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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>
Argyrios Kyrtzidis40b48a12012-11-16 00:25:28 +0000[diff] [blame]90 <li>For <a href="http://lldb.llvm.org"> <tt>LLDB</tt></a> users there are
91 data formatters for clang data structures in
92 <a href="http://llvm.org/svn/llvm-project/cfe/trunk/utils/ClangDataFormat.py">
93 <tt>utils/ClangDataFormat.py</tt></a>.</li>
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]94 </ul>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]95
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]96 <!--=====================================================================-->
Douglas Gregor3ef1ad22011-07-27 05:22:46 +0000[diff] [blame]97 <h3 id="debuggingVisualStudio">Debugging using Visual Studio</h3>
98 <!--=====================================================================-->
99
100 <p>The file <tt>utils/clangVisualizers.txt</tt> provides debugger visualizers that make debugging
101 of more complex data types much easier.</p>
102 <p>There are two ways to install them:</p>
103
104 <ul>
105 <li>Put the path to <tt>clangVisualizers.txt</tt> in the environment variable called
106 <tt>_vcee_autoexp</tt>. This method should work for Visual Studio 2008 and above.
107 </li>
108 <li>Edit your local <tt>autoexp.dat</tt> (make sure you make a backup first!),
109 located in <tt>Visual Studio Directory\Common7\Packages\Debugger</tt> and append
110 the contents of <tt>clangVisuailzers.txt</tt> to it. This method should work for
Chandler Carruth245a5382011-11-16 19:29:07 +0000[diff] [blame]111 Visual Studio 2008 and above.
Douglas Gregor3ef1ad22011-07-27 05:22:46 +0000[diff] [blame]112 </li>
113 </ul>
114
115 <p><i>[Note: To disable the visualizer for any specific variable, type
116 <tt>variable_name,!</tt> inside the watch window.]</i></p>
117
118 <!--=====================================================================-->
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]119 <h2 id="testing">Testing</h2>
120 <!--=====================================================================-->
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]121
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]122 <p><i>[Note: The test running mechanism is currently under revision, so the
123 following might change shortly.]</i></p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]124
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]125 <!--=====================================================================-->
126 <h3 id="testingNonWindows">Testing on Unix-like Systems</h3>
127 <!--=====================================================================-->
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]128
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]129 <p>Clang includes a basic regression suite in the tree which can be
130 run with <tt>make test</tt> from the top-level clang directory, or
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]131 just <tt>make</tt> in the <em>test</em> sub-directory.
132 <tt>make VERBOSE=1</tt> can be used to show more detail
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]133 about what is being run.</p>
134
Daniel Dunbardf293782010-06-10 17:01:45 +0000[diff] [blame]135 <p>If you built LLVM and Clang using CMake, the test suite can be run
136 with <tt>make clang-test</tt> from the top-level LLVM directory.</p>
137
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]138 <p>The tests primarily consist of a test runner script running the compiler
139 under test on individual test files grouped in the directories under the
140 test directory. The individual test files include comments at the
141 beginning indicating the Clang compile options to use, to be read
142 by the test runner. Embedded comments also can do things like telling
143 the test runner that an error is expected at the current line.
144 Any output files produced by the test will be placed under
145 a created Output directory.</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]146
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]147 <p>During the run of <tt>make test</tt>, the terminal output will
148 display a line similar to the following:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]149
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]150 <pre>--- Running clang tests for i686-pc-linux-gnu ---</pre>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]151
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]152 <p>followed by a line continually overwritten with the current test
153 file being compiled, and an overall completion percentage.</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]154
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]155 <p>After the <tt>make test</tt> run completes, the absence of any
156 <tt>Failing Tests (count):</tt> message indicates that no tests
157 failed unexpectedly. If any tests did fail, the
158 <tt>Failing Tests (count):</tt> message will be followed by a list
159 of the test source file paths that failed. For example:</p>
160
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]161 <pre>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]162 Failing Tests (3):
163 /home/john/llvm/tools/clang/test/SemaCXX/member-name-lookup.cpp
164 /home/john/llvm/tools/clang/test/SemaCXX/namespace-alias.cpp
165 /home/john/llvm/tools/clang/test/SemaCXX/using-directive.cpp
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]166</pre>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]167
168 <p>If you used the <tt>make VERBOSE=1</tt> option, the terminal
169 output will reflect the error messages from the compiler and
170 test runner.</p>
171
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]172 <p>The regression suite can also be run with Valgrind by running
173 <tt>make test VG=1</tt> in the top-level clang directory.</p>
174
175 <p>For more intensive changes, running
176 the <a href="http://llvm.org/docs/TestingGuide.html#testsuiterun">LLVM
177 Test Suite</a> with clang is recommended. Currently the best way to
Daniel Dunbar12e57bc2009-08-06 16:47:53 +0000[diff] [blame]178 override LLVMGCC, as in: <tt>make LLVMGCC="clang -std=gnu89"
179 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]180 full path).</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]181
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]182 <!--=====================================================================-->
183 <h3 id="testingWindows">Testing using Visual Studio on Windows</h3>
184 <!--=====================================================================-->
185
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]186 <p>The Clang test suite can be run from either Visual Studio or
187 the command line.</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]188
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]189 <p>Note that the test runner is based on
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]190 Python, which must be installed. Find Python at:
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]191 <a href="http://www.python.org/download/">http://www.python.org/download/</a>.
