1//===- llvm/ADT/SmallVector.h - 'Normally small' vectors --------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8///
9/// \file
10/// This file defines the SmallVector class.
11///
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_ADT_SMALLVECTOR_H
15#define LLVM_ADT_SMALLVECTOR_H
16
17#include "llvm/Support/Compiler.h"
18#include "llvm/Support/type_traits.h"
19#include <algorithm>
20#include <cassert>
21#include <cstddef>
22#include <cstdlib>
23#include <cstring>
24#include <functional>
25#include <initializer_list>
26#include <iterator>
27#include <limits>
28#include <memory>
29#include <new>
30#include <type_traits>
31#include <utility>
32
33namespace llvm {
34
35template <typename T> class ArrayRef;
36
37template <typename IteratorT> class iterator_range;
38
39template <class Iterator>
40using EnableIfConvertibleToInputIterator = std::enable_if_t<std::is_convertible<
41 typename std::iterator_traits<Iterator>::iterator_category,
42 std::input_iterator_tag>::value>;
43
44/// This is all the stuff common to all SmallVectors.
45///
46/// The template parameter specifies the type which should be used to hold the
47/// Size and Capacity of the SmallVector, so it can be adjusted.
48/// Using 32 bit size is desirable to shrink the size of the SmallVector.
49/// Using 64 bit size is desirable for cases like SmallVector<char>, where a
50/// 32 bit size would limit the vector to ~4GB. SmallVectors are used for
51/// buffering bitcode output - which can exceed 4GB.
52template <class Size_T> class SmallVectorBase {
53protected:
54 void *BeginX;
55 Size_T Size = 0, Capacity;
56
57 /// The maximum value of the Size_T used.
58 static constexpr size_t SizeTypeMax() {
59 return std::numeric_limits<Size_T>::max();
60 }
61
62 SmallVectorBase() = delete;
63 SmallVectorBase(void *FirstEl, size_t TotalCapacity)
64 : BeginX(FirstEl), Capacity(TotalCapacity) {}
65
66 /// This is a helper for \a grow() that's out of line to reduce code
67 /// duplication. This function will report a fatal error if it can't grow at
68 /// least to \p MinSize.
69 void *mallocForGrow(void *FirstEl, size_t MinSize, size_t TSize,
70 size_t &NewCapacity);
71
72 /// This is an implementation of the grow() method which only works
73 /// on POD-like data types and is out of line to reduce code duplication.
74 /// This function will report a fatal error if it cannot increase capacity.
75 void grow_pod(void *FirstEl, size_t MinSize, size_t TSize);
76
77 /// If vector was first created with capacity 0, getFirstEl() points to the
78 /// memory right after, an area unallocated. If a subsequent allocation,
79 /// that grows the vector, happens to return the same pointer as getFirstEl(),
80 /// get a new allocation, otherwise isSmall() will falsely return that no
81 /// allocation was done (true) and the memory will not be freed in the
82 /// destructor. If a VSize is given (vector size), also copy that many
83 /// elements to the new allocation - used if realloca fails to increase
84 /// space, and happens to allocate precisely at BeginX.
85 /// This is unlikely to be called often, but resolves a memory leak when the
86 /// situation does occur.
87 void *replaceAllocation(void *NewElts, size_t TSize, size_t NewCapacity,
88 size_t VSize = 0);
89
90public:
91 size_t size() const { return Size; }
92 size_t capacity() const { return Capacity; }
93
94 [[nodiscard]] bool empty() const { return !Size; }
95
96protected:
97 /// Set the array size to \p N, which the current array must have enough
98 /// capacity for.
99 ///
100 /// This does not construct or destroy any elements in the vector.
101 void set_size(size_t N) {
102 assert(N <= capacity());
103 Size = N;
104 }
105};
106
107template <class T>
108using SmallVectorSizeType =
109 std::conditional_t<sizeof(T) < 4 && sizeof(void *) >= 8, uint64_t,
110 uint32_t>;
111
112/// Figure out the offset of the first element.
113template <class T, typename = void> struct SmallVectorAlignmentAndSize {
114 alignas(SmallVectorBase<SmallVectorSizeType<T>>) char Base[sizeof(
115 SmallVectorBase<SmallVectorSizeType<T>>)];
116 alignas(T) char FirstEl[sizeof(T)];
117};
118
119/// This is the part of SmallVectorTemplateBase which does not depend on whether
120/// the type T is a POD. The extra dummy template argument is used by ArrayRef
121/// to avoid unnecessarily requiring T to be complete.
122template <typename T, typename = void>
123class SmallVectorTemplateCommon
124 : public SmallVectorBase<SmallVectorSizeType<T>> {
125 using Base = SmallVectorBase<SmallVectorSizeType<T>>;
126
127protected:
128 /// Find the address of the first element. For this pointer math to be valid
129 /// with small-size of 0 for T with lots of alignment, it's important that
130 /// SmallVectorStorage is properly-aligned even for small-size of 0.
131 void *getFirstEl() const {
132 return const_cast<void *>(reinterpret_cast<const void *>(
133 reinterpret_cast<const char *>(this) +
134 offsetof(SmallVectorAlignmentAndSize<T>, FirstEl)));
135 }
136 // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
137
138 SmallVectorTemplateCommon(size_t Size) : Base(getFirstEl(), Size) {}
139
140 void grow_pod(size_t MinSize, size_t TSize) {
141 Base::grow_pod(getFirstEl(), MinSize, TSize);
142 }
143
144 /// Return true if this is a smallvector which has not had dynamic
145 /// memory allocated for it.
146 bool isSmall() const { return this->BeginX == getFirstEl(); }
147
148 /// Put this vector in a state of being small.
149 void resetToSmall() {
150 this->BeginX = getFirstEl();
151 this->Size = this->Capacity = 0; // FIXME: Setting Capacity to 0 is suspect.
152 }
153
154 /// Return true if V is an internal reference to the given range.
155 bool isReferenceToRange(const void *V, const void *First, const void *Last) const {
156 // Use std::less to avoid UB.
157 std::less<> LessThan;
158 return !LessThan(V, First) && LessThan(V, Last);
159 }
160
161 /// Return true if V is an internal reference to this vector.
162 bool isReferenceToStorage(const void *V) const {
163 return isReferenceToRange(V, First: this->begin(), Last: this->end());
164 }
165
166 /// Return true if First and Last form a valid (possibly empty) range in this
167 /// vector's storage.
168 bool isRangeInStorage(const void *First, const void *Last) const {
169 // Use std::less to avoid UB.
170 std::less<> LessThan;
171 return !LessThan(First, this->begin()) && !LessThan(Last, First) &&
172 !LessThan(this->end(), Last);
173 }
174
175 /// Return true unless Elt will be invalidated by resizing the vector to
176 /// NewSize.
