Grok 10.0.5
aligned_allocator.h
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1// Copyright 2020 Google LLC
2// SPDX-License-Identifier: Apache-2.0
3//
4// Licensed under the Apache License, Version 2.0 (the "License");
5// you may not use this file except in compliance with the License.
6// You may obtain a copy of the License at
7//
8// http://www.apache.org/licenses/LICENSE-2.0
9//
10// Unless required by applicable law or agreed to in writing, software
11// distributed under the License is distributed on an "AS IS" BASIS,
12// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13// See the License for the specific language governing permissions and
14// limitations under the License.
15
16#ifndef HIGHWAY_HWY_ALIGNED_ALLOCATOR_H_
17#define HIGHWAY_HWY_ALIGNED_ALLOCATOR_H_
18
19// Memory allocator with support for alignment and offsets.
20
21#include <stddef.h>
22
23#include <memory>
24
25#include "hwy/highway_export.h"
26
27namespace hwy {
28
29// Minimum alignment of allocated memory for use in HWY_ASSUME_ALIGNED, which
30// requires a literal. This matches typical L1 cache line sizes, which prevents
31// false sharing.
32#define HWY_ALIGNMENT 64
33
34// Pointers to functions equivalent to malloc/free with an opaque void* passed
35// to them.
36using AllocPtr = void* (*)(void* opaque, size_t bytes);
37using FreePtr = void (*)(void* opaque, void* memory);
38
39// Returns null or a pointer to at least `payload_size` (which can be zero)
40// bytes of newly allocated memory, aligned to the larger of HWY_ALIGNMENT and
41// the vector size. Calls `alloc` with the passed `opaque` pointer to obtain
42// memory or malloc() if it is null.
43HWY_DLLEXPORT void* AllocateAlignedBytes(size_t payload_size,
44 AllocPtr alloc_ptr, void* opaque_ptr);
45
46// Frees all memory. No effect if `aligned_pointer` == nullptr, otherwise it
47// must have been returned from a previous call to `AllocateAlignedBytes`.
48// Calls `free_ptr` with the passed `opaque_ptr` pointer to free the memory; if
49// `free_ptr` function is null, uses the default free().
50HWY_DLLEXPORT void FreeAlignedBytes(const void* aligned_pointer,
51 FreePtr free_ptr, void* opaque_ptr);
52
53// Class that deletes the aligned pointer passed to operator() calling the
54// destructor before freeing the pointer. This is equivalent to the
55// std::default_delete but for aligned objects. For a similar deleter equivalent
56// to free() for aligned memory see AlignedFreer().
58 public:
59 AlignedDeleter() : free_(nullptr), opaque_ptr_(nullptr) {}
60 AlignedDeleter(FreePtr free_ptr, void* opaque_ptr)
61 : free_(free_ptr), opaque_ptr_(opaque_ptr) {}
62
63 template <typename T>
64 void operator()(T* aligned_pointer) const {
65 return DeleteAlignedArray(aligned_pointer, free_, opaque_ptr_,
67 }
68
69 private:
70 template <typename T>
71 static void TypedArrayDeleter(void* ptr, size_t size_in_bytes) {
72 size_t elems = size_in_bytes / sizeof(T);
73 for (size_t i = 0; i < elems; i++) {
74 // Explicitly call the destructor on each element.
75 (static_cast<T*>(ptr) + i)->~T();
76 }
77 }
78
79 // Function prototype that calls the destructor for each element in a typed
80 // array. TypeArrayDeleter<T> would match this prototype.
81 using ArrayDeleter = void (*)(void* t_ptr, size_t t_size);
82
83 HWY_DLLEXPORT static void DeleteAlignedArray(void* aligned_pointer,
84 FreePtr free_ptr,
85 void* opaque_ptr,
86 ArrayDeleter deleter);
87
90};
91
92// Unique pointer to T with custom aligned deleter. This can be a single
93// element U or an array of element if T is a U[]. The custom aligned deleter
94// will call the destructor on U or each element of a U[] in the array case.
