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17 <!--*********************************************************************-->
18 <h1>Hacking on Clang</h1>
19 <!--*********************************************************************-->
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]20
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]21 <p>This document provides some hints for how to get started hacking
22 on Clang for developers who are new to the Clang and/or LLVM
23 codebases.</p>
24 <ul>
Daniel Dunbar79bba502010-01-22 02:04:46 +0000[diff] [blame]25 <li><a href="#style">Coding Standards</a></li>
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]26 <li><a href="#docs">Developer Documentation</a></li>
27 <li><a href="#debugging">Debugging</a></li>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]28 <li><a href="#testing">Testing</a>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]29 <ul>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]30 <li><a href="#testingNonWindows">Testing on Unix-like Systems</a></li>
31 <li><a href="#testingWindows">Testing using Visual Studio on Windows</a></li>
32 <li><a href="#testingCommands">Testing on the Command Line</a></li>
33 </ul>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]34 </li>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]35 <li><a href="#patches">Creating Patch Files</a></li>
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]36 <li><a href="#irgen">LLVM IR Generation</a></li>
37 </ul>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]38
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]39 <!--=====================================================================-->
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]40 <h2 id="style">Coding Standards</h2>
Daniel Dunbar79bba502010-01-22 02:04:46 +0000[diff] [blame]41 <!--=====================================================================-->
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]42
Daniel Dunbar79bba502010-01-22 02:04:46 +0000[diff] [blame]43 <p>Clang follows the
44 LLVM <a href="http://llvm.org/docs/CodingStandards.html">Coding
45 Standards</a>. When submitting patches, please take care to follow these standards
46 and to match the style of the code to that present in Clang (for example, in
47 terms of indentation, bracing, and statement spacing).</p>
48
49 <p>Clang has a few additional coding standards:</p>
50 <ul>
51 <li><i>cstdio is forbidden</i>: library code should not output diagnostics
52 or other information using <tt>cstdio</tt>; debugging routines should
53 use <tt>llvm::errs()</tt>. Other uses of <tt>cstdio</tt> impose behavior
54 upon clients and block integrating Clang as a library. Libraries should
55 support <tt>raw_ostream</tt> based interfaces for textual
56 output. See <a href="http://llvm.org/docs/CodingStandards.html#ll_raw_ostream">Coding
57 Standards</a>.</li>
58 </ul>
59
60 <!--=====================================================================-->
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]61 <h2 id="docs">Developer Documentation</h2>
62 <!--=====================================================================-->
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]63
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]64 <p>Both Clang and LLVM use doxygen to provide API documentation. Their
65 respective web pages (generated nightly) are here:</p>
66 <ul>
67 <li><a href="http://clang.llvm.org/doxygen">Clang</a></li>
68 <li><a href="http://llvm.org/doxygen">LLVM</a></li>
69 </ul>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]70
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]71 <p>For work on the LLVM IR generation, the LLVM assembly language
72 <a href="http://llvm.org/docs/LangRef.html">reference manual</a> is
73 also useful.</p>
74
75 <!--=====================================================================-->
76 <h2 id="debugging">Debugging</h2>
77 <!--=====================================================================-->
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]78
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]79 <p>Inspecting data structures in a debugger:</p>
80 <ul>
81 <li>Many LLVM and Clang data structures provide
82 a <tt>dump()</tt> method which will print a description of the
83 data structure to <tt>stderr</tt>.</li>
84 <li>The <a href="docs/InternalsManual.html#QualType"><tt>QualType</tt></a>
85 structure is used pervasively. This is a simple value class for
86 wrapping types with qualifiers; you can use
87 the <tt>isConstQualified()</tt>, for example, to get one of the
88 qualifiers, and the <tt>getTypePtr()</tt> method to get the
89 wrapped <tt>Type*</tt> which you can then dump.</li>
90 </ul>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]91
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]92 <!--=====================================================================-->
Douglas Gregor3ef1ad22011-07-27 05:22:46 +0000[diff] [blame]93 <h3 id="debuggingVisualStudio">Debugging using Visual Studio</h3>
94 <!--=====================================================================-->
95
96 <p>The file <tt>utils/clangVisualizers.txt</tt> provides debugger visualizers that make debugging
97 of more complex data types much easier.</p>
98 <p>There are two ways to install them:</p>
99
100 <ul>
101 <li>Put the path to <tt>clangVisualizers.txt</tt> in the environment variable called
102 <tt>_vcee_autoexp</tt>. This method should work for Visual Studio 2008 and above.
103 </li>
104 <li>Edit your local <tt>autoexp.dat</tt> (make sure you make a backup first!),
105 located in <tt>Visual Studio Directory\Common7\Packages\Debugger</tt> and append
106 the contents of <tt>clangVisuailzers.txt</tt> to it. This method should work for
Chandler Carruth245a5382011-11-16 19:29:07 +0000[diff] [blame]107 Visual Studio 2008 and above.