177 bool isSafeToReferenceAfterResize(const void *Elt, size_t NewSize) {
178 // Past the end.
179 if (LLVM_LIKELY(!isReferenceToStorage(Elt)))
180 return true;
181
182 // Return false if Elt will be destroyed by shrinking.
183 if (NewSize <= this->size())
184 return Elt < this->begin() + NewSize;
185
186 // Return false if we need to grow.
187 return NewSize <= this->capacity();
188 }
189
190 /// Check whether Elt will be invalidated by resizing the vector to NewSize.
191 void assertSafeToReferenceAfterResize(const void *Elt, size_t NewSize) {
192 assert(isSafeToReferenceAfterResize(Elt, NewSize) &&
193 "Attempting to reference an element of the vector in an operation "
194 "that invalidates it");
195 }
196
197 /// Check whether Elt will be invalidated by increasing the size of the
198 /// vector by N.
199 void assertSafeToAdd(const void *Elt, size_t N = 1) {
200 this->assertSafeToReferenceAfterResize(Elt, this->size() + N);
201 }
202
203 /// Check whether any part of the range will be invalidated by clearing.
204 void assertSafeToReferenceAfterClear(const T *From, const T *To) {
205 if (From == To)
206 return;
207 this->assertSafeToReferenceAfterResize(From, 0);
208 this->assertSafeToReferenceAfterResize(To - 1, 0);
209 }
210 template <
211 class ItTy,
212 std::enable_if_t<!std::is_same<std::remove_const_t<ItTy>, T *>::value,
213 bool> = false>
214 void assertSafeToReferenceAfterClear(ItTy, ItTy) {}
215
216 /// Check whether any part of the range will be invalidated by growing.
217 void assertSafeToAddRange(const T *From, const T *To) {
218 if (From == To)
219 return;
220 this->assertSafeToAdd(From, To - From);
221 this->assertSafeToAdd(To - 1, To - From);
222 }
223 template <
224 class ItTy,
225 std::enable_if_t<!std::is_same<std::remove_const_t<ItTy>, T *>::value,
226 bool> = false>
227 void assertSafeToAddRange(ItTy, ItTy) {}
228
229 /// Reserve enough space to add one element, and return the updated element
230 /// pointer in case it was a reference to the storage.
231 template <class U>
232 static const T *reserveForParamAndGetAddressImpl(U *This, const T &Elt,
233 size_t N) {
234 size_t NewSize = This->size() + N;
235 if (LLVM_LIKELY(NewSize <= This->capacity()))
236 return &Elt;
237
238 bool ReferencesStorage = false;
239 int64_t Index = -1;
240 if (!U::TakesParamByValue) {
241 if (LLVM_UNLIKELY(This->isReferenceToStorage(&Elt))) {
242 ReferencesStorage = true;
243 Index = &Elt - This->begin();
244 }
245 }
246 This->grow(NewSize);
247 return ReferencesStorage ? This->begin() + Index : &Elt;
248 }
249
250public:
251 using size_type = size_t;
252 using difference_type = ptrdiff_t;
253 using value_type = T;
254 using iterator = T *;
255 using const_iterator = const T *;
256
257 using const_reverse_iterator = std::reverse_iterator<const_iterator>;
258 using reverse_iterator = std::reverse_iterator<iterator>;
259
260 using reference = T &;
261 using const_reference = const T &;
262 using pointer = T *;
263 using const_pointer = const T *;
264
265 using Base::capacity;
266 using Base::empty;
267 using Base::size;
268
269 // forward iterator creation methods.
270 iterator begin() { return (iterator)this->BeginX; }
271 const_iterator begin() const { return (const_iterator)this->BeginX; }
272 iterator end() { return begin() + size(); }
273 const_iterator end() const { return begin() + size(); }
274
275 // reverse iterator creation methods.
276 reverse_iterator rbegin() { return reverse_iterator(end()); }
277 const_reverse_iterator rbegin() const{ return const_reverse_iterator(end()); }
278 reverse_iterator rend() { return reverse_iterator(begin()); }
279 const_reverse_iterator rend() const { return const_reverse_iterator(begin());}
280
281 size_type size_in_bytes() const { return size() * sizeof(T); }
282 size_type max_size() const {
283 return std::min(this->SizeTypeMax(), size_type(-1) / sizeof(T));
284 }
285
286 size_t capacity_in_bytes() const { return capacity() * sizeof(T); }
287
288 /// Return a pointer to the vector's buffer, even if empty().
289 pointer data() { return pointer(begin()); }
290 /// Return a pointer to the vector's buffer, even if empty().
291 const_pointer data() const { return const_pointer(begin()); }
292
293 reference operator[](size_type idx) {
294 assert(idx < size());
295 return begin()[idx];
296 }
297 const_reference operator[](size_type idx) const {
298 assert(idx < size());
299 return begin()[idx];
300 }
301
302 reference front() {
303 assert(!empty());
304 return begin()[0];
305 }
306 const_reference front() const {
307 assert(!empty());
308 return begin()[0];
309 }
310
311 reference back() {
312 assert(!empty());
313 return end()[-1];
314 }
315 const_reference back() const {
316 assert(!empty());
317 return end()[-1];
318 }
319};
320
321/// SmallVectorTemplateBase<TriviallyCopyable = false> - This is where we put
322/// method implementations that are designed to work with non-trivial T's.
323///
324/// We approximate is_trivially_copyable with trivial move/copy construction and
325/// trivial destruction. While the standard doesn't specify that you're allowed
326/// copy these types with memcpy, there is no way for the type to observe this.
327/// This catches the important case of std::pair<POD, POD>, which is not
328/// trivially assignable.
329template <typename T, bool = (std::is_trivially_copy_constructible<T>::value) &&
330 (std::is_trivially_move_constructible<T>::value) &&
331 std::is_trivially_destructible<T>::value>
332class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
333 friend class SmallVectorTemplateCommon<T>;
334
335protected:
336 static constexpr bool TakesParamByValue = false;
337 using ValueParamT = const T &;
338
339 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
340
341 static void destroy_range(T *S, T *E) {
342 while (S != E) {
343 --E;
344 E->~T();
345 }
346 }
347
348 /// Move the range [I, E) into the uninitialized memory starting with "Dest",
349 /// constructing elements as needed.
350 template<typename It1, typename It2>
351 static void uninitialized_move(It1 I, It1 E, It2 Dest) {
352 std::uninitialized_move(I, E, Dest);
353 }
354
355 /// Copy the range [I, E) onto the uninitialized memory starting with "Dest",
356 /// constructing elements as needed.
