1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<!-- Material used from: HTML 4.01 specs: http://www.w3.org/TR/html401/ -->
<html>
<head>
<META http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title><atomic> design</title>
<link type="text/css" rel="stylesheet" href="menu.css">
<link type="text/css" rel="stylesheet" href="content.css">
</head>
<body>
<div id="menu">
<div>
<a href="http://llvm.org/">LLVM Home</a>
</div>
<div class="submenu">
<label>libc++ Info</label>
<a href="/index.html">About</a>
</div>
<div class="submenu">
<label>Quick Links</label>
<a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">cfe-dev</a>
<a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits">cfe-commits</a>
<a href="http://llvm.org/bugs/">Bug Reports</a>
<a href="http://llvm.org/svn/llvm-project/libcxx/trunk/">Browse SVN</a>
<a href="http://llvm.org/viewvc/llvm-project/libcxx/trunk/">Browse ViewVC</a>
</div>
</div>
<div id="content">
<!--*********************************************************************-->
<h1><atomic> design</h1>
<!--*********************************************************************-->
<p>
This is more of a synopsis than a true description. The compiler supplies all
of the intrinsics as described below. This list of intrinsics roughly parallels
the requirements of the C and C++ atomics proposals. The C and C++ library
imlpementations simply drop through to these intrinsics. Anything the platform
does not support in hardware, the compiler arranges for a (compiler-rt) library
call to be made which will do the job with a mutex, and in this case ignoring
the memory ordering parameter.
</p>
<blockquote><pre>
<font color="#C80000">// type can be any pod</font>
<font color="#C80000">// Behavior is defined for mem_ord = 0, 1, 2, 5</font>
type __atomic_load(const volatile type* atomic_obj, int mem_ord);
<font color="#C80000">// type can be any pod</font>
<font color="#C80000">// Behavior is defined for mem_ord = 0, 3, 5</font>
type __atomic_store(volatile type* atomic_obj, type desired, int mem_ord);
<font color="#C80000">// type can be any pod</font>
<font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font>
type __atomic_exchange(volatile type* atomic_obj, type desired, int mem_ord);
<font color="#C80000">// type can be any pod</font>
<font color="#C80000">// Behavior is defined for mem_success = [0 ... 5],</font>
<font color="#C80000">// mem_falure <= mem_success && mem_failure != [3, 4]</font>
bool __atomic_compare_exchange_strong(volatile type* atomic_obj,
type* expected, type desired,
int mem_success, int mem_failure);
<font color="#C80000">// type can be any pod</font>
<font color="#C80000">// Behavior is defined for mem_success = [0 ... 5],</font>
<font color="#C80000">// mem_falure <= mem_success && mem_failure != [3, 4]</font>
bool __atomic_compare_exchange_weak(volatile type* atomic_obj,
type* expected, type desired,
int mem_success, int mem_failure);
<font color="#C80000">// type is one of: char, signed char, unsigned char, short, unsigned short, int,</font>
<font color="#C80000">// unsigned int, long, unsigned long, long long, unsigned long long,</font>
<font color="#C80000">// char16_t, char32_t, wchar_t</font>
<font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font>
type __atomic_fetch_add(volatile type* atomic_obj, type operand, int mem_ord);
<font color="#C80000">// type is one of: char, signed char, unsigned char, short, unsigned short, int,</font>
<font color="#C80000">// unsigned int, long, unsigned long, long long, unsigned long long,</font>
<font color="#C80000">// char16_t, char32_t, wchar_t</font>
<font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font>
type __atomic_fetch_sub(volatile type* atomic_obj, type operand, int mem_ord);
<font color="#C80000">// type is one of: char, signed char, unsigned char, short, unsigned short, int,</font>
<font color="#C80000">// unsigned int, long, unsigned long, long long, unsigned long long,</font>
<font color="#C80000">// char16_t, char32_t, wchar_t</font>
<font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font>
type __atomic_fetch_and(volatile type* atomic_obj, type operand, int mem_ord);
<font color="#C80000">// type is one of: char, signed char, unsigned char, short, unsigned short, int,</font>
<font color="#C80000">// unsigned int, long, unsigned long, long long, unsigned long long,</font>
<font color="#C80000">// char16_t, char32_t, wchar_t</font>
<font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font>
type __atomic_fetch_or(volatile type* atomic_obj, type operand, int mem_ord);
<font color="#C80000">// type is one of: char, signed char, unsigned char, short, unsigned short, int,</font>
<font color="#C80000">// unsigned int, long, unsigned long, long long, unsigned long long,</font>
<font color="#C80000">// char16_t, char32_t, wchar_t</font>
<font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font>
type __atomic_fetch_xor(volatile type* atomic_obj, type operand, int mem_ord);
<font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font>
void* __atomic_fetch_add(void* volatile* atomic_obj, ptrdiff_t operand, int mem_ord);
void* __atomic_fetch_sub(void* volatile* atomic_obj, ptrdiff_t operand, int mem_ord);
<font color="#C80000">// Behavior is defined for mem_ord = [0 ... 5]</font>
void __atomic_thread_fence(int mem_ord);
void __atomic_signal_fence(int mem_ord);
</pre></blockquote>
<p>
If desired the intrinsics taking a single <tt>mem_ord</tt> parameter can default
this argument to 5.
</p>
<p>
If desired the intrinsics taking two ordering parameters can default
<tt>mem_success</tt> to 5, and <tt>mem_failure</tt> to <tt>mem_success</tt>.
</p>
</div>
</body>
</html>
|
