| //===- 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 |