Coverage Report

Created: 2021-01-16 07:00

/Users/buildslave/jenkins/workspace/coverage/llvm-project/libcxx/src/memory.cpp
Line
Count
Source (jump to first uncovered line)
1
//===------------------------ memory.cpp ----------------------------------===//
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
#include "memory"
10
#ifndef _LIBCPP_HAS_NO_THREADS
11
#include "mutex"
12
#include "thread"
13
#if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
14
#pragma comment(lib, "pthread")
15
#endif
16
#endif
17
#include "include/atomic_support.h"
18
19
_LIBCPP_BEGIN_NAMESPACE_STD
20
21
const allocator_arg_t allocator_arg = allocator_arg_t();
22
23
0
bad_weak_ptr::~bad_weak_ptr() _NOEXCEPT {}
24
25
const char*
26
bad_weak_ptr::what() const _NOEXCEPT
27
0
{
28
0
    return "bad_weak_ptr";
29
0
}
30
31
__shared_count::~__shared_count()
32
111
{
33
111
}
34
35
__shared_weak_count::~__shared_weak_count()
36
0
{
37
0
}
38
39
#if defined(_LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS)
40
void
41
__shared_count::__add_shared() _NOEXCEPT
42
739M
{
43
739M
    __libcpp_atomic_refcount_increment(__shared_owners_);
44
739M
}
45
46
bool
47
__shared_count::__release_shared() _NOEXCEPT
48
2.52G
{
49
2.52G
    if (__libcpp_atomic_refcount_decrement(__shared_owners_) == -1)
50
113M
    {
51
113M
        __on_zero_shared();
52
113M
        return true;
53
113M
    }
54
2.41G
    return false;
55
2.41G
}
56
57
void
58
__shared_weak_count::__add_shared() _NOEXCEPT
59
387M
{
60
387M
    __shared_count::__add_shared();
61
387M
}
62
63
void
64
__shared_weak_count::__add_weak() _NOEXCEPT
65
510M
{
66
510M
    __libcpp_atomic_refcount_increment(__shared_weak_owners_);
67
510M
}
68
69
void
70
__shared_weak_count::__release_shared() _NOEXCEPT
71
2.17G
{
72
2.17G
    if (__shared_count::__release_shared())
73
113M
        __release_weak();
74
2.17G
}
75
76
#endif // _LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS
77
78
void
79
__shared_weak_count::__release_weak() _NOEXCEPT
80
987k
{
81
    // NOTE: The acquire load here is an optimization of the very
82
    // common case where a shared pointer is being destructed while
83
    // having no other contended references.
84
    //
85
    // BENEFIT: We avoid expensive atomic stores like XADD and STREX
86
    // in a common case.  Those instructions are slow and do nasty
87
    // things to caches.
88
    //
89
    // IS THIS SAFE?  Yes.  During weak destruction, if we see that we
90
    // are the last reference, we know that no-one else is accessing
91
    // us. If someone were accessing us, then they would be doing so
92
    // while the last shared / weak_ptr was being destructed, and
93
    // that's undefined anyway.
94
    //
95
    // If we see anything other than a 0, then we have possible
96
    // contention, and need to use an atomicrmw primitive.
97
    // The same arguments don't apply for increment, where it is legal
98
    // (though inadvisable) to share shared_ptr references between
99
    // threads, and have them all get copied at once.  The argument
100
    // also doesn't apply for __release_shared, because an outstanding
101
    // weak_ptr::lock() could read / modify the shared count.
102
987k
    if (__libcpp_atomic_load(&__shared_weak_owners_, _AO_Acquire) == 0)
103
427k
    {
104
        // no need to do this store, because we are about
105
        // to destroy everything.
