Warning: That file was not part of the compilation database. It may have many parsing errors.

1//===- Allocator.h - Simple memory allocation abstraction -------*- C++ -*-===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9/// \file
10///
11/// This file defines the MallocAllocator and BumpPtrAllocator interfaces. Both
12/// of these conform to an LLVM "Allocator" concept which consists of an
13/// Allocate method accepting a size and alignment, and a Deallocate accepting
14/// a pointer and size. Further, the LLVM "Allocator" concept has overloads of
15/// Allocate and Deallocate for setting size and alignment based on the final
16/// type. These overloads are typically provided by a base class template \c
17/// AllocatorBase.
18///
19//===----------------------------------------------------------------------===//
20
21#ifndef LLVM_SUPPORT_ALLOCATOR_H
22#define LLVM_SUPPORT_ALLOCATOR_H
23
24#include "llvm/ADT/SmallVector.h"
25#include "llvm/Support/Compiler.h"
26#include "llvm/Support/ErrorHandling.h"
27#include "llvm/Support/MathExtras.h"
28#include "llvm/Support/MemAlloc.h"
29#include <algorithm>
30#include <cassert>
31#include <cstddef>
32#include <cstdint>
33#include <cstdlib>
34#include <iterator>
35#include <type_traits>
36#include <utility>
37
38namespace llvm {
39
40/// CRTP base class providing obvious overloads for the core \c
41/// Allocate() methods of LLVM-style allocators.
42///
43/// This base class both documents the full public interface exposed by all
44/// LLVM-style allocators, and redirects all of the overloads to a single core
45/// set of methods which the derived class must define.
46template <typename DerivedT> class AllocatorBase {
47public:
48 /// Allocate \a Size bytes of \a Alignment aligned memory. This method
49 /// must be implemented by \c DerivedT.
50 void *Allocate(size_t Size, size_t Alignment) {
51#ifdef __clang__
52 static_assert(static_cast<void *(AllocatorBase::*)(size_t, size_t)>(
53 &AllocatorBase::Allocate) !=
54 static_cast<void *(DerivedT::*)(size_t, size_t)>(
55 &DerivedT::Allocate),
56 "Class derives from AllocatorBase without implementing the "
57 "core Allocate(size_t, size_t) overload!");
58#endif
59 return static_cast<DerivedT *>(this)->Allocate(Size, Alignment);
60 }
61
62 /// Deallocate \a Ptr to \a Size bytes of memory allocated by this
63 /// allocator.
64 void Deallocate(const void *Ptr, size_t Size) {
65#ifdef __clang__
66 static_assert(static_cast<void (AllocatorBase::*)(const void *, size_t)>(
67 &AllocatorBase::Deallocate) !=
68 static_cast<void (DerivedT::*)(const void *, size_t)>(
69 &DerivedT::Deallocate),
70 "Class derives from AllocatorBase without implementing the "
71 "core Deallocate(void *) overload!");
72#endif
73 return static_cast<DerivedT *>(this)->Deallocate(Ptr, Size);
74 }
75
76 // The rest of these methods are helpers that redirect to one of the above
77 // core methods.
78
79 /// Allocate space for a sequence of objects without constructing them.
80 template <typename T> T *Allocate(size_t Num = 1) {
81 return static_cast<T *>(Allocate(Num * sizeof(T), alignof(T)));
82 }
83
84 /// Deallocate space for a sequence of objects without constructing them.
85 template <typename T>
86 typename std::enable_if<
87 !std::is_same<typename std::remove_cv<T>::type, void>::value, void>::type
88 Deallocate(T *Ptr, size_t Num = 1) {
89 Deallocate(static_cast<const void *>(Ptr), Num * sizeof(T));
90 }
91};
92
93class MallocAllocator : public AllocatorBase<MallocAllocator> {
94public:
95 void Reset() {}
96
97 LLVM_ATTRIBUTE_RETURNS_NONNULL void *Allocate(size_t Size,
98 size_t /*Alignment*/) {
99 return safe_malloc(Size);
100 }
101
102 // Pull in base class overloads.
