| //===- llvm/ADT/SmallPtrSet.h - 'Normally small' pointer set ----*- 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 defines the SmallPtrSet class. See the doxygen comment for |
| // SmallPtrSetImplBase for more details on the algorithm used. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_ADT_SMALLPTRSET_H |
| #define LLVM_ADT_SMALLPTRSET_H |
| |
| #include "llvm/ADT/EpochTracker.h" |
| #include "llvm/Support/Compiler.h" |
| #include "llvm/Support/ReverseIteration.h" |
| #include "llvm/Support/type_traits.h" |
| #include <cassert> |
| #include <cstddef> |
| #include <cstdlib> |
| #include <cstring> |
| #include <initializer_list> |
| #include <iterator> |
| #include <utility> |
| |
| namespace llvm { |
| |
| /// SmallPtrSetImplBase - This is the common code shared among all the |
| /// SmallPtrSet<>'s, which is almost everything. SmallPtrSet has two modes, one |
| /// for small and one for large sets. |
| /// |
| /// Small sets use an array of pointers allocated in the SmallPtrSet object, |
| /// which is treated as a simple array of pointers. When a pointer is added to |
| /// the set, the array is scanned to see if the element already exists, if not |
| /// the element is 'pushed back' onto the array. If we run out of space in the |
| /// array, we grow into the 'large set' case. SmallSet should be used when the |
| /// sets are often small. In this case, no memory allocation is used, and only |
| /// light-weight and cache-efficient scanning is used. |
| /// |
| /// Large sets use a classic exponentially-probed hash table. Empty buckets are |
| /// represented with an illegal pointer value (-1) to allow null pointers to be |
| /// inserted. Tombstones are represented with another illegal pointer value |
| /// (-2), to allow deletion. The hash table is resized when the table is 3/4 or |
| /// more. When this happens, the table is doubled in size. |
| /// |
| class SmallPtrSetImplBase : public DebugEpochBase { |
| friend class SmallPtrSetIteratorImpl; |
| |
| protected: |
| /// SmallArray - Points to a fixed size set of buckets, used in 'small mode'. |
| const void **SmallArray; |
| /// CurArray - This is the current set of buckets. If equal to SmallArray, |
| /// then the set is in 'small mode'. |
| const void **CurArray; |
| /// CurArraySize - The allocated size of CurArray, always a power of two. |
| unsigned CurArraySize; |
| |
| /// Number of elements in CurArray that contain a value or are a tombstone. |
| /// If small, all these elements are at the beginning of CurArray and the rest |
| /// is uninitialized. |
| unsigned NumNonEmpty; |
| /// Number of tombstones in CurArray. |
| unsigned NumTombstones; |
| |
| // Helpers to copy and move construct a SmallPtrSet. |
| SmallPtrSetImplBase(const void **SmallStorage, |
| const SmallPtrSetImplBase &that); |
| SmallPtrSetImplBase(const void **SmallStorage, unsigned SmallSize, |
| SmallPtrSetImplBase &&that); |
| |
| explicit SmallPtrSetImplBase(const void **SmallStorage, unsigned SmallSize) |
| : SmallArray(SmallStorage), CurArray(SmallStorage), |
| CurArraySize(SmallSize), NumNonEmpty(0), NumTombstones(0) { |
| assert(SmallSize && (SmallSize & (SmallSize-1)) == 0 && |
| "Initial size must be a power of two!"); |
| } |
| |
| ~SmallPtrSetImplBase() { |
| if (!isSmall()) |
| free(CurArray); |
| } |
| |
| public: |
| using size_type = unsigned; |
| |
| SmallPtrSetImplBase &operator=(const SmallPtrSetImplBase &) = delete; |
| |
| LLVM_NODISCARD bool empty() const { return size() == 0; } |
| size_type size() const { return NumNonEmpty - NumTombstones; } |
