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15 <a href="http://llvm.org/">LLVM Home</a>
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Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]17
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]18 <div class="submenu">
19 <label>libc++ Info</label>
20 <a href="/index.html">About</a>
21 </div>
22
23 <div class="submenu">
24 <label>Quick Links</label>
Chris Lattner3c9af342010-05-11 20:53:16 +0000[diff] [blame]25 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">cfe-dev</a>
26 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits">cfe-commits</a>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]27 <a href="http://llvm.org/bugs/">Bug Reports</a>
Howard Hinnant00171852010-05-11 20:51:20 +0000[diff] [blame]28 <a href="http://llvm.org/svn/llvm-project/libcxx/trunk/">Browse SVN</a>
29 <a href="http://llvm.org/viewvc/llvm-project/libcxx/trunk/">Browse ViewVC</a>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]30 </div>
31</div>
32
33<div id="content">
34 <!--*********************************************************************-->
35 <h1>"libc++" C++ Standard Library</h1>
36 <!--*********************************************************************-->
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]37
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]38 <p>libc++ is a new implementation of the C++ standard library, targeting
39 C++0X.</p>
40
Chris Lattner7b2aacc2010-11-16 21:40:19 +0000[diff] [blame]41 <p>All of the code in libc++ is <a
42 href="http://llvm.org/docs/DeveloperPolicy.html#license">dual licensed</a>
43 under the MIT license and the UIUC License (a BSD-like license).</p>
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]44
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]45 <!--=====================================================================-->
46 <h2 id="goals">Features and Goals</h2>
47 <!--=====================================================================-->
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]48
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]49 <ul>
50 <li>Correctness as defined by the (currently draft) C++0X standard.</li>
51 <li>Fast execution.</li>
52 <li>Minimal memory use.</li>
53 <li>Fast compile times.</li>
54 <li>ABI compatibility with gcc's libstdc++ for some low-level features
55 such as exception objects, rtti and memory allocation.</li>
56 <li>Extensive unit tests.</li>
57 </ul>
58
59 <!--=====================================================================-->
Chris Lattnere2b07272010-05-12 22:21:15 +0000[diff] [blame]60 <h2 id="why">Why a new C++ Standard Library for C++'0x?</h2>
61 <!--=====================================================================-->
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]62
Chris Lattnere2b07272010-05-12 22:21:15 +0000[diff] [blame]63 <p>After its initial introduction, many people have asked "why start a new
64 library instead of contributing to an existing library?" (like Apache's
65 libstdcxx, GNU's libstdc++, STLport, etc). There are many contributing
66 reasons, but some of the major ones are:</p>
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]67
Chris Lattnere2b07272010-05-12 22:21:15 +0000[diff] [blame]68 <ul>
69 <li><p>From years of experience (including having implemented the standard
70 library before), we've learned many things about implementing
71 the standard containers which require ABI breakage and fundamental changes
72 to how they are implemented. For example, it is generally accepted that
73 building std::string using the "short string optimization" instead of
74 using Copy On Write (COW) is a superior approach for multicore
Chris Lattnerc67061b2010-05-12 22:30:22 +0000[diff] [blame]75 machines (particularly in C++'0x, which has rvalue references). Breaking
76 ABI compatibility with old versions of the library was
Chris Lattnere2b07272010-05-12 22:21:15 +0000[diff] [blame]77 determined to be critical to achieving the performance goals of
78 libc++.</p></li>
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]79
Chris Lattnere2b07272010-05-12 22:21:15 +0000[diff] [blame]80 <li><p>Mainline libstdc++ has switched to GPL3, a license which the developers
81 of libc++ cannot use. libstdc++ 4.2 (the last GPL2 version) could be
82 independently extended to support C++'0x, but this would be a fork of the
Chris Lattnere7bdfe62010-05-12 22:33:00 +0000[diff] [blame]83 codebase (which is often seen as worse for a project than starting a new
84 independent one). Another problem with libstdc++ is that it is tightly
85 integrated with G++ development, tending to be tied fairly closely to the
86 matching version of G++.</p>
Chris Lattnere2b07272010-05-12 22:21:15 +0000[diff] [blame]87 </li>
88
89 <li><p>STLport and the Apache libstdcxx library are two other popular
90 candidates, but both lack C++'0x support. Our experience (and the
91 experience of libstdc++ developers) is that adding support for C++0x (in
92 particular rvalue references and move-only types) requires changes to
93 almost every class and function, essentially amounting to a rewrite.