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]192 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]193
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]194 <p>The GnuWin32 tools are also necessary for running the tests.
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]195 Get them from <a href="http://getgnuwin32.sourceforge.net/">
NAKAMURA Takumida0f45d2011-03-18 03:21:44 +0000[diff] [blame]196 http://getgnuwin32.sourceforge.net/</a>.
197 If the environment variable <tt>%PATH%</tt> does not have GnuWin32,
198 or if other grep(s) supercedes GnuWin32 on <tt>%PATH%,</tt>
199 you should specify <tt>LLVM_LIT_TOOLS_DIR</tt>
200 to CMake explicitly.</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]201
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]202 <p>The cmake build tool is set up to create Visual Studio project files
203 for running the tests, "clang-test" being the root. Therefore, to
204 run the test from Visual Studio, right-click the clang-test project
205 and select "Build".</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]206
NAKAMURA Takumida0f45d2011-03-18 03:21:44 +0000[diff] [blame]207 <p>
208 Please see also
209 <a href="http://llvm.org/docs/GettingStartedVS.html">Getting Started
210 with the LLVM System using Microsoft Visual Studio</a> and
211 <a href="http://llvm.org/docs/CMake.html">Building LLVM with CMake</a>.
212 </p>
213
Dawn Perchik217a3452010-09-03 17:01:13 +0000[diff] [blame]214 <!--=====================================================================-->
215 <h3 id="testingCommands">Testing on the Command Line</h3>
216 <!--=====================================================================-->
217
Eli Friedman275a8502012-04-16 05:04:45 +0000[diff] [blame]218 <p>If you want more control over how the tests are run, it may
219 be convenient to run the test harness on the command-line directly. Before
220 running tests from the command line, you will need to ensure that
221 <tt>lit.site.cfg</tt> files have been created for your build. You can do
222 this by running the tests as described in the previous sections. Once the
223 tests have started running, you can stop them with control+C, as the
224 files are generated before running any tests.</p>
225
226 <p>Once that is done, to run all the tests from the command line,
227 execute a command like the following:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]228
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]229 <pre>
Aaron Ballmane7d923d2012-02-09 15:23:18 +0000[diff] [blame]230 python (path to llvm)\llvm\utils\lit\lit.py -sv
231 --param=build_mode=Win32 --param=build_config=Debug
232 --param=clang_site_config=(build dir)\tools\clang\test\lit.site.cfg
233 (path to llvm)\llvm\tools\clang\test
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]234</pre>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]235
Douglas Gregora71ef5d2011-01-24 18:04:58 +0000[diff] [blame]236 <p>For CMake builds e.g. on Windows with Visual Studio, you will need
237 to specify your build configuration (Debug, Release, etc.) via
Aaron Ballmane7d923d2012-02-09 15:23:18 +0000[diff] [blame]238 <tt>--param=build_config=(build config)</tt>. You may also need to specify
239 the build mode (Win32, etc) via <tt>--param=build_mode=(build mode)</tt>.</p>
240
241 <p>Additionally, you will need to specify the lit site configuration which
242 lives in (build dir)\tools\clang\test, via
243 <tt>--param=clang_site_config=(build dir)\tools\clang\test\lit.site.cfg</tt>.
