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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 : // This file defines the SmallVector class.
10 : //
11 : //===----------------------------------------------------------------------===//
12 :
13 : // ATen: modified from llvm::SmallVector.
14 : // used std::is_trivially_{copy,move}_constructible
15 : // replaced iterator_range constructor with inline Container&& constructor
16 : // replaced LLVM_NODISCARD, LLVM_LIKELY, and LLVM_UNLIKELY with c10 equivalents
17 : // removed LLVM_GSL_OWNER
18 : // added SmallVector::at
19 : // added operator<< for std::ostream
20 : // added C10_API to export SmallVectorBase
21 :
22 : #pragma once
23 :
24 : #include <c10/macros/Macros.h>
25 : #include <c10/util/AlignOf.h>
26 :
27 : #include <algorithm>
28 : #include <cassert>
29 : #include <cstddef>
30 : #include <cstdlib>
31 : #include <cstring>
32 : #include <functional>
33 : #include <initializer_list>
34 : #include <iterator>
35 : #include <limits>
36 : #include <memory>
37 : #include <new>
38 : #include <ostream>
39 : #include <type_traits>
40 : #include <utility>
41 :
42 : C10_CLANG_DIAGNOSTIC_PUSH()
43 : #if C10_CLANG_HAS_WARNING("-Wshorten-64-to-32")
44 : C10_CLANG_DIAGNOSTIC_IGNORE("-Wshorten-64-to-32")
45 : #endif
46 :
47 : namespace c10 {
48 :
49 : /// This is all the stuff common to all SmallVectors.
50 : ///
51 : /// The template parameter specifies the type which should be used to hold the
52 : /// Size and Capacity of the SmallVector, so it can be adjusted.
53 : /// Using 32 bit size is desirable to shrink the size of the SmallVector.
54 : /// Using 64 bit size is desirable for cases like SmallVector<char>, where a
55 : /// 32 bit size would limit the vector to ~4GB. SmallVectors are used for
56 : /// buffering bitcode output - which can exceed 4GB.
57 : template <class Size_T>
58 : class C10_API SmallVectorBase {
59 : protected:
60 : void* BeginX;
61 : Size_T Size = 0, Capacity;
62 :
63 : /// The maximum value of the Size_T used.
64 : static constexpr size_t SizeTypeMax() {
65 : return std::numeric_limits<Size_T>::max();
66 : }
67 :
68 0 : SmallVectorBase(void* FirstEl, size_t TotalCapacity)
69 0 : : BeginX(FirstEl), Capacity(TotalCapacity) {}
70 :
71 : /// This is a helper for \a grow() that's out of line to reduce code
72 : /// duplication. This function will report a fatal error if it can't grow at
73 : /// least to \p MinSize.
74 : void* mallocForGrow(size_t MinSize, size_t TSize, size_t& NewCapacity);
75 :
76 : /// This is an implementation of the grow() method which only works
77 : /// on POD-like data types and is out of line to reduce code duplication.
78 : /// This function will report a fatal error if it cannot increase capacity.
79 : void grow_pod(void* FirstEl, size_t MinSize, size_t TSize);
80 :
81 : public:
82 : SmallVectorBase() = delete;
83 0 : size_t size() const {
84 0 : return Size;
85 : }
86 0 : size_t capacity() const {
87 0 : return Capacity;
88 : }
89 :
90 : C10_NODISCARD bool empty() const {
91 : return !Size;
92 : }
93 :
94 : /// Set the array size to \p N, which the current array must have enough
95 : /// capacity for.
96 : ///
97 : /// This does not construct or destroy any elements in the vector.
98 : ///
99 : /// Clients can use this in conjunction with capacity() to write past the end
100 : /// of the buffer when they know that more elements are available, and only
101 : /// update the size later. This avoids the cost of value initializing elements
102 : /// which will only be overwritten.
103 0 : void set_size(size_t N) {
104 0 : assert(N <= capacity());
105 0 : Size = N;
106 0 : }
107 : };
108 :
109 : template <class T>
110 : using SmallVectorSizeType = typename std::
111 : conditional<sizeof(T) < 4 && sizeof(void*) >= 8, uint64_t, uint32_t>::type;
112 :
113 : /// Figure out the offset of the first element.
114 : template <class T, typename = void>
115 : struct SmallVectorAlignmentAndSize {
116 : alignas(SmallVectorBase<SmallVectorSizeType<T>>) char Base[sizeof(
117 : SmallVectorBase<SmallVectorSizeType<T>>)];
118 : alignas(T) char FirstEl[sizeof(T)];
119 : };
120 :
121 : /// This is the part of SmallVectorTemplateBase which does not depend on whether
122 : /// the type T is a POD. The extra dummy template argument is used by ArrayRef
123 : /// to avoid unnecessarily requiring T to be complete.
124 : template <typename T, typename = void>
125 : class SmallVectorTemplateCommon
126 : : public SmallVectorBase<SmallVectorSizeType<T>> {
127 : using Base = SmallVectorBase<SmallVectorSizeType<T>>;
128 :
129 : /// Find the address of the first element. For this pointer math to be valid
130 : /// with small-size of 0 for T with lots of alignment, it's important that
131 : /// SmallVectorStorage is properly-aligned even for small-size of 0.
132 0 : void* getFirstEl() const {
133 : return const_cast<void*>(reinterpret_cast<const void*>(
134 : reinterpret_cast<const char*>(this) +
135 0 : offsetof(SmallVectorAlignmentAndSize<T>, FirstEl)));
136 : }
137 : // Space after 'FirstEl' is clobbered, do not add any instance vars after it.
138 :
139 : protected:
140 0 : SmallVectorTemplateCommon(size_t Size) : Base(getFirstEl(), Size) {}
141 :
142 0 : void grow_pod(size_t MinSize, size_t TSize) {
143 0 : Base::grow_pod(getFirstEl(), MinSize, TSize);
144 0 : }
145 :
146 : /// Return true if this is a smallvector which has not had dynamic
147 : /// memory allocated for it.
148 0 : bool isSmall() const {
149 0 : return this->BeginX == getFirstEl();
150 : }
151 :
152 : /// Put this vector in a state of being small.
153 : void resetToSmall() {
154 : this->BeginX = getFirstEl();
155 : this->Size = this->Capacity = 0; // FIXME: Setting Capacity to 0 is suspect.
156 : }
157 :
158 : /// Return true if V is an internal reference to the given range.
159 : bool isReferenceToRange(const void* V, const void* First, const void* Last)
160 : const {
161 : // Use std::less to avoid UB.
162 : std::less<> LessThan;
163 : return !LessThan(V, First) && LessThan(V, Last);
164 : }
165 :
166 : /// Return true if V is an internal reference to this vector.
167 : bool isReferenceToStorage(const void* V) const {
168 : return isReferenceToRange(V, this->begin(), this->end());
169 : }
170 :
171 : /// Return true if First and Last form a valid (possibly empty) range in this
172 : /// vector's storage.
173 : bool isRangeInStorage(const void* First, const void* Last) const {
174 : // Use std::less to avoid UB.
175 : std::less<> LessThan;
176 : return !LessThan(First, this->begin()) && !LessThan(Last, First) &&
177 : !LessThan(this->end(), Last);
178 : }
179 :
180 : /// Return true unless Elt will be invalidated by resizing the vector to
181 : /// NewSize.
182 : bool isSafeToReferenceAfterResize(const void* Elt, size_t NewSize) {
183 : // Past the end.
