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Chris Lattner29754e62007-12-09 08:17:09 +000014 <h1>clang: a C language family frontend for LLVM</h1>
15
Chris Lattner5ea74932007-12-09 09:05:23 +000016 <p>The goal of the Clang project is to create a new C, C++, Objective C and
17 Objective C++ front-end for the <a href="http://www.llvm.org/">LLVM</a>
18 compiler.</p>
Chris Lattner1c057262007-12-09 08:38:01 +000019
Chris Lattner6908f302007-12-10 05:52:05 +000020 <h2><a name="goals">Features and Goals</a></h2>
Chris Lattner48b7de62007-12-10 05:10:14 +000021
22 <p>Some of the goals for the project include the following:</p>
23
24 <ul>
25 <li>Real-world, production quality compiler.</li>
26 <li>A single unified parser for C, Objective C, C++, and Objective
27 C++.</li>
28 <li>Language conformance with these languages and their variants, like
29 C90, C99, etc.</li>
30 <li>GCC compatibility: support GCC extensions, but allow them to be
31 disabled.</li>
32 <li><a href="features.html#performance">High performance and low memory
33 use</a>.</li>
Chris Lattner48b7de62007-12-10 05:10:14 +000034 <li>Support many clients such as refactoring, static analysis, as well as
35 code generation.</li>
Chris Lattnerce90ba62007-12-10 05:20:47 +000036 <li>Build a library-based architecture with finely crafted APIs, allowing
37 the code to be reused in many ways.</li>
Chris Lattner48b7de62007-12-10 05:10:14 +000038 <li>Design for integration with IDEs as well as code generation with the
39 <a href="http://llvm.org">LLVM Optimizer and Code Generator</a>.</li>
40 <li><a href="features.html#expressivediags">Expressive diagnostics</a>:
41 warnings and errors that are actually helpful and make sense.</li>
42 <li>Use the LLVM <a
43 href="http://llvm.org/svn/llvm-project/cfe/trunk/LICENSE.TXT">'BSD'
44 License</a>.</li>
Chris Lattnerce90ba62007-12-10 05:20:47 +000045 <li>Finally, make the code clean and simple enough to make it understandable
46 to anyone who knows the languages involved and has a basic idea of
47 compilers work.</li>
Chris Lattner48b7de62007-12-10 05:10:14 +000048 </ul>
49
50 <p>Of course this is only a rough outline of the goals and features of
Chris Lattner1a380a02007-12-10 07:14:08 +000051 Clang. To get a true sense of what it is all about, see the <a
52 href="features.html">Features</a> section. The Features section breaks
53 each of these down and explains them in more detail.</p>
Chris Lattner48b7de62007-12-10 05:10:14 +000054
55
56 <h2>Why?</h2>
Chris Lattner5ea74932007-12-09 09:05:23 +000057
58 <p>The development of a new front-end was started out of a need -- a need
59 for a compiler that allows better diagnostics, better integration with
60 IDEs, a license that is compatible with commercial products, and a
Chris Lattner1a380a02007-12-10 07:14:08 +000061 nimble compiler that is easy to develop and maintain. All of these were
Chris Lattner5ea74932007-12-09 09:05:23 +000062 motivations for starting work on a new front-end that could
63 meet these needs.</p>
64
Chris Lattner65b3c272007-12-09 17:50:14 +000065 <p>A good (but quite dated) introduction to Clang can be found in the
Chris Lattner5ea74932007-12-09 09:05:23 +000066 following video lectures:</p>
67
Chris Lattner29754e62007-12-09 08:17:09 +000068 <ul>
69 <li><a href="clang_video-05-25-2007.html">Clang Introduction</a>
Chris Lattner5ea74932007-12-09 09:05:23 +000070 (May 2007)</li>
71 <li><a href="clang_video-07-25-2007.html">Features and Performance of
72 Clang</a> (July 2007)</li>
Chris Lattner29754e62007-12-09 08:17:09 +000073 </ul>
Chris Lattner5ea74932007-12-09 09:05:23 +000074
Chris Lattner48b7de62007-12-10 05:10:14 +000075 <p>For a more detailed comparison between Clang and other compilers, please
Chris Lattner2d8e3562007-12-10 02:25:51 +000076 see the <a href="comparison.html">clang comparison page</a>.</p>
77
Chris Lattner48b7de62007-12-10 05:10:14 +000078 <h2>Current Status</h2>
Chris Lattner5ea74932007-12-09 09:05:23 +000079
80 <p>Clang is still in early development stages. If you are looking for
81 source analysis or source-to-source transformation tools, clang is probably
82 a great solution for you. If you want to use it as a drop in C compiler, it
83 is not yet ready.</p>
84
85 <p>Clang currently has pretty good parsing and semantic analysis support for
86 C and Objective-C right now, and bugs are usually quickly fixed once
87 reported. C++ support is still very early, and we don't expect to have
88 respectable C++ support for another 2 years or so.</p>
89
Chris Lattner29754e62007-12-09 08:17:09 +000090 <h2>Get Involved</h2>
Chris Lattner5ea74932007-12-09 09:05:23 +000091
92 <p>The developers of Clang include contributers from Apple and numerous
93 other volunteers. If you are interested in joining the community or
94 learning more, please consider joining the <a
95 href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">cfe-dev</a>
96 mailing list, or start by browsing its archives.</p>
97
98 <p>If you are interested in trying out Clang, please see the build
Chris Lattner48b7de62007-12-10 05:10:14 +000099 instructions on the <a href="get_involved.html#build">Get Involved</a>
Chris Lattner5ea74932007-12-09 09:05:23 +0000100 page.</p>
Chris Lattner29754e62007-12-09 08:17:09 +0000101 </div>
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