SmallVector.h

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//===- llvm/ADT/SmallVector.h - 'Normally small' vectors --------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the SmallVector class.
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_VECSMALL_ADT_SMALLVECTOR_H
#define LLVM_VECSMALL_ADT_SMALLVECTOR_H
 
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <cstdlib>
#include <cstring>
#include <initializer_list>
#include <iterator>
#include <memory>
 
// LLVM Macros
#define LLVM_VECSMALL_NODISCARD
#define LLVM_VECSMALL_ATTRIBUTE_ALWAYS_INLINE inline
#define LLVM_VECSMALL_UNLIKELY(x) (x)
 
// LLVM External Functions
namespace llvm_vecsmall
{
namespace detail
{
inline uint64_t NextPowerOf2(uint64_t A)
{
  A |= (A >> 1);
  A |= (A >> 2);
  A |= (A >> 4);
  A |= (A >> 8);
  A |= (A >> 16);
  A |= (A >> 32);
  return A + 1;
}
}  // namespace detail
}  // namespace llvm_vecsmall
 
namespace llvm_vecsmall
{
 
// std::is_pod has been deprecated in C++20.
template <typename T>
struct IsPod : std::integral_constant<bool, std::is_standard_layout<T>::value &&
                                                std::is_trivial<T>::value>
{
};
 
class SmallVectorBase
{
protected:
  void *BeginX, *EndX, *CapacityX;
 
protected:
  SmallVectorBase(void* FirstEl, size_t Size)
    : BeginX(FirstEl), EndX(FirstEl), CapacityX((char*)FirstEl + Size)
  {
  }
 
  void grow_pod(void* FirstEl, size_t MinSizeInBytes, size_t TSize);
 
public:
  size_t size_in_bytes() const
  {
    return size_t((char*)EndX - (char*)BeginX);
  }
 
  size_t capacity_in_bytes() const
  {
    return size_t((char*)CapacityX - (char*)BeginX);
  }
 
  LLVM_VECSMALL_NODISCARD bool empty() const
  {
    return BeginX == EndX;
  }
};
 
template <typename T, unsigned N>
struct SmallVectorStorage;
 
template <typename T, typename = void>
class SmallVectorTemplateCommon : public SmallVectorBase
{
private:
  template <typename, unsigned>
  friend struct SmallVectorStorage;
 
  // Allocate raw space for N elements of type T.  If T has a ctor or dtor, we
  // don't want it to be automatically run, so we need to represent the space as
  // something else.  Use an array of char of sufficient alignment.
  typedef typename std::aligned_union<1, T>::type U;
  U FirstEl;
  // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
 
protected:
  SmallVectorTemplateCommon(size_t Size) : SmallVectorBase(&FirstEl, Size)
  {
  }
 
  void grow_pod(size_t MinSizeInBytes, size_t TSize)
  {
    SmallVectorBase::grow_pod(&FirstEl, MinSizeInBytes, TSize);
  }
 
  bool isSmall() const
  {
    return BeginX == static_cast<const void*>(&FirstEl);
  }
 
  void resetToSmall()
  {
    BeginX = EndX = CapacityX = &FirstEl;
  }
 
  void setEnd(T* P)
  {
    this->EndX = P;
  }
 
public:
  typedef size_t size_type;
  typedef ptrdiff_t difference_type;
  typedef T value_type;
  typedef T* iterator;
  typedef const T* const_iterator;
 
  typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
  typedef std::reverse_iterator<iterator> reverse_iterator;
 
  typedef T& reference;
  typedef const T& const_reference;
  typedef T* pointer;
  typedef const T* const_pointer;
 