244 </p>
Douglas Gregora71ef5d2011-01-24 18:04:58 +0000[diff] [blame]245
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]246 <p>To run a single test:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]247
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]248 <pre>
Aaron Ballmane7d923d2012-02-09 15:23:18 +0000[diff] [blame]249 python (path to llvm)\llvm\utils\lit\lit.py -sv
250 --param=build_mode=Win32 --param=build_config=Debug
251 --param=clang_site_config=(build dir)\tools\clang\test\lit.site.cfg
252 (path to llvm)\llvm\tools\clang\test\(dir)\(test)
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]253</pre>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]254
255 <p>For example:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]256
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]257 <pre>
Aaron Ballmane7d923d2012-02-09 15:23:18 +0000[diff] [blame]258 python C:\Tool\llvm\utils\lit\lit.py -sv
259 --param=build_mode=Win32 --param=build_config=Debug
260 --param=clang_site_config=c:\Tools\build\tools\clang\test\lit.site.cfg
261 C:\Tools\llvm\tools\clang\test\Sema\wchar.c
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]262</pre>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]263
264 <p>The -sv option above tells the runner to show the test output if
265 any tests failed, to help you determine the cause of failure.</p>
266
Aaron Ballmane7d923d2012-02-09 15:23:18 +0000[diff] [blame]267 <p>You can also pass in the --no-progress-bar option if you wish to disable
268 progress indications while the tests are running.</p>
269
Francois Pichetb2043d72010-09-11 21:16:11 +0000[diff] [blame]270 <p>Your output might look something like this:</p>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]271
Aaron Ballmane7d923d2012-02-09 15:23:18 +0000[diff] [blame]272 <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]273-- Testing: Testing: 2534 tests, 4 threads --
274Testing: 0 .. 10.. 20.. 30.. 40.. 50.. 60.. 70.. 80.. 90..
275Testing Time: 81.52s
276 Expected Passes : 2503
277 Expected Failures : 28
278 Unsupported Tests : 3
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]279</pre>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]280
Francois Pichetb2043d72010-09-11 21:16:11 +0000[diff] [blame]281 <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]282
283 <!--=====================================================================-->
284 <h2 id="patches">Creating Patch Files</h2>
285 <!--=====================================================================-->
286
287 <p>To return changes to the Clang team, unless you have checkin
Chris Lattnerfc8f0e12011-04-15 05:22:18 +0000[diff] [blame]288 privileges, the preferred way is to send patch files to the
Douglas Gregor8b06d6b2011-11-19 19:14:26 +0000[diff] [blame]289 cfe-commits mailing list, with an explanation of what the patch is
290 for. If your patch requires a wider discussion (for example,
291 because it is an architectural change), you can use the cfe-dev
292 mailing list. </p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]293
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]294 <p>To create these patch files, change directory
295 to the llvm/tools/clang root and run:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]296
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]297 <pre>svn diff (relative path) >(patch file name)</pre>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]298
299 <p>For example, for getting the diffs of all of clang:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]300
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]301 <pre>svn diff . >~/mypatchfile.patch</pre>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]302
303 <p>For example, for getting the diffs of a single file:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]304
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]305 <pre>svn diff lib/Parse/ParseDeclCXX.cpp >~/ParseDeclCXX.patch</pre>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]306
307 <p>Note that the paths embedded in the patch depend on where you run it,
308 so changing directory to the llvm/tools/clang directory is recommended.</p>
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]309
310 <!--=====================================================================-->
311 <h2 id="irgen">LLVM IR Generation</h2>
312 <!--=====================================================================-->
313
314 <p>The LLVM IR generation part of clang handles conversion of the
315 AST nodes output by the Sema module to the LLVM Intermediate
316 Representation (IR). Historically, this was referred to as
317 "codegen", and the Clang code for this lives
318 in <tt>lib/CodeGen</tt>.</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]319
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]320 <p>The output is most easily inspected using the <tt>-emit-llvm</tt>
321 option to clang (possibly in conjunction with <tt>-o -</tt>). You
322 can also use <tt>-emit-llvm-bc</tt> to write an LLVM bitcode file
323 which can be processed by the suite of LLVM tools
324 like <tt>llvm-dis</tt>, <tt>llvm-nm</tt>, etc. See the LLVM
325 <a href="http://llvm.org/docs/CommandGuide/">Command Guide</a>
326 for more information.</p>
327
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