llvm.org GIT mirror llvm / master include / llvm / ADT / ScopedHashTable.h
master

Tree @master (Download .tar.gz)

ScopedHashTable.h @master

7c64ca7
d10e467
6b54768
 
 
d10e467
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
553d8c8
61a10a0
553d8c8
 
d10e467
 
 
61a10a0
 
d10e467
 
4f20c6d
d10e467
 
 
 
 
553d8c8
61a10a0
3a54b3d
e4b461c
d10e467
 
 
3a54b3d
d10e467
 
 
d1769e3
61a10a0
 
 
 
 
 
 
 
 
d1769e3
61a10a0
 
d1769e3
085ee02
61a10a0
 
 
 
d10e467
 
4f20c6d
 
d10e467
 
4f20c6d
3a54b3d
d10e467
 
 
 
 
4f20c6d
e4b461c
d10e467
4f20c6d
553d8c8
 
d10e467
3a54b3d
cdac46d
 
d1769e3
d10e467
4f20c6d
553d8c8
4f20c6d
d5e9e5f
 
79ebf19
4f20c6d
d5e9e5f
 
d10e467
 
085ee02
d10e467
4f20c6d
e4b461c
d10e467
4f20c6d
3a54b3d
d10e467
 
 
 
 
 
 
3a54b3d
d10e467
 
 
 
 
 
3a54b3d
d10e467
 
 
 
 
 
 
 
 
 
61a10a0
d10e467
cdac46d
 
 
79ebf19
 
e4b461c
cdac46d
553d8c8
 
79ebf19
 
61a10a0
553d8c8
d1769e3
61a10a0
d1769e3
d10e467
553d8c8
79ebf19
553d8c8
 
 
d10e467
4ba8443
d10e467
1520962
 
d781e40
 
3a54b3d
af628cc
ed4e8a8
7f05aa7
 
 
c2913cb
 
90f8795
 
d1769e3
90f8795
7f05aa7
 
d10e467
cdac46d
d10e467
3a54b3d
79ebf19
d10e467
 
 
 
61a10a0
d10e467
 
 
 
d1769e3
cdac46d
 
 
 
 
 
 
 
 
 
 
 
 
 
d10e467
 
 
 
4f20c6d
 
 
d10e467
 
4ba8443
d10e467
 
4f20c6d
 
d10e467
 
3a54b3d
d10e467
4f20c6d
d10e467
4ba8443
d10e467
 
 
3a54b3d
4f20c6d
d10e467
 
 
3a54b3d
d10e467
 
3a54b3d
d10e467
61a10a0
d10e467
 
 
 
 
553d8c8
//===- ScopedHashTable.h - A simple scoped hash table -----------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements an efficient scoped hash table, which is useful for
// things like dominator-based optimizations.  This allows clients to do things
// like this:
//
//  ScopedHashTable<int, int> HT;
//  {
//    ScopedHashTableScope<int, int> Scope1(HT);
//    HT.insert(0, 0);
//    HT.insert(1, 1);
//    {
//      ScopedHashTableScope<int, int> Scope2(HT);
//      HT.insert(0, 42);
//    }
//  }
//
// Looking up the value for "0" in the Scope2 block will return 42.  Looking
// up the value for 0 before 42 is inserted or after Scope2 is popped will
// return 0.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_ADT_SCOPEDHASHTABLE_H
#define LLVM_ADT_SCOPEDHASHTABLE_H

#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseMapInfo.h"
#include "llvm/Support/Allocator.h"
#include <cassert>
#include <new>

namespace llvm {

template <typename K, typename V, typename KInfo = DenseMapInfo<K>,
          typename AllocatorTy = MallocAllocator>
class ScopedHashTable;

template <typename K, typename V>
class ScopedHashTableVal {
  ScopedHashTableVal *NextInScope;
  ScopedHashTableVal *NextForKey;
  K Key;
  V Val;