  // forward iterator creation methods.
  LLVM_VECSMALL_ATTRIBUTE_ALWAYS_INLINE
  iterator begin()
  {
    return (iterator)this->BeginX;
  }
  LLVM_VECSMALL_ATTRIBUTE_ALWAYS_INLINE
  const_iterator begin() const
  {
    return (const_iterator)this->BeginX;
  }
  LLVM_VECSMALL_ATTRIBUTE_ALWAYS_INLINE
  iterator end()
  {
    return (iterator)this->EndX;
  }
  LLVM_VECSMALL_ATTRIBUTE_ALWAYS_INLINE
  const_iterator end() const
  {
    return (const_iterator)this->EndX;
  }
 
protected:
  iterator capacity_ptr()
  {
    return (iterator)this->CapacityX;
  }
  const_iterator capacity_ptr() const
  {
    return (const_iterator)this->CapacityX;
  }
 
public:
  // reverse iterator creation methods.
  reverse_iterator rbegin()
  {
    return reverse_iterator(end());
  }
  const_reverse_iterator rbegin() const
  {
    return const_reverse_iterator(end());
  }
  reverse_iterator rend()
  {
    return reverse_iterator(begin());
  }
  const_reverse_iterator rend() const
  {
    return const_reverse_iterator(begin());
  }
 
  LLVM_VECSMALL_ATTRIBUTE_ALWAYS_INLINE
  size_type size() const
  {
    return end() - begin();
  }
  size_type max_size() const
  {
    return size_type(-1) / sizeof(T);
  }
 
  size_t capacity() const
  {
    return capacity_ptr() - begin();
  }
 
  pointer data()
  {
    return pointer(begin());
  }
  const_pointer data() const
  {
    return const_pointer(begin());
  }
 
  LLVM_VECSMALL_ATTRIBUTE_ALWAYS_INLINE
  reference operator[](size_type idx)
  {
    assert(idx < size());
    return begin()[idx];
  }
  LLVM_VECSMALL_ATTRIBUTE_ALWAYS_INLINE
  const_reference operator[](size_type idx) const
  {
    assert(idx < size());
    return begin()[idx];
  }
 
  reference front()
  {
    assert(!empty());
    return begin()[0];
  }
  const_reference front() const
  {
    assert(!empty());
    return begin()[0];
  }
 
  reference back()
  {
    assert(!empty());
    return end()[-1];
  }
  const_reference back() const
  {
    assert(!empty());
    return end()[-1];
  }
};
 
template <typename T, bool isPodLike>
class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T>
{
protected:
  SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size)
  {
  }
 
  static void destroy_range(T* S, T* E)
  {
    while (S != E)
    {
      --E;
      E->~T();
    }
  }
 
  template <typename It1, typename It2>
  static void uninitialized_move(It1 I, It1 E, It2 Dest)
  {
    std::uninitialized_copy(std::make_move_iterator(I), std::make_move_iterator(E), Dest);
  }
 
  template <typename It1, typename It2>
  static void uninitialized_copy(It1 I, It1 E, It2 Dest)
  {
    std::uninitialized_copy(I, E, Dest);
  }
 
  void grow(size_t MinSize = 0);
 
public:
  void push_back(const T& Elt)
  {
    if (LLVM_VECSMALL_UNLIKELY(this->EndX >= this->CapacityX))
      this->grow();
    ::new ((void*)this->end()) T(Elt);
    this->setEnd(this->end() + 1);
  }
 
  void push_back(T&& Elt)
  {
    if (LLVM_VECSMALL_UNLIKELY(this->EndX >= this->CapacityX))
      this->grow();
    ::new ((void*)this->end()) T(::std::move(Elt));
    this->setEnd(this->end() + 1);
  }
 
  void pop_back()
  {
    this->setEnd(this->end() - 1);
    this->end()->~T();
  }
};
 
// Define this out-of-line to dissuade the C++ compiler from inlining it.
template <typename T, bool isPodLike>
void SmallVectorTemplateBase<T, isPodLike>::grow(size_t MinSize)
{
  size_t CurCapacity = this->capacity();
  size_t CurSize = this->size();
  // Always grow, even from zero.
  size_t NewCapacity = size_t(llvm_vecsmall::detail::NextPowerOf2(CurCapacity + 2));
  if (NewCapacity < MinSize)
    NewCapacity = MinSize;
  T* NewElts = static_cast<T*>(malloc(NewCapacity * sizeof(T)));
 