95template <typename T>
96using AlignedUniquePtr = std::unique_ptr<T, AlignedDeleter>;
97
98// Aligned memory equivalent of make_unique<T> using the custom allocators
99// alloc/free with the passed `opaque` pointer. This function calls the
100// constructor with the passed Args... and calls the destructor of the object
101// when the AlignedUniquePtr is destroyed.
102template <typename T, typename... Args>
104 void* opaque, Args&&... args) {
105 T* ptr = static_cast<T*>(AllocateAlignedBytes(sizeof(T), alloc, opaque));
106 return AlignedUniquePtr<T>(new (ptr) T(std::forward<Args>(args)...),
107 AlignedDeleter(free, opaque));
108}
109
110// Similar to MakeUniqueAlignedWithAlloc but using the default alloc/free
111// functions.
112template <typename T, typename... Args>
114 T* ptr = static_cast<T*>(AllocateAlignedBytes(
115 sizeof(T), /*alloc_ptr=*/nullptr, /*opaque_ptr=*/nullptr));
116 return AlignedUniquePtr<T>(new (ptr) T(std::forward<Args>(args)...),
118}
119
120// Helpers for array allocators (avoids overflow)
121namespace detail {
122
123// Returns x such that 1u << x == n (if n is a power of two).
124static inline constexpr size_t ShiftCount(size_t n) {
125 return (n <= 1) ? 0 : 1 + ShiftCount(n / 2);
126}
127
128template <typename T>
129T* AllocateAlignedItems(size_t items, AllocPtr alloc_ptr, void* opaque_ptr) {
130 constexpr size_t size = sizeof(T);
131
132 constexpr bool is_pow2 = (size & (size - 1)) == 0;
133 constexpr size_t bits = ShiftCount(size);
134 static_assert(!is_pow2 || (1ull << bits) == size, "ShiftCount is incorrect");
135
136 const size_t bytes = is_pow2 ? items << bits : items * size;
137 const size_t check = is_pow2 ? bytes >> bits : bytes / size;
138 if (check != items) {
139 return nullptr; // overflowed
140 }
141 return static_cast<T*>(AllocateAlignedBytes(bytes, alloc_ptr, opaque_ptr));
142}
143
144} // namespace detail
145
146// Aligned memory equivalent of make_unique<T[]> for array types using the
147// custom allocators alloc/free. This function calls the constructor with the
148// passed Args... on every created item. The destructor of each element will be
149// called when the AlignedUniquePtr is destroyed.
150template <typename T, typename... Args>
152 size_t items, AllocPtr alloc, FreePtr free, void* opaque, Args&&... args) {
153 T* ptr = detail::AllocateAlignedItems<T>(items, alloc, opaque);
154 if (ptr != nullptr) {
155 for (size_t i = 0; i < items; i++) {
156 new (ptr + i) T(std::forward<Args>(args)...);
157 }
158 }
159 return AlignedUniquePtr<T[]>(ptr, AlignedDeleter(free, opaque));
160}
161
162template <typename T, typename... Args>
163AlignedUniquePtr<T[]> MakeUniqueAlignedArray(size_t items, Args&&... args) {
164 return MakeUniqueAlignedArrayWithAlloc<T, Args...>(
165 items, nullptr, nullptr, nullptr, std::forward<Args>(args)...);
166}
167
168// Custom deleter for std::unique_ptr equivalent to using free() as a deleter
169// but for aligned memory.
171 public:
172 // Pass address of this to ctor to skip deleting externally-owned memory.
173 static void DoNothing(void* /*opaque*/, void* /*aligned_pointer*/) {}
174
175 AlignedFreer() : free_(nullptr), opaque_ptr_(nullptr) {}
176 AlignedFreer(FreePtr free_ptr, void* opaque_ptr)
177 : free_(free_ptr), opaque_ptr_(opaque_ptr) {}
178
179 template <typename T>
180 void operator()(T* aligned_pointer) const {
181 // TODO(deymo): assert that we are using a POD type T.
182 FreeAlignedBytes(aligned_pointer, free_, opaque_ptr_);
183 }
184
185 private:
188};
189
190// Unique pointer to single POD, or (if T is U[]) an array of POD. For non POD
191// data use AlignedUniquePtr.
