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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>
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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>
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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
41 <p>All of the code in libc++ is available under the standard
42 <a href="http://llvm.org/docs/DeveloperPolicy.html#license">LLVM
43 License</a>, a "BSD-style" 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
124 <p>libc++ is currently dependent upon a separate library for the low-level
125 ABI compatibility with gcc. As a workaround it can be linked against
Howard Hinnant2a955832010-09-05 17:31:48 +0000[diff] [blame]126 gcc's libstdc++, or on Mac OS X
127 <a href="http://home.roadrunner.com/~hinnant/libcppabi.zip">this library</a>.</p>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]128
Howard Hinnant075ac852010-05-13 20:10:39 +0000[diff] [blame]129 <p><a href="libcxx_by_chapter.pdf">Here</a> is a by-chapter breakdown of what
130 is passing tests and what isn't. This chart is currently based on testing
Dan Gohmane6591402010-06-04 14:16:02 +0000[diff] [blame]131 against g++-4.4.0 with -std=c++0x. </p>
Howard Hinnant075ac852010-05-13 20:10:39 +0000[diff] [blame]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 Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]137 <p>To check out the code, use:</p>
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]138
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]139 <ul>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]140 <li><code>svn co http://llvm.org/svn/llvm-project/libcxx/trunk libcxx</code></li>
141 <li><code>cd libcxx/lib</code></li>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]142 <li><code>./buildit</code></li>
143 </ul>
144
145 <p>To run the libc++ test suit (recommended):</p>
146
147 <ul>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]148 <li><code>cd libcxx/test</code></li>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]149 <li><code>./testit</code></li>
150 </ul>
151
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]152 <p>Send discussions to the
Howard Hinnantc5b02f22010-05-11 19:53:34 +0000[diff] [blame]153 (<a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">clang mailing list</a>).</p>
154
Howard Hinnantbded6c92010-10-05 16:44:40 +0000[diff] [blame^]155 <!--=====================================================================-->
156 <h2>Design Documents</h2>
157 <!--=====================================================================-->
158
159<ul>
160<li><a href="atomic_design.html"><tt>&lt;atomic&gt;</tt></a></li>
161</ul>
162
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]163</div>
164</body>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]165</html>