  // Move the elements over.
  this->uninitialized_move(this->begin(), this->end(), NewElts);
 
  // Destroy the original elements.
  destroy_range(this->begin(), this->end());
 
  // If this wasn't grown from the inline copy, deallocate the old space.
  if (!this->isSmall())
    free(this->begin());
 
  this->setEnd(NewElts + CurSize);
  this->BeginX = NewElts;
  this->CapacityX = this->begin() + NewCapacity;
}
 
template <typename T>
class SmallVectorTemplateBase<T, true> : public SmallVectorTemplateCommon<T>
{
protected:
  SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size)
  {
  }
 
  // No need to do a destroy loop for POD's.
  static void destroy_range(T*, T*)
  {
  }
 
  template <typename It1, typename It2>
  static void uninitialized_move(It1 I, It1 E, It2 Dest)
  {
    // Just do a copy.
    uninitialized_copy(I, E, Dest);
  }
 
  template <typename It1, typename It2>
  static void uninitialized_copy(It1 I, It1 E, It2 Dest)
  {
    // Arbitrary iterator types; just use the basic implementation.
    std::uninitialized_copy(I, E, Dest);
  }
 
  template <typename T1, typename T2>
  static void uninitialized_copy(
      T1* I, T1* E, T2* Dest,
      typename std::enable_if<
          std::is_same<typename std::remove_const<T1>::type, T2>::value>::type* = nullptr)
  {
    // Use memcpy for PODs iterated by pointers (which includes SmallVector
    // iterators): std::uninitialized_copy optimizes to memmove, but we can
    // use memcpy here. Note that I and E are iterators and thus might be
    // invalid for memcpy if they are equal.
    if (I != E)
      memcpy(Dest, I, (E - I) * sizeof(T));
  }
 
  void grow(size_t MinSize = 0)
  {
    this->grow_pod(MinSize * sizeof(T), sizeof(T));
  }
 
public:
  void push_back(const T& Elt)
  {
    if (LLVM_VECSMALL_UNLIKELY(this->EndX >= this->CapacityX))
      this->grow();
    memcpy(this->end(), &Elt, sizeof(T));
    this->setEnd(this->end() + 1);
  }
 
  void pop_back()
  {
    this->setEnd(this->end() - 1);
  }
};
 
template <typename T>
class SmallVectorImpl : public SmallVectorTemplateBase<T, IsPod<T>::value>
{
  typedef SmallVectorTemplateBase<T, IsPod<T>::value> SuperClass;
 
  SmallVectorImpl(const SmallVectorImpl&) = delete;
 
public:
  typedef typename SuperClass::iterator iterator;
  typedef typename SuperClass::const_iterator const_iterator;
  typedef typename SuperClass::size_type size_type;
 
protected:
  // Default ctor - Initialize to empty.
  explicit SmallVectorImpl(unsigned N)
    : SmallVectorTemplateBase<T, IsPod<T>::value>(N * sizeof(T))
  {
  }
 
public:
  ~SmallVectorImpl()
  {
    // Destroy the constructed elements in the vector.
    this->destroy_range(this->begin(), this->end());
 
    // If this wasn't grown from the inline copy, deallocate the old space.
    if (!this->isSmall())
      free(this->begin());
  }
 
  void clear()
  {
    this->destroy_range(this->begin(), this->end());
    this->EndX = this->BeginX;
  }
 
  void resize(size_type N)
  {
    if (N < this->size())
    {
      this->destroy_range(this->begin() + N, this->end());
      this->setEnd(this->begin() + N);
    }
    else if (N > this->size())
    {
      if (this->capacity() < N)
        this->grow(N);
      for (auto I = this->end(), E = this->begin() + N; I != E; ++I)
        new (&*I) T();
      this->setEnd(this->begin() + N);
    }
  }
 
  void resize(size_type N, const T& NV)
  {
    if (N < this->size())
    {
      this->destroy_range(this->begin() + N, this->end());
      this->setEnd(this->begin() + N);
    }
    else if (N > this->size())
    {
      if (this->capacity() < N)
        this->grow(N);
      std::uninitialized_fill(this->end(), this->begin() + N, NV);
      this->setEnd(this->begin() + N);
    }
  }
 
  void reserve(size_type N)
  {
    if (this->capacity() < N)
      this->grow(N);
  }
 