103 using AllocatorBase<MallocAllocator>::Allocate;
104
105 void Deallocate(const void *Ptr, size_t /*Size*/) {
106 free(const_cast<void *>(Ptr));
107 }
108
109 // Pull in base class overloads.
110 using AllocatorBase<MallocAllocator>::Deallocate;
111
112 void PrintStats() const {}
113};
114
115namespace detail {
116
117// We call out to an external function to actually print the message as the
118// printing code uses Allocator.h in its implementation.
119void printBumpPtrAllocatorStats(unsigned NumSlabs, size_t BytesAllocated,
120 size_t TotalMemory);
121
122} // end namespace detail
123
124/// Allocate memory in an ever growing pool, as if by bump-pointer.
125///
126/// This isn't strictly a bump-pointer allocator as it uses backing slabs of
127/// memory rather than relying on a boundless contiguous heap. However, it has
128/// bump-pointer semantics in that it is a monotonically growing pool of memory
129/// where every allocation is found by merely allocating the next N bytes in
130/// the slab, or the next N bytes in the next slab.
131///
132/// Note that this also has a threshold for forcing allocations above a certain
133/// size into their own slab.
134///
135/// The BumpPtrAllocatorImpl template defaults to using a MallocAllocator
136/// object, which wraps malloc, to allocate memory, but it can be changed to
137/// use a custom allocator.
138template <typename AllocatorT = MallocAllocator, size_t SlabSize = 4096,
139 size_t SizeThreshold = SlabSize>
140class BumpPtrAllocatorImpl
141 : public AllocatorBase<
142 BumpPtrAllocatorImpl<AllocatorT, SlabSize, SizeThreshold>> {
143public:
144 static_assert(SizeThreshold <= SlabSize,
145 "The SizeThreshold must be at most the SlabSize to ensure "
146 "that objects larger than a slab go into their own memory "
147 "allocation.");
148
149 BumpPtrAllocatorImpl() = default;
150
151 template <typename T>
152 BumpPtrAllocatorImpl(T &&Allocator)
153 : Allocator(std::forward<T &&>(Allocator)) {}
154
155 // Manually implement a move constructor as we must clear the old allocator's
156 // slabs as a matter of correctness.
157 BumpPtrAllocatorImpl(BumpPtrAllocatorImpl &&Old)
158 : CurPtr(Old.CurPtr), End(Old.End), Slabs(std::move(Old.Slabs)),
159 CustomSizedSlabs(std::move(Old.CustomSizedSlabs)),
160 BytesAllocated(Old.BytesAllocated), RedZoneSize(Old.RedZoneSize),
161 Allocator(std::move(Old.Allocator)) {
162 Old.CurPtr = Old.End = nullptr;
163 Old.BytesAllocated = 0;
164 Old.Slabs.clear();
165 Old.CustomSizedSlabs.clear();
166 }
167
168 ~BumpPtrAllocatorImpl() {
169 DeallocateSlabs(Slabs.begin(), Slabs.end());
170 DeallocateCustomSizedSlabs();
171 }
172
173 BumpPtrAllocatorImpl &operator=(BumpPtrAllocatorImpl &&RHS) {
174 DeallocateSlabs(Slabs.begin(), Slabs.end());
175 DeallocateCustomSizedSlabs();
176
177 CurPtr = RHS.CurPtr;
178 End = RHS.End;
179 BytesAllocated = RHS.BytesAllocated;
180 RedZoneSize = RHS.RedZoneSize;
181 Slabs = std::move(RHS.Slabs);
182 CustomSizedSlabs = std::move(RHS.CustomSizedSlabs);
183 Allocator = std::move(RHS.Allocator);
184
185 RHS.CurPtr = RHS.End = nullptr;
186 RHS.BytesAllocated = 0;
187 RHS.Slabs.clear();
188 RHS.CustomSizedSlabs.clear();
189 return *this;
190 }
191
192 /// Deallocate all but the current slab and reset the current pointer
193 /// to the beginning of it, freeing all memory allocated so far.
