Gitiles
Code Review Sign In
gerrit-public.fairphone.software / fp2-dev / platform / external / clang / dc01a153f20be7121c4d3fdc17bb28ff4442231c / . / www / hacking.html
blob: 07a0d6c85bf585b655828fa28a2b25fa09a48c13 [file] [log] [blame]
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]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>Hacking on clang</title>
8 <link type="text/css" rel="stylesheet" href="menu.css" />
9 <link type="text/css" rel="stylesheet" href="content.css" />
10</head>
11<body>
12<!--#include virtual="menu.html.incl"-->
13<div id="content">
14 <!--*********************************************************************-->
15 <h1>Hacking on Clang</h1>
16 <!--*********************************************************************-->
17
18 <p>This document provides some hints for how to get started hacking
19 on Clang for developers who are new to the Clang and/or LLVM
20 codebases.</p>
21 <ul>
Daniel Dunbar79bba502010-01-22 02:04:46 +0000[diff] [blame]22 <li><a href="#style">Coding Standards</a></li>
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]23 <li><a href="#docs">Developer Documentation</a></li>
24 <li><a href="#debugging">Debugging</a></li>
25 <li><a href="#testing">Testing</a></li>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]26 <ul>
27 <li><a href="#testingNonWindows">Testing on Unix-like Systems</a></li>
28 <li><a href="#testingWindows">Testing using Visual Studio on Windows</a></li>
29 </ul>
30 <li><a href="#patches">Creating Patch Files</a></li>
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]31 <li><a href="#irgen">LLVM IR Generation</a></li>
32 </ul>
33
34 <!--=====================================================================-->
Daniel Dunbar79bba502010-01-22 02:04:46 +0000[diff] [blame]35 <h2 id="docs">Coding Standards</h2>
36 <!--=====================================================================-->
37
38 <p>Clang follows the
39 LLVM <a href="http://llvm.org/docs/CodingStandards.html">Coding
40 Standards</a>. When submitting patches, please take care to follow these standards
41 and to match the style of the code to that present in Clang (for example, in
42 terms of indentation, bracing, and statement spacing).</p>
43
44 <p>Clang has a few additional coding standards:</p>
45 <ul>
46 <li><i>cstdio is forbidden</i>: library code should not output diagnostics
47 or other information using <tt>cstdio</tt>; debugging routines should
48 use <tt>llvm::errs()</tt>. Other uses of <tt>cstdio</tt> impose behavior
49 upon clients and block integrating Clang as a library. Libraries should
50 support <tt>raw_ostream</tt> based interfaces for textual
51 output. See <a href="http://llvm.org/docs/CodingStandards.html#ll_raw_ostream">Coding
52 Standards</a>.</li>
53 </ul>
54
55 <!--=====================================================================-->
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]56 <h2 id="docs">Developer Documentation</h2>
57 <!--=====================================================================-->
58
59 <p>Both Clang and LLVM use doxygen to provide API documentation. Their
60 respective web pages (generated nightly) are here:</p>
61 <ul>
62 <li><a href="http://clang.llvm.org/doxygen">Clang</a></li>
63 <li><a href="http://llvm.org/doxygen">LLVM</a></li>
64 </ul>
65
66 <p>For work on the LLVM IR generation, the LLVM assembly language
67 <a href="http://llvm.org/docs/LangRef.html">reference manual</a> is
68 also useful.</p>
69
70 <!--=====================================================================-->
71 <h2 id="debugging">Debugging</h2>
72 <!--=====================================================================-->
73
74 <p>Inspecting data structures in a debugger:</p>
75 <ul>
76 <li>Many LLVM and Clang data structures provide
77 a <tt>dump()</tt> method which will print a description of the
78 data structure to <tt>stderr</tt>.</li>
79 <li>The <a href="docs/InternalsManual.html#QualType"><tt>QualType</tt></a>
80 structure is used pervasively. This is a simple value class for
81 wrapping types with qualifiers; you can use
82 the <tt>isConstQualified()</tt>, for example, to get one of the
83 qualifiers, and the <tt>getTypePtr()</tt> method to get the
84 wrapped <tt>Type*</tt> which you can then dump.</li>
85 </ul>
86
87 <!--=====================================================================-->
88 <h2 id="testing">Testing</h2>
89 <!--=====================================================================-->
90
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]91 <p><i>[Note: The test running mechanism is currently under revision, so the
92 following might change shortly.]</i></p>
93
94 <!--=====================================================================-->
95 <h3 id="testingNonWindows">Testing on Unix-like Systems</h3>
96 <!--=====================================================================-->
97
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]98 <p>Clang includes a basic regression suite in the tree which can be
99 run with <tt>make test</tt> from the top-level clang directory, or
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]100 just <tt>make</tt> in the <em>test</em> sub-directory.