| |
| void clear() { |
| incrementEpoch(); |
| // If the capacity of the array is huge, and the # elements used is small, |
| // shrink the array. |
| if (!isSmall()) { |
| if (size() * 4 < CurArraySize && CurArraySize > 32) |
| return shrink_and_clear(); |
| // Fill the array with empty markers. |
| memset(CurArray, -1, CurArraySize * sizeof(void *)); |
| } |
| |
| NumNonEmpty = 0; |
| NumTombstones = 0; |
| } |
| |
| protected: |
| static void *getTombstoneMarker() { return reinterpret_cast<void*>(-2); } |
| |
| static void *getEmptyMarker() { |
| // Note that -1 is chosen to make clear() efficiently implementable with |
| // memset and because it's not a valid pointer value. |
| return reinterpret_cast<void*>(-1); |
| } |
| |
| const void **EndPointer() const { |
| return isSmall() ? CurArray + NumNonEmpty : CurArray + CurArraySize; |
| } |
| |
| /// insert_imp - This returns true if the pointer was new to the set, false if |
| /// it was already in the set. This is hidden from the client so that the |
| /// derived class can check that the right type of pointer is passed in. |
| std::pair<const void *const *, bool> insert_imp(const void *Ptr) { |
| if (isSmall()) { |
| // Check to see if it is already in the set. |
| const void **LastTombstone = nullptr; |
| for (const void **APtr = SmallArray, **E = SmallArray + NumNonEmpty; |
| APtr != E; ++APtr) { |
| const void *Value = *APtr; |
| if (Value == Ptr) |
| return std::make_pair(APtr, false); |
| if (Value == getTombstoneMarker()) |
| LastTombstone = APtr; |
| } |
| |
| // Did we find any tombstone marker? |
| if (LastTombstone != nullptr) { |
| *LastTombstone = Ptr; |
| --NumTombstones; |
| incrementEpoch(); |
| return std::make_pair(LastTombstone, true); |
| } |
| |
| // Nope, there isn't. If we stay small, just 'pushback' now. |
| if (NumNonEmpty < CurArraySize) { |
| SmallArray[NumNonEmpty++] = Ptr; |
| incrementEpoch(); |
| return std::make_pair(SmallArray + (NumNonEmpty - 1), true); |
| } |
| // Otherwise, hit the big set case, which will call grow. |
| } |
| return insert_imp_big(Ptr); |
| } |
| |
| /// erase_imp - If the set contains the specified pointer, remove it and |
| /// return true, otherwise return false. This is hidden from the client so |
| /// that the derived class can check that the right type of pointer is passed |
| /// in. |
| bool erase_imp(const void * Ptr) { |
| const void *const *P = find_imp(Ptr); |
| if (P == EndPointer()) |
| return false; |
| |
| const void **Loc = const_cast<const void **>(P); |
| assert(*Loc == Ptr && "broken find!"); |
| *Loc = getTombstoneMarker(); |
| NumTombstones++; |
| return true; |
| } |
| |
| /// Returns the raw pointer needed to construct an iterator. If element not |
| /// found, this will be EndPointer. Otherwise, it will be a pointer to the |
| /// slot which stores Ptr; |
| const void *const * find_imp(const void * Ptr) const { |
| if (isSmall()) { |
| // Linear search for the item. |
| for (const void *const *APtr = SmallArray, |
| *const *E = SmallArray + NumNonEmpty; APtr != E; ++APtr) |
| if (*APtr == Ptr) |
| return APtr; |
| return EndPointer(); |
| } |
| |
| // Big set case. |
| auto *Bucket = FindBucketFor(Ptr); |
| if (*Bucket == Ptr) |
| return Bucket; |
| return EndPointer(); |
| } |
| |
| private: |
| bool isSmall() const { return CurArray == SmallArray; } |
| |
| std::pair<const void *const *, bool> insert_imp_big(const void *Ptr); |
| |
| const void * const *FindBucketFor(const void *Ptr) const; |
| void shrink_and_clear(); |
| |
