1 //===------------------------ memory.cpp ----------------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 #define _LIBCPP_BUILDING_MEMORY
11 #include "memory"
12 #include "mutex"
13 #include "thread"
14
15 _LIBCPP_BEGIN_NAMESPACE_STD
16
17 namespace
18 {
19
20 template <class T>
21 inline T
increment(T & t)22 increment(T& t) _NOEXCEPT
23 {
24 return __sync_add_and_fetch(&t, 1);
25 }
26
27 template <class T>
28 inline T
decrement(T & t)29 decrement(T& t) _NOEXCEPT
30 {
31 return __sync_add_and_fetch(&t, -1);
32 }
33
34 } // namespace
35
36 const allocator_arg_t allocator_arg = allocator_arg_t();
37
~bad_weak_ptr()38 bad_weak_ptr::~bad_weak_ptr() _NOEXCEPT {}
39
40 const char*
what() const41 bad_weak_ptr::what() const _NOEXCEPT
42 {
43 return "bad_weak_ptr";
44 }
45
~__shared_count()46 __shared_count::~__shared_count()
47 {
48 }
49
50 void
__add_shared()51 __shared_count::__add_shared() _NOEXCEPT
52 {
53 increment(__shared_owners_);
54 }
55
56 bool
__release_shared()57 __shared_count::__release_shared() _NOEXCEPT
58 {
59 if (decrement(__shared_owners_) == -1)
60 {
61 __on_zero_shared();
62 return true;
63 }
64 return false;
65 }
66
~__shared_weak_count()67 __shared_weak_count::~__shared_weak_count()
68 {
69 }
70
71 void
__add_shared()72 __shared_weak_count::__add_shared() _NOEXCEPT
73 {
74 __shared_count::__add_shared();
75 }
76
77 void
__add_weak()78 __shared_weak_count::__add_weak() _NOEXCEPT
79 {
80 increment(__shared_weak_owners_);
81 }
82
83 void
__release_shared()84 __shared_weak_count::__release_shared() _NOEXCEPT
85 {
86 if (__shared_count::__release_shared())
87 __release_weak();
88 }
89
90 void
__release_weak()91 __shared_weak_count::__release_weak() _NOEXCEPT
92 {
93 if (decrement(__shared_weak_owners_) == -1)
94 __on_zero_shared_weak();
95 }
96
97 __shared_weak_count*
lock()98 __shared_weak_count::lock() _NOEXCEPT
99 {
100 long object_owners = __shared_owners_;
101 while (object_owners != -1)
102 {
103 if (__sync_bool_compare_and_swap(&__shared_owners_,
104 object_owners,
105 object_owners+1))
106 return this;
107 object_owners = __shared_owners_;
108 }
109 return 0;
110 }
111
112 #ifndef _LIBCPP_NO_RTTI
113
114 const void*
__get_deleter(const type_info &) const115 __shared_weak_count::__get_deleter(const type_info&) const _NOEXCEPT
116 {
117 return 0;
118 }
119
120 #endif // _LIBCPP_NO_RTTI
121
122 #if __has_feature(cxx_atomic) && !_LIBCPP_SINGLE_THREADED
123
124 static const std::size_t __sp_mut_count = 16;
125 static pthread_mutex_t mut_back_imp[__sp_mut_count] =
126 {
127 PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
128 PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
129 PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
130 PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER
131 };
132
133 static mutex* mut_back = reinterpret_cast<std::mutex*>(mut_back_imp);
134
__sp_mut(void * p)135 _LIBCPP_CONSTEXPR __sp_mut::__sp_mut(void* p) _NOEXCEPT
136 : __lx(p)
137 {
138 }
139
140 void
lock()141 __sp_mut::lock() _NOEXCEPT
142 {
143 mutex& m = *static_cast<mutex*>(__lx);
144 unsigned count = 0;
145 while (!m.try_lock())
146 {
147 if (++count > 16)
148 {
149 m.lock();
150 break;
151 }
152 this_thread::yield();
153 }
154 }
155
156 void
unlock()157 __sp_mut::unlock() _NOEXCEPT
158 {
159 static_cast<mutex*>(__lx)->unlock();
160 }
161
162 __sp_mut&
__get_sp_mut(const void * p)163 __get_sp_mut(const void* p)
164 {
165 static __sp_mut muts[__sp_mut_count]
166 {
167 &mut_back[ 0], &mut_back[ 1], &mut_back[ 2], &mut_back[ 3],
168 &mut_back[ 4], &mut_back[ 5], &mut_back[ 6], &mut_back[ 7],
169 &mut_back[ 8], &mut_back[ 9], &mut_back[10], &mut_back[11],
170 &mut_back[12], &mut_back[13], &mut_back[14], &mut_back[15]
171 };
172 return muts[hash<const void*>()(p) & (__sp_mut_count-1)];
173 }
174
175 #endif // __has_feature(cxx_atomic) && LIBCPP_HAS_PTHREADS
176
177 void
declare_reachable(void *)178 declare_reachable(void*)
179 {
180 }
181
182 void
declare_no_pointers(char *,size_t)183 declare_no_pointers(char*, size_t)
184 {
185 }
186
187 void
undeclare_no_pointers(char *,size_t)188 undeclare_no_pointers(char*, size_t)
189 {
190 }
191
192 pointer_safety
get_pointer_safety()193 get_pointer_safety() _NOEXCEPT
194 {
195 return pointer_safety::relaxed;
196 }
197
198 void*
__undeclare_reachable(void * p)199 __undeclare_reachable(void* p)
200 {
201 return p;
202 }
203
204 void*
align(size_t alignment,size_t size,void * & ptr,size_t & space)205 align(size_t alignment, size_t size, void*& ptr, size_t& space)
206 {
207 void* r = nullptr;
208 if (size <= space)
209 {
210 char* p1 = static_cast<char*>(ptr);
211 char* p2 = reinterpret_cast<char*>(reinterpret_cast<size_t>(p1 + (alignment - 1)) & -alignment);
212 size_t d = static_cast<size_t>(p2 - p1);
213 if (d <= space - size)
214 {
215 r = p2;
216 ptr = r;
217 space -= d;
218 }
219 }
220 return r;
221 }
222
223 _LIBCPP_END_NAMESPACE_STD
224