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5 <title>System Library</title>
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9
Misha Brukmanebbbf252004-07-21 18:02:43 +0000[diff] [blame]10<div class="doc_title">System Library</div>
Reid Spencer4f6015a2004-07-17 10:04:49 +0000[diff] [blame]11
Misha Brukmanebbbf252004-07-21 18:02:43 +0000[diff] [blame]12<div class="doc_warning">
13 <p>Warning: This document is a work in progress.</p>
14</div>
Reid Spencer4f6015a2004-07-17 10:04:49 +0000[diff] [blame]15
16<ul>
17 <li><a href="#abstract">Abstract</a></li>
18 <li><a href="#requirements">System Library Requirements</a>
19 <ol>
20 <li><a href="#headers">Hide System Header Files</a></li>
21 <li><a href="#nofunc">No Exposed Functions</a></li>
22 <li><a href="#nodata">No Exposed Data</a></li>
23 <li><a href="#xcptns">No Exceptions</a></li>
24 <li><a href="#errors">Standard Error Codes</a></li>
25 <li><a href="#overhead">Minimize Overhead</a></li>
26 </ol></li>
27 <li><a href="#design">System Library Design</a>
28 <ol>
29 <li><a href="#opaque">Use Opaque Classes</a></li>
30 <li><a href="#common">Common Implementations</a></li>
31 <li><a href="#multi_imps">Multiple Implementations</a></li>
32 <li><a href="#lowlevel">Use Low Level Interfaces</a></li>
33 <li><a href="#memalloc">No Memory Allocation</a></li>
34 <li><a href="#virtuals">No Virtual Methods</a></li>
35 </ol></li>
36 <li><a href="#detail">System Library Details</a>
37 <ol>
38 <li><a href="#bug">Tracking Bugzilla Bug: 351</a></li>
39 <li><a href="#refimpl">Reference Implementatation</a></li>
40 </ol></li>
41</ul>
42
43<div class="doc_author">
Misha Brukman17217842004-07-21 18:04:27 +0000[diff] [blame]44 <p>Written by <a href="rspencer@x10sys.com">Reid Spencer</a></p>
Reid Spencer4f6015a2004-07-17 10:04:49 +0000[diff] [blame]45</div>
46
47
48<!-- *********************************************************************** -->
49<div class="doc_section"><a name="abstract">Abstract</a></div>
50<div class="doc_text">
51 <p>This document describes the requirements, design, and implementation
52 details of LLVM's System Library. The library is composed of the header files
53 in <tt>llvm/include/llvm/System</tt> and the source files in
54 <tt>llvm/lib/System</tt>. The goal of this library is to completely shield
55 LLVM from the variations in operating system interfaces. By centralizing
56 LLVM's use of operating system interfaces, we make it possible for the LLVM
57 tool chain and runtime libraries to be more easily ported to new platforms.