  LLVM_VECSMALL_NODISCARD T pop_back_val()
  {
    T Result = ::std::move(this->back());
    this->pop_back();
    return Result;
  }
 
  void swap(SmallVectorImpl& RHS);
 
  template <typename in_iter>
  void append(in_iter in_start, in_iter in_end)
  {
    size_type NumInputs = std::distance(in_start, in_end);
    // Grow allocated space if needed.
    if (NumInputs > size_type(this->capacity_ptr() - this->end()))
      this->grow(this->size() + NumInputs);
 
    // Copy the new elements over.
    this->uninitialized_copy(in_start, in_end, this->end());
    this->setEnd(this->end() + NumInputs);
  }
 
  void append(size_type NumInputs, const T& Elt)
  {
    // Grow allocated space if needed.
    if (NumInputs > size_type(this->capacity_ptr() - this->end()))
      this->grow(this->size() + NumInputs);
 
    // Copy the new elements over.
    std::uninitialized_fill_n(this->end(), NumInputs, Elt);
    this->setEnd(this->end() + NumInputs);
  }
 
  void append(std::initializer_list<T> IL)
  {
    append(IL.begin(), IL.end());
  }
 
  void assign(size_type NumElts, const T& Elt)
  {
    clear();
    if (this->capacity() < NumElts)
      this->grow(NumElts);
    this->setEnd(this->begin() + NumElts);
    std::uninitialized_fill(this->begin(), this->end(), Elt);
  }
 
  void assign(std::initializer_list<T> IL)
  {
    clear();
    append(IL);
  }
 
  iterator erase(const_iterator CI)
  {
    // Just cast away constness because this is a non-const member function.
    iterator I = const_cast<iterator>(CI);
 
    assert(I >= this->begin() && "Iterator to erase is out of bounds.");
    assert(I < this->end() && "Erasing at past-the-end iterator.");
 
    iterator N = I;
    // Shift all elts down one.
    std::move(I + 1, this->end(), I);
    // Drop the last elt.
    this->pop_back();
    return (N);
  }
 
  iterator erase(const_iterator CS, const_iterator CE)
  {
    // Just cast away constness because this is a non-const member function.
    iterator S = const_cast<iterator>(CS);
    iterator E = const_cast<iterator>(CE);
 
    assert(S >= this->begin() && "Range to erase is out of bounds.");
    assert(S <= E && "Trying to erase invalid range.");
    assert(E <= this->end() && "Trying to erase past the end.");
 
    iterator N = S;
    // Shift all elts down.
    iterator I = std::move(E, this->end(), S);
    // Drop the last elts.
    this->destroy_range(I, this->end());
    this->setEnd(I);
    return (N);
  }
 
  iterator insert(iterator I, T&& Elt)
  {
    if (I == this->end())
    {  // Important special case for empty vector.
      this->push_back(::std::move(Elt));
      return this->end() - 1;
    }
 
    assert(I >= this->begin() && "Insertion iterator is out of bounds.");
    assert(I <= this->end() && "Inserting past the end of the vector.");
 
    if (this->EndX >= this->CapacityX)
    {
      size_t EltNo = I - this->begin();
      this->grow();
      I = this->begin() + EltNo;
    }
 
    ::new ((void*)this->end()) T(::std::move(this->back()));
    // Push everything else over.
    std::move_backward(I, this->end() - 1, this->end());
    this->setEnd(this->end() + 1);
 
    // If we just moved the element we're inserting, be sure to update
    // the reference.
    T* EltPtr = &Elt;
    if (I <= EltPtr && EltPtr < this->EndX)
      ++EltPtr;
 
