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//===- llvm/ADT/SmallVector.h - 'Normally small' vectors --------*- 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file defines the SmallVector class.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_SMALLVECTOR_H
#define LLVM_ADT_SMALLVECTOR_H
#include "llvm/Support/Compiler.h"
#include "llvm/Support/type_traits.h"
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <initializer_list>
#include <iterator>
#include <limits>
#include <memory>
#include <new>
#include <type_traits>
#include <utility>
namespace llvm {
template <typename T> class ArrayRef;
template <typename IteratorT> class iterator_range;
template <class Iterator>
using EnableIfConvertibleToInputIterator = std::enable_if_t<std::is_convertible<
typename std::iterator_traits<Iterator>::iterator_category,
std::input_iterator_tag>::value>;
/// This is all the stuff common to all SmallVectors.
///
/// The template parameter specifies the type which should be used to hold the
/// Size and Capacity of the SmallVector, so it can be adjusted.
/// Using 32 bit size is desirable to shrink the size of the SmallVector.
/// Using 64 bit size is desirable for cases like SmallVector<char>, where a
/// 32 bit size would limit the vector to ~4GB. SmallVectors are used for
/// buffering bitcode output - which can exceed 4GB.
template <class Size_T> class SmallVectorBase {
protected:
void *BeginX;
Size_T Size = 0, Capacity;
/// The maximum value of the Size_T used.
static constexpr size_t SizeTypeMax() {
return std::numeric_limits<Size_T>::max();
}
SmallVectorBase() = delete;
SmallVectorBase(void *FirstEl, size_t TotalCapacity)
: BeginX(FirstEl), Capacity(static_cast<Size_T>(TotalCapacity)) {}
/// This is a helper for \a grow() that's out of line to reduce code
/// duplication. This function will report a fatal error if it can't grow at
/// least to \p MinSize.
void *mallocForGrow(void *FirstEl, size_t MinSize, size_t TSize,
size_t &NewCapacity);
/// This is an implementation of the grow() method which only works
/// on POD-like data types and is out of line to reduce code duplication.
/// This function will report a fatal error if it cannot increase capacity.
void grow_pod(void *FirstEl, size_t MinSize, size_t TSize);
/// If vector was first created with capacity 0, getFirstEl() points to the
/// memory right after, an area unallocated. If a subsequent allocation,
/// that grows the vector, happens to return the same pointer as getFirstEl(),
/// get a new allocation, otherwise isSmall() will falsely return that no
/// allocation was done (true) and the memory will not be freed in the
/// destructor. If a VSize is given (vector size), also copy that many
/// elements to the new allocation - used if realloca fails to increase
/// space, and happens to allocate precisely at BeginX.
/// This is unlikely to be called often, but resolves a memory leak when the
/// situation does occur.
void *replaceAllocation(void *NewElts, size_t TSize, size_t NewCapacity,
size_t VSize = 0);
public:
size_t size() const { return Size; }
size_t capacity() const { return Capacity; }
[[nodiscard]] bool empty() const { return !Size; }
protected:
/// Set the array size to \p N, which the current array must have enough
/// capacity for.
///
/// This does not construct or destroy any elements in the vector.
void set_size(size_t N) {
assert(N <= capacity()); // implies no overflow in assignment
Size = static_cast<Size_T>(N);
}
/// Set the array data pointer to \p Begin and capacity to \p N.
///
/// This does not construct or destroy any elements in the vector.
// This does not clean up any existing allocation.
void set_allocation_range(void *Begin, size_t N) {
assert(N <= SizeTypeMax());
BeginX = Begin;
Capacity = static_cast<Size_T>(N);
}
};
template <class T>
using SmallVectorSizeType =
std::conditional_t<sizeof(T) < 4 && sizeof(void *) >= 8, uint64_t,
uint32_t>;
/// Figure out the offset of the first element.
template <class T, typename = void> struct SmallVectorAlignmentAndSize {
alignas(SmallVectorBase<SmallVectorSizeType<T>>) char Base[sizeof(
SmallVectorBase<SmallVectorSizeType<T>>)];
alignas(T) char FirstEl[sizeof(T)];
};
/// This is the part of SmallVectorTemplateBase which does not depend on whether
/// the type T is a POD. The extra dummy template argument is used by ArrayRef
/// to avoid unnecessarily requiring T to be complete.
template <typename T, typename = void>
class SmallVectorTemplateCommon
: public SmallVectorBase<SmallVectorSizeType<T>> {
using Base = SmallVectorBase<SmallVectorSizeType<T>>;
protected:
/// Find the address of the first element. For this pointer math to be valid
/// with small-size of 0 for T with lots of alignment, it's important that
/// SmallVectorStorage is properly-aligned even for small-size of 0.
void *getFirstEl() const {
return const_cast<void *>(reinterpret_cast<const void *>(
reinterpret_cast<const char *>(this) +
offsetof(SmallVectorAlignmentAndSize<T>, FirstEl)));
}
// Space after 'FirstEl' is clobbered, do not add any instance vars after it.