101 <tt>make VERBOSE=1</tt> can be used to show more detail
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]102 about what is being run.</p>
103
Daniel Dunbardf293782010-06-10 17:01:45 +0000[diff] [blame]104 <p>If you built LLVM and Clang using CMake, the test suite can be run
105 with <tt>make clang-test</tt> from the top-level LLVM directory.</p>
106
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]107 <p>The tests primarily consist of a test runner script running the compiler
108 under test on individual test files grouped in the directories under the
109 test directory. The individual test files include comments at the
110 beginning indicating the Clang compile options to use, to be read
111 by the test runner. Embedded comments also can do things like telling
112 the test runner that an error is expected at the current line.
113 Any output files produced by the test will be placed under
114 a created Output directory.</p>
115
116 <p>During the run of <tt>make test</tt>, the terminal output will
117 display a line similar to the following:</p>
118
119 <ul><tt>--- Running clang tests for i686-pc-linux-gnu ---</tt></ul>
120
121 <p>followed by a line continually overwritten with the current test
122 file being compiled, and an overall completion percentage.</p>
123
124 <p>After the <tt>make test</tt> run completes, the absence of any
125 <tt>Failing Tests (count):</tt> message indicates that no tests
126 failed unexpectedly. If any tests did fail, the
127 <tt>Failing Tests (count):</tt> message will be followed by a list
128 of the test source file paths that failed. For example:</p>
129
130 <tt><pre>
131 Failing Tests (3):
132 /home/john/llvm/tools/clang/test/SemaCXX/member-name-lookup.cpp
133 /home/john/llvm/tools/clang/test/SemaCXX/namespace-alias.cpp
134 /home/john/llvm/tools/clang/test/SemaCXX/using-directive.cpp
135 </pre></tt>
136
137 <p>If you used the <tt>make VERBOSE=1</tt> option, the terminal
138 output will reflect the error messages from the compiler and
139 test runner.</p>
140
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]141 <p>The regression suite can also be run with Valgrind by running
142 <tt>make test VG=1</tt> in the top-level clang directory.</p>
143
144 <p>For more intensive changes, running
145 the <a href="http://llvm.org/docs/TestingGuide.html#testsuiterun">LLVM
146 Test Suite</a> with clang is recommended. Currently the best way to
Daniel Dunbar12e57bc2009-08-06 16:47:53 +0000[diff] [blame]147 override LLVMGCC, as in: <tt>make LLVMGCC="clang -std=gnu89"
148 TEST=nightly report</tt> (make sure <tt>clang</tt> is in your PATH or use the
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]149 full path).</p>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]150
151 <!--=====================================================================-->
152 <h3 id="testingWindows">Testing using Visual Studio on Windows</h3>
153 <!--=====================================================================-->
154
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]155 <p>The Clang test suite can be run from either Visual Studio or
156 the command line.</p>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]157
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]158 <p>Note that the test runner is based on
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]159 Python, which must be installed. Find Python at:
160 <a href="http://www.python.org/download">http://www.python.org/download</a>.
161 Download the latest stable version (2.6.2 at the time of this writing).</p>
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]162
163 <p>The GnuWin32 tools are also necessary for running the tests.
164 (Note that the grep from MSYS or Cygwin doesn't work with the tests
165 because of embedded double-quotes in the search strings. The GNU
166 grep does work in this case.)