| /// Grow - Allocate a larger backing store for the buckets and move it over. |
| void Grow(unsigned NewSize); |
| |
| protected: |
| /// swap - Swaps the elements of two sets. |
| /// Note: This method assumes that both sets have the same small size. |
| void swap(SmallPtrSetImplBase &RHS); |
| |
| void CopyFrom(const SmallPtrSetImplBase &RHS); |
| void MoveFrom(unsigned SmallSize, SmallPtrSetImplBase &&RHS); |
| |
| private: |
| /// Code shared by MoveFrom() and move constructor. |
| void MoveHelper(unsigned SmallSize, SmallPtrSetImplBase &&RHS); |
| /// Code shared by CopyFrom() and copy constructor. |
| void CopyHelper(const SmallPtrSetImplBase &RHS); |
| }; |
| |
| /// SmallPtrSetIteratorImpl - This is the common base class shared between all |
| /// instances of SmallPtrSetIterator. |
| class SmallPtrSetIteratorImpl { |
| protected: |
| const void *const *Bucket; |
| const void *const *End; |
| |
| public: |
| explicit SmallPtrSetIteratorImpl(const void *const *BP, const void*const *E) |
| : Bucket(BP), End(E) { |
| if (shouldReverseIterate()) { |
| RetreatIfNotValid(); |
| return; |
| } |
| AdvanceIfNotValid(); |
| } |
| |
| bool operator==(const SmallPtrSetIteratorImpl &RHS) const { |
| return Bucket == RHS.Bucket; |
| } |
| bool operator!=(const SmallPtrSetIteratorImpl &RHS) const { |
| return Bucket != RHS.Bucket; |
| } |
| |
| protected: |
| /// AdvanceIfNotValid - If the current bucket isn't valid, advance to a bucket |
| /// that is. This is guaranteed to stop because the end() bucket is marked |
| /// valid. |
| void AdvanceIfNotValid() { |
| assert(Bucket <= End); |
| while (Bucket != End && |
| (*Bucket == SmallPtrSetImplBase::getEmptyMarker() || |
| *Bucket == SmallPtrSetImplBase::getTombstoneMarker())) |
| ++Bucket; |
| } |
| void RetreatIfNotValid() { |
| assert(Bucket >= End); |
| while (Bucket != End && |
| (Bucket[-1] == SmallPtrSetImplBase::getEmptyMarker() || |
| Bucket[-1] == SmallPtrSetImplBase::getTombstoneMarker())) { |
| --Bucket; |
| } |
| } |
| }; |
| |
| /// SmallPtrSetIterator - This implements a const_iterator for SmallPtrSet. |
| template <typename PtrTy> |
| class SmallPtrSetIterator : public SmallPtrSetIteratorImpl, |
| DebugEpochBase::HandleBase { |
| using PtrTraits = PointerLikeTypeTraits<PtrTy>; |
| |
| public: |
| using value_type = PtrTy; |
| using reference = PtrTy; |
| using pointer = PtrTy; |
| using difference_type = std::ptrdiff_t; |
| using iterator_category = std::forward_iterator_tag; |
| |
| explicit SmallPtrSetIterator(const void *const *BP, const void *const *E, |
| const DebugEpochBase &Epoch) |
| : SmallPtrSetIteratorImpl(BP, E), DebugEpochBase::HandleBase(&Epoch) {} |
| |
| // Most methods provided by baseclass. |
| |
| const PtrTy operator*() const { |
| assert(isHandleInSync() && "invalid iterator access!"); |
| if (shouldReverseIterate()) { |
| assert(Bucket > End); |
| return PtrTraits::getFromVoidPointer(const_cast<void *>(Bucket[-1])); |
| } |
| assert(Bucket < End); |
| return PtrTraits::getFromVoidPointer(const_cast<void*>(*Bucket)); |
| } |
| |
| inline SmallPtrSetIterator& operator++() { // Preincrement |
| assert(isHandleInSync() && "invalid iterator access!"); |
| if (shouldReverseIterate()) { |
| --Bucket; |
| RetreatIfNotValid(); |
| return *this; |
| } |
| ++Bucket; |
| AdvanceIfNotValid(); |
| return *this; |
| } |
| |
| SmallPtrSetIterator operator++(int) { // Postincrement |
| SmallPtrSetIterator tmp = *this; |
| ++*this; |
| return tmp; |
| } |
| }; |
| |
| /// RoundUpToPowerOfTwo - This is a helper template that rounds N up to the next |