SmallVectorTemplateCommon(size_t Size) : Base(getFirstEl(), Size) {}
void grow_pod(size_t MinSize, size_t TSize) {
Base::grow_pod(getFirstEl(), MinSize, TSize);
}
/// Return true if this is a smallvector which has not had dynamic
/// memory allocated for it.
bool isSmall() const { return this->BeginX == getFirstEl(); }
/// Put this vector in a state of being small.
void resetToSmall() {
this->BeginX = getFirstEl();
this->Size = this->Capacity = 0; // FIXME: Setting Capacity to 0 is suspect.
}
/// Return true if V is an internal reference to the given range.
bool isReferenceToRange(const void *V, const void *First, const void *Last) const {
// Use std::less to avoid UB.
std::less<> LessThan;
return !LessThan(V, First) && LessThan(V, Last);
}
/// Return true if V is an internal reference to this vector.
bool isReferenceToStorage(const void *V) const {
return isReferenceToRange(V, this->begin(), this->end());
}
/// Return true if First and Last form a valid (possibly empty) range in this
/// vector's storage.
bool isRangeInStorage(const void *First, const void *Last) const {
// Use std::less to avoid UB.
std::less<> LessThan;
return !LessThan(First, this->begin()) && !LessThan(Last, First) &&
!LessThan(this->end(), Last);
}
/// Return true unless Elt will be invalidated by resizing the vector to
/// NewSize.
bool isSafeToReferenceAfterResize(const void *Elt, size_t NewSize) {
// Past the end.
if (LLVM_LIKELY(!isReferenceToStorage(Elt)))
return true;
// Return false if Elt will be destroyed by shrinking.
if (NewSize <= this->size())
return Elt < this->begin() + NewSize;
// Return false if we need to grow.
return NewSize <= this->capacity();
}
/// Check whether Elt will be invalidated by resizing the vector to NewSize.
void assertSafeToReferenceAfterResize(const void *Elt, size_t NewSize) {
assert(isSafeToReferenceAfterResize(Elt, NewSize) &&
"Attempting to reference an element of the vector in an operation "
"that invalidates it");
}
/// Check whether Elt will be invalidated by increasing the size of the
/// vector by N.
void assertSafeToAdd(const void *Elt, size_t N = 1) {
this->assertSafeToReferenceAfterResize(Elt, this->size() + N);
}
/// Check whether any part of the range will be invalidated by clearing.
void assertSafeToReferenceAfterClear(const T *From, const T *To) {
if (From == To)
return;
this->assertSafeToReferenceAfterResize(From, 0);
this->assertSafeToReferenceAfterResize(To - 1, 0);
}
template <
class ItTy,
std::enable_if_t<!std::is_same<std::remove_const_t<ItTy>, T *>::value,
bool> = false>
void assertSafeToReferenceAfterClear(ItTy, ItTy) {}
/// Check whether any part of the range will be invalidated by growing.
void assertSafeToAddRange(const T *From, const T *To) {
if (From == To)
return;
this->assertSafeToAdd(From, To - From);
this->assertSafeToAdd(To - 1, To - From);
}
template <
class ItTy,
std::enable_if_t<!std::is_same<std::remove_const_t<ItTy>, T *>::value,
bool> = false>
void assertSafeToAddRange(ItTy, ItTy) {}
/// Reserve enough space to add one element, and return the updated element
/// pointer in case it was a reference to the storage.
template <class U>
static const T *reserveForParamAndGetAddressImpl(U *This, const T &Elt,
size_t N) {
size_t NewSize = This->size() + N;
if (LLVM_LIKELY(NewSize <= This->capacity()))
return &Elt;
bool ReferencesStorage = false;
int64_t Index = -1;
if (!U::TakesParamByValue) {
if (LLVM_UNLIKELY(This->isReferenceToStorage(&Elt))) {
ReferencesStorage = true;
Index = &Elt - This->begin();
}
}
This->grow(NewSize);
return ReferencesStorage ? This->begin() + Index : &Elt;
}
public:
using size_type = size_t;
using difference_type = ptrdiff_t;
using value_type = T;
using iterator = T *;
using const_iterator = const T *;
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
using reverse_iterator = std::reverse_iterator<iterator>;
using reference = T &;
using const_reference = const T &;
using pointer = T *;
using const_pointer = const T *;
using Base::capacity;
using Base::empty;
using Base::size;
// forward iterator creation methods.