194 void Reset() {
195 // Deallocate all but the first slab, and deallocate all custom-sized slabs.
196 DeallocateCustomSizedSlabs();
197 CustomSizedSlabs.clear();
198
199 if (Slabs.empty())
200 return;
201
202 // Reset the state.
203 BytesAllocated = 0;
204 CurPtr = (char *)Slabs.front();
205 End = CurPtr + SlabSize;
206
207 __asan_poison_memory_region(*Slabs.begin(), computeSlabSize(0));
208 DeallocateSlabs(std::next(Slabs.begin()), Slabs.end());
209 Slabs.erase(std::next(Slabs.begin()), Slabs.end());
210 }
211
212 /// Allocate space at the specified alignment.
213 LLVM_ATTRIBUTE_RETURNS_NONNULL LLVM_ATTRIBUTE_RETURNS_NOALIAS void *
214 Allocate(size_t Size, size_t Alignment) {
215 assert(Alignment > 0 && "0-byte alignnment is not allowed. Use 1 instead.");
216
217 // Keep track of how many bytes we've allocated.
218 BytesAllocated += Size;
219
220 size_t Adjustment = alignmentAdjustment(CurPtr, Alignment);
221 assert(Adjustment + Size >= Size && "Adjustment + Size must not overflow");
222
223 size_t SizeToAllocate = Size;
224#if LLVM_ADDRESS_SANITIZER_BUILD
225 // Add trailing bytes as a "red zone" under ASan.
226 SizeToAllocate += RedZoneSize;
227#endif
228
229 // Check if we have enough space.
230 if (Adjustment + SizeToAllocate <= size_t(End - CurPtr)) {
231 char *AlignedPtr = CurPtr + Adjustment;
232 CurPtr = AlignedPtr + SizeToAllocate;
233 // Update the allocation point of this memory block in MemorySanitizer.
234 // Without this, MemorySanitizer messages for values originated from here
235 // will point to the allocation of the entire slab.
236 __msan_allocated_memory(AlignedPtr, Size);
237 // Similarly, tell ASan about this space.
238 __asan_unpoison_memory_region(AlignedPtr, Size);
239 return AlignedPtr;
240 }
241
242 // If Size is really big, allocate a separate slab for it.
243 size_t PaddedSize = SizeToAllocate + Alignment - 1;
244 if (PaddedSize > SizeThreshold) {
245 void *NewSlab = Allocator.Allocate(PaddedSize, 0);
246 // We own the new slab and don't want anyone reading anyting other than
247 // pieces returned from this method. So poison the whole slab.
248 __asan_poison_memory_region(NewSlab, PaddedSize);
249 CustomSizedSlabs.push_back(std::make_pair(NewSlab, PaddedSize));
250
251 uintptr_t AlignedAddr = alignAddr(NewSlab, Alignment);
252 assert(AlignedAddr + Size <= (uintptr_t)NewSlab + PaddedSize);
253 char *AlignedPtr = (char*)AlignedAddr;
254 __msan_allocated_memory(AlignedPtr, Size);
255 __asan_unpoison_memory_region(AlignedPtr, Size);
256 return AlignedPtr;
257 }
258
259 // Otherwise, start a new slab and try again.
260 StartNewSlab();
261 uintptr_t AlignedAddr = alignAddr(CurPtr, Alignment);
262 assert(AlignedAddr + SizeToAllocate <= (uintptr_t)End &&
263 "Unable to allocate memory!");
264 char *AlignedPtr = (char*)AlignedAddr;
265 CurPtr = AlignedPtr + SizeToAllocate;
266 __msan_allocated_memory(AlignedPtr, Size);
267 __asan_unpoison_memory_region(AlignedPtr, Size);
268 return AlignedPtr;
269 }
270
271 // Pull in base class overloads.