167 Get them from <a href="http://getgnuwin32.sourceforge.net">
168 http://getgnuwin32.sourceforge.net</a>.</p>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]169
170 <p>The cmake build tool is set up to create Visual Studio project files
171 for running the tests, "clang-test" being the root. Therefore, to
172 run the test from Visual Studio, right-click the clang-test project
173 and select "Build".</p>
174
175 <p>To run all the tests from the command line, execute a command like
176 the following:</p>
177
178 <tt>
179 python (path to llvm)/llvm/utils/lit/lit.py -sv --no-progress-bar
180 (path to llvm)/llvm/tools/clang/test
181 </tt>
182
183 <p>To run a single test:</p>
184
185 <tt>
186 python (path to llvm)/llvm/utils/lit/lit.py -sv --no-progress-bar
187 (path to llvm)/llvm/tools/clang/test/(dir)/(test)
188 </tt>
189
190 <p>For example:</p>
191
192 <tt>
193 python C:/Tools/llvm/utils/lit/lit.py -sv --no-progress-bar
194 C:/Tools/llvm/tools/clang/test/Sema/wchar.c
195 </tt>
196
197 <p>The -sv option above tells the runner to show the test output if
198 any tests failed, to help you determine the cause of failure.</p>
199
200 <p>Note that a few tests currently fail on Windows. We are working to
201 correct this. Therefore your output might look something like this:</p>
202
203<tt><pre>lit.py: lit.cfg:152: note: using clang: 'C:/Tools/llvm/bin/Debug\\clang.EXE'
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]204-- Testing: 1723 tests, 2 threads --
205FAIL: Clang::(test path) (659 of 1723)
206******************** TEST 'Clang::(test path)' FAILED ********************
207Script:
208 (commands run)
209Command Output (stdout):
210 (output here)
211Command Output (stderr):
212 (output here)
213********************
214Testing Time: 83.66s
215********************
216Failing Tests (1):
217 Clang::(test path)
218 Expected Passes : 1704
219 Expected Failures : 18
220 Unexpected Failures: 1
221</pre></tt>
222
223 <p>The last statistic, "Unexpected Failures", is the important one.</p>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]224
225 <!--=====================================================================-->
226 <h2 id="patches">Creating Patch Files</h2>
227 <!--=====================================================================-->
228
229 <p>To return changes to the Clang team, unless you have checkin
230 privileges, the prefered way is to send patch files to the
231 cfe-commits mailing list, with an explanation of what the patch is for.
232 Or, if you have questions, or want to have a wider discussion of what
233 you are doing, such as if you are new to Clang development, you can use
234 the cfe-dev mailing list also.
235 </p>
236
237 <p>To create these patch files, change directory
238 to the llvm/tools/clang root and run:</p>
239
240 <ul><tt>svn diff (relative path) >(patch file name)</tt></ul>
241
242 <p>For example, for getting the diffs of all of clang:</p>
243
244 <ul><tt>svn diff . >~/mypatchfile.patch</tt></ul>
245
246 <p>For example, for getting the diffs of a single file:</p>
247
248 <ul><tt>svn diff lib/Parse/ParseDeclCXX.cpp >~/ParseDeclCXX.patch</tt></ul>
249
250 <p>Note that the paths embedded in the patch depend on where you run it,
251 so changing directory to the llvm/tools/clang directory is recommended.</p>
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]252
253 <!--=====================================================================-->
254 <h2 id="irgen">LLVM IR Generation</h2>
255 <!--=====================================================================-->
256
257 <p>The LLVM IR generation part of clang handles conversion of the
258 AST nodes output by the Sema module to the LLVM Intermediate
259 Representation (IR). Historically, this was referred to as
260 "codegen", and the Clang code for this lives
261 in <tt>lib/CodeGen</tt>.</p>
262
263 <p>The output is most easily inspected using the <tt>-emit-llvm</tt>
264 option to clang (possibly in conjunction with <tt>-o -</tt>). You
265 can also use <tt>-emit-llvm-bc</tt> to write an LLVM bitcode file
266 which can be processed by the suite of LLVM tools
267 like <tt>llvm-dis</tt>, <tt>llvm-nm</tt>, etc. See the LLVM
268 <a href="http://llvm.org/docs/CommandGuide/">Command Guide</a>
269 for more information.</p>
270
271</div>
272</body>
273</html>