iterator begin() { return (iterator)this->BeginX; }
const_iterator begin() const { return (const_iterator)this->BeginX; }
iterator end() { return begin() + size(); }
const_iterator end() const { return begin() + size(); }
// 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());}
size_type size_in_bytes() const { return size() * sizeof(T); }
size_type max_size() const {
return std::min(this->SizeTypeMax(), size_type(-1) / sizeof(T));
}
size_t capacity_in_bytes() const { return capacity() * sizeof(T); }
/// Return a pointer to the vector's buffer, even if empty().
pointer data() { return pointer(begin()); }
/// Return a pointer to the vector's buffer, even if empty().
const_pointer data() const { return const_pointer(begin()); }
reference operator[](size_type idx) {
assert(idx < size());
return begin()[idx];
}
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];
}
};
/// SmallVectorTemplateBase<TriviallyCopyable = false> - This is where we put
/// method implementations that are designed to work with non-trivial T's.
///
/// We approximate is_trivially_copyable with trivial move/copy construction and
/// trivial destruction. While the standard doesn't specify that you're allowed
/// copy these types with memcpy, there is no way for the type to observe this.
/// This catches the important case of std::pair<POD, POD>, which is not
/// trivially assignable.
template <typename T, bool = (std::is_trivially_copy_constructible<T>::value) &&
(std::is_trivially_move_constructible<T>::value) &&
std::is_trivially_destructible<T>::value>
class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
friend class SmallVectorTemplateCommon<T>;
protected:
static constexpr bool TakesParamByValue = false;
using ValueParamT = const T &;
SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
static void destroy_range(T *S, T *E) {
while (S != E) {
--E;
E->~T();
}
}
/// Move the range [I, E) into the uninitialized memory starting with "Dest",
/// constructing elements as needed.
template<typename It1, typename It2>
static void uninitialized_move(It1 I, It1 E, It2 Dest) {
std::uninitialized_move(I, E, Dest);
}
/// Copy the range [I, E) onto the uninitialized memory starting with "Dest",
/// constructing elements as needed.
template<typename It1, typename It2>
static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
std::uninitialized_copy(I, E, Dest);
}
/// Grow the allocated memory (without initializing new elements), doubling
/// the size of the allocated memory. Guarantees space for at least one more
/// element, or MinSize more elements if specified.
void grow(size_t MinSize = 0);
/// Create a new allocation big enough for \p MinSize and pass back its size
/// in \p NewCapacity. This is the first section of \a grow().
T *mallocForGrow(size_t MinSize, size_t &NewCapacity);
/// Move existing elements over to the new allocation \p NewElts, the middle
/// section of \a grow().
void moveElementsForGrow(T *NewElts);
/// Transfer ownership of the allocation, finishing up \a grow().
void takeAllocationForGrow(T *NewElts, size_t NewCapacity);
/// Reserve enough space to add one element, and return the updated element
/// pointer in case it was a reference to the storage.
const T *reserveForParamAndGetAddress(const T &Elt, size_t N = 1) {
return this->reserveForParamAndGetAddressImpl(this, Elt, N);
}
/// Reserve enough space to add one element, and return the updated element
/// pointer in case it was a reference to the storage.
T *reserveForParamAndGetAddress(T &Elt, size_t N = 1) {
return const_cast<T *>(
this->reserveForParamAndGetAddressImpl(this, Elt, N));
}
static T &&forward_value_param(T &&V) { return std::move(V); }
static const T &forward_value_param(const T &V) { return V; }
void growAndAssign(size_t NumElts, const T &Elt) {
// Grow manually in case Elt is an internal reference.
size_t NewCapacity;
T *NewElts = mallocForGrow(NumElts, NewCapacity);
std::uninitialized_fill_n(NewElts, NumElts, Elt);
this->destroy_range(this->begin(), this->end());
takeAllocationForGrow(NewElts, NewCapacity);
this->set_size(NumElts);
}
template <typename... ArgTypes> T &growAndEmplaceBack(ArgTypes &&... Args) {
// Grow manually in case one of Args is an internal reference.
size_t NewCapacity;
T *NewElts = mallocForGrow(0, NewCapacity);
::new ((void *)(NewElts + this->size())) T(std::forward<ArgTypes>(Args)...);
moveElementsForGrow(NewElts);
takeAllocationForGrow(NewElts, NewCapacity);
this->set_size(this->size() + 1);
return this->back();
}
public:
void push_back(const T &Elt) {
const T *EltPtr = reserveForParamAndGetAddress(Elt);
::new ((void *)this->end()) T(*EltPtr);
this->set_size(this->size() + 1);
}
void push_back(T &&Elt) {
T *EltPtr = reserveForParamAndGetAddress(Elt);
::new ((void *)this->end()) T(::std::move(*EltPtr));
this->set_size(this->size() + 1);
}
void pop_back() {
this->set_size(this->size() - 1);
this->end()->~T();
}
};
// Define this out-of-line to dissuade the C++ compiler from inlining it.