184 : if (C10_LIKELY(!isReferenceToStorage(Elt)))
185 : return true;
186 :
187 : // Return false if Elt will be destroyed by shrinking.
188 : if (NewSize <= this->size())
189 : return Elt < this->begin() + NewSize;
190 :
191 : // Return false if we need to grow.
192 : return NewSize <= this->capacity();
193 : }
194 :
195 : /// Check whether Elt will be invalidated by resizing the vector to NewSize.
196 : void assertSafeToReferenceAfterResize(const void* Elt, size_t NewSize) {
197 : (void)Elt; // Suppress unused variable warning
198 : (void)NewSize; // Suppress unused variable warning
199 : assert(
200 : isSafeToReferenceAfterResize(Elt, NewSize) &&
201 : "Attempting to reference an element of the vector in an operation "
202 : "that invalidates it");
203 : }
204 :
205 : /// Check whether Elt will be invalidated by increasing the size of the
206 : /// vector by N.
207 : void assertSafeToAdd(const void* Elt, size_t N = 1) {
208 : this->assertSafeToReferenceAfterResize(Elt, this->size() + N);
209 : }
210 :
211 : /// Check whether any part of the range will be invalidated by clearing.
212 : void assertSafeToReferenceAfterClear(const T* From, const T* To) {
213 : if (From == To)
214 : return;
215 : this->assertSafeToReferenceAfterResize(From, 0);
216 : this->assertSafeToReferenceAfterResize(To - 1, 0);
217 : }
218 : template <
219 : class ItTy,
220 : std::enable_if_t<
221 : !std::is_same<std::remove_const_t<ItTy>, T*>::value,
222 : bool> = false>
223 : void assertSafeToReferenceAfterClear(ItTy, ItTy) {}
224 :
225 : /// Check whether any part of the range will be invalidated by growing.
226 : void assertSafeToAddRange(const T* From, const T* To) {
227 : if (From == To)
228 : return;
229 : this->assertSafeToAdd(From, To - From);
230 : this->assertSafeToAdd(To - 1, To - From);
231 : }
232 : template <
233 : class ItTy,
234 : std::enable_if_t<
235 : !std::is_same<std::remove_const_t<ItTy>, T*>::value,
236 : bool> = false>
237 : void assertSafeToAddRange(ItTy, ItTy) {}
238 :
239 : /// Reserve enough space to add one element, and return the updated element
240 : /// pointer in case it was a reference to the storage.
241 : template <class U>
242 0 : static const T* reserveForParamAndGetAddressImpl(
243 : U* This,
244 : const T& Elt,
245 : size_t N) {
246 0 : size_t NewSize = This->size() + N;
247 0 : if (C10_LIKELY(NewSize <= This->capacity()))
248 0 : return &Elt;
249 :
250 0 : bool ReferencesStorage = false;
251 0 : int64_t Index = -1;
252 : if (!U::TakesParamByValue) {
253 : if (C10_UNLIKELY(This->isReferenceToStorage(&Elt))) {
254 : ReferencesStorage = true;
255 : Index = &Elt - This->begin();
256 : }
257 : }
258 0 : This->grow(NewSize);
259 0 : return ReferencesStorage ? This->begin() + Index : &Elt;
260 : }
261 :
262 : public:
263 : using size_type = size_t;
264 : using difference_type = ptrdiff_t;
265 : using value_type = T;
266 : using iterator = T*;
267 : using const_iterator = const T*;
268 :
269 : using const_reverse_iterator = std::reverse_iterator<const_iterator>;
270 : using reverse_iterator = std::reverse_iterator<iterator>;
271 :
272 : using reference = T&;
273 : using const_reference = const T&;
274 : using pointer = T*;
275 : using const_pointer = const T*;
276 :
277 : using Base::capacity;
278 : using Base::empty;
279 : using Base::size;
280 :
281 : // forward iterator creation methods.
282 0 : iterator begin() {
283 0 : return (iterator)this->BeginX;
284 : }
285 : const_iterator begin() const {
286 : return (const_iterator)this->BeginX;
287 : }
288 0 : iterator end() {
289 0 : return begin() + size();
290 : }
291 : const_iterator end() const {
292 : return begin() + size();
293 : }
294 :
295 : // reverse iterator creation methods.
296 : reverse_iterator rbegin() {
297 : return reverse_iterator(end());
298 : }
299 : const_reverse_iterator rbegin() const {
300 : return const_reverse_iterator(end());
301 : }
302 : reverse_iterator rend() {
303 : return reverse_iterator(begin());
304 : }
305 : const_reverse_iterator rend() const {
306 : return const_reverse_iterator(begin());
307 : }
308 :
309 : size_type size_in_bytes() const {
310 : return size() * sizeof(T);
311 : }
312 : size_type max_size() const {
313 : return std::min(this->SizeTypeMax(), size_type(-1) / sizeof(T));
314 : }
315 :
316 : size_t capacity_in_bytes() const {
317 : return capacity() * sizeof(T);
318 : }
319 :
320 : /// Return a pointer to the vector's buffer, even if empty().
321 : pointer data() {
322 : return pointer(begin());
323 : }
324 : /// Return a pointer to the vector's buffer, even if empty().
325 : const_pointer data() const {
326 : return const_pointer(begin());
327 : }
328 :
329 : // SmallVector::at is NOT from LLVM.
330 : reference at(size_type idx) {
331 : assert(idx < size());
332 : return begin()[idx];
333 : }
334 : const_reference at(size_type idx) const {
335 : assert(idx < size());
336 : return begin()[idx];
337 : }
338 : reference operator[](size_type idx) {
339 : assert(idx < size());
340 : return begin()[idx];
341 : }
342 : const_reference operator[](size_type idx) const {
343 : assert(idx < size());
344 : return begin()[idx];
345 : }
346 :
347 : reference front() {
348 : assert(!empty());
349 : return begin()[0];
350 : }
351 : const_reference front() const {
352 : assert(!empty());
353 : return begin()[0];
354 : }
355 :
356 : reference back() {
357 : assert(!empty());
358 : return end()[-1];
359 : }
360 : const_reference back() const {
361 : assert(!empty());
362 : return end()[-1];
363 : }
364 : };
365 :
366 : /// SmallVectorTemplateBase<TriviallyCopyable = false> - This is where we put
367 : /// method implementations that are designed to work with non-trivial T's.
368 : ///
369 : /// We approximate is_trivially_copyable with trivial move/copy construction and
370 : /// trivial destruction. While the standard doesn't specify that you're allowed
371 : /// copy these types with memcpy, there is no way for the type to observe this.
372 : /// This catches the important case of std::pair<POD, POD>, which is not
373 : /// trivially assignable.
374 : ///
375 : /// XXX: if build fails here fall back to C10_IS_TRIVIALLY_COPYABLE and make a
376 : /// note
377 : template <
378 : typename T,
379 : bool = (std::is_trivially_copy_constructible<T>::value) &&
380 : (std::is_trivially_move_constructible<T>::value) &&
381 : std::is_trivially_destructible<T>::value>
382 : class SmallVectorTemplateBase : public SmallVectorTemplateCommon<T> {
383 : friend class SmallVectorTemplateCommon<T>;
384 :
385 : protected:
386 : static constexpr bool TakesParamByValue = false;
387 : using ValueParamT = const T&;
388 :
389 : SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
390 :
391 : static void destroy_range(T* S, T* E) {
392 : while (S != E) {
393 : --E;
394 : E->~T();
395 : }
396 : }
397 :
398 : /// Move the range [I, E) into the uninitialized memory starting with "Dest",
399 : /// constructing elements as needed.