192template <typename T>
193using AlignedFreeUniquePtr = std::unique_ptr<T, AlignedFreer>;
194
195// Allocate an aligned and uninitialized array of POD values as a unique_ptr.
196// Upon destruction of the unique_ptr the aligned array will be freed.
197template <typename T>
199 FreePtr free, void* opaque) {
201 detail::AllocateAlignedItems<T>(items, alloc, opaque),
202 AlignedFreer(free, opaque));
203}
204
205// Same as previous AllocateAligned(), using default allocate/free functions.
206template <typename T>
208 return AllocateAligned<T>(items, nullptr, nullptr, nullptr);
209}
210
211} // namespace hwy
212#endif // HIGHWAY_HWY_ALIGNED_ALLOCATOR_H_
uint8_t * bits
Definition TileProcessor.h:59
Definition aligned_allocator.h:57
void * opaque_ptr_
Definition aligned_allocator.h:89
void operator()(T *aligned_pointer) const
Definition aligned_allocator.h:64
AlignedDeleter(FreePtr free_ptr, void *opaque_ptr)
Definition aligned_allocator.h:60
AlignedDeleter()
Definition aligned_allocator.h:59
void(*)(void *t_ptr, size_t t_size) ArrayDeleter
Definition aligned_allocator.h:81
FreePtr free_
Definition aligned_allocator.h:88
static HWY_DLLEXPORT void DeleteAlignedArray(void *aligned_pointer, FreePtr free_ptr, void *opaque_ptr, ArrayDeleter deleter)
static void TypedArrayDeleter(void *ptr, size_t size_in_bytes)
Definition aligned_allocator.h:71
Definition aligned_allocator.h:170
AlignedFreer()
Definition aligned_allocator.h:175
void operator()(T *aligned_pointer) const
Definition aligned_allocator.h:180
AlignedFreer(FreePtr free_ptr, void *opaque_ptr)
Definition aligned_allocator.h:176
void * opaque_ptr_
Definition aligned_allocator.h:187
FreePtr free_
Definition aligned_allocator.h:186
static void DoNothing(void *, void *)
Definition aligned_allocator.h:173
#define HWY_DLLEXPORT
Definition highway_export.h:13
static constexpr size_t ShiftCount(size_t n)
Definition aligned_allocator.h:124
T * AllocateAlignedItems(size_t items, AllocPtr alloc_ptr, void *opaque_ptr)
Definition aligned_allocator.h:129
Definition aligned_allocator.h:27
std::unique_ptr< T, AlignedFreer > AlignedFreeUniquePtr
Definition aligned_allocator.h:193
std::unique_ptr< T, AlignedDeleter > AlignedUniquePtr
Definition aligned_allocator.h:96
HWY_DLLEXPORT void * AllocateAlignedBytes(size_t payload_size, AllocPtr alloc_ptr, void *opaque_ptr)
AlignedUniquePtr< T[]> MakeUniqueAlignedArrayWithAlloc(size_t items, AllocPtr alloc, FreePtr free, void *opaque, Args &&... args)
Definition aligned_allocator.h:151
void *(*)(void *opaque, size_t bytes) AllocPtr
Definition aligned_allocator.h:36
void(*)(void *opaque, void *memory) FreePtr
Definition aligned_allocator.h:37
AlignedUniquePtr< T[]> MakeUniqueAlignedArray(size_t items, Args &&... args)
Definition aligned_allocator.h:163
AlignedFreeUniquePtr< T[]> AllocateAligned(const size_t items, AllocPtr alloc, FreePtr free, void *opaque)
Definition aligned_allocator.h:198
HWY_DLLEXPORT void FreeAlignedBytes(const void *aligned_pointer, FreePtr free_ptr, void *opaque_ptr)
AlignedUniquePtr< T > MakeUniqueAlignedWithAlloc(AllocPtr alloc, FreePtr free, void *opaque, Args &&... args)
Definition aligned_allocator.h:103
AlignedUniquePtr< T > MakeUniqueAligned(Args &&... args)
Definition aligned_allocator.h:113