template <typename T, bool TriviallyCopyable>
void SmallVectorTemplateBase<T, TriviallyCopyable>::grow(size_t MinSize) {
size_t NewCapacity;
T *NewElts = mallocForGrow(MinSize, NewCapacity);
moveElementsForGrow(NewElts);
takeAllocationForGrow(NewElts, NewCapacity);
}
template <typename T, bool TriviallyCopyable>
T *SmallVectorTemplateBase<T, TriviallyCopyable>::mallocForGrow(
size_t MinSize, size_t &NewCapacity) {
return static_cast<T *>(
SmallVectorBase<SmallVectorSizeType<T>>::mallocForGrow(
this->getFirstEl(), MinSize, sizeof(T), NewCapacity));
}
// Define this out-of-line to dissuade the C++ compiler from inlining it.
template <typename T, bool TriviallyCopyable>
void SmallVectorTemplateBase<T, TriviallyCopyable>::moveElementsForGrow(
T *NewElts) {
// Move the elements over.
this->uninitialized_move(this->begin(), this->end(), NewElts);
// Destroy the original elements.
destroy_range(this->begin(), this->end());
}
// Define this out-of-line to dissuade the C++ compiler from inlining it.
template <typename T, bool TriviallyCopyable>
void SmallVectorTemplateBase<T, TriviallyCopyable>::takeAllocationForGrow(
T *NewElts, size_t NewCapacity) {
// If this wasn't grown from the inline copy, deallocate the old space.
if (!this->isSmall())
free(this->begin());
this->set_allocation_range(NewElts, NewCapacity);
}
/// SmallVectorTemplateBase<TriviallyCopyable = true> - This is where we put
/// method implementations that are designed to work with trivially copyable
/// T's. This allows using memcpy in place of copy/move construction and
/// skipping destruction.
template <typename T>
class SmallVectorTemplateBase<T, true> : public SmallVectorTemplateCommon<T> {
friend class SmallVectorTemplateCommon<T>;
protected:
/// True if it's cheap enough to take parameters by value. Doing so avoids
/// overhead related to mitigations for reference invalidation.
static constexpr bool TakesParamByValue = sizeof(T) <= 2 * sizeof(void *);
/// Either const T& or T, depending on whether it's cheap enough to take
/// parameters by value.
using ValueParamT = std::conditional_t<TakesParamByValue, T, const T &>;
SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
// No need to do a destroy loop for POD's.
static void destroy_range(T *, T *) {}
/// Move the range [I, E) onto the uninitialized memory
/// starting with "Dest", constructing elements into it as needed.
template<typename It1, typename It2>
static void uninitialized_move(It1 I, It1 E, It2 Dest) {
// Just do a copy.
uninitialized_copy(I, E, Dest);
}
/// Copy the range [I, E) onto the uninitialized memory
/// starting with "Dest", constructing elements into it as needed.
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);
}
/// Copy the range [I, E) onto the uninitialized memory
/// starting with "Dest", constructing elements into it as needed.
template <typename T1, typename T2>
static void uninitialized_copy(
T1 *I, T1 *E, T2 *Dest,
std::enable_if_t<std::is_same<std::remove_const_t<T1>, T2>::value> * =
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(reinterpret_cast<void *>(Dest), I, (E - I) * sizeof(T));
}
/// Double the size of the allocated memory, guaranteeing space for at
/// least one more element or MinSize if specified.
void grow(size_t MinSize = 0) { this->grow_pod(MinSize, sizeof(T)); }
/// Reserve enough space to add one element, and return the updated element
/// pointer in case it was a reference to the storage.
const T *reserveForParamAndGetAddress(const T &Elt, size_t N = 1) {
return this->reserveForParamAndGetAddressImpl(this, Elt, N);
}
/// Reserve enough space to add one element, and return the updated element
/// pointer in case it was a reference to the storage.