    *I = ::std::move(*EltPtr);
    return I;
  }
 
  iterator insert(iterator I, const T& Elt)
  {
    if (I == this->end())
    {  // Important special case for empty vector.
      this->push_back(Elt);
      return this->end() - 1;
    }
 
    assert(I >= this->begin() && "Insertion iterator is out of bounds.");
    assert(I <= this->end() && "Inserting past the end of the vector.");
 
    if (this->EndX >= this->CapacityX)
    {
      size_t EltNo = I - this->begin();
      this->grow();
      I = this->begin() + EltNo;
    }
    ::new ((void*)this->end()) T(std::move(this->back()));
    // Push everything else over.
    std::move_backward(I, this->end() - 1, this->end());
    this->setEnd(this->end() + 1);
 
    // If we just moved the element we're inserting, be sure to update
    // the reference.
    const T* EltPtr = &Elt;
    if (I <= EltPtr && EltPtr < this->EndX)
      ++EltPtr;
 
    *I = *EltPtr;
    return I;
  }
 
  iterator insert(iterator I, size_type NumToInsert, const T& Elt)
  {
    // Convert iterator to elt# to avoid invalidating iterator when we reserve()
    size_t InsertElt = I - this->begin();
 
    if (I == this->end())
    {  // Important special case for empty vector.
      append(NumToInsert, Elt);
      return this->begin() + InsertElt;
    }
 
    assert(I >= this->begin() && "Insertion iterator is out of bounds.");
    assert(I <= this->end() && "Inserting past the end of the vector.");
 
    // Ensure there is enough space.
    reserve(this->size() + NumToInsert);
 
    // Uninvalidate the iterator.
    I = this->begin() + InsertElt;
 
    // If there are more elements between the insertion point and the end of the
    // range than there are being inserted, we can use a simple approach to
    // insertion.  Since we already reserved space, we know that this won't
    // reallocate the vector.
    if (size_t(this->end() - I) >= NumToInsert)
    {
      T* OldEnd = this->end();
      append(std::move_iterator<iterator>(this->end() - NumToInsert),
             std::move_iterator<iterator>(this->end()));
 
      // Copy the existing elements that get replaced.
      std::move_backward(I, OldEnd - NumToInsert, OldEnd);
 
      std::fill_n(I, NumToInsert, Elt);
      return I;
    }
 
    // Otherwise, we're inserting more elements than exist already, and we're
    // not inserting at the end.
 
    // Move over the elements that we're about to overwrite.
    T* OldEnd = this->end();
    this->setEnd(this->end() + NumToInsert);
    size_t NumOverwritten = OldEnd - I;
    this->uninitialized_move(I, OldEnd, this->end() - NumOverwritten);
 
    // Replace the overwritten part.
    std::fill_n(I, NumOverwritten, Elt);
 
    // Insert the non-overwritten middle part.
    std::uninitialized_fill_n(OldEnd, NumToInsert - NumOverwritten, Elt);
    return I;
  }
 
  template <typename ItTy>
  iterator insert(iterator I, ItTy From, ItTy To)
  {
    // Convert iterator to elt# to avoid invalidating iterator when we reserve()
    size_t InsertElt = I - this->begin();
 
    if (I == this->end())
    {  // Important special case for empty vector.
      append(From, To);
      return this->begin() + InsertElt;
    }
 
    assert(I >= this->begin() && "Insertion iterator is out of bounds.");
    assert(I <= this->end() && "Inserting past the end of the vector.");
 
    size_t NumToInsert = std::distance(From, To);
 
    // Ensure there is enough space.
    reserve(this->size() + NumToInsert);
 
    // Uninvalidate the iterator.
    I = this->begin() + InsertElt;
 
    // If there are more elements between the insertion point and the end of the
    // range than there are being inserted, we can use a simple approach to
    // insertion.  Since we already reserved space, we know that this won't
    // reallocate the vector.
    if (size_t(this->end() - I) >= NumToInsert)
    {
      T* OldEnd = this->end();
      append(std::move_iterator<iterator>(this->end() - NumToInsert),
             std::move_iterator<iterator>(this->end()));
 
      // Copy the existing elements that get replaced.
      std::move_backward(I, OldEnd - NumToInsert, OldEnd);
 
      std::copy(From, To, I);
      return I;
    }
 
    // Otherwise, we're inserting more elements than exist already, and we're
    // not inserting at the end.
 