  ScopedHashTableVal(const K &key, const V &val) : Key(key), Val(val) {}

public:
  const K &getKey() const { return Key; }
  const V &getValue() const { return Val; }
  V &getValue() { return Val; }

  ScopedHashTableVal *getNextForKey() { return NextForKey; }
  const ScopedHashTableVal *getNextForKey() const { return NextForKey; }
  ScopedHashTableVal *getNextInScope() { return NextInScope; }

  template <typename AllocatorTy>
  static ScopedHashTableVal *Create(ScopedHashTableVal *nextInScope,
                                    ScopedHashTableVal *nextForKey,
                                    const K &key, const V &val,
                                    AllocatorTy &Allocator) {
    ScopedHashTableVal *New = Allocator.template Allocate<ScopedHashTableVal>();
    // Set up the value.
    new (New) ScopedHashTableVal(key, val);
    New->NextInScope = nextInScope;
    New->NextForKey = nextForKey;
    return New;
  }

  template <typename AllocatorTy> void Destroy(AllocatorTy &Allocator) {
    // Free memory referenced by the item.
    this->~ScopedHashTableVal();
    Allocator.Deallocate(this);
  }
};

template <typename K, typename V, typename KInfo = DenseMapInfo<K>,
          typename AllocatorTy = MallocAllocator>
class ScopedHashTableScope {
  /// HT - The hashtable that we are active for.
  ScopedHashTable<K, V, KInfo, AllocatorTy> &HT;

  /// PrevScope - This is the scope that we are shadowing in HT.
  ScopedHashTableScope *PrevScope;

  /// LastValInScope - This is the last value that was inserted for this scope
  /// or null if none have been inserted yet.
  ScopedHashTableVal<K, V> *LastValInScope;

public:
  ScopedHashTableScope(ScopedHashTable<K, V, KInfo, AllocatorTy> &HT);
  ScopedHashTableScope(ScopedHashTableScope &) = delete;
  ScopedHashTableScope &operator=(ScopedHashTableScope &) = delete;
  ~ScopedHashTableScope();

  ScopedHashTableScope *getParentScope() { return PrevScope; }
  const ScopedHashTableScope *getParentScope() const { return PrevScope; }

private:
  friend class ScopedHashTable<K, V, KInfo, AllocatorTy>;

  ScopedHashTableVal<K, V> *getLastValInScope() {
    return LastValInScope;
  }

  void setLastValInScope(ScopedHashTableVal<K, V> *Val) {
    LastValInScope = Val;
  }
};

template <typename K, typename V, typename KInfo = DenseMapInfo<K>>
class ScopedHashTableIterator {
  ScopedHashTableVal<K, V> *Node;

public:
  ScopedHashTableIterator(ScopedHashTableVal<K, V> *node) : Node(node) {}

  V &operator*() const {
    assert(Node && "Dereference end()");
    return Node->getValue();
  }
  V *operator->() const {
    return &Node->getValue();
  }

  bool operator==(const ScopedHashTableIterator &RHS) const {
    return Node == RHS.Node;
  }
  bool operator!=(const ScopedHashTableIterator &RHS) const {
    return Node != RHS.Node;
  }

  inline ScopedHashTableIterator& operator++() {          // Preincrement
    assert(Node && "incrementing past end()");
    Node = Node->getNextForKey();
    return *this;
  }
  ScopedHashTableIterator operator++(int) {        // Postincrement
    ScopedHashTableIterator tmp = *this; ++*this; return tmp;
  }
};

template <typename K, typename V, typename KInfo, typename AllocatorTy>
class ScopedHashTable {
public:
  /// ScopeTy - This is a helpful typedef that allows clients to get easy access
  /// to the name of the scope for this hash table.
  using ScopeTy = ScopedHashTableScope<K, V, KInfo, AllocatorTy>;
  using size_type = unsigned;

private:
  friend class ScopedHashTableScope<K, V, KInfo, AllocatorTy>;

  using ValTy = ScopedHashTableVal<K, V>;