357 template<typename It1, typename It2>
358 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
359 std::uninitialized_copy(I, E, Dest);
360 }
361
362 /// Grow the allocated memory (without initializing new elements), doubling
363 /// the size of the allocated memory. Guarantees space for at least one more
364 /// element, or MinSize more elements if specified.
365 void grow(size_t MinSize = 0);
366
367 /// Create a new allocation big enough for \p MinSize and pass back its size
368 /// in \p NewCapacity. This is the first section of \a grow().
369 T *mallocForGrow(size_t MinSize, size_t &NewCapacity);
370
371 /// Move existing elements over to the new allocation \p NewElts, the middle
372 /// section of \a grow().
373 void moveElementsForGrow(T *NewElts);
374
375 /// Transfer ownership of the allocation, finishing up \a grow().
376 void takeAllocationForGrow(T *NewElts, size_t NewCapacity);
377
378 /// Reserve enough space to add one element, and return the updated element
379 /// pointer in case it was a reference to the storage.
380 const T *reserveForParamAndGetAddress(const T &Elt, size_t N = 1) {
381 return this->reserveForParamAndGetAddressImpl(this, Elt, N);
382 }
383
384 /// Reserve enough space to add one element, and return the updated element
385 /// pointer in case it was a reference to the storage.
386 T *reserveForParamAndGetAddress(T &Elt, size_t N = 1) {
387 return const_cast<T *>(
388 this->reserveForParamAndGetAddressImpl(this, Elt, N));
389 }
390
391 static T &&forward_value_param(T &&V) { return std::move(V); }
392 static const T &forward_value_param(const T &V) { return V; }
393
394 void growAndAssign(size_t NumElts, const T &Elt) {
395 // Grow manually in case Elt is an internal reference.
396 size_t NewCapacity;
397 T *NewElts = mallocForGrow(MinSize: NumElts, NewCapacity);
398 std::uninitialized_fill_n(NewElts, NumElts, Elt);
399 this->destroy_range(this->begin(), this->end());
400 takeAllocationForGrow(NewElts, NewCapacity);
401 this->set_size(NumElts);
402 }
403
404 template <typename... ArgTypes> T &growAndEmplaceBack(ArgTypes &&... Args) {
405 // Grow manually in case one of Args is an internal reference.
406 size_t NewCapacity;
407 T *NewElts = mallocForGrow(MinSize: 0, NewCapacity);
408 ::new ((void *)(NewElts + this->size())) T(std::forward<ArgTypes>(Args)...);
409 moveElementsForGrow(NewElts);
410 takeAllocationForGrow(NewElts, NewCapacity);
411 this->set_size(this->size() + 1);
412 return this->back();
413 }
414
415public:
416 void push_back(const T &Elt) {
417 const T *EltPtr = reserveForParamAndGetAddress(Elt);
418 ::new ((void *)this->end()) T(*EltPtr);
419 this->set_size(this->size() + 1);
420 }
421
422 void push_back(T &&Elt) {
423 T *EltPtr = reserveForParamAndGetAddress(Elt);
424 ::new ((void *)this->end()) T(::std::move(*EltPtr));
425 this->set_size(this->size() + 1);
426 }
427
428 void pop_back() {
429 this->set_size(this->size() - 1);
430 this->end()->~T();
431 }
432};
433
434// Define this out-of-line to dissuade the C++ compiler from inlining it.
435template <typename T, bool TriviallyCopyable>
436void SmallVectorTemplateBase<T, TriviallyCopyable>::grow(size_t MinSize) {
437 size_t NewCapacity;
438 T *NewElts = mallocForGrow(MinSize, NewCapacity);
439 moveElementsForGrow(NewElts);
440 takeAllocationForGrow(NewElts, NewCapacity);
441}
442
443template <typename T, bool TriviallyCopyable>
444T *SmallVectorTemplateBase<T, TriviallyCopyable>::mallocForGrow(
445 size_t MinSize, size_t &NewCapacity) {
446 return static_cast<T *>(
447 SmallVectorBase<SmallVectorSizeType<T>>::mallocForGrow(
448 this->getFirstEl(), MinSize, sizeof(T), NewCapacity));
449}
450
451// Define this out-of-line to dissuade the C++ compiler from inlining it.
452template <typename T, bool TriviallyCopyable>
453void SmallVectorTemplateBase<T, TriviallyCopyable>::moveElementsForGrow(
454 T *NewElts) {
455 // Move the elements over.
456 this->uninitialized_move(this->begin(), this->end(), NewElts);
457
458 // Destroy the original elements.
459 destroy_range(S: this->begin(), E: this->end());
460}
461
462// Define this out-of-line to dissuade the C++ compiler from inlining it.
463template <typename T, bool TriviallyCopyable>
464void SmallVectorTemplateBase<T, TriviallyCopyable>::takeAllocationForGrow(
465 T *NewElts, size_t NewCapacity) {
466 // If this wasn't grown from the inline copy, deallocate the old space.
467 if (!this->isSmall())
468 free(this->begin());
469
470 this->BeginX = NewElts;
471 this->Capacity = NewCapacity;
472}
473
474/// SmallVectorTemplateBase<TriviallyCopyable = true> - This is where we put
475/// method implementations that are designed to work with trivially copyable
476/// T's. This allows using memcpy in place of copy/move construction and
477/// skipping destruction.
478template <typename T>
479class SmallVectorTemplateBase<T, true> : public SmallVectorTemplateCommon<T> {
480 friend class SmallVectorTemplateCommon<T>;
481
482protected:
483 /// True if it's cheap enough to take parameters by value. Doing so avoids
484 /// overhead related to mitigations for reference invalidation.
485 static constexpr bool TakesParamByValue = sizeof(T) <= 2 * sizeof(void *);
486
487 /// Either const T& or T, depending on whether it's cheap enough to take
488 /// parameters by value.
489 using ValueParamT = std::conditional_t<TakesParamByValue, T, const T &>;
490
491 SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
492
493 // No need to do a destroy loop for POD's.
494 static void destroy_range(T *, T *) {}
495
496 /// Move the range [I, E) onto the uninitialized memory
497 /// starting with "Dest", constructing elements into it as needed.
498 template<typename It1, typename It2>
499 static void uninitialized_move(It1 I, It1 E, It2 Dest) {
500 // Just do a copy.
501 uninitialized_copy(I, E, Dest);
502 }
503
504 /// Copy the range [I, E) onto the uninitialized memory
505 /// starting with "Dest", constructing elements into it as needed.
506 template<typename It1, typename It2>
507 static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
508 // Arbitrary iterator types; just use the basic implementation.