T *reserveForParamAndGetAddress(T &Elt, size_t N = 1) {
return const_cast<T *>(
this->reserveForParamAndGetAddressImpl(this, Elt, N));
}
/// Copy \p V or return a reference, depending on \a ValueParamT.
static ValueParamT forward_value_param(ValueParamT V) { return V; }
void growAndAssign(size_t NumElts, T Elt) {
// Elt has been copied in case it's an internal reference, side-stepping
// reference invalidation problems without losing the realloc optimization.
this->set_size(0);
this->grow(NumElts);
std::uninitialized_fill_n(this->begin(), NumElts, Elt);
this->set_size(NumElts);
}
template <typename... ArgTypes> T &growAndEmplaceBack(ArgTypes &&... Args) {
// Use push_back with a copy in case Args has an internal reference,
// side-stepping reference invalidation problems without losing the realloc
// optimization.
push_back(T(std::forward<ArgTypes>(Args)...));
return this->back();
}
public:
void push_back(ValueParamT Elt) {
const T *EltPtr = reserveForParamAndGetAddress(Elt);
memcpy(reinterpret_cast<void *>(this->end()), EltPtr, sizeof(T));
this->set_size(this->size() + 1);
}
void pop_back() { this->set_size(this->size() - 1); }
};
/// This class consists of common code factored out of the SmallVector class to
/// reduce code duplication based on the SmallVector 'N' template parameter.
template <typename T>
class SmallVectorImpl : public SmallVectorTemplateBase<T> {
using SuperClass = SmallVectorTemplateBase<T>;
public:
using iterator = typename SuperClass::iterator;
using const_iterator = typename SuperClass::const_iterator;
using reference = typename SuperClass::reference;
using size_type = typename SuperClass::size_type;
protected:
using SmallVectorTemplateBase<T>::TakesParamByValue;
using ValueParamT = typename SuperClass::ValueParamT;
// Default ctor - Initialize to empty.
explicit SmallVectorImpl(unsigned N)
: SmallVectorTemplateBase<T>(N) {}
void assignRemote(SmallVectorImpl &&RHS) {
this->destroy_range(this->begin(), this->end());
if (!this->isSmall())
free(this->begin());
this->BeginX = RHS.BeginX;
this->Size = RHS.Size;
this->Capacity = RHS.Capacity;
RHS.resetToSmall();
}
~SmallVectorImpl() {
// Subclass has already destructed this vector's elements.
// If this wasn't grown from the inline copy, deallocate the old space.
if (!this->isSmall())
free(this->begin());
}
public:
SmallVectorImpl(const SmallVectorImpl &) = delete;
void clear() {
this->destroy_range(this->begin(), this->end());
this->Size = 0;
}
private:
// Make set_size() private to avoid misuse in subclasses.
using SuperClass::set_size;
template <bool ForOverwrite> void resizeImpl(size_type N) {
if (N == this->size())
return;
if (N < this->size()) {
this->truncate(N);
return;
}
this->reserve(N);
for (auto I = this->end(), E = this->begin() + N; I != E; ++I)
if (ForOverwrite)
new (&*I) T;
else
new (&*I) T();
this->set_size(N);
}
public:
void resize(size_type N) { resizeImpl<false>(N); }
/// Like resize, but \ref T is POD, the new values won't be initialized.
void resize_for_overwrite(size_type N) { resizeImpl<true>(N); }
/// Like resize, but requires that \p N is less than \a size().
void truncate(size_type N) {
assert(this->size() >= N && "Cannot increase size with truncate");
this->destroy_range(this->begin() + N, this->end());
this->set_size(N);
}
void resize(size_type N, ValueParamT NV) {
if (N == this->size())
return;
if (N < this->size()) {
this->truncate(N);
return;
}
// N > this->size(). Defer to append.
this->append(N - this->size(), NV);
}
void reserve(size_type N) {
if (this->capacity() < N)
this->grow(N);
}
void pop_back_n(size_type NumItems) {
assert(this->size() >= NumItems);
truncate(this->size() - NumItems);
}
[[nodiscard]] T pop_back_val() {
T Result = ::std::move(this->back());
this->pop_back();
return Result;
}
void swap(SmallVectorImpl &RHS);
/// Add the specified range to the end of the SmallVector.
template <typename ItTy, typename = EnableIfConvertibleToInputIterator<ItTy>>
void append(ItTy in_start, ItTy in_end) {
this->assertSafeToAddRange(in_start, in_end);
size_type NumInputs = std::distance(in_start, in_end);
this->reserve(this->size() + NumInputs);
this->uninitialized_copy(in_start, in_end, this->end());
this->set_size(this->size() + NumInputs);
}
/// Append \p NumInputs copies of \p Elt to the end.
void append(size_type NumInputs, ValueParamT Elt) {
const T *EltPtr = this->reserveForParamAndGetAddress(Elt, NumInputs);
std::uninitialized_fill_n(this->end(), NumInputs, *EltPtr);
this->set_size(this->size() + NumInputs);
}
void append(std::initializer_list<T> IL) {
append(IL.begin(), IL.end());
}
void append(const SmallVectorImpl &RHS) { append(RHS.begin(), RHS.end()); }
void assign(size_type NumElts, ValueParamT Elt) {
// Note that Elt could be an internal reference.