400 : template <typename It1, typename It2>
401 : static void uninitialized_move(It1 I, It1 E, It2 Dest) {
402 : std::uninitialized_copy(
403 : std::make_move_iterator(I), std::make_move_iterator(E), Dest);
404 : }
405 :
406 : /// Copy the range [I, E) onto the uninitialized memory starting with "Dest",
407 : /// constructing elements as needed.
408 : template <typename It1, typename It2>
409 : static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
410 : std::uninitialized_copy(I, E, Dest);
411 : }
412 :
413 : /// Grow the allocated memory (without initializing new elements), doubling
414 : /// the size of the allocated memory. Guarantees space for at least one more
415 : /// element, or MinSize more elements if specified.
416 : void grow(size_t MinSize = 0);
417 :
418 : /// Create a new allocation big enough for \p MinSize and pass back its size
419 : /// in \p NewCapacity. This is the first section of \a grow().
420 : T* mallocForGrow(size_t MinSize, size_t& NewCapacity) {
421 : return static_cast<T*>(
422 : SmallVectorBase<SmallVectorSizeType<T>>::mallocForGrow(
423 : MinSize, sizeof(T), NewCapacity));
424 : }
425 :
426 : /// Move existing elements over to the new allocation \p NewElts, the middle
427 : /// section of \a grow().
428 : void moveElementsForGrow(T* NewElts);
429 :
430 : /// Transfer ownership of the allocation, finishing up \a grow().
431 : void takeAllocationForGrow(T* NewElts, size_t NewCapacity);
432 :
433 : /// Reserve enough space to add one element, and return the updated element
434 : /// pointer in case it was a reference to the storage.
435 : const T* reserveForParamAndGetAddress(const T& Elt, size_t N = 1) {
436 : return this->reserveForParamAndGetAddressImpl(this, Elt, N);
437 : }
438 :
439 : /// Reserve enough space to add one element, and return the updated element
440 : /// pointer in case it was a reference to the storage.
441 : T* reserveForParamAndGetAddress(T& Elt, size_t N = 1) {
442 : return const_cast<T*>(this->reserveForParamAndGetAddressImpl(this, Elt, N));
443 : }
444 :
445 : static T&& forward_value_param(T&& V) {
446 : return std::move(V);
447 : }
448 : static const T& forward_value_param(const T& V) {
449 : return V;
450 : }
451 :
452 : void growAndAssign(size_t NumElts, const T& Elt) {
453 : // Grow manually in case Elt is an internal reference.
454 : size_t NewCapacity = 0;
455 : T* NewElts = mallocForGrow(NumElts, NewCapacity);
456 : std::uninitialized_fill_n(NewElts, NumElts, Elt);
457 : this->destroy_range(this->begin(), this->end());
458 : takeAllocationForGrow(NewElts, NewCapacity);
459 : this->set_size(NumElts);
460 : }
461 :
462 : template <typename... ArgTypes>
463 : T& growAndEmplaceBack(ArgTypes&&... Args) {
464 : // Grow manually in case one of Args is an internal reference.
465 : size_t NewCapacity = 0;
466 : T* NewElts = mallocForGrow(0, NewCapacity);
467 : ::new ((void*)(NewElts + this->size())) T(std::forward<ArgTypes>(Args)...);
468 : moveElementsForGrow(NewElts);
469 : takeAllocationForGrow(NewElts, NewCapacity);
470 : this->set_size(this->size() + 1);
471 : return this->back();
472 : }
473 :
474 : public:
475 : void push_back(const T& Elt) {
476 : const T* EltPtr = reserveForParamAndGetAddress(Elt);
477 : ::new ((void*)this->end()) T(*EltPtr);
478 : this->set_size(this->size() + 1);
479 : }
480 :
481 : void push_back(T&& Elt) {
482 : T* EltPtr = reserveForParamAndGetAddress(Elt);
483 : ::new ((void*)this->end()) T(::std::move(*EltPtr));
484 : this->set_size(this->size() + 1);
485 : }
486 :
487 : void pop_back() {
488 : this->set_size(this->size() - 1);
489 : this->end()->~T();
490 : }
491 : };
492 :
493 : // Define this out-of-line to dissuade the C++ compiler from inlining it.
494 : template <typename T, bool TriviallyCopyable>
495 : void SmallVectorTemplateBase<T, TriviallyCopyable>::grow(size_t MinSize) {
496 : size_t NewCapacity = 0;
497 : T* NewElts = mallocForGrow(MinSize, NewCapacity);
498 : moveElementsForGrow(NewElts);
499 : takeAllocationForGrow(NewElts, NewCapacity);
500 : }
501 :
502 : // Define this out-of-line to dissuade the C++ compiler from inlining it.
503 : template <typename T, bool TriviallyCopyable>
504 : void SmallVectorTemplateBase<T, TriviallyCopyable>::moveElementsForGrow(
505 : T* NewElts) {
506 : // Move the elements over.
507 : this->uninitialized_move(this->begin(), this->end(), NewElts);
508 :
509 : // Destroy the original elements.
510 : destroy_range(this->begin(), this->end());
511 : }
512 :
513 : // Define this out-of-line to dissuade the C++ compiler from inlining it.
514 : template <typename T, bool TriviallyCopyable>
515 : void SmallVectorTemplateBase<T, TriviallyCopyable>::takeAllocationForGrow(
516 : T* NewElts,
517 : size_t NewCapacity) {
518 : // If this wasn't grown from the inline copy, deallocate the old space.
519 : if (!this->isSmall())
520 : free(this->begin());
521 :
522 : this->BeginX = NewElts;
523 : this->Capacity = NewCapacity;
524 : }
525 :
526 : /// SmallVectorTemplateBase<TriviallyCopyable = true> - This is where we put
527 : /// method implementations that are designed to work with trivially copyable
528 : /// T's. This allows using memcpy in place of copy/move construction and
529 : /// skipping destruction.
530 : template <typename T>
531 : class SmallVectorTemplateBase<T, true> : public SmallVectorTemplateCommon<T> {
532 : friend class SmallVectorTemplateCommon<T>;
533 :
534 : protected:
535 : /// True if it's cheap enough to take parameters by value. Doing so avoids
536 : /// overhead related to mitigations for reference invalidation.
537 : static constexpr bool TakesParamByValue = sizeof(T) <= 2 * sizeof(void*);
538 :
539 : /// Either const T& or T, depending on whether it's cheap enough to take
540 : /// parameters by value.
541 : using ValueParamT =
542 : typename std::conditional<TakesParamByValue, T, const T&>::type;
543 :
544 0 : SmallVectorTemplateBase(size_t Size) : SmallVectorTemplateCommon<T>(Size) {}
545 :
546 : // No need to do a destroy loop for POD's.
547 0 : static void destroy_range(T*, T*) {}
548 :
549 : /// Move the range [I, E) onto the uninitialized memory
550 : /// starting with "Dest", constructing elements into it as needed.
551 : template <typename It1, typename It2>
552 : static void uninitialized_move(It1 I, It1 E, It2 Dest) {
553 : // Just do a copy.
554 : uninitialized_copy(I, E, Dest);
555 : }
556 :
557 : /// Copy the range [I, E) onto the uninitialized memory
558 : /// starting with "Dest", constructing elements into it as needed.
559 : template <typename It1, typename It2>
560 : static void uninitialized_copy(It1 I, It1 E, It2 Dest) {
561 : // Arbitrary iterator types; just use the basic implementation.