509 std::uninitialized_copy(I, E, Dest);
510 }
511
512 /// Copy the range [I, E) onto the uninitialized memory
513 /// starting with "Dest", constructing elements into it as needed.
514 template <typename T1, typename T2>
515 static void uninitialized_copy(
516 T1 *I, T1 *E, T2 *Dest,
517 std::enable_if_t<std::is_same<std::remove_const_t<T1>, T2>::value> * =
518 nullptr) {
519 // Use memcpy for PODs iterated by pointers (which includes SmallVector
520 // iterators): std::uninitialized_copy optimizes to memmove, but we can
521 // use memcpy here. Note that I and E are iterators and thus might be
522 // invalid for memcpy if they are equal.
523 if (I != E)
524 memcpy(reinterpret_cast<void *>(Dest), I, (E - I) * sizeof(T));
525 }
526
527 /// Double the size of the allocated memory, guaranteeing space for at
528 /// least one more element or MinSize if specified.
529 void grow(size_t MinSize = 0) { this->grow_pod(MinSize, sizeof(T)); }
530
531 /// Reserve enough space to add one element, and return the updated element
532 /// pointer in case it was a reference to the storage.
533 const T *reserveForParamAndGetAddress(const T &Elt, size_t N = 1) {
534 return this->reserveForParamAndGetAddressImpl(this, Elt, N);
535 }
536
537 /// Reserve enough space to add one element, and return the updated element
538 /// pointer in case it was a reference to the storage.
539 T *reserveForParamAndGetAddress(T &Elt, size_t N = 1) {
540 return const_cast<T *>(
541 this->reserveForParamAndGetAddressImpl(this, Elt, N));
542 }
543
544 /// Copy \p V or return a reference, depending on \a ValueParamT.
545 static ValueParamT forward_value_param(ValueParamT V) { return V; }
546
547 void growAndAssign(size_t NumElts, T Elt) {
548 // Elt has been copied in case it's an internal reference, side-stepping
549 // reference invalidation problems without losing the realloc optimization.
550 this->set_size(0);
551 this->grow(NumElts);
552 std::uninitialized_fill_n(this->begin(), NumElts, Elt);
553 this->set_size(NumElts);
554 }
555
556 template <typename... ArgTypes> T &growAndEmplaceBack(ArgTypes &&... Args) {
557 // Use push_back with a copy in case Args has an internal reference,
558 // side-stepping reference invalidation problems without losing the realloc
559 // optimization.
560 push_back(Elt: T(std::forward<ArgTypes>(Args)...));
561 return this->back();
562 }
563
564public:
565 void push_back(ValueParamT Elt) {
566 const T *EltPtr = reserveForParamAndGetAddress(Elt);
567 memcpy(reinterpret_cast<void *>(this->end()), EltPtr, sizeof(T));
568 this->set_size(this->size() + 1);
569 }
570
571 void pop_back() { this->set_size(this->size() - 1); }
572};
573
574/// This class consists of common code factored out of the SmallVector class to
575/// reduce code duplication based on the SmallVector 'N' template parameter.
576template <typename T>
577class SmallVectorImpl : public SmallVectorTemplateBase<T> {
578 using SuperClass = SmallVectorTemplateBase<T>;
579
580public:
581 using iterator = typename SuperClass::iterator;
582 using const_iterator = typename SuperClass::const_iterator;
583 using reference = typename SuperClass::reference;
584 using size_type = typename SuperClass::size_type;
585
586protected:
587 using SmallVectorTemplateBase<T>::TakesParamByValue;
588 using ValueParamT = typename SuperClass::ValueParamT;
589
590 // Default ctor - Initialize to empty.
591 explicit SmallVectorImpl(unsigned N)
592 : SmallVectorTemplateBase<T>(N) {}
593
594 void assignRemote(SmallVectorImpl &&RHS) {
595 this->destroy_range(this->begin(), this->end());
596 if (!this->isSmall())
597 free(this->begin());
598 this->BeginX = RHS.BeginX;
599 this->Size = RHS.Size;
600 this->Capacity = RHS.Capacity;
601 RHS.resetToSmall();
602 }
603
604public:
605 SmallVectorImpl(const SmallVectorImpl &) = delete;
606
607 ~SmallVectorImpl() {
608 // Subclass has already destructed this vector's elements.
609 // If this wasn't grown from the inline copy, deallocate the old space.
610 if (!this->isSmall())
611 free(this->begin());
612 }
613
614 void clear() {
615 this->destroy_range(this->begin(), this->end());
616 this->Size = 0;
617 }
618
619private:
620 // Make set_size() private to avoid misuse in subclasses.
621 using SuperClass::set_size;
622
623 template <bool ForOverwrite> void resizeImpl(size_type N) {
624 if (N == this->size())
625 return;
626
627 if (N < this->size()) {
628 this->truncate(N);
629 return;
630 }
631
632 this->reserve(N);
633 for (auto I = this->end(), E = this->begin() + N; I != E; ++I)
634 if (ForOverwrite)
635 new (&*I) T;
636 else
637 new (&*I) T();
638 this->set_size(N);
639 }
640
641public:
642 void resize(size_type N) { resizeImpl<false>(N); }
643
644 /// Like resize, but \ref T is POD, the new values won't be initialized.
645 void resize_for_overwrite(size_type N) { resizeImpl<true>(N); }
646
647 /// Like resize, but requires that \p N is less than \a size().
648 void truncate(size_type N) {
649 assert(this->size() >= N && "Cannot increase size with truncate");
650 this->destroy_range(this->begin() + N, this->end());
651 this->set_size(N);
652 }
653
654 void resize(size_type N, ValueParamT NV) {
655 if (N == this->size())
656 return;
657
658 if (N < this->size()) {
659 this->truncate(N);
660 return;
661 }
662
663 // N > this->size(). Defer to append.
664 this->append(N - this->size(), NV);
665 }
666
667 void reserve(size_type N) {
668 if (this->capacity() < N)
669 this->grow(N);
670 }
671
672 void pop_back_n(size_type NumItems) {
673 assert(this->size() >= NumItems);
674 truncate(N: this->size() - NumItems);
675 }
676
677 [[nodiscard]] T pop_back_val() {
678 T Result = ::std::move(this->back());
679 this->pop_back();
680 return Result;
681 }
682
683 void swap(SmallVectorImpl &RHS);
684
685 /// Add the specified range to the end of the SmallVector.
686 template <typename ItTy, typename = EnableIfConvertibleToInputIterator<ItTy>>
687 void append(ItTy in_start, ItTy in_end) {
688 this->assertSafeToAddRange(in_start, in_end);
689 size_type NumInputs = std::distance(in_start, in_end);
690 this->reserve(this->size() + NumInputs);
691 this->uninitialized_copy(in_start, in_end, this->end());
692 this->set_size(this->size() + NumInputs);
693 }
694
695 /// Append \p NumInputs copies of \p Elt to the end.