if (NumElts > this->capacity()) {
this->growAndAssign(NumElts, Elt);
return;
}
// Assign over existing elements.
std::fill_n(this->begin(), std::min(NumElts, this->size()), Elt);
if (NumElts > this->size())
std::uninitialized_fill_n(this->end(), NumElts - this->size(), Elt);
else if (NumElts < this->size())
this->destroy_range(this->begin() + NumElts, this->end());
this->set_size(NumElts);
}
// FIXME: Consider assigning over existing elements, rather than clearing &
// re-initializing them - for all assign(...) variants.
template <typename ItTy, typename = EnableIfConvertibleToInputIterator<ItTy>>
void assign(ItTy in_start, ItTy in_end) {
this->assertSafeToReferenceAfterClear(in_start, in_end);
clear();
append(in_start, in_end);
}
void assign(std::initializer_list<T> IL) {
clear();
append(IL);
}
void assign(const SmallVectorImpl &RHS) { assign(RHS.begin(), RHS.end()); }
iterator erase(const_iterator CI) {
// Just cast away constness because this is a non-const member function.
iterator I = const_cast<iterator>(CI);
assert(this->isReferenceToStorage(CI) && "Iterator to erase is out of bounds.");
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(this->isRangeInStorage(S, E) && "Range to erase is out of bounds.");
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->set_size(I - this->begin());
return(N);
}
private:
template <class ArgType> iterator insert_one_impl(iterator I, ArgType &&Elt) {
// Callers ensure that ArgType is derived from T.
static_assert(
std::is_same<std::remove_const_t<std::remove_reference_t<ArgType>>,
T>::value,
"ArgType must be derived from T!");
if (I == this->end()) { // Important special case for empty vector.
this->push_back(::std::forward<ArgType>(Elt));
return this->end()-1;
}
assert(this->isReferenceToStorage(I) && "Insertion iterator is out of bounds.");
// Grow if necessary.
size_t Index = I - this->begin();
std::remove_reference_t<ArgType> *EltPtr =
this->reserveForParamAndGetAddress(Elt);
I = this->begin() + Index;
::new ((void*) this->end()) T(::std::move(this->back()));
// Push everything else over.
std::move_backward(I, this->end()-1, this->end());
this->set_size(this->size() + 1);
// If we just moved the element we're inserting, be sure to update
// the reference (never happens if TakesParamByValue).
static_assert(!TakesParamByValue || std::is_same<ArgType, T>::value,
"ArgType must be 'T' when taking by value!");
if (!TakesParamByValue && this->isReferenceToRange(EltPtr, I, this->end()))
++EltPtr;
*I = ::std::forward<ArgType>(*EltPtr);
return I;
}
public:
iterator insert(iterator I, T &&Elt) {
return insert_one_impl(I, this->forward_value_param(std::move(Elt)));
}
iterator insert(iterator I, const T &Elt) {
return insert_one_impl(I, this->forward_value_param(Elt));
}
iterator insert(iterator I, size_type NumToInsert, ValueParamT 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(this->isReferenceToStorage(I) && "Insertion iterator is out of bounds.");
// Ensure there is enough space, and get the (maybe updated) address of
// Elt.
const T *EltPtr = this->reserveForParamAndGetAddress(Elt, 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);
// If we just moved the element we're inserting, be sure to update
// the reference (never happens if TakesParamByValue).
if (!TakesParamByValue && I <= EltPtr && EltPtr < this->end())
EltPtr += NumToInsert;
std::fill_n(I, NumToInsert, *EltPtr);
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->set_size(this->size() + NumToInsert);
size_t NumOverwritten = OldEnd-I;
this->uninitialized_move(I, OldEnd, this->end()-NumOverwritten);
// If we just moved the element we're inserting, be sure to update
// the reference (never happens if TakesParamByValue).
if (!TakesParamByValue && I <= EltPtr && EltPtr < this->end())
EltPtr += NumToInsert;
// Replace the overwritten part.
std::fill_n(I, NumOverwritten, *EltPtr);
// Insert the non-overwritten middle part.
std::uninitialized_fill_n(OldEnd, NumToInsert - NumOverwritten, *EltPtr);
return I;
}
template <typename ItTy, typename = EnableIfConvertibleToInputIterator<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(this->isReferenceToStorage(I) && "Insertion iterator is out of bounds.");
// Check that the reserve that follows doesn't invalidate the iterators.