58 The library also unclutters the rest of LLVM from #ifdef use and special
59 cases for specific operating systems.</p>
60 <p>The System Library was donated to LLVM by Reid Spencer who formulated the
61 original design as part of the eXtensible Programming System (XPS) which is
62 based, in part, on LLVM.</p>
63</div>
64
65<!-- *********************************************************************** -->
66<div class="doc_section">
67 <a name="requirements">System Library Requirements</a>
68</div>
69<div class="doc_text">
70 <p>The System library's requirements are aimed at shielding LLVM from the
71 variations in operating system interfaces. The following sections define the
72 requirements needed to fulfill this objective.</p>
73</div>
74
75<!-- ======================================================================= -->
76<div class="doc_subsection"><a name="headers">Hide System Header Files</a></div>
77<div class="doc_text">
78 <p>To be written.</p>
79</div>
80
81<!-- ======================================================================= -->
82<div class="doc_subsection"><a name="nofunc">No Exposed Functions</a></div>
83<div class="doc_text">
84 <p>To be written.</p>
85</div>
86
87<!-- ======================================================================= -->
88<div class="doc_subsection"><a name="nodata">No Exposed Data</a></div>
89<div class="doc_text">
90 <p>To be written.</p>
91</div>
92
93<!-- ======================================================================= -->
94<div class="doc_subsection"><a name="xcptns">No Exceptions</a></div>
95<div class="doc_text">
96 <p>To be written.</p>
97</div>
98
99<!-- ======================================================================= -->
100<div class="doc_subsection"><a name="errors">Standard Error Codes</a></div>
101<div class="doc_text">
102 <p>To be written.</p>
103</div>
104
105<!-- ======================================================================= -->
106<div class="doc_subsection"><a name="overhead">Minimize Overhead</a></div>
107<div class="doc_text">
108 <p>To be written.</p>
109</div>
110
111<!-- *********************************************************************** -->
112<div class="doc_section"><a name="design">System Library Design</a></div>
113<div class="doc_text">
114 <p>In order to fulfill the requirements of the system library, strict design
115 objectives must be maintained in the library as it evolves. The goal here
116 is to provide interfaces to operating system concepts (files, memory maps,
117 sockets, signals, locking, etc) efficiently and in such a way that the
118 remainder of LLVM is completely operating system agnostic.</p>
119</div>
120
121<!-- ======================================================================= -->
122<div class="doc_subsection"><a name="opaque">Use Opaque Classes</a></div>
123<div class="doc_text">
124 <p>no public data</p>
125 <p>onlyprimitive typed private/protected data</p>
126 <p>data size is "right" for platform, not max of all platforms</p>
127 <p>each class corresponds to O/S concept</p>
128</div>
129
130<!-- ======================================================================= -->
131<div class="doc_subsection"><a name="common">Common Implementations</a></div>
132<div class="doc_text">
133 <p>To be written.</p>
134</div>
135
136<!-- ======================================================================= -->
137<div class="doc_subsection">
138 <a name="multi_imps">Multiple Implementations</a>
139</div>
140<div class="doc_text">
141 <p>To be written.</p>
142</div>
143
144<!-- ======================================================================= -->
145<div class="doc_subsection">
146 <a name="low_level">Use Low Level Interfaces</a>
147</div>
148<div class="doc_text">
149 <p>To be written.</p>
150</div>
151
152<!-- ======================================================================= -->
153<div class="doc_subsection"><a name="memalloc">No Memory Allocation</a></div>
154<div class="doc_text">
155 <p>To be written.</p>
156</div>
157
158<!-- ======================================================================= -->
159<div class="doc_subsection"><a name="virtuals">No Virtual Methods</a></div>
160<div class="doc_text">
161 <p>To be written.</p>
162</div>
163
164<!-- *********************************************************************** -->
165<div class="doc_section"><a name="detail">System Library Details</a></div>
166<div class="doc_text">
167 <p>To be written.</p>
168</div>
169
170<!-- ======================================================================= -->
Chris Lattner05540a72004-07-17 18:50:19 +0000[diff] [blame]171<div class="doc_subsection"><a name="bug">Bug 351</a></div>
Reid Spencer4f6015a2004-07-17 10:04:49 +0000[diff] [blame]172<div class="doc_text">
Chris Lattner05540a72004-07-17 18:50:19 +0000[diff] [blame]173 <p>See <a href="http://llvm.cs.uiuc.edu/PR351">bug 351</a>
Reid Spencer4f6015a2004-07-17 10:04:49 +0000[diff] [blame]174 for further details on the progress of this work</p>
175</div>
176
177<!-- ======================================================================= -->
178<div class="doc_subsection">
179 <a name="refimpl">Reference Implementation</a>
180</div>
181<div class="doc_text">
182 <p>The <tt>linux</tt> implementation of the system library will always be the
183 reference implementation. This means that (a) the concepts defined by the
184 linux must be identically replicated in the other implementations and (b) the
185 linux implementation must always be complete (provide implementations for all
186 concepts).</p>
187</div>
188
189<!-- *********************************************************************** -->
190
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