562 : std::uninitialized_copy(I, E, Dest);
563 : }
564 :
565 : /// Copy the range [I, E) onto the uninitialized memory
566 : /// starting with "Dest", constructing elements into it as needed.
567 : template <typename T1, typename T2>
568 : static void uninitialized_copy(
569 : T1* I,
570 : T1* E,
571 : T2* Dest,
572 : std::enable_if_t<
573 : std::is_same<typename std::remove_const<T1>::type, T2>::value>* =
574 : nullptr) {
575 : // Use memcpy for PODs iterated by pointers (which includes SmallVector
576 : // iterators): std::uninitialized_copy optimizes to memmove, but we can
577 : // use memcpy here. Note that I and E are iterators and thus might be
578 : // invalid for memcpy if they are equal.
579 : if (I != E)
580 : memcpy(reinterpret_cast<void*>(Dest), I, (E - I) * sizeof(T));
581 : }
582 :
583 : /// Double the size of the allocated memory, guaranteeing space for at
584 : /// least one more element or MinSize if specified.
585 0 : void grow(size_t MinSize = 0) {
586 0 : this->grow_pod(MinSize, sizeof(T));
587 0 : }
588 :
589 : /// Reserve enough space to add one element, and return the updated element
590 : /// pointer in case it was a reference to the storage.
591 : const T* reserveForParamAndGetAddress(const T& Elt, size_t N = 1) {
592 : return this->reserveForParamAndGetAddressImpl(this, Elt, N);
593 : }
594 :
595 : /// Reserve enough space to add one element, and return the updated element
596 : /// pointer in case it was a reference to the storage.
597 0 : T* reserveForParamAndGetAddress(T& Elt, size_t N = 1) {
598 0 : return const_cast<T*>(this->reserveForParamAndGetAddressImpl(this, Elt, N));
599 : }
600 :
601 : /// Copy \p V or return a reference, depending on \a ValueParamT.
602 : static ValueParamT forward_value_param(ValueParamT V) {
603 : return V;
604 : }
605 :
606 : void growAndAssign(size_t NumElts, T Elt) {
607 : // Elt has been copied in case it's an internal reference, side-stepping
608 : // reference invalidation problems without losing the realloc optimization.
609 : this->set_size(0);
610 : this->grow(NumElts);
611 : std::uninitialized_fill_n(this->begin(), NumElts, Elt);
612 : this->set_size(NumElts);
613 : }
614 :
615 : template <typename... ArgTypes>
616 : T& growAndEmplaceBack(ArgTypes&&... Args) {
617 : // Use push_back with a copy in case Args has an internal reference,
618 : // side-stepping reference invalidation problems without losing the realloc
619 : // optimization.
620 : push_back(T(std::forward<ArgTypes>(Args)...));
621 : return this->back();
622 : }
623 :
624 : public:
625 0 : void push_back(ValueParamT Elt) {
626 0 : const T* EltPtr = reserveForParamAndGetAddress(Elt);
627 0 : memcpy(reinterpret_cast<void*>(this->end()), EltPtr, sizeof(T));
628 0 : this->set_size(this->size() + 1);
629 0 : }
630 :
631 : void pop_back() {
632 : this->set_size(this->size() - 1);
633 : }
634 : };
635 :
636 : /// This class consists of common code factored out of the SmallVector class to
637 : /// reduce code duplication based on the SmallVector 'N' template parameter.
638 : template <typename T>
639 : class SmallVectorImpl : public SmallVectorTemplateBase<T> {
640 : using SuperClass = SmallVectorTemplateBase<T>;
641 :
642 : public:
643 : using iterator = typename SuperClass::iterator;
644 : using const_iterator = typename SuperClass::const_iterator;
645 : using reference = typename SuperClass::reference;
646 : using size_type = typename SuperClass::size_type;
647 :
648 : protected:
649 : using SmallVectorTemplateBase<T>::TakesParamByValue;
650 : using ValueParamT = typename SuperClass::ValueParamT;
651 :
652 : // Default ctor - Initialize to empty.
653 0 : explicit SmallVectorImpl(unsigned N) : SmallVectorTemplateBase<T>(N) {}
654 :
655 : public:
656 : SmallVectorImpl(const SmallVectorImpl&) = delete;
657 :
658 0 : ~SmallVectorImpl() {
659 : // Subclass has already destructed this vector's elements.
660 : // If this wasn't grown from the inline copy, deallocate the old space.
661 0 : if (!this->isSmall())
662 0 : free(this->begin());
663 0 : }
664 :
665 : void clear() {
666 : this->destroy_range(this->begin(), this->end());
667 : this->Size = 0;
668 : }
669 :
670 : private:
671 : template <bool ForOverwrite>
672 : void resizeImpl(size_type N) {
673 : if (N < this->size()) {
674 : this->pop_back_n(this->size() - N);
675 : } else if (N > this->size()) {
676 : this->reserve(N);
677 : for (auto I = this->end(), E = this->begin() + N; I != E; ++I)
678 : if (ForOverwrite)
679 : new (&*I) T;
680 : else
681 : new (&*I) T();
682 : this->set_size(N);
683 : }
684 : }
685 :
686 : public:
687 : void resize(size_type N) {
688 : resizeImpl<false>(N);
689 : }
690 :
691 : /// Like resize, but \ref T is POD, the new values won't be initialized.
692 : void resize_for_overwrite(size_type N) {
693 : resizeImpl<true>(N);
694 : }
695 :
696 : void resize(size_type N, ValueParamT NV) {
697 : if (N == this->size())
698 : return;
699 :
700 : if (N < this->size()) {
701 : this->pop_back_n(this->size() - N);
702 : return;
703 : }
704 :
705 : // N > this->size(). Defer to append.
706 : this->append(N - this->size(), NV);
707 : }
708 :
709 0 : void reserve(size_type N) {
710 0 : if (this->capacity() < N)
711 0 : this->grow(N);
712 0 : }
713 :
714 : void pop_back_n(size_type NumItems) {
715 : assert(this->size() >= NumItems);
716 : this->destroy_range(this->end() - NumItems, this->end());
717 : this->set_size(this->size() - NumItems);
718 : }
719 :
720 : C10_NODISCARD T pop_back_val() {
721 : T Result = ::std::move(this->back());
722 : this->pop_back();
723 : return Result;
724 : }
725 :
726 : void swap(SmallVectorImpl& RHS);
727 :
728 : /// Add the specified range to the end of the SmallVector.
729 : template <
730 : typename in_iter,
731 : typename = std::enable_if_t<std::is_convertible<
732 : typename std::iterator_traits<in_iter>::iterator_category,
733 : std::input_iterator_tag>::value>>
734 : void append(in_iter in_start, in_iter in_end) {
735 : this->assertSafeToAddRange(in_start, in_end);
736 : size_type NumInputs = std::distance(in_start, in_end);
737 : this->reserve(this->size() + NumInputs);
738 : this->uninitialized_copy(in_start, in_end, this->end());
739 : this->set_size(this->size() + NumInputs);
740 : }
741 :
742 : /// Append \p NumInputs copies of \p Elt to the end.
743 : void append(size_type NumInputs, ValueParamT Elt) {
744 : const T* EltPtr = this->reserveForParamAndGetAddress(Elt, NumInputs);
745 : std::uninitialized_fill_n(this->end(), NumInputs, *EltPtr);
746 : this->set_size(this->size() + NumInputs);
747 : }
748 :
749 : void append(std::initializer_list<T> IL) {
750 : append(IL.begin(), IL.end());
751 : }
752 :
753 : void append(const SmallVectorImpl& RHS) {
754 : append(RHS.begin(), RHS.end());
755 : }
756 :
757 : void assign(size_type NumElts, ValueParamT Elt) {
758 : // Note that Elt could be an internal reference.