    // Move over the elements that we're about to overwrite.
    T* OldEnd = this->end();
    this->setEnd(this->end() + NumToInsert);
    size_t NumOverwritten = OldEnd - I;
    this->uninitialized_move(I, OldEnd, this->end() - NumOverwritten);
 
    // Replace the overwritten part.
    for (T* J = I; NumOverwritten > 0; --NumOverwritten)
    {
      *J = *From;
      ++J;
      ++From;
    }
 
    // Insert the non-overwritten middle part.
    this->uninitialized_copy(From, To, OldEnd);
    return I;
  }
 
  void insert(iterator I, std::initializer_list<T> IL)
  {
    insert(I, IL.begin(), IL.end());
  }
 
  template <typename... ArgTypes>
  void emplace_back(ArgTypes&&... Args)
  {
    if (LLVM_VECSMALL_UNLIKELY(this->EndX >= this->CapacityX))
      this->grow();
    ::new ((void*)this->end()) T(std::forward<ArgTypes>(Args)...);
    this->setEnd(this->end() + 1);
  }
 
  SmallVectorImpl& operator=(const SmallVectorImpl& RHS);
 
  SmallVectorImpl& operator=(SmallVectorImpl&& RHS);
 
  bool operator==(const SmallVectorImpl& RHS) const
  {
    if (this->size() != RHS.size())
      return false;
    return std::equal(this->begin(), this->end(), RHS.begin());
  }
  bool operator!=(const SmallVectorImpl& RHS) const
  {
    return !(*this == RHS);
  }
 
  bool operator<(const SmallVectorImpl& RHS) const
  {
    return std::lexicographical_compare(this->begin(), this->end(), RHS.begin(),
                                        RHS.end());
  }
 
  void set_size(size_type N)
  {
    assert(N <= this->capacity());
    this->setEnd(this->begin() + N);
  }
};
 
template <typename T>
void SmallVectorImpl<T>::swap(SmallVectorImpl<T>& RHS)
{
  if (this == &RHS)
    return;
 
  // We can only avoid copying elements if neither vector is small.
  if (!this->isSmall() && !RHS.isSmall())
  {
    std::swap(this->BeginX, RHS.BeginX);
    std::swap(this->EndX, RHS.EndX);
    std::swap(this->CapacityX, RHS.CapacityX);
    return;
  }
  if (RHS.size() > this->capacity())
    this->grow(RHS.size());
  if (this->size() > RHS.capacity())
    RHS.grow(this->size());
 
  // Swap the shared elements.
  size_t NumShared = this->size();
  if (NumShared > RHS.size())
    NumShared = RHS.size();
  for (size_type i = 0; i != NumShared; ++i)
    std::swap((*this)[i], RHS[i]);
 
  // Copy over the extra elts.
  if (this->size() > RHS.size())
  {
    size_t EltDiff = this->size() - RHS.size();
    this->uninitialized_copy(this->begin() + NumShared, this->end(), RHS.end());
    RHS.setEnd(RHS.end() + EltDiff);
    this->destroy_range(this->begin() + NumShared, this->end());
    this->setEnd(this->begin() + NumShared);
  }
  else if (RHS.size() > this->size())
  {
    size_t EltDiff = RHS.size() - this->size();
    this->uninitialized_copy(RHS.begin() + NumShared, RHS.end(), this->end());
    this->setEnd(this->end() + EltDiff);
    this->destroy_range(RHS.begin() + NumShared, RHS.end());
    RHS.setEnd(RHS.begin() + NumShared);
  }
}
 
template <typename T>
SmallVectorImpl<T>& SmallVectorImpl<T>::operator=(const SmallVectorImpl<T>& RHS)
{
  // Avoid self-assignment.
  if (this == &RHS)
    return *this;
 