| /// power of two (which means N itself if N is already a power of two). |
| template<unsigned N> |
| struct RoundUpToPowerOfTwo; |
| |
| /// RoundUpToPowerOfTwoH - If N is not a power of two, increase it. This is a |
| /// helper template used to implement RoundUpToPowerOfTwo. |
| template<unsigned N, bool isPowerTwo> |
| struct RoundUpToPowerOfTwoH { |
| enum { Val = N }; |
| }; |
| template<unsigned N> |
| struct RoundUpToPowerOfTwoH<N, false> { |
| enum { |
| // We could just use NextVal = N+1, but this converges faster. N|(N-1) sets |
| // the right-most zero bits to one all at once, e.g. 0b0011000 -> 0b0011111. |
| Val = RoundUpToPowerOfTwo<(N|(N-1)) + 1>::Val |
| }; |
| }; |
| |
| template<unsigned N> |
| struct RoundUpToPowerOfTwo { |
| enum { Val = RoundUpToPowerOfTwoH<N, (N&(N-1)) == 0>::Val }; |
| }; |
| |
| /// A templated base class for \c SmallPtrSet which provides the |
| /// typesafe interface that is common across all small sizes. |
| /// |
| /// This is particularly useful for passing around between interface boundaries |
| /// to avoid encoding a particular small size in the interface boundary. |
| template <typename PtrType> |
| class SmallPtrSetImpl : public SmallPtrSetImplBase { |
| using ConstPtrType = typename add_const_past_pointer<PtrType>::type; |
| using PtrTraits = PointerLikeTypeTraits<PtrType>; |
| using ConstPtrTraits = PointerLikeTypeTraits<ConstPtrType>; |
| |
| protected: |
| // Constructors that forward to the base. |
| SmallPtrSetImpl(const void **SmallStorage, const SmallPtrSetImpl &that) |
| : SmallPtrSetImplBase(SmallStorage, that) {} |
| SmallPtrSetImpl(const void **SmallStorage, unsigned SmallSize, |
| SmallPtrSetImpl &&that) |
| : SmallPtrSetImplBase(SmallStorage, SmallSize, std::move(that)) {} |
| explicit SmallPtrSetImpl(const void **SmallStorage, unsigned SmallSize) |
| : SmallPtrSetImplBase(SmallStorage, SmallSize) {} |
| |
| public: |
| using iterator = SmallPtrSetIterator<PtrType>; |
| using const_iterator = SmallPtrSetIterator<PtrType>; |
| using key_type = ConstPtrType; |
| using value_type = PtrType; |
| |
| SmallPtrSetImpl(const SmallPtrSetImpl &) = delete; |
| |
| /// Inserts Ptr if and only if there is no element in the container equal to |
| /// Ptr. The bool component of the returned pair is true if and only if the |
| /// insertion takes place, and the iterator component of the pair points to |
| /// the element equal to Ptr. |
| std::pair<iterator, bool> insert(PtrType Ptr) { |
| auto p = insert_imp(PtrTraits::getAsVoidPointer(Ptr)); |
| return std::make_pair(makeIterator(p.first), p.second); |
| } |
| |
| /// erase - If the set contains the specified pointer, remove it and return |
| /// true, otherwise return false. |
| bool erase(PtrType Ptr) { |
| return erase_imp(PtrTraits::getAsVoidPointer(Ptr)); |
| } |
| /// count - Return 1 if the specified pointer is in the set, 0 otherwise. |
| size_type count(ConstPtrType Ptr) const { return find(Ptr) != end() ? 1 : 0; } |
| iterator find(ConstPtrType Ptr) const { |
| return makeIterator(find_imp(ConstPtrTraits::getAsVoidPointer(Ptr))); |
| } |
| |
| template <typename IterT> |
| void insert(IterT I, IterT E) { |
| for (; I != E; ++I) |
| insert(*I); |
| } |
| |
| void insert(std::initializer_list<PtrType> IL) { |
| insert(IL.begin(), IL.end()); |
| } |
| |
| iterator begin() const { |
| if (shouldReverseIterate()) |
| return makeIterator(EndPointer() - 1); |
| return makeIterator(CurArray); |
| } |
| iterator end() const { return makeIterator(EndPointer()); } |
| |
| private: |