this->assertSafeToAddRange(From, To);
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->set_size(this->size() + 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> reference emplace_back(ArgTypes &&... Args) {
if (LLVM_UNLIKELY(this->size() >= this->capacity()))
return this->growAndEmplaceBack(std::forward<ArgTypes>(Args)...);
::new ((void *)this->end()) T(std::forward<ArgTypes>(Args)...);
this->set_size(this->size() + 1);
return this->back();
}
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());
}
bool operator>(const SmallVectorImpl &RHS) const { return RHS < *this; }
bool operator<=(const SmallVectorImpl &RHS) const { return !(*this > RHS); }
bool operator>=(const SmallVectorImpl &RHS) const { return !(*this < RHS); }
};
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->Size, RHS.Size);
std::swap(this->Capacity, RHS.Capacity);
return;
}
this->reserve(RHS.size());
RHS.reserve(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.set_size(RHS.size() + EltDiff);
this->destroy_range(this->begin()+NumShared, this->end());
this->set_size(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->set_size(this->size() + EltDiff);
this->destroy_range(RHS.begin()+NumShared, RHS.end());
RHS.set_size(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->set_size(RHSSize);
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->clear();
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->set_size(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->assignRemote(std::move(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 = 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->set_size(RHSSize);
// 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->clear();
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->set_size(RHSSize);
RHS.clear();
return *this;
}
/// Storage for the SmallVector elements. This is specialized for the N=0 case
/// to avoid allocating unnecessary storage.
template <typename T, unsigned N>
struct SmallVectorStorage {
alignas(T) char InlineElts[N * sizeof(T)];
};
/// We need the storage to be properly aligned even for small-size of 0 so that
/// the pointer math in \a SmallVectorTemplateCommon::getFirstEl() is
/// well-defined.
template <typename T> struct alignas(T) SmallVectorStorage<T, 0> {};
/// Forward declaration of SmallVector so that
/// calculateSmallVectorDefaultInlinedElements can reference
/// `sizeof(SmallVector<T, 0>)`.
template <typename T, unsigned N> class LLVM_GSL_OWNER SmallVector;
/// Helper class for calculating the default number of inline elements for
/// `SmallVector<T>`.
///
/// This should be migrated to a constexpr function when our minimum
/// compiler support is enough for multi-statement constexpr functions.
template <typename T> struct CalculateSmallVectorDefaultInlinedElements {
// Parameter controlling the default number of inlined elements
// for `SmallVector<T>`.
//
// The default number of inlined elements ensures that
// 1. There is at least one inlined element.
// 2. `sizeof(SmallVector<T>) <= kPreferredSmallVectorSizeof` unless
// it contradicts 1.
static constexpr size_t kPreferredSmallVectorSizeof = 64;
// static_assert that sizeof(T) is not "too big".
//
// Because our policy guarantees at least one inlined element, it is possible
// for an arbitrarily large inlined element to allocate an arbitrarily large
// amount of inline storage. We generally consider it an antipattern for a
// SmallVector to allocate an excessive amount of inline storage, so we want
// to call attention to these cases and make sure that users are making an
// intentional decision if they request a lot of inline storage.
//
// We want this assertion to trigger in pathological cases, but otherwise
// not be too easy to hit. To accomplish that, the cutoff is actually somewhat
// larger than kPreferredSmallVectorSizeof (otherwise,
// `SmallVector<SmallVector<T>>` would be one easy way to trip it, and that
// pattern seems useful in practice).
//
// One wrinkle is that this assertion is in theory non-portable, since
// sizeof(T) is in general platform-dependent. However, we don't expect this
// to be much of an issue, because most LLVM development happens on 64-bit
// hosts, and therefore sizeof(T) is expected to *decrease* when compiled for
// 32-bit hosts, dodging the issue. The reverse situation, where development
// happens on a 32-bit host and then fails due to sizeof(T) *increasing* on a
// 64-bit host, is expected to be very rare.
static_assert(
sizeof(T) <= 256,
"You are trying to use a default number of inlined elements for "
"`SmallVector<T>` but `sizeof(T)` is really big! Please use an "
"explicit number of inlined elements with `SmallVector<T, N>` to make "
"sure you really want that much inline storage.");
// Discount the size of the header itself when calculating the maximum inline
// bytes.
static constexpr size_t PreferredInlineBytes =
kPreferredSmallVectorSizeof - sizeof(SmallVector<T, 0>);
static constexpr size_t NumElementsThatFit = PreferredInlineBytes / sizeof(T);
static constexpr size_t value =
NumElementsThatFit == 0 ? 1 : NumElementsThatFit;
};
/// This is a 'vector' (really, a variable-sized array), optimized
/// for the case when the array is small. It contains some number of elements
/// in-place, which allows it to avoid heap allocation when the actual number of
/// elements is below that threshold. This allows normal "small" cases to be
/// fast without losing generality for large inputs.