759 : if (NumElts > this->capacity()) {
760 : this->growAndAssign(NumElts, Elt);
761 : return;
762 : }
763 :
764 : // Assign over existing elements.
765 : std::fill_n(this->begin(), std::min(NumElts, this->size()), Elt);
766 : if (NumElts > this->size())
767 : std::uninitialized_fill_n(this->end(), NumElts - this->size(), Elt);
768 : else if (NumElts < this->size())
769 : this->destroy_range(this->begin() + NumElts, this->end());
770 : this->set_size(NumElts);
771 : }
772 :
773 : // FIXME: Consider assigning over existing elements, rather than clearing &
774 : // re-initializing them - for all assign(...) variants.
775 :
776 : template <
777 : typename in_iter,
778 : typename = std::enable_if_t<std::is_convertible<
779 : typename std::iterator_traits<in_iter>::iterator_category,
780 : std::input_iterator_tag>::value>>
781 : void assign(in_iter in_start, in_iter in_end) {
782 : this->assertSafeToReferenceAfterClear(in_start, in_end);
783 : clear();
784 : append(in_start, in_end);
785 : }
786 :
787 : void assign(std::initializer_list<T> IL) {
788 : clear();
789 : append(IL);
790 : }
791 :
792 : void assign(const SmallVectorImpl& RHS) {
793 : assign(RHS.begin(), RHS.end());
794 : }
795 :
796 : iterator erase(const_iterator CI) {
797 : // Just cast away constness because this is a non-const member function.
798 : iterator I = const_cast<iterator>(CI);
799 :
800 : assert(
801 : this->isReferenceToStorage(CI) &&
802 : "Iterator to erase is out of bounds.");
803 :
804 : iterator N = I;
805 : // Shift all elts down one.
806 : std::move(I + 1, this->end(), I);
807 : // Drop the last elt.
808 : this->pop_back();
809 : return (N);
810 : }
811 :
812 : iterator erase(const_iterator CS, const_iterator CE) {
813 : // Just cast away constness because this is a non-const member function.
814 : iterator S = const_cast<iterator>(CS);
815 : iterator E = const_cast<iterator>(CE);
816 :
817 : assert(this->isRangeInStorage(S, E) && "Range to erase is out of bounds.");
818 :
819 : iterator N = S;
820 : // Shift all elts down.
821 : iterator I = std::move(E, this->end(), S);
822 : // Drop the last elts.
823 : this->destroy_range(I, this->end());
824 : this->set_size(I - this->begin());
825 : return (N);
826 : }
827 :
828 : private:
829 : template <class ArgType>
830 : iterator insert_one_impl(iterator I, ArgType&& Elt) {
831 : // Callers ensure that ArgType is derived from T.
832 : static_assert(
833 : std::is_same<std::remove_const_t<std::remove_reference_t<ArgType>>, T>::
834 : value,
835 : "ArgType must be derived from T!");
836 :
837 : if (I == this->end()) { // Important special case for empty vector.
838 : this->push_back(::std::forward<ArgType>(Elt));
839 : return this->end() - 1;
840 : }
841 :
842 : assert(
843 : this->isReferenceToStorage(I) &&
844 : "Insertion iterator is out of bounds.");
845 :
846 : // Grow if necessary.
847 : size_t Index = I - this->begin();
848 : std::remove_reference_t<ArgType>* EltPtr =
849 : this->reserveForParamAndGetAddress(Elt);
850 : I = this->begin() + Index;
851 :
852 : ::new ((void*)this->end()) T(::std::move(this->back()));
853 : // Push everything else over.
854 : std::move_backward(I, this->end() - 1, this->end());
855 : this->set_size(this->size() + 1);
856 :
857 : // If we just moved the element we're inserting, be sure to update
858 : // the reference (never happens if TakesParamByValue).
859 : static_assert(
860 : !TakesParamByValue || std::is_same<ArgType, T>::value,
861 : "ArgType must be 'T' when taking by value!");
862 : if (!TakesParamByValue && this->isReferenceToRange(EltPtr, I, this->end()))
863 : ++EltPtr;
864 :
865 : *I = ::std::forward<ArgType>(*EltPtr);
866 : return I;
867 : }
868 :
869 : public:
870 : iterator insert(iterator I, T&& Elt) {
871 : return insert_one_impl(I, this->forward_value_param(std::move(Elt)));
872 : }
873 :
874 : iterator insert(iterator I, const T& Elt) {
875 : return insert_one_impl(I, this->forward_value_param(Elt));
876 : }
877 :
878 : iterator insert(iterator I, size_type NumToInsert, ValueParamT Elt) {
879 : // Convert iterator to elt# to avoid invalidating iterator when we reserve()
880 : size_t InsertElt = I - this->begin();
881 :
882 : if (I == this->end()) { // Important special case for empty vector.
883 : append(NumToInsert, Elt);
884 : return this->begin() + InsertElt;
885 : }
886 :
887 : assert(
888 : this->isReferenceToStorage(I) &&
889 : "Insertion iterator is out of bounds.");
890 :
891 : // Ensure there is enough space, and get the (maybe updated) address of
892 : // Elt.
893 : const T* EltPtr = this->reserveForParamAndGetAddress(Elt, NumToInsert);
894 :
895 : // Uninvalidate the iterator.
896 : I = this->begin() + InsertElt;
897 :
898 : // If there are more elements between the insertion point and the end of the
899 : // range than there are being inserted, we can use a simple approach to
900 : // insertion. Since we already reserved space, we know that this won't
901 : // reallocate the vector.
902 : if (size_t(this->end() - I) >= NumToInsert) {
903 : T* OldEnd = this->end();
904 : append(
905 : std::move_iterator<iterator>(this->end() - NumToInsert),
906 : std::move_iterator<iterator>(this->end()));
907 :
908 : // Copy the existing elements that get replaced.
909 : std::move_backward(I, OldEnd - NumToInsert, OldEnd);
910 :
911 : // If we just moved the element we're inserting, be sure to update
912 : // the reference (never happens if TakesParamByValue).
913 : if (!TakesParamByValue && I <= EltPtr && EltPtr < this->end())
914 : EltPtr += NumToInsert;
915 :
916 : std::fill_n(I, NumToInsert, *EltPtr);
917 : return I;
918 : }
919 :
920 : // Otherwise, we're inserting more elements than exist already, and we're
921 : // not inserting at the end.
922 :
923 : // Move over the elements that we're about to overwrite.
924 : T* OldEnd = this->end();
925 : this->set_size(this->size() + NumToInsert);
926 : size_t NumOverwritten = OldEnd - I;
927 : this->uninitialized_move(I, OldEnd, this->end() - NumOverwritten);
928 :
929 : // If we just moved the element we're inserting, be sure to update
930 : // the reference (never happens if TakesParamByValue).
931 : if (!TakesParamByValue && I <= EltPtr && EltPtr < this->end())
932 : EltPtr += NumToInsert;
933 :
934 : // Replace the overwritten part.
935 : std::fill_n(I, NumOverwritten, *EltPtr);
936 :
937 : // Insert the non-overwritten middle part.