  // If we already have sufficient space, assign the common elements, then
  // destroy any excess.
  size_t RHSSize = RHS.size();
  size_t CurSize = this->size();
  if (CurSize >= RHSSize)
  {
    // Assign common elements.
    iterator NewEnd;
    if (RHSSize)
      NewEnd = std::copy(RHS.begin(), RHS.begin() + RHSSize, this->begin());
    else
      NewEnd = this->begin();
 
    // Destroy excess elements.
    this->destroy_range(NewEnd, this->end());
 
    // Trim.
    this->setEnd(NewEnd);
    return *this;
  }
 
  // If we have to grow to have enough elements, destroy the current elements.
  // This allows us to avoid copying them during the grow.
  // FIXME: don't do this if they're efficiently moveable.
  if (this->capacity() < RHSSize)
  {
    // Destroy current elements.
    this->destroy_range(this->begin(), this->end());
    this->setEnd(this->begin());
    CurSize = 0;
    this->grow(RHSSize);
  }
  else if (CurSize)
  {
    // Otherwise, use assignment for the already-constructed elements.
    std::copy(RHS.begin(), RHS.begin() + CurSize, this->begin());
  }
 
  // Copy construct the new elements in place.
  this->uninitialized_copy(RHS.begin() + CurSize, RHS.end(), this->begin() + CurSize);
 
  // Set end.
  this->setEnd(this->begin() + RHSSize);
  return *this;
}
 
template <typename T>
SmallVectorImpl<T>& SmallVectorImpl<T>::operator=(SmallVectorImpl<T>&& RHS)
{
  // Avoid self-assignment.
  if (this == &RHS)
    return *this;
 
  // If the RHS isn't small, clear this vector and then steal its buffer.
  if (!RHS.isSmall())
  {
    this->destroy_range(this->begin(), this->end());
    if (!this->isSmall())
      free(this->begin());
    this->BeginX = RHS.BeginX;
    this->EndX = RHS.EndX;
    this->CapacityX = RHS.CapacityX;
    RHS.resetToSmall();
    return *this;
  }
 
  // If we already have sufficient space, assign the common elements, then
  // destroy any excess.
  size_t RHSSize = RHS.size();
  size_t CurSize = this->size();
  if (CurSize >= RHSSize)
  {
    // Assign common elements.
    iterator NewEnd = this->begin();
    if (RHSSize)
      NewEnd = std::move(RHS.begin(), RHS.end(), NewEnd);
 
    // Destroy excess elements and trim the bounds.
    this->destroy_range(NewEnd, this->end());
    this->setEnd(NewEnd);
 
    // Clear the RHS.
    RHS.clear();
 
    return *this;
  }
 
  // If we have to grow to have enough elements, destroy the current elements.
  // This allows us to avoid copying them during the grow.
  // FIXME: this may not actually make any sense if we can efficiently move
  // elements.
  if (this->capacity() < RHSSize)
  {
    // Destroy current elements.
    this->destroy_range(this->begin(), this->end());
    this->setEnd(this->begin());
    CurSize = 0;
    this->grow(RHSSize);
  }
  else if (CurSize)
  {
    // Otherwise, use assignment for the already-constructed elements.
    std::move(RHS.begin(), RHS.begin() + CurSize, this->begin());
  }
 
  // Move-construct the new elements in place.
  this->uninitialized_move(RHS.begin() + CurSize, RHS.end(), this->begin() + CurSize);
 
  // Set end.
  this->setEnd(this->begin() + RHSSize);
 