106
        //__libcpp_atomic_store(&__shared_weak_owners_, -1, _AO_Release);
107
427k
        __on_zero_shared_weak();
108
427k
    }
109
560k
    else if (__libcpp_atomic_refcount_decrement(__shared_weak_owners_) == -1)
110
0
        __on_zero_shared_weak();
111
987k
}
112
113
__shared_weak_count*
114
__shared_weak_count::lock() _NOEXCEPT
115
2.35M
{
116
2.35M
    long object_owners = __libcpp_atomic_load(&__shared_owners_);
117
2.35M
    while (object_owners != -1)
118
2.35M
    {
119
2.35M
        if (__libcpp_atomic_compare_exchange(&__shared_owners_,
120
2.35M
                                             &object_owners,
121
2.35M
                                             object_owners+1))
122
2.35M
            return this;
123
2.35M
    }
124
87
    return nullptr;
125
2.35M
}
126
127
const void*
128
__shared_weak_count::__get_deleter(const type_info&) const _NOEXCEPT
129
0
{
130
0
    return nullptr;
131
0
}
132
133
#if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
134
135
_LIBCPP_SAFE_STATIC static const std::size_t __sp_mut_count = 16;
136
_LIBCPP_SAFE_STATIC static __libcpp_mutex_t mut_back[__sp_mut_count] =
137
{
138
    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,
139
    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,
140
    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER,
141
    _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER
142
};
143
144
_LIBCPP_CONSTEXPR __sp_mut::__sp_mut(void* p) _NOEXCEPT
145
   : __lx(p)
146
{
147
}
148
149
void
150
__sp_mut::lock() _NOEXCEPT
151
0
{
152
0
    auto m = static_cast<__libcpp_mutex_t*>(__lx);
153
0
    unsigned count = 0;
154
0
    while (!__libcpp_mutex_trylock(m))
155
0
    {
156
0
        if (++count > 16)
157
0
        {
158
0
            __libcpp_mutex_lock(m);
159
0
            break;
160
0
        }
161
0
        this_thread::yield();
162
0
    }
163
0
}
164
165
void
166
__sp_mut::unlock() _NOEXCEPT
167
0
{
168
0
    __libcpp_mutex_unlock(static_cast<__libcpp_mutex_t*>(__lx));
169
0
}
170
171
__sp_mut&
172
__get_sp_mut(const void* p)
173
0
{
174
0
    static __sp_mut muts[__sp_mut_count]
175
0
    {
176
0
        &mut_back[ 0], &mut_back[ 1], &mut_back[ 2], &mut_back[ 3],
177
0
        &mut_back[ 4], &mut_back[ 5], &mut_back[ 6], &mut_back[ 7],
178
0
        &mut_back[ 8], &mut_back[ 9], &mut_back[10], &mut_back[11],
179
0
        &mut_back[12], &mut_back[13], &mut_back[14], &mut_back[15]
180
0
    };
181
0
    return muts[hash<const void*>()(p) & (__sp_mut_count-1)];
182
0
}
183
184
#endif // !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
185
186
void
187
declare_reachable(void*)
188
0
{
189
0
}
190
191
void
192
declare_no_pointers(char*, size_t)
193
0
{
194
0
}
195
196
void
197
undeclare_no_pointers(char*, size_t)
198
0
{
199
0
}
200
201
#if !defined(_LIBCPP_ABI_POINTER_SAFETY_ENUM_TYPE)
202
pointer_safety get_pointer_safety() _NOEXCEPT
203
0
{
204
0
    return pointer_safety::relaxed;
205
0
}
206
#endif
207
208
void*
209
__undeclare_reachable(void* p)
210
0
{
211
0
    return p;
212
0
}
213
214
void*
215
align(size_t alignment, size_t size, void*& ptr, size_t& space)
216
0
{
217
0
    void* r = nullptr;
218
0
    if (size <= space)
219
0
    {
220
0
        char* p1 = static_cast<char*>(ptr);
221
0
        char* p2 = reinterpret_cast<char*>(reinterpret_cast<size_t>(p1 + (alignment - 1)) & -alignment);
222
0
        size_t d = static_cast<size_t>(p2 - p1);
223
0
        if (d <= space - size)
224
0
        {
225
0
            r = p2;
226
0
            ptr = r;
227
0
            space -= d;
228
0
        }
229
0
    }
230
0
    return r;
231
0
}
232
233
_LIBCPP_END_NAMESPACE_STD