| /// Create an iterator that dereferences to same place as the given pointer. |
| iterator makeIterator(const void *const *P) const { |
| if (shouldReverseIterate()) |
| return iterator(P == EndPointer() ? CurArray : P + 1, CurArray, *this); |
| return iterator(P, EndPointer(), *this); |
| } |
| }; |
| |
| /// Equality comparison for SmallPtrSet. |
| /// |
| /// Iterates over elements of LHS confirming that each value from LHS is also in |
| /// RHS, and that no additional values are in RHS. |
| template <typename PtrType> |
| bool operator==(const SmallPtrSetImpl<PtrType> &LHS, |
| const SmallPtrSetImpl<PtrType> &RHS) { |
| if (LHS.size() != RHS.size()) |
| return false; |
| |
| for (const auto *KV : LHS) |
| if (!RHS.count(KV)) |
| return false; |
| |
| return true; |
| } |
| |
| /// Inequality comparison for SmallPtrSet. |
| /// |
| /// Equivalent to !(LHS == RHS). |
| template <typename PtrType> |
| bool operator!=(const SmallPtrSetImpl<PtrType> &LHS, |
| const SmallPtrSetImpl<PtrType> &RHS) { |
| return !(LHS == RHS); |
| } |
| |
| /// SmallPtrSet - This class implements a set which is optimized for holding |
| /// SmallSize or less elements. This internally rounds up SmallSize to the next |
| /// power of two if it is not already a power of two. See the comments above |
| /// SmallPtrSetImplBase for details of the algorithm. |
| template<class PtrType, unsigned SmallSize> |
| class SmallPtrSet : public SmallPtrSetImpl<PtrType> { |
| // In small mode SmallPtrSet uses linear search for the elements, so it is |
| // not a good idea to choose this value too high. You may consider using a |
| // DenseSet<> instead if you expect many elements in the set. |
| static_assert(SmallSize <= 32, "SmallSize should be small"); |
| |
| using BaseT = SmallPtrSetImpl<PtrType>; |
| |
| // Make sure that SmallSize is a power of two, round up if not. |
| enum { SmallSizePowTwo = RoundUpToPowerOfTwo<SmallSize>::Val }; |
| /// SmallStorage - Fixed size storage used in 'small mode'. |
| const void *SmallStorage[SmallSizePowTwo]; |
| |
| public: |
| SmallPtrSet() : BaseT(SmallStorage, SmallSizePowTwo) {} |
| SmallPtrSet(const SmallPtrSet &that) : BaseT(SmallStorage, that) {} |
| SmallPtrSet(SmallPtrSet &&that) |
| : BaseT(SmallStorage, SmallSizePowTwo, std::move(that)) {} |
| |
| template<typename It> |
| SmallPtrSet(It I, It E) : BaseT(SmallStorage, SmallSizePowTwo) { |
| this->insert(I, E); |
| } |
| |
| SmallPtrSet(std::initializer_list<PtrType> IL) |
| : BaseT(SmallStorage, SmallSizePowTwo) { |
| this->insert(IL.begin(), IL.end()); |
| } |
| |
| SmallPtrSet<PtrType, SmallSize> & |
| operator=(const SmallPtrSet<PtrType, SmallSize> &RHS) { |
| if (&RHS != this) |
| this->CopyFrom(RHS); |
| return *this; |
| } |
| |
| SmallPtrSet<PtrType, SmallSize> & |
| operator=(SmallPtrSet<PtrType, SmallSize> &&RHS) { |
| if (&RHS != this) |
| this->MoveFrom(SmallSizePowTwo, std::move(RHS)); |
| return *this; |
| } |
| |
| SmallPtrSet<PtrType, SmallSize> & |
| operator=(std::initializer_list<PtrType> IL) { |
| this->clear(); |
| this->insert(IL.begin(), IL.end()); |
| return *this; |
| } |
| |
| /// swap - Swaps the elements of two sets. |
| void swap(SmallPtrSet<PtrType, SmallSize> &RHS) { |
| SmallPtrSetImplBase::swap(RHS); |
| } |
| }; |
| |
| } // end namespace llvm |
| |
| namespace std { |
| |
| /// Implement std::swap in terms of SmallPtrSet swap. |
| template<class T, unsigned N> |
| inline void swap(llvm::SmallPtrSet<T, N> &LHS, llvm::SmallPtrSet<T, N> &RHS) { |
| LHS.swap(RHS); |
| } |
| |
| } // end namespace std |
| |
| #endif // LLVM_ADT_SMALLPTRSET_H |