  RHS.clear();
  return *this;
}
 
template <typename T, unsigned N>
struct SmallVectorStorage
{
  typename SmallVectorTemplateCommon<T>::U InlineElts[N - 1];
};
template <typename T>
struct SmallVectorStorage<T, 1>
{
};
template <typename T>
struct SmallVectorStorage<T, 0>
{
};
 
template <typename T, unsigned N>
class SmallVector : public SmallVectorImpl<T>
{
  SmallVectorStorage<T, N> Storage;
 
public:
  SmallVector() : SmallVectorImpl<T>(N)
  {
  }
 
  explicit SmallVector(size_t Size, const T& Value = T()) : SmallVectorImpl<T>(N)
  {
    this->assign(Size, Value);
  }
 
  template <typename ItTy>
  SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(N)
  {
    this->append(S, E);
  }
 
  /*
    template <typename RangeTy>
    explicit SmallVector(const llvm_vecsmall::iterator_range<RangeTy> &R)
        : SmallVectorImpl<T>(N) {
      this->append(R.begin(), R.end());
    }
  */
 
  SmallVector(std::initializer_list<T> IL) : SmallVectorImpl<T>(N)
  {
    this->assign(IL);
  }
 
  SmallVector(const SmallVector& RHS) : SmallVectorImpl<T>(N)
  {
    if (!RHS.empty())
      SmallVectorImpl<T>::operator=(RHS);
  }
 
  const SmallVector& operator=(const SmallVector& RHS)
  {
    SmallVectorImpl<T>::operator=(RHS);
    return *this;
  }
 
  SmallVector(SmallVector&& RHS) : SmallVectorImpl<T>(N)
  {
    if (!RHS.empty())
      SmallVectorImpl<T>::operator=(::std::move(RHS));
  }
 
  const SmallVector& operator=(SmallVector&& RHS)
  {
    SmallVectorImpl<T>::operator=(::std::move(RHS));
    return *this;
  }
 
  SmallVector(SmallVectorImpl<T>&& RHS) : SmallVectorImpl<T>(N)
  {
    if (!RHS.empty())
      SmallVectorImpl<T>::operator=(::std::move(RHS));
  }
 
  const SmallVector& operator=(SmallVectorImpl<T>&& RHS)
  {
    SmallVectorImpl<T>::operator=(::std::move(RHS));
    return *this;
  }
 
  const SmallVector& operator=(std::initializer_list<T> IL)
  {
    this->assign(IL);
    return *this;
  }
};
 
template <typename T, unsigned N>
static inline size_t capacity_in_bytes(const SmallVector<T, N>& X)
{
  return X.capacity_in_bytes();
}
 
}  // namespace llvm_vecsmall
 
namespace std
{
template <typename T>
inline void swap(llvm_vecsmall::SmallVectorImpl<T>& LHS,
                 llvm_vecsmall::SmallVectorImpl<T>& RHS)
{
  LHS.swap(RHS);
}
 
template <typename T, unsigned N>
inline void swap(llvm_vecsmall::SmallVector<T, N>& LHS,
                 llvm_vecsmall::SmallVector<T, N>& RHS)
{
  LHS.swap(RHS);
}
}  // namespace std
 
namespace llvm_vecsmall
{
inline void SmallVectorBase::grow_pod(void* FirstEl, size_t MinSizeInBytes, size_t TSize)
{
  size_t CurSizeBytes = size_in_bytes();
  size_t NewCapacityInBytes = 2 * capacity_in_bytes() + TSize;  // Always grow.
  if (NewCapacityInBytes < MinSizeInBytes)
    NewCapacityInBytes = MinSizeInBytes;
 
  void* NewElts;
  if (BeginX == FirstEl)
  {
    NewElts = malloc(NewCapacityInBytes);
 
    // Copy the elements over.  No need to run dtors on PODs.
    memcpy(NewElts, this->BeginX, CurSizeBytes);
  }
  else
  {
    // If this wasn't grown from the inline copy, grow the allocated space.
    NewElts = realloc(this->BeginX, NewCapacityInBytes);
  }
  assert(NewElts && "Out of memory");
 
  this->EndX = (char*)NewElts + CurSizeBytes;
  this->BeginX = NewElts;
  this->CapacityX = (char*)this->BeginX + NewCapacityInBytes;
}
}  // namespace llvm_vecsmall
 
#endif