938 : std::uninitialized_fill_n(OldEnd, NumToInsert - NumOverwritten, *EltPtr);
939 : return I;
940 : }
941 :
942 : template <
943 : typename ItTy,
944 : typename = std::enable_if_t<std::is_convertible<
945 : typename std::iterator_traits<ItTy>::iterator_category,
946 : std::input_iterator_tag>::value>>
947 : iterator insert(iterator I, ItTy From, ItTy To) {
948 : // Convert iterator to elt# to avoid invalidating iterator when we reserve()
949 : size_t InsertElt = I - this->begin();
950 :
951 : if (I == this->end()) { // Important special case for empty vector.
952 : append(From, To);
953 : return this->begin() + InsertElt;
954 : }
955 :
956 : assert(
957 : this->isReferenceToStorage(I) &&
958 : "Insertion iterator is out of bounds.");
959 :
960 : // Check that the reserve that follows doesn't invalidate the iterators.
961 : this->assertSafeToAddRange(From, To);
962 :
963 : size_t NumToInsert = std::distance(From, To);
964 :
965 : // Ensure there is enough space.
966 : reserve(this->size() + NumToInsert);
967 :
968 : // Uninvalidate the iterator.
969 : I = this->begin() + InsertElt;
970 :
971 : // If there are more elements between the insertion point and the end of the
972 : // range than there are being inserted, we can use a simple approach to
973 : // insertion. Since we already reserved space, we know that this won't
974 : // reallocate the vector.
975 : if (size_t(this->end() - I) >= NumToInsert) {
976 : T* OldEnd = this->end();
977 : append(
978 : std::move_iterator<iterator>(this->end() - NumToInsert),
979 : std::move_iterator<iterator>(this->end()));
980 :
981 : // Copy the existing elements that get replaced.
982 : std::move_backward(I, OldEnd - NumToInsert, OldEnd);
983 :
984 : std::copy(From, To, I);
985 : return I;
986 : }
987 :
988 : // Otherwise, we're inserting more elements than exist already, and we're
989 : // not inserting at the end.
990 :
991 : // Move over the elements that we're about to overwrite.
992 : T* OldEnd = this->end();
993 : this->set_size(this->size() + NumToInsert);
994 : size_t NumOverwritten = OldEnd - I;
995 : this->uninitialized_move(I, OldEnd, this->end() - NumOverwritten);
996 :
997 : // Replace the overwritten part.
998 : for (T* J = I; NumOverwritten > 0; --NumOverwritten) {
999 : *J = *From;
1000 : ++J;
1001 : ++From;
1002 : }
1003 :
1004 : // Insert the non-overwritten middle part.
1005 : this->uninitialized_copy(From, To, OldEnd);
1006 : return I;
1007 : }
1008 :
1009 : void insert(iterator I, std::initializer_list<T> IL) {
1010 : insert(I, IL.begin(), IL.end());
1011 : }
1012 :
1013 : template <typename... ArgTypes>
1014 : reference emplace_back(ArgTypes&&... Args) {
1015 : if (C10_UNLIKELY(this->size() >= this->capacity()))
1016 : return this->growAndEmplaceBack(std::forward<ArgTypes>(Args)...);
1017 :
1018 : ::new ((void*)this->end()) T(std::forward<ArgTypes>(Args)...);
1019 : this->set_size(this->size() + 1);
1020 : return this->back();
1021 : }
1022 :
1023 : SmallVectorImpl& operator=(const SmallVectorImpl& RHS);
1024 :
1025 : SmallVectorImpl& operator=(SmallVectorImpl&& RHS);
1026 :
1027 : bool operator==(const SmallVectorImpl& RHS) const {
1028 : if (this->size() != RHS.size())
1029 : return false;
1030 : return std::equal(this->begin(), this->end(), RHS.begin());
1031 : }
1032 : bool operator!=(const SmallVectorImpl& RHS) const {
1033 : return !(*this == RHS);
1034 : }
1035 :
1036 : bool operator<(const SmallVectorImpl& RHS) const {
1037 : return std::lexicographical_compare(
1038 : this->begin(), this->end(), RHS.begin(), RHS.end());
1039 : }
1040 : };
1041 :
1042 : template <typename T>
1043 : void SmallVectorImpl<T>::swap(SmallVectorImpl<T>& RHS) {
1044 : if (this == &RHS)
1045 : return;
1046 :
1047 : // We can only avoid copying elements if neither vector is small.
1048 : if (!this->isSmall() && !RHS.isSmall()) {
1049 : std::swap(this->BeginX, RHS.BeginX);
1050 : std::swap(this->Size, RHS.Size);
1051 : std::swap(this->Capacity, RHS.Capacity);
1052 : return;
1053 : }
1054 : this->reserve(RHS.size());
1055 : RHS.reserve(this->size());
1056 :
1057 : // Swap the shared elements.
1058 : size_t NumShared = this->size();
1059 : if (NumShared > RHS.size())
1060 : NumShared = RHS.size();
1061 : for (size_type i = 0; i != NumShared; ++i)
1062 : std::swap((*this)[i], RHS[i]);
1063 :
1064 : // Copy over the extra elts.
1065 : if (this->size() > RHS.size()) {
1066 : size_t EltDiff = this->size() - RHS.size();
1067 : this->uninitialized_copy(this->begin() + NumShared, this->end(), RHS.end());
1068 : RHS.set_size(RHS.size() + EltDiff);
1069 : this->destroy_range(this->begin() + NumShared, this->end());
1070 : this->set_size(NumShared);
1071 : } else if (RHS.size() > this->size()) {
1072 : size_t EltDiff = RHS.size() - this->size();
1073 : this->uninitialized_copy(RHS.begin() + NumShared, RHS.end(), this->end());
1074 : this->set_size(this->size() + EltDiff);
1075 : this->destroy_range(RHS.begin() + NumShared, RHS.end());
1076 : RHS.set_size(NumShared);
1077 : }
1078 : }
1079 :
1080 : template <typename T>
1081 : SmallVectorImpl<T>& SmallVectorImpl<T>::operator=(
1082 : const SmallVectorImpl<T>& RHS) {
1083 : // Avoid self-assignment.
1084 : if (this == &RHS)
1085 : return *this;
1086 :
1087 : // If we already have sufficient space, assign the common elements, then
1088 : // destroy any excess.
1089 : size_t RHSSize = RHS.size();
1090 : size_t CurSize = this->size();
1091 : if (CurSize >= RHSSize) {
1092 : // Assign common elements.
1093 : iterator NewEnd;
1094 : if (RHSSize)
1095 : NewEnd = std::copy(RHS.begin(), RHS.begin() + RHSSize, this->begin());
1096 : else
1097 : NewEnd = this->begin();
1098 :
1099 : // Destroy excess elements.
1100 : this->destroy_range(NewEnd, this->end());
1101 :
1102 : // Trim.
1103 : this->set_size(RHSSize);
1104 : return *this;
1105 : }
1106 :
1107 : // If we have to grow to have enough elements, destroy the current elements.
1108 : // This allows us to avoid copying them during the grow.
1109 : // FIXME: don't do this if they're efficiently moveable.
1110 : if (this->capacity() < RHSSize) {
1111 : // Destroy current elements.
1112 : this->clear();
1113 : CurSize = 0;
1114 : this->grow(RHSSize);
1115 : } else if (CurSize) {
1116 : // Otherwise, use assignment for the already-constructed elements.
1117 : std::copy(RHS.begin(), RHS.begin() + CurSize, this->begin());
1118 : }
1119 :
1120 : // Copy construct the new elements in place.
1121 : this->uninitialized_copy(
1122 : RHS.begin() + CurSize, RHS.end(), this->begin() + CurSize);
1123 :
1124 : // Set end.