696 void append(size_type NumInputs, ValueParamT Elt) {
697 const T *EltPtr = this->reserveForParamAndGetAddress(Elt, NumInputs);
698 std::uninitialized_fill_n(this->end(), NumInputs, *EltPtr);
699 this->set_size(this->size() + NumInputs);
700 }
701
702 void append(std::initializer_list<T> IL) {
703 append(IL.begin(), IL.end());
704 }
705
706 void append(const SmallVectorImpl &RHS) { append(RHS.begin(), RHS.end()); }
707
708 void assign(size_type NumElts, ValueParamT Elt) {
709 // Note that Elt could be an internal reference.
710 if (NumElts > this->capacity()) {
711 this->growAndAssign(NumElts, Elt);
712 return;
713 }
714
715 // Assign over existing elements.
716 std::fill_n(this->begin(), std::min(NumElts, this->size()), Elt);
717 if (NumElts > this->size())
718 std::uninitialized_fill_n(this->end(), NumElts - this->size(), Elt);
719 else if (NumElts < this->size())
720 this->destroy_range(this->begin() + NumElts, this->end());
721 this->set_size(NumElts);
722 }
723
724 // FIXME: Consider assigning over existing elements, rather than clearing &
725 // re-initializing them - for all assign(...) variants.
726
727 template <typename ItTy, typename = EnableIfConvertibleToInputIterator<ItTy>>
728 void assign(ItTy in_start, ItTy in_end) {
729 this->assertSafeToReferenceAfterClear(in_start, in_end);
730 clear();
731 append(in_start, in_end);
732 }
733
734 void assign(std::initializer_list<T> IL) {
735 clear();
736 append(IL);
737 }
738
739 void assign(const SmallVectorImpl &RHS) { assign(RHS.begin(), RHS.end()); }
740
741 iterator erase(const_iterator CI) {
742 // Just cast away constness because this is a non-const member function.
743 iterator I = const_cast<iterator>(CI);
744
745 assert(this->isReferenceToStorage(CI) && "Iterator to erase is out of bounds.");
746
747 iterator N = I;
748 // Shift all elts down one.
749 std::move(I+1, this->end(), I);
750 // Drop the last elt.
751 this->pop_back();
752 return(N);
753 }
754
755 iterator erase(const_iterator CS, const_iterator CE) {
756 // Just cast away constness because this is a non-const member function.
757 iterator S = const_cast<iterator>(CS);
758 iterator E = const_cast<iterator>(CE);
759
760 assert(this->isRangeInStorage(S, E) && "Range to erase is out of bounds.");
761
762 iterator N = S;
763 // Shift all elts down.
764 iterator I = std::move(E, this->end(), S);
765 // Drop the last elts.
766 this->destroy_range(I, this->end());
767 this->set_size(I - this->begin());
768 return(N);
769 }
770
771private:
772 template <class ArgType> iterator insert_one_impl(iterator I, ArgType &&Elt) {
773 // Callers ensure that ArgType is derived from T.
774 static_assert(
775 std::is_same<std::remove_const_t<std::remove_reference_t<ArgType>>,
776 T>::value,
777 "ArgType must be derived from T!");
778
779 if (I == this->end()) { // Important special case for empty vector.
780 this->push_back(::std::forward<ArgType>(Elt));
781 return this->end()-1;
782 }
783
784 assert(this->isReferenceToStorage(I) && "Insertion iterator is out of bounds.");
785
786 // Grow if necessary.
787 size_t Index = I - this->begin();
788 std::remove_reference_t<ArgType> *EltPtr =
789 this->reserveForParamAndGetAddress(Elt);
790 I = this->begin() + Index;
791
792 ::new ((void*) this->end()) T(::std::move(this->back()));
793 // Push everything else over.
794 std::move_backward(I, this->end()-1, this->end());
795 this->set_size(this->size() + 1);
796
797 // If we just moved the element we're inserting, be sure to update
798 // the reference (never happens if TakesParamByValue).
799 static_assert(!TakesParamByValue || std::is_same<ArgType, T>::value,
800 "ArgType must be 'T' when taking by value!");
801 if (!TakesParamByValue && this->isReferenceToRange(EltPtr, I, this->end()))
802 ++EltPtr;
803
804 *I = ::std::forward<ArgType>(*EltPtr);
805 return I;
806 }
807
808public:
809 iterator insert(iterator I, T &&Elt) {
810 return insert_one_impl(I, this->forward_value_param(std::move(Elt)));
811 }
812
813 iterator insert(iterator I, const T &Elt) {
814 return insert_one_impl(I, this->forward_value_param(Elt));
815 }
816
817 iterator insert(iterator I, size_type NumToInsert, ValueParamT Elt) {
818 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
819 size_t InsertElt = I - this->begin();
820
821 if (I == this->end()) { // Important special case for empty vector.
822 append(NumToInsert, Elt);
823 return this->begin()+InsertElt;
824 }
825
826 assert(this->isReferenceToStorage(I) && "Insertion iterator is out of bounds.");
827
828 // Ensure there is enough space, and get the (maybe updated) address of
829 // Elt.
830 const T *EltPtr = this->reserveForParamAndGetAddress(Elt, NumToInsert);
831
832 // Uninvalidate the iterator.
833 I = this->begin()+InsertElt;
834
835 // If there are more elements between the insertion point and the end of the
836 // range than there are being inserted, we can use a simple approach to
837 // insertion. Since we already reserved space, we know that this won't
838 // reallocate the vector.
839 if (size_t(this->end()-I) >= NumToInsert) {
840 T *OldEnd = this->end();
841 append(std::move_iterator<iterator>(this->end() - NumToInsert),
842 std::move_iterator<iterator>(this->end()));
843
844 // Copy the existing elements that get replaced.
845 std::move_backward(I, OldEnd-NumToInsert, OldEnd);
846
847 // If we just moved the element we're inserting, be sure to update
848 // the reference (never happens if TakesParamByValue).
849 if (!TakesParamByValue && I <= EltPtr && EltPtr < this->end())
850 EltPtr += NumToInsert;
851
852 std::fill_n(I, NumToInsert, *EltPtr);
853 return I;
854 }
855
856 // Otherwise, we're inserting more elements than exist already, and we're
857 // not inserting at the end.
858
859 // Move over the elements that we're about to overwrite.
860 T *OldEnd = this->end();
861 this->set_size(this->size() + NumToInsert);
862 size_t NumOverwritten = OldEnd-I;
863 this->uninitialized_move(I, OldEnd, this->end()-NumOverwritten);
864
865 // If we just moved the element we're inserting, be sure to update
866 // the reference (never happens if TakesParamByValue).