Douglas Gregor3ef1ad22011-07-27 05:22:46 +0000[diff] [blame]108 </li>
109 </ul>
110
111 <p><i>[Note: To disable the visualizer for any specific variable, type
112 <tt>variable_name,!</tt> inside the watch window.]</i></p>
113
114 <!--=====================================================================-->
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]115 <h2 id="testing">Testing</h2>
116 <!--=====================================================================-->
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]117
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]118 <p><i>[Note: The test running mechanism is currently under revision, so the
119 following might change shortly.]</i></p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]120
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]121 <!--=====================================================================-->
122 <h3 id="testingNonWindows">Testing on Unix-like Systems</h3>
123 <!--=====================================================================-->
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]124
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]125 <p>Clang includes a basic regression suite in the tree which can be
126 run with <tt>make test</tt> from the top-level clang directory, or
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]127 just <tt>make</tt> in the <em>test</em> sub-directory.
128 <tt>make VERBOSE=1</tt> can be used to show more detail
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]129 about what is being run.</p>
130
Daniel Dunbardf293782010-06-10 17:01:45 +0000[diff] [blame]131 <p>If you built LLVM and Clang using CMake, the test suite can be run
132 with <tt>make clang-test</tt> from the top-level LLVM directory.</p>
133
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]134 <p>The tests primarily consist of a test runner script running the compiler
135 under test on individual test files grouped in the directories under the
136 test directory. The individual test files include comments at the
137 beginning indicating the Clang compile options to use, to be read
138 by the test runner. Embedded comments also can do things like telling
139 the test runner that an error is expected at the current line.
140 Any output files produced by the test will be placed under
141 a created Output directory.</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]142
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]143 <p>During the run of <tt>make test</tt>, the terminal output will
144 display a line similar to the following:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]145
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]146 <pre>--- Running clang tests for i686-pc-linux-gnu ---</pre>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]147
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]148 <p>followed by a line continually overwritten with the current test
149 file being compiled, and an overall completion percentage.</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]150
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]151 <p>After the <tt>make test</tt> run completes, the absence of any
152 <tt>Failing Tests (count):</tt> message indicates that no tests
153 failed unexpectedly. If any tests did fail, the
154 <tt>Failing Tests (count):</tt> message will be followed by a list
155 of the test source file paths that failed. For example:</p>
156
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]157 <pre>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]158 Failing Tests (3):
159 /home/john/llvm/tools/clang/test/SemaCXX/member-name-lookup.cpp
160 /home/john/llvm/tools/clang/test/SemaCXX/namespace-alias.cpp
161 /home/john/llvm/tools/clang/test/SemaCXX/using-directive.cpp
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]162</pre>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]163
164 <p>If you used the <tt>make VERBOSE=1</tt> option, the terminal
165 output will reflect the error messages from the compiler and
166 test runner.</p>
167
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]168 <p>The regression suite can also be run with Valgrind by running
169 <tt>make test VG=1</tt> in the top-level clang directory.</p>
170
171 <p>For more intensive changes, running
172 the <a href="http://llvm.org/docs/TestingGuide.html#testsuiterun">LLVM
173 Test Suite</a> with clang is recommended. Currently the best way to
Daniel Dunbar12e57bc2009-08-06 16:47:53 +0000[diff] [blame]174 override LLVMGCC, as in: <tt>make LLVMGCC="clang -std=gnu89"
175 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]176 full path).</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]177
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]178 <!--=====================================================================-->
179 <h3 id="testingWindows">Testing using Visual Studio on Windows</h3>
180 <!--=====================================================================-->
181
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]182 <p>The Clang test suite can be run from either Visual Studio or
183 the command line.</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]184
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]185 <p>Note that the test runner is based on
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]186 Python, which must be installed. Find Python at:
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]187 <a href="http://www.python.org/download/">http://www.python.org/download/</a>.
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]188 Download the latest stable version (2.6.2 at the time of this writing).</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]189
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]190 <p>The GnuWin32 tools are also necessary for running the tests.
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]191 Get them from <a href="http://getgnuwin32.sourceforge.net/">
NAKAMURA Takumida0f45d2011-03-18 03:21:44 +0000[diff] [blame]192 http://getgnuwin32.sourceforge.net/</a>.
193 If the environment variable <tt>%PATH%</tt> does not have GnuWin32,
194 or if other grep(s) supercedes GnuWin32 on <tt>%PATH%,</tt>
195 you should specify <tt>LLVM_LIT_TOOLS_DIR</tt>
196 to CMake explicitly.</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]197
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]198 <p>The cmake build tool is set up to create Visual Studio project files
199 for running the tests, "clang-test" being the root. Therefore, to
200 run the test from Visual Studio, right-click the clang-test project
201 and select "Build".</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]202
NAKAMURA Takumida0f45d2011-03-18 03:21:44 +0000[diff] [blame]203 <p>
204 Please see also
205 <a href="http://llvm.org/docs/GettingStartedVS.html">Getting Started
206 with the LLVM System using Microsoft Visual Studio</a> and
207 <a href="http://llvm.org/docs/CMake.html">Building LLVM with CMake</a>.
