| Daniel Dunbar | 0d7c3f9 | 2008-11-13 22:49:41 +0000 | [diff] [blame^] | 1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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| 4 | <html>
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| 5 | <head>
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| 6 | <META http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" />
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| 7 | <title>Hacking on clang</title>
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| 8 | <link type="text/css" rel="stylesheet" href="menu.css" />
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| 10 | </head>
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| 11 | <body>
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| 12 | <!--#include virtual="menu.html.incl"-->
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| 13 | <div id="content">
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| 14 | <!--*********************************************************************-->
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| 15 | <h1>Hacking on Clang</h1>
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| 16 | <!--*********************************************************************-->
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| 17 |
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| 18 | <p>This document provides some hints for how to get started hacking
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| 19 | on Clang for developers who are new to the Clang and/or LLVM
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| 20 | codebases.
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| 21 | <ul>
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| 22 | <li><a href="#docs">Developer Documentation</a></li>
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| 23 | <li><a href="#debugging">Debugging</a></li>
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| 24 | <li><a href="#irgen">LLVM IR Generation</a></li>
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| 25 | </ul>
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| 26 | </p>
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| 27 |
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| 28 | <!--=====================================================================-->
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| 29 | <h2 id="debugging">Developer Documentation</h2>
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| 30 | <!--=====================================================================-->
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| 31 |
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| 32 | <p>Both Clang and LLVM use doxygen to provide API documentation. Their
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| 33 | respective web pages (generated nightly) are here:
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| 34 | <ul>
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| 35 | <li><a href="http://clang.llvm.org/doxygen">Clang</a></li>
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| 36 | <li><a href="http://llvm.org/doxygen">LLVM</a></li>
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| 37 | </ul>
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| 38 | </p>
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| 39 |
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| 40 | <p>For work on the LLVM IR generation, the LLVM assembly language
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| 41 | <a href="http://llvm.org/docs/LangRef.html">reference manual</a> is
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| 42 | also useful.</p>
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| 43 |
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| 44 | <!--=====================================================================-->
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| 45 | <h2 id="debugging">Debugging</h2>
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| 46 | <!--=====================================================================-->
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| 47 |
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| 48 | <p>Inspecting data structures in a debugger:
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| 49 | <ul>
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| 50 | <li>Many LLVM and Clang data structures provide
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| 51 | a <tt>dump()</tt> method which will print a description of the
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| 52 | data structure to <tt>stderr</tt>.</li>
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| 53 | <li>The <a href="docs/InternalsManual.html#QualType"><tt>QualType</tt></a>
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| 54 | structure is used pervasively. This is a simple value class for
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| 55 | wrapping types with qualifiers; you can use
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| 56 | the <tt>isConstQualified()</tt>, for example, to get one of the
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| 57 | qualifiers, and the <tt>getTypePtr()</tt> method to get the
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| 58 | wrapped <tt>Type*</tt> which you can then dump.</li>
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| 59 | </ul>
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| 60 | </p>
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| 61 |
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| 62 | <!--=====================================================================-->
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| 63 | <h2 id="irgen">LLVM IR Generation</h2>
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| 64 | <!--=====================================================================-->
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| 65 |
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| 66 | <p>The LLVM IR generation part of clang handles conversion of the
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| 67 | AST nodes output by the Sema module to the LLVM Intermediate
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| 68 | Representation (IR). Historically, this was referred to as
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| 69 | "codegen", and the Clang code for this lives
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| 70 | in <tt>lib/CodeGen</tt>.</p>
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| 71 |
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| 72 | <p>The output is most easily inspected using the <tt>-emit-llvm</tt>
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| 73 | option to clang (possibly in conjunction with <tt>-o -</tt>). You
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| 74 | can also use <tt>-emit-llvm-bc</tt> to write an LLVM bitcode file
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| 75 | which can be processed by the suite of LLVM tools
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| 76 | like <tt>llvm-dis</tt>, <tt>llvm-nm</tt>, etc. See the LLVM
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| 77 | <a href="http://llvm.org/docs/CommandGuide/">Command Guide</tt>
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| 78 | for more information.</p>
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| 79 |
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| 80 | </div>
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| 81 | </body>
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| 82 | </html>
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