Howard Hinnant | d213ffd | 2011-05-05 15:27:28 +0000 | [diff] [blame] | 1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" |
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| 19 | <label>libc++abi Info</label> |
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| 24 | <label>Quick Links</label> |
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| 34 | <!--*********************************************************************--> |
| 35 | <h1>"libc++abi" C++ Standard Library Support</h1> |
| 36 | <!--*********************************************************************--> |
| 37 | |
| 38 | <p>libc++abi is a new implementation of low level support for a standard |
| 39 | C++ library.</p> |
| 40 | |
| 41 | <p>All of the code in libc++abi 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> |
| 44 | |
| 45 | <!--=====================================================================--> |
| 46 | <h2 id="goals">Features and Goals</h2> |
| 47 | <!--=====================================================================--> |
| 48 | |
| 49 | <ul> |
| 50 | <li>Correctness as defined by the C++11 standard.</li> |
Sylvestre Ledru | f59526d | 2012-07-20 17:21:42 +0000 | [diff] [blame] | 51 | <li>Provide a portable sublayer to ease the porting of <a href="http://libcxx.llvm.org/">libc++</a></li> |
Howard Hinnant | 628bfc4 | 2011-05-19 23:38:38 +0000 | [diff] [blame] | 52 | <li>On Mac OS X, be ABI compatible with the existing low-level support.</li> |
Howard Hinnant | d213ffd | 2011-05-05 15:27:28 +0000 | [diff] [blame] | 53 | </ul> |
| 54 | |
| 55 | <!--=====================================================================--> |
| 56 | <h2 id="requirements">Platform Support</h2> |
| 57 | <!--=====================================================================--> |
| 58 | |
| 59 | <p>libc++abi is known to work on the following platforms, using clang.</p> |
| 60 | |
| 61 | <ul> |
Howard Hinnant | de2b109 | 2012-08-02 22:06:41 +0000 | [diff] [blame] | 62 | <li>Darwin</li> |
Howard Hinnant | d213ffd | 2011-05-05 15:27:28 +0000 | [diff] [blame] | 63 | </ul> |
| 64 | |
| 65 | <!--=====================================================================--> |
| 66 | <h2 id="dir-structure">Current Status</h2> |
| 67 | <!--=====================================================================--> |
| 68 | |
Howard Hinnant | de2b109 | 2012-08-02 22:06:41 +0000 | [diff] [blame] | 69 | <p>libc++abi is complete. <a href="spec.html">Here</a> is a |
| 70 | list of functionality.</p> |
Howard Hinnant | d213ffd | 2011-05-05 15:27:28 +0000 | [diff] [blame] | 71 | |
| 72 | <!--=====================================================================--> |
| 73 | <h2>Get it and get involved!</h2> |
| 74 | <!--=====================================================================--> |
| 75 | |
| 76 | <p>To check out the code, use:</p> |
| 77 | |
| 78 | <ul> |
| 79 | <li><code>svn co http://llvm.org/svn/llvm-project/libcxxabi/trunk libcxxabi</code></li> |
| 80 | </ul> |
| 81 | |
Dan Albert | e11c1a7 | 2014-07-03 19:35:48 +0000 | [diff] [blame] | 82 | <p>To build:</p> |
| 83 | <ul> |
| 84 | <li>Check out libcxxabi into <code>llvm/projects</code></li> |
| 85 | <li><code>cd llvm</code></li> |
| 86 | <li><code>mkdir build && cd build</code></li> |
| 87 | <li><code>cmake .. # on linux you may need to prefix with CC=clang CXX=clang++</code></li> |
| 88 | <li><code>make</code></li> |
| 89 | </ul> |
| 90 | |
| 91 | <p>To do a standalone build:</p> |
| 92 | <ul> |
| 93 | <li><code>cd libcxxabi</code></li> |
| 94 | <li><code>mkdir build && cd build</code></li> |
Dan Albert | fd961bd | 2014-07-10 02:20:11 +0000 | [diff] [blame^] | 95 | <li><code>cmake -DLIBCXXABI_LIBCXX_INCLUDES=path/to/libcxx/include .. # on |
| 96 | linux you may need -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++</code></li> |
Dan Albert | e11c1a7 | 2014-07-03 19:35:48 +0000 | [diff] [blame] | 97 | <li><code>make</code></li> |
| 98 | </ul> |
| 99 | |
Dan Albert | fd961bd | 2014-07-10 02:20:11 +0000 | [diff] [blame^] | 100 | <p>To run the tests:</p> |
| 101 | <ul> |
| 102 | <li><code>make check-libcxxabi</code></li> |
| 103 | </ul> |
| 104 | <p>Note: in a standalone build, the system's libc++ will be used for tests. If |
| 105 | the system's libc++ was statically linked against libc++abi (or linked against |
| 106 | a different ABI library), this may interfere with test results.</p> |
| 107 | |
Howard Hinnant | d213ffd | 2011-05-05 15:27:28 +0000 | [diff] [blame] | 108 | <p>Send discussions to the |
| 109 | (<a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">clang mailing list</a>).</p> |
| 110 | |
Marshall Clow | c9d6b42 | 2014-06-11 16:54:09 +0000 | [diff] [blame] | 111 | <!--=====================================================================--> |
| 112 | <h2>Frequently asked questions</h2> |
| 113 | <!--=====================================================================--> |
| 114 | |
| 115 | <p>Q: Why are the destructors for the standard exception classes defined in libc++abi? |
| 116 | They're just empty, can't they be defined inline?</p> |
| 117 | <p>A: The destructors for them live in libc++abi because they are "key" functions. |
| 118 | The Itanium ABI describes a "key" function as the first virtual declared. |
| 119 | And wherever the key function is defined, that is where the <code>type_info</code> gets defined. |
| 120 | And in libc++ types are the same type if and only if they have the same <code>type_info</code> |
| 121 | (as in there must be only one type info per type in the entire application). |
| 122 | And on OS X, libstdc++ and libc++ share these exception types. |
| 123 | So to be able to throw in one dylib and catch in another (a <code>std::exception</code> for example), |
| 124 | there must be only one <code>std::exception type_info</code> in the entire app. |
| 125 | That typeinfo gets laid down beside <code>~exception()</code> in libc++abi (for both libstdc++ and libc++).</p> |
| 126 | <p>--Howard Hinnant</p> |
Howard Hinnant | d213ffd | 2011-05-05 15:27:28 +0000 | [diff] [blame] | 127 | |
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