTy &Allocator) {
68  ScopedHashTableVal *New = Allocator.template Allocate<ScopedHashTableVal>();
69  // Set up the value.
70  new (New) ScopedHashTableVal(key, val);
71  New->NextInScope = nextInScope;
72  New->NextForKey = nextForKey;
73  return New;
74  }
75 
76  template <typename AllocatorTy> void Destroy(AllocatorTy &Allocator) {
77  // Free memory referenced by the item.
78  this->~ScopedHashTableVal();
79  Allocator.Deallocate(this);
80  }
81 };
82 
83 template <typename K, typename V, typename KInfo = DenseMapInfo<K>,
84  typename AllocatorTy = MallocAllocator>
86  /// HT - The hashtable that we are active for.
88 
89  /// PrevScope - This is the scope that we are shadowing in HT.
90  ScopedHashTableScope *PrevScope;
91 
92  /// LastValInScope - This is the last value that was inserted for this scope
93  /// or null if none have been inserted yet.
94  ScopedHashTableVal<K, V> *LastValInScope;
95 
96 public:
99  ScopedHashTableScope &operator=(ScopedHashTableScope &) = delete;
101 
102  ScopedHashTableScope *getParentScope() { return PrevScope; }
103  const ScopedHashTableScope *getParentScope() const { return PrevScope; }
104 
105 private:
106  friend class ScopedHashTable<K, V, KInfo, AllocatorTy>;
107 
108  ScopedHashTableVal<K, V> *getLastValInScope() {
109  return LastValInScope;
110  }
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.
156 
157 private:
158  friend class ScopedHashTableScope<K, V, KInfo, AllocatorTy>;
159 
161 
162  DenseMap<K, ValTy*, KInfo> TopLevelMap;
163  ScopeTy *CurScope = nullptr;
164 
165  AllocatorTy Allocator;
166 
167 public:
168  ScopedHashTable() = default;
169  ScopedHashTable(AllocatorTy A) : Allocator(A) {}
170  ScopedHashTable(const ScopedHashTable &) = delete;
171  ScopedHashTable &operator=(const ScopedHashTable &) = delete;
172 
174  assert(!CurScope && TopLevelMap.empty() && "Scope imbalance!");
175  }
176 
177  /// Access to the allocator.
178  AllocatorTy &getAllocator() { return Allocator; }
179  const AllocatorTy &getAllocator() const { return Allocator; }
180 
181  /// Return 1 if the specified key is in the table, 0 otherwise.
182  size_type count(const K &Key) const {
183  return TopLevelMap.count(Key);
184  }
185 
186  V lookup(const K &Key) const {
187  auto I = TopLevelMap.find(Key);
188  if (I != TopLevelMap.end())
189  return I->second->getValue();
190 
191  return V();
192  }
193 
194  void insert(const K &Key, const V &Val) {
195  insertIntoScope(CurScope, Key, Val);
196  }
197 
199 
200  iterator end() { return iterator(0); }
201 
202  iterator begin(const K &Key) {
204  TopLevelMap.find(Key);
205  if (I == TopLevelMap.end()) return end();
206  return iterator(I->second);
207  }
208 
209  ScopeTy *getCurScope() { return CurScope; }
210  const ScopeTy *getCurScope() const { return CurScope; }
211 
212  /// insertIntoScope - This inserts the specified key/value at the specified
213  /// (possibly not the current) scope. While it is ok to insert into a scope
214  /// that isn't the current one, it isn't ok to insert *underneath* an existing
215  /// value of the specified key.
216  void insertIntoScope(ScopeTy *S, const K &Key, const V &Val) {
217  assert(S && "No scope active!");
218  ScopedHashTableVal<K, V> *&KeyEntry = TopLevelMap[Key];
219  KeyEntry = ValTy::Create(S->getLastValInScope(), KeyEntry, Key, Val,
220  Allocator);
221  S->setLastValInScope(KeyEntry);
222  }
223 };
224 
225 /// ScopedHashTableScope ctor - Install this as the current scope for the hash
226 /// table.
227 template <typename K, typename V, typename KInfo, typename Allocator>
230  PrevScope = HT.CurScope;
231  HT.CurScope = this;
232  LastValInScope = nullptr;
233 }
234 
235 template <typename K, typename V, typename KInfo, typename Allocator>
237  assert(HT.CurScope == this && "Scope imbalance!");
238  HT.CurScope = PrevScope;
239 
240  // Pop and delete all values corresponding to this scope.
241  while (ScopedHashTableVal<K, V> *ThisEntry = LastValInScope) {
242  // Pop this value out of the TopLevelMap.
243  if (!ThisEntry->getNextForKey()) {
244  assert(HT.TopLevelMap[ThisEntry->getKey()] == ThisEntry &&
245  "Scope imbalance!");
246  HT.TopLevelMap.erase(ThisEntry->getKey());
247  } else {
248  ScopedHashTableVal<K, V> *&KeyEntry = HT.TopLevelMap[ThisEntry->getKey()];
249  assert(KeyEntry == ThisEntry && "Scope imbalance!");
250  KeyEntry = ThisEntry->getNextForKey();
251  }
252 
253  // Pop this value out of the scope.
254  LastValInScope = ThisEntry->getNextInScope();
255 
256  // Delete this entry.
257  ThisEntry->Destroy(HT.getAllocator());
258  }
259 }
260 
261 } // end namespace llvm
262 
263 #endif // LLVM_ADT_SCOPEDHASHTABLE_H
ScopedHashTableVal * getNextInScope()
const_iterator end(StringRef path)
Get end iterator over path.
Definition: Path.cpp:233
ScopedHashTableIterator operator++(int)
This class represents lattice values for constants.
Definition: AllocatorList.h:23
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...
bool operator==(const ScopedHashTableIterator &RHS) const
size_type count(const K &Key) const
Return 1 if the specified key is in the table, 0 otherwise.
const ScopedHashTableScope * getParentScope() const
This file defines the MallocAllocator and BumpPtrAllocator interfaces.
static ScopedHashTableVal * Create(ScopedHashTableVal *nextInScope, ScopedHashTableVal *nextForKey, const K &key, const V &val, AllocatorTy &Allocator)
Key
PAL metadata keys.
const K & getKey() const
bool operator!=(const ScopedHashTableIterator &RHS) const
ScopedHashTableScope * getParentScope()
const AllocatorTy & getAllocator() const
const ScopedHashTableVal * getNextForKey() const
AllocatorTy & getAllocator()
Access to the allocator.
V lookup(const K &Key) const
ScopedHashTableVal * getNextForKey()
Basic Register Allocator
const V & getValue() 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:58
static GCRegistry::Add< ErlangGC > A("erlang", "erlang-compatible garbage collector")
ScopedHashTableScope(ScopedHashTable< K, V, KInfo, AllocatorTy > &HT)
ScopedHashTableIterator(ScopedHashTableVal< K, V > *node)
size_type count(const_arg_type_t< KeyT > Val) const
Return 1 if the specified key is in the map, 0 otherwise.
Definition: DenseMap.h:171
const ScopeTy * getCurScope() const
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
void Destroy(AllocatorTy &Allocator)