867 if (!TakesParamByValue && I <= EltPtr && EltPtr < this->end())
868 EltPtr += NumToInsert;
869
870 // Replace the overwritten part.
871 std::fill_n(I, NumOverwritten, *EltPtr);
872
873 // Insert the non-overwritten middle part.
874 std::uninitialized_fill_n(OldEnd, NumToInsert - NumOverwritten, *EltPtr);
875 return I;
876 }
877
878 template <typename ItTy, typename = EnableIfConvertibleToInputIterator<ItTy>>
879 iterator insert(iterator I, ItTy From, ItTy To) {
880 // Convert iterator to elt# to avoid invalidating iterator when we reserve()
881 size_t InsertElt = I - this->begin();
882
883 if (I == this->end()) { // Important special case for empty vector.
884 append(From, To);
885 return this->begin()+InsertElt;
886 }
887
888 assert(this->isReferenceToStorage(I) && "Insertion iterator is out of bounds.");
889
890 // Check that the reserve that follows doesn't invalidate the iterators.
891 this->assertSafeToAddRange(From, To);
892
893 size_t NumToInsert = std::distance(From, To);
894
895 // Ensure there is enough space.
896 reserve(N: this->size() + NumToInsert);
897
898 // Uninvalidate the iterator.
899 I = this->begin()+InsertElt;
900
901 // If there are more elements between the insertion point and the end of the
902 // range than there are being inserted, we can use a simple approach to
903 // insertion. Since we already reserved space, we know that this won't
904 // reallocate the vector.
905 if (size_t(this->end()-I) >= NumToInsert) {
906 T *OldEnd = this->end();
907 append(std::move_iterator<iterator>(this->end() - NumToInsert),
908 std::move_iterator<iterator>(this->end()));
909
910 // Copy the existing elements that get replaced.
911 std::move_backward(I, OldEnd-NumToInsert, OldEnd);
912
913 std::copy(From, To, I);
914 return I;
915 }
916
917 // Otherwise, we're inserting more elements than exist already, and we're
918 // not inserting at the end.
919
920 // Move over the elements that we're about to overwrite.
921 T *OldEnd = this->end();
922 this->set_size(this->size() + NumToInsert);
923 size_t NumOverwritten = OldEnd-I;
924 this->uninitialized_move(I, OldEnd, this->end()-NumOverwritten);
925
926 // Replace the overwritten part.
927 for (T *J = I; NumOverwritten > 0; --NumOverwritten) {
928 *J = *From;
929 ++J; ++From;
930 }
931
932 // Insert the non-overwritten middle part.
933 this->uninitialized_copy(From, To, OldEnd);
934 return I;
935 }
936
937 void insert(iterator I, std::initializer_list<T> IL) {
938 insert(I, IL.begin(), IL.end());
939 }
940
941 template <typename... ArgTypes> reference emplace_back(ArgTypes &&... Args) {
942 if (LLVM_UNLIKELY(this->size() >= this->capacity()))
943 return this->growAndEmplaceBack(std::forward<ArgTypes>(Args)...);
944
945 ::new ((void *)this->end()) T(std::forward<ArgTypes>(Args)...);
946 this->set_size(this->size() + 1);
947 return this->back();
948 }
949
950 SmallVectorImpl &operator=(const SmallVectorImpl &RHS);
951
952 SmallVectorImpl &operator=(SmallVectorImpl &&RHS);
953
954 bool operator==(const SmallVectorImpl &RHS) const {
955 if (this->size() != RHS.size()) return false;
956 return std::equal(this->begin(), this->end(), RHS.begin());
957 }
958 bool operator!=(const SmallVectorImpl &RHS) const {
959 return !(*this == RHS);
960 }
961
962 bool operator<(const SmallVectorImpl &RHS) const {
963 return std::lexicographical_compare(this->begin(), this->end(),
964 RHS.begin(), RHS.end());
965 }
966 bool operator>(const SmallVectorImpl &RHS) const { return RHS < *this; }
967 bool operator<=(const SmallVectorImpl &RHS) const { return !(*this > RHS); }
968 bool operator>=(const SmallVectorImpl &RHS) const { return !(*this < RHS); }
969};
970
971template <typename T>
972void SmallVectorImpl<T>::swap(SmallVectorImpl<T> &RHS) {
973 if (this == &RHS) return;
974
975 // We can only avoid copying elements if neither vector is small.
976 if (!this->isSmall() && !RHS.isSmall()) {
977 std::swap(this->BeginX, RHS.BeginX);
978 std::swap(this->Size, RHS.Size);
979 std::swap(this->Capacity, RHS.Capacity);
980 return;
981 }
982 this->reserve(RHS.size());
983 RHS.reserve(this->size());
984
985 // Swap the shared elements.
986 size_t NumShared = this->size();
987 if (NumShared > RHS.size()) NumShared = RHS.size();
988 for (size_type i = 0; i != NumShared; ++i)
989 std::swap((*this)[i], RHS[i]);
990
991 // Copy over the extra elts.
992 if (this->size() > RHS.size()) {
993 size_t EltDiff = this->size() - RHS.size();
994 this->uninitialized_copy(this->begin()+NumShared, this->end(), RHS.end());
995 RHS.set_size(RHS.size() + EltDiff);
996 this->destroy_range(this->begin()+NumShared, this->end());
997 this->set_size(NumShared);
998 } else if (RHS.size() > this->size()) {
999 size_t EltDiff = RHS.size() - this->size();
1000 this->uninitialized_copy(RHS.begin()+NumShared, RHS.end(), this->end());
1001 this->set_size(this->size() + EltDiff);
1002 this->destroy_range(RHS.begin()+NumShared, RHS.end());
1003 RHS.set_size(NumShared);
1004 }
1005}
1006
1007template <typename T>
1008SmallVectorImpl<T> &SmallVectorImpl<T>::
1009 operator=(const SmallVectorImpl<T> &RHS) {
1010 // Avoid self-assignment.
1011 if (this == &RHS) return *this;
1012
1013 // If we already have sufficient space, assign the common elements, then
1014 // destroy any excess.
1015 size_t RHSSize = RHS.size();
1016 size_t CurSize = this->size();
1017 if (CurSize >= RHSSize) {
1018 // Assign common elements.
1019 iterator NewEnd;
1020 if (RHSSize)
1021 NewEnd = std::copy(RHS.begin(), RHS.begin()+RHSSize, this->begin());
1022 else
1023 NewEnd = this->begin();
1024
1025 // Destroy excess elements.