1125 : this->set_size(RHSSize);
1126 : return *this;
1127 : }
1128 :
1129 : template <typename T>
1130 : SmallVectorImpl<T>& SmallVectorImpl<T>::operator=(SmallVectorImpl<T>&& RHS) {
1131 : // Avoid self-assignment.
1132 : if (this == &RHS)
1133 : return *this;
1134 :
1135 : // If the RHS isn't small, clear this vector and then steal its buffer.
1136 : if (!RHS.isSmall()) {
1137 : this->destroy_range(this->begin(), this->end());
1138 : if (!this->isSmall())
1139 : free(this->begin());
1140 : this->BeginX = RHS.BeginX;
1141 : this->Size = RHS.Size;
1142 : this->Capacity = RHS.Capacity;
1143 : RHS.resetToSmall();
1144 : return *this;
1145 : }
1146 :
1147 : // If we already have sufficient space, assign the common elements, then
1148 : // destroy any excess.
1149 : size_t RHSSize = RHS.size();
1150 : size_t CurSize = this->size();
1151 : if (CurSize >= RHSSize) {
1152 : // Assign common elements.
1153 : iterator NewEnd = this->begin();
1154 : if (RHSSize)
1155 : NewEnd = std::move(RHS.begin(), RHS.end(), NewEnd);
1156 :
1157 : // Destroy excess elements and trim the bounds.
1158 : this->destroy_range(NewEnd, this->end());
1159 : this->set_size(RHSSize);
1160 :
1161 : // Clear the RHS.
1162 : RHS.clear();
1163 :
1164 : return *this;
1165 : }
1166 :
1167 : // If we have to grow to have enough elements, destroy the current elements.
1168 : // This allows us to avoid copying them during the grow.
1169 : // FIXME: this may not actually make any sense if we can efficiently move
1170 : // elements.
1171 : if (this->capacity() < RHSSize) {
1172 : // Destroy current elements.
1173 : this->clear();
1174 : CurSize = 0;
1175 : this->grow(RHSSize);
1176 : } else if (CurSize) {
1177 : // Otherwise, use assignment for the already-constructed elements.
1178 : std::move(RHS.begin(), RHS.begin() + CurSize, this->begin());
1179 : }
1180 :
1181 : // Move-construct the new elements in place.
1182 : this->uninitialized_move(
1183 : RHS.begin() + CurSize, RHS.end(), this->begin() + CurSize);
1184 :
1185 : // Set end.
1186 : this->set_size(RHSSize);
1187 :
1188 : RHS.clear();
1189 : return *this;
1190 : }
1191 :
1192 : /// Storage for the SmallVector elements. This is specialized for the N=0 case
1193 : /// to avoid allocating unnecessary storage.
1194 : template <typename T, unsigned N>
1195 : struct SmallVectorStorage {
1196 : alignas(T) char InlineElts[N * sizeof(T)];
1197 : };
1198 :
1199 : /// We need the storage to be properly aligned even for small-size of 0 so that
1200 : /// the pointer math in \a SmallVectorTemplateCommon::getFirstEl() is
1201 : /// well-defined.
1202 : template <typename T>
1203 : struct alignas(T) SmallVectorStorage<T, 0> {};
1204 :
1205 : /// Forward declaration of SmallVector so that
1206 : /// calculateSmallVectorDefaultInlinedElements can reference
1207 : /// `sizeof(SmallVector<T, 0>)`.
1208 : template <typename T, unsigned N>
1209 : class /* LLVM_GSL_OWNER */ SmallVector;
1210 :
1211 : /// Helper class for calculating the default number of inline elements for
1212 : /// `SmallVector<T>`.
1213 : ///
1214 : /// This should be migrated to a constexpr function when our minimum
1215 : /// compiler support is enough for multi-statement constexpr functions.
1216 : template <typename T>
1217 : struct CalculateSmallVectorDefaultInlinedElements {
1218 : // Parameter controlling the default number of inlined elements
1219 : // for `SmallVector<T>`.
1220 : //
1221 : // The default number of inlined elements ensures that
1222 : // 1. There is at least one inlined element.
1223 : // 2. `sizeof(SmallVector<T>) <= kPreferredSmallVectorSizeof` unless
1224 : // it contradicts 1.
1225 : static constexpr size_t kPreferredSmallVectorSizeof = 64;
1226 :
1227 : // static_assert that sizeof(T) is not "too big".
1228 : //
1229 : // Because our policy guarantees at least one inlined element, it is possible
1230 : // for an arbitrarily large inlined element to allocate an arbitrarily large
1231 : // amount of inline storage. We generally consider it an antipattern for a
1232 : // SmallVector to allocate an excessive amount of inline storage, so we want
1233 : // to call attention to these cases and make sure that users are making an
1234 : // intentional decision if they request a lot of inline storage.
1235 : //
1236 : // We want this assertion to trigger in pathological cases, but otherwise
1237 : // not be too easy to hit. To accomplish that, the cutoff is actually somewhat
1238 : // larger than kPreferredSmallVectorSizeof (otherwise,
1239 : // `SmallVector<SmallVector<T>>` would be one easy way to trip it, and that
1240 : // pattern seems useful in practice).
1241 : //
1242 : // One wrinkle is that this assertion is in theory non-portable, since
1243 : // sizeof(T) is in general platform-dependent. However, we don't expect this
1244 : // to be much of an issue, because most LLVM development happens on 64-bit
1245 : // hosts, and therefore sizeof(T) is expected to *decrease* when compiled for
1246 : // 32-bit hosts, dodging the issue. The reverse situation, where development
1247 : // happens on a 32-bit host and then fails due to sizeof(T) *increasing* on a
1248 : // 64-bit host, is expected to be very rare.
1249 : static_assert(
1250 : sizeof(T) <= 256,
1251 : "You are trying to use a default number of inlined elements for "
1252 : "`SmallVector<T>` but `sizeof(T)` is really big! Please use an "
1253 : "explicit number of inlined elements with `SmallVector<T, N>` to make "
1254 : "sure you really want that much inline storage.");
1255 :
1256 : // Discount the size of the header itself when calculating the maximum inline
1257 : // bytes.
1258 : static constexpr size_t PreferredInlineBytes =
1259 : kPreferredSmallVectorSizeof - sizeof(SmallVector<T, 0>);
1260 : static constexpr size_t NumElementsThatFit = PreferredInlineBytes / sizeof(T);
1261 : static constexpr size_t value =
1262 : NumElementsThatFit == 0 ? 1 : NumElementsThatFit;
1263 : };
1264 :
1265 : /// This is a 'vector' (really, a variable-sized array), optimized
1266 : /// for the case when the array is small. It contains some number of elements
1267 : /// in-place, which allows it to avoid heap allocation when the actual number of
1268 : /// elements is below that threshold. This allows normal "small" cases to be
1269 : /// fast without losing generality for large inputs.
1270 : ///
1271 : /// \note
1272 : /// In the absence of a well-motivated choice for the number of inlined
1273 : /// elements \p N, it is recommended to use \c SmallVector<T> (that is,
1274 : /// omitting the \p N). This will choose a default number of inlined elements
1275 : /// reasonable for allocation on the stack (for example, trying to keep \c
1276 : /// sizeof(SmallVector<T>) around 64 bytes).
1277 : ///
1278 : /// \warning This does not attempt to be exception safe.