272 using AllocatorBase<BumpPtrAllocatorImpl>::Allocate;
273
274 // Bump pointer allocators are expected to never free their storage; and
275 // clients expect pointers to remain valid for non-dereferencing uses even
276 // after deallocation.
277 void Deallocate(const void *Ptr, size_t Size) {
278 __asan_poison_memory_region(Ptr, Size);
279 }
280
281 // Pull in base class overloads.
282 using AllocatorBase<BumpPtrAllocatorImpl>::Deallocate;
283
284 size_t GetNumSlabs() const { return Slabs.size() + CustomSizedSlabs.size(); }
285
286 size_t getTotalMemory() const {
287 size_t TotalMemory = 0;
288 for (auto I = Slabs.begin(), E = Slabs.end(); I != E; ++I)
289 TotalMemory += computeSlabSize(std::distance(Slabs.begin(), I));
290 for (auto &PtrAndSize : CustomSizedSlabs)
291 TotalMemory += PtrAndSize.second;
292 return TotalMemory;
293 }
294
295 size_t getBytesAllocated() const { return BytesAllocated; }
296
297 void setRedZoneSize(size_t NewSize) {
298 RedZoneSize = NewSize;
299 }
300
301 void PrintStats() const {
302 detail::printBumpPtrAllocatorStats(Slabs.size(), BytesAllocated,
303 getTotalMemory());
304 }
305
306private:
307 /// The current pointer into the current slab.
308 ///
309 /// This points to the next free byte in the slab.
310 char *CurPtr = nullptr;
311
312 /// The end of the current slab.
313 char *End = nullptr;
314
315 /// The slabs allocated so far.
316 SmallVector<void *, 4> Slabs;
317
318 /// Custom-sized slabs allocated for too-large allocation requests.
319 SmallVector<std::pair<void *, size_t>, 0> CustomSizedSlabs;
320
321 /// How many bytes we've allocated.
322 ///
323 /// Used so that we can compute how much space was wasted.
324 size_t BytesAllocated = 0;
325
326 /// The number of bytes to put between allocations when running under
327 /// a sanitizer.
328 size_t RedZoneSize = 1;
329
330 /// The allocator instance we use to get slabs of memory.
331 AllocatorT Allocator;
332
333 static size_t computeSlabSize(unsigned SlabIdx) {
334 // Scale the actual allocated slab size based on the number of slabs
335 // allocated. Every 128 slabs allocated, we double the allocated size to
336 // reduce allocation frequency, but saturate at multiplying the slab size by
337 // 2^30.
338 return SlabSize * ((size_t)1 << std::min<size_t>(30, SlabIdx / 128));
339 }
340
341 /// Allocate a new slab and move the bump pointers over into the new
342 /// slab, modifying CurPtr and End.
343 void StartNewSlab() {
344 size_t AllocatedSlabSize = computeSlabSize(Slabs.size());
345
346 void *NewSlab = Allocator.Allocate(AllocatedSlabSize, 0);
347 // We own the new slab and don't want anyone reading anything other than
348 // pieces returned from this method. So poison the whole slab.
349 __asan_poison_memory_region(NewSlab, AllocatedSlabSize);
350
351 Slabs.push_back(NewSlab);
352 CurPtr = (char *)(NewSlab);
353 End = ((char *)NewSlab) + AllocatedSlabSize;
354 }
355
356 /// Deallocate a sequence of slabs.
357 void DeallocateSlabs(SmallVectorImpl<void *>::iterator I,
358 SmallVectorImpl<void *>::iterator E) {
359 for (; I != E; ++I) {
360 size_t AllocatedSlabSize =
361 computeSlabSize(std::distance(Slabs.begin(), I));
362 Allocator.Deallocate(*I, AllocatedSlabSize);
363 }
364 }
365
366 /// Deallocate all memory for custom sized slabs.
