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

source code of include/llvm-20/llvm/ADT/SmallVector.h