1026 this->destroy_range(NewEnd, this->end());
1027
1028 // Trim.
1029 this->set_size(RHSSize);
1030 return *this;
1031 }
1032
1033 // If we have to grow to have enough elements, destroy the current elements.
1034 // This allows us to avoid copying them during the grow.
1035 // FIXME: don't do this if they're efficiently moveable.
1036 if (this->capacity() < RHSSize) {
1037 // Destroy current elements.
1038 this->clear();
1039 CurSize = 0;
1040 this->grow(RHSSize);
1041 } else if (CurSize) {
1042 // Otherwise, use assignment for the already-constructed elements.
1043 std::copy(RHS.begin(), RHS.begin()+CurSize, this->begin());
1044 }
1045
1046 // Copy construct the new elements in place.
1047 this->uninitialized_copy(RHS.begin()+CurSize, RHS.end(),
1048 this->begin()+CurSize);
1049
1050 // Set end.
1051 this->set_size(RHSSize);
1052 return *this;
1053}
1054
1055template <typename T>
1056SmallVectorImpl<T> &SmallVectorImpl<T>::operator=(SmallVectorImpl<T> &&RHS) {
1057 // Avoid self-assignment.
1058 if (this == &RHS) return *this;
1059
1060 // If the RHS isn't small, clear this vector and then steal its buffer.
1061 if (!RHS.isSmall()) {
1062 this->assignRemote(std::move(RHS));
1063 return *this;
1064 }
1065
1066 // If we already have sufficient space, assign the common elements, then
1067 // destroy any excess.
1068 size_t RHSSize = RHS.size();
1069 size_t CurSize = this->size();
1070 if (CurSize >= RHSSize) {
1071 // Assign common elements.
1072 iterator NewEnd = this->begin();
1073 if (RHSSize)
1074 NewEnd = std::move(RHS.begin(), RHS.end(), NewEnd);
1075
1076 // Destroy excess elements and trim the bounds.
1077 this->destroy_range(NewEnd, this->end());
1078 this->set_size(RHSSize);
1079
1080 // Clear the RHS.
1081 RHS.clear();
1082
1083 return *this;
1084 }
1085
1086 // If we have to grow to have enough elements, destroy the current elements.
1087 // This allows us to avoid copying them during the grow.
1088 // FIXME: this may not actually make any sense if we can efficiently move
1089 // elements.
1090 if (this->capacity() < RHSSize) {
1091 // Destroy current elements.
1092 this->clear();
1093 CurSize = 0;
1094 this->grow(RHSSize);
1095 } else if (CurSize) {
1096 // Otherwise, use assignment for the already-constructed elements.
1097 std::move(RHS.begin(), RHS.begin()+CurSize, this->begin());
1098 }
1099
1100 // Move-construct the new elements in place.
1101 this->uninitialized_move(RHS.begin()+CurSize, RHS.end(),
1102 this->begin()+CurSize);
1103
1104 // Set end.
1105 this->set_size(RHSSize);
1106
1107 RHS.clear();
1108 return *this;
1109}
1110
1111/// Storage for the SmallVector elements. This is specialized for the N=0 case
1112/// to avoid allocating unnecessary storage.
1113template <typename T, unsigned N>
1114struct SmallVectorStorage {
1115 alignas(T) char InlineElts[N * sizeof(T)];
1116};
1117
1118/// We need the storage to be properly aligned even for small-size of 0 so that
1119/// the pointer math in \a SmallVectorTemplateCommon::getFirstEl() is
1120/// well-defined.
1121template <typename T> struct alignas(T) SmallVectorStorage<T, 0> {};
1122
1123/// Forward declaration of SmallVector so that
1124/// calculateSmallVectorDefaultInlinedElements can reference
1125/// `sizeof(SmallVector<T, 0>)`.
1126template <typename T, unsigned N> class LLVM_GSL_OWNER SmallVector;
1127
1128/// Helper class for calculating the default number of inline elements for
1129/// `SmallVector<T>`.
1130///
1131/// This should be migrated to a constexpr function when our minimum
1132/// compiler support is enough for multi-statement constexpr functions.
1133template <typename T> struct CalculateSmallVectorDefaultInlinedElements {
1134 // Parameter controlling the default number of inlined elements
1135 // for `SmallVector<T>`.
1136 //
1137 // The default number of inlined elements ensures that
1138 // 1. There is at least one inlined element.
1139 // 2. `sizeof(SmallVector<T>) <= kPreferredSmallVectorSizeof` unless
1140 // it contradicts 1.
1141 static constexpr size_t kPreferredSmallVectorSizeof = 64;
1142
1143 // static_assert that sizeof(T) is not "too big".
1144 //
1145 // Because our policy guarantees at least one inlined element, it is possible
1146 // for an arbitrarily large inlined element to allocate an arbitrarily large
1147 // amount of inline storage. We generally consider it an antipattern for a
1148 // SmallVector to allocate an excessive amount of inline storage, so we want
1149 // to call attention to these cases and make sure that users are making an
1150 // intentional decision if they request a lot of inline storage.
1151 //
1152 // We want this assertion to trigger in pathological cases, but otherwise
1153 // not be too easy to hit. To accomplish that, the cutoff is actually somewhat
1154 // larger than kPreferredSmallVectorSizeof (otherwise,
1155 // `SmallVector<SmallVector<T>>` would be one easy way to trip it, and that
1156 // pattern seems useful in practice).
1157 //
1158 // One wrinkle is that this assertion is in theory non-portable, since
1159 // sizeof(T) is in general platform-dependent. However, we don't expect this
1160 // to be much of an issue, because most LLVM development happens on 64-bit
1161 // hosts, and therefore sizeof(T) is expected to *decrease* when compiled for
1162 // 32-bit hosts, dodging the issue. The reverse situation, where development
1163 // happens on a 32-bit host and then fails due to sizeof(T) *increasing* on a
1164 // 64-bit host, is expected to be very rare.
1165 static_assert(
1166 sizeof(T) <= 256,
1167 "You are trying to use a default number of inlined elements for "
1168 "`SmallVector<T>` but `sizeof(T)` is really big! Please use an "
1169 "explicit number of inlined elements with `SmallVector<T, N>` to make "
1170 "sure you really want that much inline storage.");
1171
1172 // Discount the size of the header itself when calculating the maximum inline
1173 // bytes.
1174 static constexpr size_t PreferredInlineBytes =
1175 kPreferredSmallVectorSizeof - sizeof(SmallVector<T, 0>);
1176 static constexpr size_t NumElementsThatFit = PreferredInlineBytes / sizeof(T);
1177 static constexpr size_t value =
1178 NumElementsThatFit == 0 ? 1 : NumElementsThatFit;
1179};
1180
1181/// This is a 'vector' (really, a variable-sized array), optimized
1182/// for the case when the array is small. It contains some number of elements
1183/// in-place, which allows it to avoid heap allocation when the actual number of
1184/// elements is below that threshold. This allows normal "small" cases to be
1185/// fast without losing generality for large inputs.