208 </p>
209
Dawn Perchik217a3452010-09-03 17:01:13 +0000[diff] [blame]210 <!--=====================================================================-->
211 <h3 id="testingCommands">Testing on the Command Line</h3>
212 <!--=====================================================================-->
213
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]214 <p>To run all the tests from the command line, execute a command like
215 the following:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]216
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]217 <pre>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]218 python (path to llvm)/llvm/utils/lit/lit.py -sv --no-progress-bar
219 (path to llvm)/llvm/tools/clang/test
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]220</pre>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]221
Douglas Gregora71ef5d2011-01-24 18:04:58 +0000[diff] [blame]222 <p>For CMake builds e.g. on Windows with Visual Studio, you will need
223 to specify your build configuration (Debug, Release, etc.) via
224 <tt>--param=build_config=(build config)</tt>.</p>
225
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]226 <p>To run a single test:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]227
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]228 <pre>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]229 python (path to llvm)/llvm/utils/lit/lit.py -sv --no-progress-bar
230 (path to llvm)/llvm/tools/clang/test/(dir)/(test)
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]231</pre>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]232
233 <p>For example:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]234
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]235 <pre>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]236 python C:/Tools/llvm/utils/lit/lit.py -sv --no-progress-bar
237 C:/Tools/llvm/tools/clang/test/Sema/wchar.c
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]238</pre>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]239
240 <p>The -sv option above tells the runner to show the test output if
241 any tests failed, to help you determine the cause of failure.</p>
242
Francois Pichetb2043d72010-09-11 21:16:11 +0000[diff] [blame]243 <p>Your output might look something like this:</p>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]244
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]245 <pre>lit.py: lit.cfg:152: note: using clang: 'C:/Tools/llvm/bin/Release\\clang.EXE'
Francois Pichetb2043d72010-09-11 21:16:11 +0000[diff] [blame]246-- Testing: Testing: 2534 tests, 4 threads --
247Testing: 0 .. 10.. 20.. 30.. 40.. 50.. 60.. 70.. 80.. 90..
248Testing Time: 81.52s
249 Expected Passes : 2503
250 Expected Failures : 28
251 Unsupported Tests : 3
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]252</pre>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]253
Francois Pichetb2043d72010-09-11 21:16:11 +0000[diff] [blame]254 <p>The statistic, "Unexpected Failures" (not shown if all tests pass), is the important one.</p>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]255
256 <!--=====================================================================-->
257 <h2 id="patches">Creating Patch Files</h2>
258 <!--=====================================================================-->
259
260 <p>To return changes to the Clang team, unless you have checkin
Chris Lattnerfc8f0e12011-04-15 05:22:18 +0000[diff] [blame]261 privileges, the preferred way is to send patch files to the
Douglas Gregor8b06d6b2011-11-19 19:14:26 +0000[diff] [blame]262 cfe-commits mailing list, with an explanation of what the patch is
263 for. If your patch requires a wider discussion (for example,
264 because it is an architectural change), you can use the cfe-dev
265 mailing list. </p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]266
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]267 <p>To create these patch files, change directory
268 to the llvm/tools/clang root and run:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]269
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]270 <pre>svn diff (relative path) >(patch file name)</pre>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]271
272 <p>For example, for getting the diffs of all of clang:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]273
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]274 <pre>svn diff . >~/mypatchfile.patch</pre>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]275
276 <p>For example, for getting the diffs of a single file:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]277
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]278 <pre>svn diff lib/Parse/ParseDeclCXX.cpp >~/ParseDeclCXX.patch</pre>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]279
280 <p>Note that the paths embedded in the patch depend on where you run it,
281 so changing directory to the llvm/tools/clang directory is recommended.</p>
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]282
283 <!--=====================================================================-->
284 <h2 id="irgen">LLVM IR Generation</h2>
285 <!--=====================================================================-->
286
287 <p>The LLVM IR generation part of clang handles conversion of the
288 AST nodes output by the Sema module to the LLVM Intermediate
289 Representation (IR). Historically, this was referred to as
290 "codegen", and the Clang code for this lives
291 in <tt>lib/CodeGen</tt>.</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]292
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]293 <p>The output is most easily inspected using the <tt>-emit-llvm</tt>
294 option to clang (possibly in conjunction with <tt>-o -</tt>). You
295 can also use <tt>-emit-llvm-bc</tt> to write an LLVM bitcode file
296 which can be processed by the suite of LLVM tools
297 like <tt>llvm-dis</tt>, <tt>llvm-nm</tt>, etc. See the LLVM
298 <a href="http://llvm.org/docs/CommandGuide/">Command Guide</a>
299 for more information.</p>
300
301</div>
302</body>
303</html>