367 void DeallocateCustomSizedSlabs() {
368 for (auto &PtrAndSize : CustomSizedSlabs) {
369 void *Ptr = PtrAndSize.first;
370 size_t Size = PtrAndSize.second;
371 Allocator.Deallocate(Ptr, Size);
372 }
373 }
374
375 template <typename T> friend class SpecificBumpPtrAllocator;
376};
377
378/// The standard BumpPtrAllocator which just uses the default template
379/// parameters.
380typedef BumpPtrAllocatorImpl<> BumpPtrAllocator;
381
382/// A BumpPtrAllocator that allows only elements of a specific type to be
383/// allocated.
384///
385/// This allows calling the destructor in DestroyAll() and when the allocator is
386/// destroyed.
387template <typename T> class SpecificBumpPtrAllocator {
388 BumpPtrAllocator Allocator;
389
390public:
391 SpecificBumpPtrAllocator() {
392 // Because SpecificBumpPtrAllocator walks the memory to call destructors,
393 // it can't have red zones between allocations.
394 Allocator.setRedZoneSize(0);
395 }
396 SpecificBumpPtrAllocator(SpecificBumpPtrAllocator &&Old)
397 : Allocator(std::move(Old.Allocator)) {}
398 ~SpecificBumpPtrAllocator() { DestroyAll(); }
399
400 SpecificBumpPtrAllocator &operator=(SpecificBumpPtrAllocator &&RHS) {
401 Allocator = std::move(RHS.Allocator);
402 return *this;
403 }
404
405 /// Call the destructor of each allocated object and deallocate all but the
406 /// current slab and reset the current pointer to the beginning of it, freeing
407 /// all memory allocated so far.
408 void DestroyAll() {
409 auto DestroyElements = [](char *Begin, char *End) {
410 assert(Begin == (char *)alignAddr(Begin, alignof(T)));
411 for (char *Ptr = Begin; Ptr + sizeof(T) <= End; Ptr += sizeof(T))
412 reinterpret_cast<T *>(Ptr)->~T();
413 };
414
415 for (auto I = Allocator.Slabs.begin(), E = Allocator.Slabs.end(); I != E;
416 ++I) {
417 size_t AllocatedSlabSize = BumpPtrAllocator::computeSlabSize(
418 std::distance(Allocator.Slabs.begin(), I));
419 char *Begin = (char *)alignAddr(*I, alignof(T));
420 char *End = *I == Allocator.Slabs.back() ? Allocator.CurPtr
421 : (char *)*I + AllocatedSlabSize;
422
423 DestroyElements(Begin, End);
424 }
425
426 for (auto &PtrAndSize : Allocator.CustomSizedSlabs) {
427 void *Ptr = PtrAndSize.first;
428 size_t Size = PtrAndSize.second;
429 DestroyElements((char *)alignAddr(Ptr, alignof(T)), (char *)Ptr + Size);
430 }
431
432 Allocator.Reset();
433 }
434
435 /// Allocate space for an array of objects without constructing them.
436 T *Allocate(size_t num = 1) { return Allocator.Allocate<T>(num); }
437};
438
439} // end namespace llvm
440
441template <typename AllocatorT, size_t SlabSize, size_t SizeThreshold>
442void *operator new(size_t Size,
443 llvm::BumpPtrAllocatorImpl<AllocatorT, SlabSize,
444 SizeThreshold> &Allocator) {
445 struct S {
446 char c;
447 union {
448 double D;
449 long double LD;
450 long long L;
451 void *P;
452 } x;
453 };
454 return Allocator.Allocate(
455 Size, std::min((size_t)llvm::NextPowerOf2(Size), offsetof(S, x)));
456}
457
458template <typename AllocatorT, size_t SlabSize, size_t SizeThreshold>
459void operator delete(
460 void *, llvm::BumpPtrAllocatorImpl<AllocatorT, SlabSize, SizeThreshold> &) {
461}
462
463#endif // LLVM_SUPPORT_ALLOCATOR_H
464

Warning: That file was not part of the compilation database. It may have many parsing errors.