1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" 2 "http://www.w3.org/TR/html4/strict.dtd"> 3<!-- Material used from: HTML 4.01 specs: http://www.w3.org/TR/html401/ --> 4<html> 5<head> 6 <META http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> 7 <title>"libc++abi" C++ Standard Library Support</title> 8 <link type="text/css" rel="stylesheet" href="menu.css"> 9 <link type="text/css" rel="stylesheet" href="content.css"> 10</head> 11 12<body> 13<div id="menu"> 14 <div> 15 <a href="http://llvm.org/">LLVM Home</a> 16 </div> 17 18 <div class="submenu"> 19 <label>libc++abi Info</label> 20 <a href="/index.html">About</a> 21 </div> 22 23 <div class="submenu"> 24 <label>Quick Links</label> 25 <a href="https://libcxx.llvm.org/">libc++</a> 26 <a href="http://lists.llvm.org/mailman/listinfo/libcxx-dev">libcxx-dev</a> 27 <a href="http://lists.llvm.org/mailman/listinfo/libcxx-commits">libcxx-commits</a> 28 <a href="http://llvm.org/bugs/">Bug Reports</a> 29 <a href="http://llvm.org/svn/llvm-project/libcxxabi/trunk/">Browse SVN</a> 30 <a href="http://llvm.org/viewvc/llvm-project/libcxxabi/trunk/">Browse ViewVC</a> 31 </div> 32</div> 33 34<div id="content"> 35 <!--*********************************************************************--> 36 <h1>"libc++abi" C++ Standard Library Support</h1> 37 <!--*********************************************************************--> 38 39 <p>libc++abi is a new implementation of low level support for a standard 40 C++ library.</p> 41 42 <p>All of the code in libc++abi is <a 43 href="http://llvm.org/docs/DeveloperPolicy.html#license">dual licensed</a> 44 under the MIT license and the UIUC License (a BSD-like license).</p> 45 46 <!--=====================================================================--> 47 <h2 id="goals">Features and Goals</h2> 48 <!--=====================================================================--> 49 50 <ul> 51 <li>Correctness as defined by the C++11 standard.</li> 52 <li>Provide a portable sublayer to ease the porting of <a href="http://libcxx.llvm.org/">libc++</a></li> 53 <li>On Mac OS X, be ABI compatible with the existing low-level support.</li> 54 </ul> 55 56 <!--=====================================================================--> 57 <h2 id="requirements">Platform Support</h2> 58 <!--=====================================================================--> 59 60 <p>libc++abi is known to work on the following platforms, using clang.</p> 61 62 <ul> 63 <li>Darwin</li> 64 </ul> 65 66 <!--=====================================================================--> 67 <h2 id="dir-structure">Current Status</h2> 68 <!--=====================================================================--> 69 70 <p>libc++abi is complete. <a href="spec.html">Here</a> is a 71 list of functionality.</p> 72 73 <!--=====================================================================--> 74 <h2>Get it and get involved!</h2> 75 <!--=====================================================================--> 76 77 <p>To check out the code, use:</p> 78 79 <ul> 80 <li><code>svn co http://llvm.org/svn/llvm-project/libcxxabi/trunk libcxxabi</code></li> 81 </ul> 82 83 <p>To build:</p> 84 <ul> 85 <li>Check out libcxxabi into <code>llvm/projects</code></li> 86 <li><code>cd llvm</code></li> 87 <li><code>mkdir build && cd build</code></li> 88 <li><code>cmake .. # on linux you may need to prefix with CC=clang CXX=clang++</code></li> 89 <li><code>make</code></li> 90 </ul> 91 92 <p>To do a standalone build:</p> 93 <ul> 94 <li> 95 Check out the <a href="http://libcxx.llvm.org">libcxx source</a> tree. 96 </li> 97 <li><code>cd libcxxabi</code></li> 98 <li><code>mkdir build && cd build</code></li> 99 <li><code>cmake -DLIBCXXABI_LIBCXX_PATH=path/to/libcxx .. # on 100 linux you may need -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++</code></li> 101 <li><code>make</code></li> 102 </ul> 103 <p> By default CMake uses <code>llvm-config</code> to locate the required 104 LLVM sources. If CMake cannot find <code>llvm-config</code> then you must 105 configure CMake using either of the following options. 106 </p> 107 <ul> 108 <li><code>-DLLVM_CONFIG_PATH=path/to/llvm-config</code></li> 109 <li><code>-DLLVM_PATH=path/to/llvm-source-root</code></li> 110 </ul> 111 112 </p> 113 114 <p>To run the tests:</p> 115 <ul> 116 <li><code>make check-cxxabi</code></li> 117 </ul> 118 <p>Note: in a standalone build, the system's libc++ will be used for tests. If 119 the system's libc++ was statically linked against libc++abi (or linked against 120 a different ABI library), this may interfere with test results.</p> 121 122 <p>Send discussions to the 123 (<a href="http://lists.llvm.org/mailman/listinfo/libcxx-dev">libcxx-dev mailing list</a>).</p> 124 125 <!--=====================================================================--> 126 <h2>Frequently asked questions</h2> 127 <!--=====================================================================--> 128 129 <p>Q: Why are the destructors for the standard exception classes defined in libc++abi? 130 They're just empty, can't they be defined inline?</p> 131 <p>A: The destructors for them live in libc++abi because they are "key" functions. 132 The Itanium ABI describes a "key" function as the first virtual declared. 133 And wherever the key function is defined, that is where the <code>type_info</code> gets defined. 134 And in libc++ types are the same type if and only if they have the same <code>type_info</code> 135 (as in there must be only one type info per type in the entire application). 136 And on OS X, libstdc++ and libc++ share these exception types. 137 So to be able to throw in one dylib and catch in another (a <code>std::exception</code> for example), 138 there must be only one <code>std::exception type_info</code> in the entire app. 139 That typeinfo gets laid down beside <code>~exception()</code> in libc++abi (for both libstdc++ and libc++).</p> 140 <p>--Howard Hinnant</p> 141 142</div> 143</body> 144</html> 145