1186///
1187/// \note
1188/// In the absence of a well-motivated choice for the number of inlined
1189/// elements \p N, it is recommended to use \c SmallVector<T> (that is,
1190/// omitting the \p N). This will choose a default number of inlined elements
1191/// reasonable for allocation on the stack (for example, trying to keep \c
1192/// sizeof(SmallVector<T>) around 64 bytes).
1193///
1194/// \warning This does not attempt to be exception safe.
1195///
1196/// \see https://llvm.org/docs/ProgrammersManual.html#llvm-adt-smallvector-h
1197template <typename T,
1198 unsigned N = CalculateSmallVectorDefaultInlinedElements<T>::value>
1199class LLVM_GSL_OWNER SmallVector : public SmallVectorImpl<T>,
1200 SmallVectorStorage<T, N> {
1201public:
1202 SmallVector() : SmallVectorImpl<T>(N) {}
1203
1204 ~SmallVector() {
1205 // Destroy the constructed elements in the vector.
1206 this->destroy_range(this->begin(), this->end());
1207 }
1208
1209 explicit SmallVector(size_t Size)
1210 : SmallVectorImpl<T>(N) {
1211 this->resize(Size);
1212 }
1213
1214 SmallVector(size_t Size, const T &Value)
1215 : SmallVectorImpl<T>(N) {
1216 this->assign(Size, Value);
1217 }
1218
1219 template <typename ItTy, typename = EnableIfConvertibleToInputIterator<ItTy>>
1220 SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(N) {
1221 this->append(S, E);
1222 }
1223
1224 template <typename RangeTy>
1225 explicit SmallVector(const iterator_range<RangeTy> &R)
1226 : SmallVectorImpl<T>(N) {
1227 this->append(R.begin(), R.end());
1228 }
1229
1230 SmallVector(std::initializer_list<T> IL) : SmallVectorImpl<T>(N) {
1231 this->append(IL);
1232 }
1233
1234 template <typename U,
1235 typename = std::enable_if_t<std::is_convertible<U, T>::value>>
1236 explicit SmallVector(ArrayRef<U> A) : SmallVectorImpl<T>(N) {
1237 this->append(A.begin(), A.end());
1238 }
1239
1240 SmallVector(const SmallVector &RHS) : SmallVectorImpl<T>(N) {
1241 if (!RHS.empty())
1242 SmallVectorImpl<T>::operator=(RHS);
1243 }
1244
1245 SmallVector &operator=(const SmallVector &RHS) {
1246 SmallVectorImpl<T>::operator=(RHS);
1247 return *this;
1248 }
1249
1250 SmallVector(SmallVector &&RHS) : SmallVectorImpl<T>(N) {
1251 if (!RHS.empty())
1252 SmallVectorImpl<T>::operator=(::std::move(RHS));
1253 }
1254
1255 SmallVector(SmallVectorImpl<T> &&RHS) : SmallVectorImpl<T>(N) {
1256 if (!RHS.empty())
1257 SmallVectorImpl<T>::operator=(::std::move(RHS));
1258 }
1259
1260 SmallVector &operator=(SmallVector &&RHS) {
1261 if (N) {
1262 SmallVectorImpl<T>::operator=(::std::move(RHS));
1263 return *this;
1264 }
1265 // SmallVectorImpl<T>::operator= does not leverage N==0. Optimize the
1266 // case.
1267 if (this == &RHS)
1268 return *this;
1269 if (RHS.empty()) {
1270 this->destroy_range(this->begin(), this->end());
1271 this->Size = 0;
1272 } else {
1273 this->assignRemote(std::move(RHS));
1274 }
1275 return *this;
1276 }
1277
1278 SmallVector &operator=(SmallVectorImpl<T> &&RHS) {
1279 SmallVectorImpl<T>::operator=(::std::move(RHS));
1280 return *this;
1281 }
1282
1283 SmallVector &operator=(std::initializer_list<T> IL) {
1284 this->assign(IL);
1285 return *this;
1286 }
1287};
1288
1289template <typename T, unsigned N>
1290inline size_t capacity_in_bytes(const SmallVector<T, N> &X) {
1291 return X.capacity_in_bytes();
1292}
1293
1294template <typename RangeType>
1295using ValueTypeFromRangeType =
1296 std::remove_const_t<std::remove_reference_t<decltype(*std::begin(
1297 std::declval<RangeType &>()))>>;
1298
1299/// Given a range of type R, iterate the entire range and return a
1300/// SmallVector with elements of the vector. This is useful, for example,
1301/// when you want to iterate a range and then sort the results.
1302template <unsigned Size, typename R>
1303SmallVector<ValueTypeFromRangeType<R>, Size> to_vector(R &&Range) {
1304 return {std::begin(Range), std::end(Range)};
1305}
1306template <typename R>
1307SmallVector<ValueTypeFromRangeType<R>> to_vector(R &&Range) {
1308 return {std::begin(Range), std::end(Range)};
1309}
1310
1311template <typename Out, unsigned Size, typename R>
1312SmallVector<Out, Size> to_vector_of(R &&Range) {
1313 return {std::begin(Range), std::end(Range)};
1314}
1315
1316template <typename Out, typename R> SmallVector<Out> to_vector_of(R &&Range) {
1317 return {std::begin(Range), std::end(Range)};
1318}
1319
1320// Explicit instantiations
1321extern template class llvm::SmallVectorBase<uint32_t>;
1322#if SIZE_MAX > UINT32_MAX
1323extern template class llvm::SmallVectorBase<uint64_t>;
1324#endif
1325
1326} // end namespace llvm
1327
1328namespace std {
1329
1330 /// Implement std::swap in terms of SmallVector swap.
1331 template<typename T>
1332 inline void
1333 swap(llvm::SmallVectorImpl<T> &LHS, llvm::SmallVectorImpl<T> &RHS) {
1334 LHS.swap(RHS);
1335 }
1336
1337 /// Implement std::swap in terms of SmallVector swap.
1338 template<typename T, unsigned N>
1339 inline void
1340 swap(llvm::SmallVector<T, N> &LHS, llvm::SmallVector<T, N> &RHS) {
1341 LHS.swap(RHS);
1342 }
1343
1344} // end namespace std
1345
1346#endif // LLVM_ADT_SMALLVECTOR_H
1347

source code of include/llvm-17/llvm/ADT/SmallVector.h