1279 : ///
1280 : /// \see https://llvm.org/docs/ProgrammersManual.html#llvm-adt-smallvector-h
1281 : template <
1282 : typename T,
1283 : unsigned N = CalculateSmallVectorDefaultInlinedElements<T>::value>
1284 : class /* LLVM_GSL_OWNER */ SmallVector : public SmallVectorImpl<T>,
1285 : SmallVectorStorage<T, N> {
1286 : public:
1287 0 : SmallVector() : SmallVectorImpl<T>(N) {}
1288 :
1289 0 : ~SmallVector() {
1290 : // Destroy the constructed elements in the vector.
1291 0 : this->destroy_range(this->begin(), this->end());
1292 0 : }
1293 :
1294 : explicit SmallVector(size_t Size, const T& Value = T())
1295 : : SmallVectorImpl<T>(N) {
1296 : this->assign(Size, Value);
1297 : }
1298 :
1299 : template <
1300 : typename ItTy,
1301 : typename = std::enable_if_t<std::is_convertible<
1302 : typename std::iterator_traits<ItTy>::iterator_category,
1303 : std::input_iterator_tag>::value>>
1304 : SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(N) {
1305 : this->append(S, E);
1306 : }
1307 :
1308 : // note: The enable_if restricts Container to types that have a .begin() and
1309 : // .end() that return valid input iterators.
1310 : template <
1311 : typename Container,
1312 : std::enable_if_t<
1313 : std::is_convertible<
1314 : typename std::iterator_traits<
1315 : decltype(std::declval<Container>()
1316 : .begin())>::iterator_category,
1317 : std::input_iterator_tag>::value &&
1318 : std::is_convertible<
1319 : typename std::iterator_traits<
1320 : decltype(std::declval<Container>()
1321 : .end())>::iterator_category,
1322 : std::input_iterator_tag>::value,
1323 : int> = 0>
1324 : explicit SmallVector(Container&& c) : SmallVectorImpl<T>(N) {
1325 : this->append(c.begin(), c.end());
1326 : }
1327 :
1328 : SmallVector(std::initializer_list<T> IL) : SmallVectorImpl<T>(N) {
1329 : this->assign(IL);
1330 : }
1331 :
1332 : SmallVector(const SmallVector& RHS) : SmallVectorImpl<T>(N) {
1333 : if (!RHS.empty())
1334 : SmallVectorImpl<T>::operator=(RHS);
1335 : }
1336 :
1337 : SmallVector& operator=(const SmallVector& RHS) {
1338 : SmallVectorImpl<T>::operator=(RHS);
1339 : return *this;
1340 : }
1341 :
1342 : SmallVector(SmallVector&& RHS) : SmallVectorImpl<T>(N) {
1343 : if (!RHS.empty())
1344 : SmallVectorImpl<T>::operator=(::std::move(RHS));
1345 : }
1346 :
1347 : // note: The enable_if restricts Container to types that have a .begin() and
1348 : // .end() that return valid input iterators.
1349 : template <
1350 : typename Container,
1351 : std::enable_if_t<
1352 : std::is_convertible<
1353 : typename std::iterator_traits<
1354 : decltype(std::declval<Container>()
1355 : .begin())>::iterator_category,
1356 : std::input_iterator_tag>::value &&
1357 : std::is_convertible<
1358 : typename std::iterator_traits<
1359 : decltype(std::declval<Container>()
1360 : .end())>::iterator_category,
1361 : std::input_iterator_tag>::value,
1362 : int> = 0>
1363 : const SmallVector& operator=(const Container& RHS) {
1364 : this->assign(RHS.begin(), RHS.end());
1365 : return *this;
1366 : }
1367 :
1368 : SmallVector(SmallVectorImpl<T>&& RHS) : SmallVectorImpl<T>(N) {
1369 : if (!RHS.empty())
1370 : SmallVectorImpl<T>::operator=(::std::move(RHS));
1371 : }
1372 :
1373 : SmallVector& operator=(SmallVector&& RHS) {
1374 : SmallVectorImpl<T>::operator=(::std::move(RHS));
1375 : return *this;
1376 : }
1377 :
1378 : SmallVector& operator=(SmallVectorImpl<T>&& RHS) {
1379 : SmallVectorImpl<T>::operator=(::std::move(RHS));
1380 : return *this;
1381 : }
1382 :
1383 : // note: The enable_if restricts Container to types that have a .begin() and
1384 : // .end() that return valid input iterators.
1385 : template <
1386 : typename Container,
1387 : std::enable_if_t<
1388 : std::is_convertible<
1389 : typename std::iterator_traits<
1390 : decltype(std::declval<Container>()
1391 : .begin())>::iterator_category,
1392 : std::input_iterator_tag>::value &&
1393 : std::is_convertible<
1394 : typename std::iterator_traits<
1395 : decltype(std::declval<Container>()
1396 : .end())>::iterator_category,
1397 : std::input_iterator_tag>::value,
1398 : int> = 0>
1399 : const SmallVector& operator=(Container&& C) {
1400 : this->assign(C.begin(), C.end());
1401 : return *this;
1402 : }
1403 :
1404 : SmallVector& operator=(std::initializer_list<T> IL) {
1405 : this->assign(IL);
1406 : return *this;
1407 : }
1408 : };
1409 :
1410 : template <typename T, unsigned N>
1411 : inline size_t capacity_in_bytes(const SmallVector<T, N>& X) {
1412 : return X.capacity_in_bytes();
1413 : }
1414 :
1415 : template <typename T, unsigned N>
1416 : std::ostream& operator<<(std::ostream& out, const SmallVector<T, N>& list) {
1417 : int i = 0;
1418 : out << "[";
1419 : for (auto e : list) {
1420 : if (i++ > 0)
1421 : out << ", ";
1422 : out << e;
1423 : }
1424 : out << "]";
1425 : return out;
1426 : }
1427 :
1428 : template <typename RangeType>
1429 : using ValueTypeFromRangeType =
1430 : typename std::remove_const<typename std::remove_reference<
1431 : decltype(*std::begin(std::declval<RangeType&>()))>::type>::type;
1432 :
1433 : /// Given a range of type R, iterate the entire range and return a
1434 : /// SmallVector with elements of the vector. This is useful, for example,
1435 : /// when you want to iterate a range and then sort the results.
1436 : template <unsigned Size, typename R>
1437 : SmallVector<ValueTypeFromRangeType<R>, Size> to_vector(R&& Range) {
1438 : return {std::begin(Range), std::end(Range)};
1439 : }
1440 : template <typename R>
1441 : SmallVector<
1442 : ValueTypeFromRangeType<R>,
1443 : CalculateSmallVectorDefaultInlinedElements<
1444 : ValueTypeFromRangeType<R>>::value>
1445 : to_vector(R&& Range) {
1446 : return {std::begin(Range), std::end(Range)};
1447 : }
1448 :
1449 : } // end namespace c10
1450 :
1451 : namespace std {
1452 :
1453 : /// Implement std::swap in terms of SmallVector swap.
1454 : template <typename T>
1455 : inline void swap(c10::SmallVectorImpl<T>& LHS, c10::SmallVectorImpl<T>& RHS) {
1456 : LHS.swap(RHS);
1457 : }
1458 :
1459 : /// Implement std::swap in terms of SmallVector swap.
1460 : template <typename T, unsigned N>
1461 : inline void swap(c10::SmallVector<T, N>& LHS, c10::SmallVector<T, N>& RHS) {
1462 : LHS.swap(RHS);
1463 : }
1464 :
1465 : } // end namespace std
1466 :
1467 : C10_CLANG_DIAGNOSTIC_POP()
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