Chris Lattner48035ce2010-05-12 22:34:21 +0000[diff] [blame]94 Faced with a rewrite, we decided to start from scratch and evaluate every
95 design decision from first principles based on experience.</p>
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]96
Chris Lattnere2b07272010-05-12 22:21:15 +0000[diff] [blame]97 <p>Further, both projects are apparently abandoned: STLport 5.2.1 was
98 released in Oct'08, and STDCXX 4.2.1 in May'08.</p>
99
100 </ul>
101
102 <!--=====================================================================-->
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]103 <h2 id="requirements">Platform Support</h2>
104 <!--=====================================================================-->
105
106 <p>libc++ is known to work on the following platforms, using g++-4.2 and
107 clang (lack of C++0X language support disables some functionality).</p>
108
109 <ul>
110 <li>Mac OS X i386</li>
111 <li>Mac OS X x86_64</li>
112 </ul>
113
114 <!--=====================================================================-->
115 <h2 id="dir-structure">Current Status</h2>
116 <!--=====================================================================-->
117
Howard Hinnant2a955832010-09-05 17:31:48 +0000[diff] [blame]118 <p>libc++ is still under development. It has about 98% of
119 <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3126.pdf">N3126</a>
Chris Lattnere2b07272010-05-12 22:21:15 +0000[diff] [blame]120 implemented/tested. C++'98 support is fully featured, and most of C++'0x
Howard Hinnant2a955832010-09-05 17:31:48 +0000[diff] [blame]121 support is as well. The only major missing piece of C++'0x support is
122 <code>&lt;atomic&gt;</code>.</p>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]123
Howard Hinnant075ac852010-05-13 20:10:39 +0000[diff] [blame]124 <p><a href="libcxx_by_chapter.pdf">Here</a> is a by-chapter breakdown of what
125 is passing tests and what isn't. This chart is currently based on testing
Dan Gohmane6591402010-06-04 14:16:02 +0000[diff] [blame]126 against g++-4.4.0 with -std=c++0x. </p>
Howard Hinnant075ac852010-05-13 20:10:39 +0000[diff] [blame]127
Howard Hinnant2347d2f2011-09-28 15:44:39 +0000[diff] [blame]128 <p>
129 A Windows port is underway. <a href="results.Windows.html">Here</a> are
130 recent test results.
131 </p>
132
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]133 <!--=====================================================================-->
134 <h2>Get it and get involved!</h2>
135 <!--=====================================================================-->
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]136
Howard Hinnantf0721aa2011-09-30 16:58:02 +0000[diff] [blame^]137 <p>First please review our
138 <a href="http://llvm.org/docs/DeveloperPolicy.html">Developer's Policy</a>.
139
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]140 <p>To check out the code, use:</p>
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]141
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]142 <ul>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]143 <li><code>svn co http://llvm.org/svn/llvm-project/libcxx/trunk libcxx</code></li>
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]144 </ul>
145
146 <p>To build on Mac OS X 10.6, you need a helper library and header
147 <a href="http://home.roadrunner.com/~hinnant/libcppabi.zip">found here</a>.
148 cp cxxabi.h to /usr/include, and cp libc++abi.dylib to /usr/lib.
149 <p>
150
151 <p>
152 Next:
153 </p>
154
155 <ul>
156 <li><code>cd libcxx/lib</code></li>
157 <li><code>export TRIPLE=-apple-</code></li>
158 <li><code>./buildit</code></li>
159 </ul>
160
161 <p>
162 That should result in a libc++.1.dylib. To install it I like to use links
163 instead of copying, but either should work:
164 </p>
165
166 <ul>
167 <li><code>cd /usr/lib</code></li>
Howard Hinnant38438dd2011-02-22 14:18:34 +0000[diff] [blame]168 <li><code>sudo ln -sf path-to-libcxx/lib/libc++.1.dylib libc++.1.dylib</code></li>
169 <li><code>sudo ln -sf libc++.1.dylib libc++.dylib</code></li>
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]170 <li><code>cd /usr/include/c++</code></li>
171 <li><code>sudo ln -sf path-to-libcxx/include v1</code></li>
172 </ul>
173
174 <p>
175 To use with clang you can:
176 </p>
177
178 <ul>
179 <li><code>clang++ -stdlib=libc++ test.cpp</code></li>
180 <li><code>clang++ -std=c++0x -stdlib=libc++ test.cpp</code></li>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]181 </ul>
182
183 <p>To run the libc++ test suit (recommended):</p>
184
185 <ul>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]186 <li><code>cd libcxx/test</code></li>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]187 <li><code>./testit</code></li>
Howard Hinnant14c2a082011-06-22 12:13:55 +0000[diff] [blame]188 <ul>
Howard Hinnanta42b3d02011-09-12 14:15:45 +0000[diff] [blame]189 <li>On Mac OS 10.6, to work around bugs in libc headers like
190 math.h and inttypes.h, add "-U__STRICT_ANSI__" and
191 "-D__STDC_FORMAT_MACROS" to the command line with:
192 <blockquote>
193 <pre>export OPTIONS="-std=c++0x -stdlib=libc++ -U__STRICT_ANSI__ -D__STDC_FORMAT_MACROS"</pre>
194 </blockquote></li>
195 <li>People porting libc++ to other OSes will likely have to
196 define similar macros.</li>
Howard Hinnant14c2a082011-06-22 12:13:55 +0000[diff] [blame]197 </ul>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]198 </ul>
199
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]200 <p>Send discussions to the
Howard Hinnantc5b02f22010-05-11 19:53:34 +0000[diff] [blame]201 (<a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">clang mailing list</a>).</p>
202
Howard Hinnantbded6c92010-10-05 16:44:40 +0000[diff] [blame]203 <!--=====================================================================-->
204 <h2>Design Documents</h2>
205 <!--=====================================================================-->
206
207<ul>
208<li><a href="atomic_design.html"><tt>&lt;atomic&gt;</tt></a></li>
Howard Hinnante20b8de2010-11-19 01:38:58 +0000[diff] [blame]209<li><a href="type_traits_design.html"><tt>&lt;type_traits&gt;</tt></a></li>
Howard Hinnantbded6c92010-10-05 16:44:40 +0000[diff] [blame]210</ul>
211
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]212</div>
213</body>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]214</html>