  DenseMap<K, ValTy*, KInfo> TopLevelMap;
  ScopeTy *CurScope = nullptr;

  AllocatorTy Allocator;

public:
  ScopedHashTable() = default;
  ScopedHashTable(AllocatorTy A) : Allocator(A) {}
  ScopedHashTable(const ScopedHashTable &) = delete;
  ScopedHashTable &operator=(const ScopedHashTable &) = delete;

  ~ScopedHashTable() {
    assert(!CurScope && TopLevelMap.empty() && "Scope imbalance!");
  }

  /// Access to the allocator.
  AllocatorTy &getAllocator() { return Allocator; }
  const AllocatorTy &getAllocator() const { return Allocator; }

  /// Return 1 if the specified key is in the table, 0 otherwise.
  size_type count(const K &Key) const {
    return TopLevelMap.count(Key);
  }

  V lookup(const K &Key) const {
    auto I = TopLevelMap.find(Key);
    if (I != TopLevelMap.end())
      return I->second->getValue();

    return V();
  }

  void insert(const K &Key, const V &Val) {
    insertIntoScope(CurScope, Key, Val);
  }

  using iterator = ScopedHashTableIterator<K, V, KInfo>;

  iterator end() { return iterator(0); }

  iterator begin(const K &Key) {
    typename DenseMap<K, ValTy*, KInfo>::iterator I =
      TopLevelMap.find(Key);
    if (I == TopLevelMap.end()) return end();
    return iterator(I->second);
  }

  ScopeTy *getCurScope() { return CurScope; }
  const ScopeTy *getCurScope() const { return CurScope; }

  /// insertIntoScope - This inserts the specified key/value at the specified
  /// (possibly not the current) scope.  While it is ok to insert into a scope
  /// that isn't the current one, it isn't ok to insert *underneath* an existing
  /// value of the specified key.
  void insertIntoScope(ScopeTy *S, const K &Key, const V &Val) {
    assert(S && "No scope active!");
    ScopedHashTableVal<K, V> *&KeyEntry = TopLevelMap[Key];
    KeyEntry = ValTy::Create(S->getLastValInScope(), KeyEntry, Key, Val,
                             Allocator);
    S->setLastValInScope(KeyEntry);
  }
};

/// ScopedHashTableScope ctor - Install this as the current scope for the hash
/// table.
template <typename K, typename V, typename KInfo, typename Allocator>
ScopedHashTableScope<K, V, KInfo, Allocator>::
  ScopedHashTableScope(ScopedHashTable<K, V, KInfo, Allocator> &ht) : HT(ht) {
  PrevScope = HT.CurScope;
  HT.CurScope = this;
  LastValInScope = nullptr;
}

template <typename K, typename V, typename KInfo, typename Allocator>
ScopedHashTableScope<K, V, KInfo, Allocator>::~ScopedHashTableScope() {
  assert(HT.CurScope == this && "Scope imbalance!");
  HT.CurScope = PrevScope;

  // Pop and delete all values corresponding to this scope.
  while (ScopedHashTableVal<K, V> *ThisEntry = LastValInScope) {
    // Pop this value out of the TopLevelMap.
    if (!ThisEntry->getNextForKey()) {
      assert(HT.TopLevelMap[ThisEntry->getKey()] == ThisEntry &&
             "Scope imbalance!");
      HT.TopLevelMap.erase(ThisEntry->getKey());
    } else {
      ScopedHashTableVal<K, V> *&KeyEntry = HT.TopLevelMap[ThisEntry->getKey()];
      assert(KeyEntry == ThisEntry && "Scope imbalance!");
      KeyEntry = ThisEntry->getNextForKey();
    }

    // Pop this value out of the scope.
    LastValInScope = ThisEntry->getNextInScope();

    // Delete this entry.
    ThisEntry->Destroy(HT.getAllocator());
  }
}

} // end namespace llvm

#endif // LLVM_ADT_SCOPEDHASHTABLE_H