1 /*
2     Copyright (c) 2005-2022 Intel Corporation
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 
17 #ifndef __TBB_cache_aligned_allocator_H
18 #define __TBB_cache_aligned_allocator_H
19 
20 #include "detail/_utils.h"
21 #include "detail/_namespace_injection.h"
22 #include <cstdlib>
23 #include <utility>
24 
25 #if __TBB_CPP17_MEMORY_RESOURCE_PRESENT
26 #include <memory_resource>
27 #endif
28 
29 namespace tbb {
30 namespace detail {
31 
32 namespace r1 {
33 TBB_EXPORT void*       __TBB_EXPORTED_FUNC cache_aligned_allocate(std::size_t size);
34 TBB_EXPORT void        __TBB_EXPORTED_FUNC cache_aligned_deallocate(void* p);
35 TBB_EXPORT std::size_t __TBB_EXPORTED_FUNC cache_line_size();
36 }
37 
38 namespace d1 {
39 
40 template<typename T>
41 class cache_aligned_allocator {
42 public:
43     using value_type = T;
44     using propagate_on_container_move_assignment = std::true_type;
45 
46     //! Always defined for TBB containers (supported since C++17 for std containers)
47     using is_always_equal = std::true_type;
48 
49     cache_aligned_allocator() = default;
50     template<typename U> cache_aligned_allocator(const cache_aligned_allocator<U>&) noexcept {}
51 
52     //! Allocate space for n objects, starting on a cache/sector line.
53     __TBB_nodiscard T* allocate(std::size_t n) {
54         return static_cast<T*>(r1::cache_aligned_allocate(n * sizeof(value_type)));
55     }
56 
57     //! Free block of memory that starts on a cache line
58     void deallocate(T* p, std::size_t) {
59         r1::cache_aligned_deallocate(p);
60     }
61 
62     //! Largest value for which method allocate might succeed.
63     std::size_t max_size() const noexcept {
64         return (~std::size_t(0) - r1::cache_line_size()) / sizeof(value_type);
65     }
66 
67 #if TBB_ALLOCATOR_TRAITS_BROKEN
68     using pointer = value_type*;
69     using const_pointer = const value_type*;
70     using reference = value_type&;
71     using const_reference = const value_type&;
72     using difference_type = std::ptrdiff_t;
73     using size_type = std::size_t;
74     template<typename U> struct rebind {
75         using other = cache_aligned_allocator<U>;
76     };
77     template<typename U, typename... Args>
78     void construct(U *p, Args&&... args)
79         { ::new (p) U(std::forward<Args>(args)...); }
80     void destroy(pointer p) { p->~value_type(); }
81     pointer address(reference x) const { return &x; }
82     const_pointer address(const_reference x) const { return &x; }
83 #endif // TBB_ALLOCATOR_TRAITS_BROKEN
84 };
85 
86 #if TBB_ALLOCATOR_TRAITS_BROKEN
87     template<>
88     class cache_aligned_allocator<void> {
89     public:
90         using pointer = void*;
91         using const_pointer = const void*;
92         using value_type = void;
93         template<typename U> struct rebind {
94             using other = cache_aligned_allocator<U>;
95         };
96     };
97 #endif
98 
99 template<typename T, typename U>
100 bool operator==(const cache_aligned_allocator<T>&, const cache_aligned_allocator<U>&) noexcept { return true; }
101 
102 #if !__TBB_CPP20_COMPARISONS_PRESENT
103 template<typename T, typename U>
104 bool operator!=(const cache_aligned_allocator<T>&, const cache_aligned_allocator<U>&) noexcept { return false; }
105 #endif
106 
107 #if __TBB_CPP17_MEMORY_RESOURCE_PRESENT
108 
109 //! C++17 memory resource wrapper to ensure cache line size alignment
110 class cache_aligned_resource : public std::pmr::memory_resource {
111 public:
112     cache_aligned_resource() : cache_aligned_resource(std::pmr::get_default_resource()) {}
113     explicit cache_aligned_resource(std::pmr::memory_resource* upstream) : m_upstream(upstream) {}
114 
115     std::pmr::memory_resource* upstream_resource() const {
116         return m_upstream;
117     }
118 
119 private:
120     //! We don't know what memory resource set. Use padding to guarantee alignment
121     void* do_allocate(std::size_t bytes, std::size_t alignment) override {
122         // TODO: make it common with tbb_allocator.cpp
123         std::size_t cache_line_alignment = correct_alignment(alignment);
124         std::size_t space = correct_size(bytes) + cache_line_alignment;
125         std::uintptr_t base = reinterpret_cast<std::uintptr_t>(m_upstream->allocate(space));
126         __TBB_ASSERT(base != 0, "Upstream resource returned nullptr.");
127 
128         // Round up to the next cache line (align the base address)
129         std::uintptr_t result = (base + cache_line_alignment) & ~(cache_line_alignment - 1);
130         __TBB_ASSERT((result - base) >= sizeof(std::uintptr_t), "Can`t store a base pointer to the header");
131         __TBB_ASSERT(space - (result - base) >= bytes, "Not enough space for the storage");
132 
133         // Record where block actually starts.
134         (reinterpret_cast<std::uintptr_t*>(result))[-1] = base;
135         return reinterpret_cast<void*>(result);
136     }
137 
138     void do_deallocate(void* ptr, std::size_t bytes, std::size_t alignment) override {
139         if (ptr) {
140             // Recover where block actually starts
141             std::uintptr_t base = (reinterpret_cast<std::uintptr_t*>(ptr))[-1];
142             m_upstream->deallocate(reinterpret_cast<void*>(base), correct_size(bytes) + correct_alignment(alignment));
143         }
144     }
145 
146     bool do_is_equal(const std::pmr::memory_resource& other) const noexcept override {
147         if (this == &other) { return true; }
148 #if __TBB_USE_OPTIONAL_RTTI
149         const cache_aligned_resource* other_res = dynamic_cast<const cache_aligned_resource*>(&other);
150         return other_res && (upstream_resource() == other_res->upstream_resource());
151 #else
152         return false;
153 #endif
154     }
155 
156     std::size_t correct_alignment(std::size_t alignment) {
157         __TBB_ASSERT(tbb::detail::is_power_of_two(alignment), "Alignment is not a power of 2");
158 #if __TBB_CPP17_HW_INTERFERENCE_SIZE_PRESENT
159         std::size_t cache_line_size = std::hardware_destructive_interference_size;
160 #else
161         std::size_t cache_line_size = r1::cache_line_size();
162 #endif
163         return alignment < cache_line_size ? cache_line_size : alignment;
164     }
165 
166     std::size_t correct_size(std::size_t bytes) {
167         // To handle the case, when small size requested. There could be not
168         // enough space to store the original pointer.
169         return bytes < sizeof(std::uintptr_t) ? sizeof(std::uintptr_t) : bytes;
170     }
171 
172     std::pmr::memory_resource* m_upstream;
173 };
174 
175 #endif // __TBB_CPP17_MEMORY_RESOURCE_PRESENT
176 
177 } // namespace d1
178 } // namespace detail
179 
180 inline namespace v1 {
181 using detail::d1::cache_aligned_allocator;
182 #if __TBB_CPP17_MEMORY_RESOURCE_PRESENT
183 using detail::d1::cache_aligned_resource;
184 #endif
185 } // namespace v1
186 } // namespace tbb
187 
188 #endif /* __TBB_cache_aligned_allocator_H */
189 
190