///
/// \note
/// In the absence of a well-motivated choice for the number of inlined
/// elements \p N, it is recommended to use \c SmallVector<T> (that is,
/// omitting the \p N). This will choose a default number of inlined elements
/// reasonable for allocation on the stack (for example, trying to keep \c
/// sizeof(SmallVector<T>) around 64 bytes).
///
/// \warning This does not attempt to be exception safe.
///
/// \see https://llvm.org/docs/ProgrammersManual.html#llvm-adt-smallvector-h
template <typename T,
unsigned N = CalculateSmallVectorDefaultInlinedElements<T>::value>
class LLVM_GSL_OWNER SmallVector : public SmallVectorImpl<T>,
SmallVectorStorage<T, N> {
public:
SmallVector() : SmallVectorImpl<T>(N) {}
~SmallVector() {
// Destroy the constructed elements in the vector.
this->destroy_range(this->begin(), this->end());
}
explicit SmallVector(size_t Size)
: SmallVectorImpl<T>(N) {
this->resize(Size);
}
SmallVector(size_t Size, const T &Value)
: SmallVectorImpl<T>(N) {
this->assign(Size, Value);
}
template <typename ItTy, typename = EnableIfConvertibleToInputIterator<ItTy>>
SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(N) {
this->append(S, E);
}
template <typename RangeTy>
explicit SmallVector(const iterator_range<RangeTy> &R)
: SmallVectorImpl<T>(N) {
this->append(R.begin(), R.end());
}
SmallVector(std::initializer_list<T> IL) : SmallVectorImpl<T>(N) {
this->append(IL);
}
template <typename U,
typename = std::enable_if_t<std::is_convertible<U, T>::value>>
explicit SmallVector(ArrayRef<U> A) : SmallVectorImpl<T>(N) {
this->append(A.begin(), A.end());
}
SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(N) {
if (!RHS.empty())
SmallVectorImpl<T>::operator=(RHS);
}
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));
}
SmallVector(SmallVectorImpl<T> &&RHS) : SmallVectorImpl<T>(N) {
if (!RHS.empty())
SmallVectorImpl<T>::operator=(::std::move(RHS));
}
SmallVector &operator=(SmallVector &&RHS) {
if (N) {
SmallVectorImpl<T>::operator=(::std::move(RHS));
return *this;
}
// SmallVectorImpl<T>::operator= does not leverage N==0. Optimize the
// case.
if (this == &RHS)
return *this;
if (RHS.empty()) {
this->destroy_range(this->begin(), this->end());
this->Size = 0;
} else {
this->assignRemote(std::move(RHS));
}
return *this;
}
SmallVector &operator=(SmallVectorImpl<T> &&RHS) {
SmallVectorImpl<T>::operator=(::std::move(RHS));
return *this;
}
SmallVector &operator=(std::initializer_list<T> IL) {
this->assign(IL);
return *this;
}
};
template <typename T, unsigned N>
inline size_t capacity_in_bytes(const SmallVector<T, N> &X) {
return X.capacity_in_bytes();
}
template <typename RangeType>
using ValueTypeFromRangeType =
std::remove_const_t<std::remove_reference_t<decltype(*std::begin(
std::declval<RangeType &>()))>>;
/// Given a range of type R, iterate the entire range and return a
/// SmallVector with elements of the vector. This is useful, for example,
/// when you want to iterate a range and then sort the results.
template <unsigned Size, typename R>
SmallVector<ValueTypeFromRangeType<R>, Size> to_vector(R &&Range) {
return {std::begin(Range), std::end(Range)};
}
template <typename R>
SmallVector<ValueTypeFromRangeType<R>> to_vector(R &&Range) {
return {std::begin(Range), std::end(Range)};
}
template <typename Out, unsigned Size, typename R>
SmallVector<Out, Size> to_vector_of(R &&Range) {
return {std::begin(Range), std::end(Range)};
}
template <typename Out, typename R> SmallVector<Out> to_vector_of(R &&Range) {
return {std::begin(Range), std::end(Range)};
}
// Explicit instantiations
extern template class llvm::SmallVectorBase<uint32_t>;
#if SIZE_MAX > UINT32_MAX
extern template class llvm::SmallVectorBase<uint64_t>;
#endif
} // end namespace llvm
namespace std {
/// Implement std::swap in terms of SmallVector swap.
template<typename T>
inline void
swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
LHS.swap(RHS);
}
/// Implement std::swap in terms of SmallVector swap.
template<typename T, unsigned N>
inline void
swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {
LHS.swap(RHS);
}
} // end namespace std
#endif // LLVM_ADT_SMALLVECTOR_H
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