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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
Stephen Hines651f13c2014-04-23 16:59:28 -0700[diff] [blame]100 <p>The files
101 <a href="http://llvm.org/svn/llvm-project/llvm/trunk/utils/llvm.natvis">
102 <tt>utils/llvm.natvis</tt></a> and
103 <a href="http://llvm.org/svn/llvm-project/cfe/trunk/utils/clang.natvis">
104 <tt>utils/clang.natvis</tt></a> provide debugger visualizers
105 that make debugging of more complex data types much easier.</p>
106 <p>Put the files into
107 <tt>%USERPROFILE%\Documents\Visual Studio 2012\Visualizers</tt> or
108 create a symbolic link so they update automatically.</p>
Douglas Gregor3ef1ad22011-07-27 05:22:46 +0000[diff] [blame]109
110 <!--=====================================================================-->
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]111 <h2 id="testing">Testing</h2>
112 <!--=====================================================================-->
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]113
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]114 <p><i>[Note: The test running mechanism is currently under revision, so the
115 following might change shortly.]</i></p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]116
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]117 <!--=====================================================================-->
118 <h3 id="testingNonWindows">Testing on Unix-like Systems</h3>
119 <!--=====================================================================-->
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]120
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]121 <p>Clang includes a basic regression suite in the tree which can be
122 run with <tt>make test</tt> from the top-level clang directory, or
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]123 just <tt>make</tt> in the <em>test</em> sub-directory.
124 <tt>make VERBOSE=1</tt> can be used to show more detail
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]125 about what is being run.</p>
126
Daniel Dunbardf293782010-06-10 17:01:45 +0000[diff] [blame]127 <p>If you built LLVM and Clang using CMake, the test suite can be run
128 with <tt>make clang-test</tt> from the top-level LLVM directory.</p>
129
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]130 <p>The tests primarily consist of a test runner script running the compiler
131 under test on individual test files grouped in the directories under the
132 test directory. The individual test files include comments at the
133 beginning indicating the Clang compile options to use, to be read
134 by the test runner. Embedded comments also can do things like telling
135 the test runner that an error is expected at the current line.
136 Any output files produced by the test will be placed under
137 a created Output directory.</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]138
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]139 <p>During the run of <tt>make test</tt>, the terminal output will
140 display a line similar to the following:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]141
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]142 <pre>--- Running clang tests for i686-pc-linux-gnu ---</pre>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]143
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]144 <p>followed by a line continually overwritten with the current test
145 file being compiled, and an overall completion percentage.</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]146
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]147 <p>After the <tt>make test</tt> run completes, the absence of any
148 <tt>Failing Tests (count):</tt> message indicates that no tests
149 failed unexpectedly. If any tests did fail, the
150 <tt>Failing Tests (count):</tt> message will be followed by a list
151 of the test source file paths that failed. For example:</p>
152
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]153 <pre>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]154 Failing Tests (3):
155 /home/john/llvm/tools/clang/test/SemaCXX/member-name-lookup.cpp
156 /home/john/llvm/tools/clang/test/SemaCXX/namespace-alias.cpp
157 /home/john/llvm/tools/clang/test/SemaCXX/using-directive.cpp
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]158</pre>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]159
160 <p>If you used the <tt>make VERBOSE=1</tt> option, the terminal
161 output will reflect the error messages from the compiler and
162 test runner.</p>
163
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]164 <p>The regression suite can also be run with Valgrind by running
165 <tt>make test VG=1</tt> in the top-level clang directory.</p>
166
167 <p>For more intensive changes, running
168 the <a href="http://llvm.org/docs/TestingGuide.html#testsuiterun">LLVM
169 Test Suite</a> with clang is recommended. Currently the best way to
Daniel Dunbar12e57bc2009-08-06 16:47:53 +0000[diff] [blame]170 override LLVMGCC, as in: <tt>make LLVMGCC="clang -std=gnu89"
171 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]172 full path).</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]173
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]174 <!--=====================================================================-->
175 <h3 id="testingWindows">Testing using Visual Studio on Windows</h3>
176 <!--=====================================================================-->
177
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]178 <p>The Clang test suite can be run from either Visual Studio or
179 the command line.</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]180
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]181 <p>Note that the test runner is based on
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]182 Python, which must be installed. Find Python at:
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]183 <a href="http://www.python.org/download/">http://www.python.org/download/</a>.
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]184 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]185
Chris Lattner357f7ce2009-08-20 06:17:11 +0000[diff] [blame]186 <p>The GnuWin32 tools are also necessary for running the tests.
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]187 Get them from <a href="http://getgnuwin32.sourceforge.net/">
NAKAMURA Takumida0f45d2011-03-18 03:21:44 +0000[diff] [blame]188 http://getgnuwin32.sourceforge.net/</a>.
189 If the environment variable <tt>%PATH%</tt> does not have GnuWin32,
190 or if other grep(s) supercedes GnuWin32 on <tt>%PATH%,</tt>
191 you should specify <tt>LLVM_LIT_TOOLS_DIR</tt>
192 to CMake explicitly.</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]193
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]194 <p>The cmake build tool is set up to create Visual Studio project files
195 for running the tests, "clang-test" being the root. Therefore, to
196 run the test from Visual Studio, right-click the clang-test project
197 and select "Build".</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]198
NAKAMURA Takumida0f45d2011-03-18 03:21:44 +0000[diff] [blame]199 <p>
200 Please see also
201 <a href="http://llvm.org/docs/GettingStartedVS.html">Getting Started
202 with the LLVM System using Microsoft Visual Studio</a> and
203 <a href="http://llvm.org/docs/CMake.html">Building LLVM with CMake</a>.
204 </p>
205
Dawn Perchik217a3452010-09-03 17:01:13 +0000[diff] [blame]206 <!--=====================================================================-->
207 <h3 id="testingCommands">Testing on the Command Line</h3>
208 <!--=====================================================================-->
209
Eli Friedman275a8502012-04-16 05:04:45 +0000[diff] [blame]210 <p>If you want more control over how the tests are run, it may
211 be convenient to run the test harness on the command-line directly. Before
212 running tests from the command line, you will need to ensure that
213 <tt>lit.site.cfg</tt> files have been created for your build. You can do
214 this by running the tests as described in the previous sections. Once the
215 tests have started running, you can stop them with control+C, as the
216 files are generated before running any tests.</p>
217
218 <p>Once that is done, to run all the tests from the command line,
219 execute a command like the following:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]220
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]221 <pre>
Aaron Ballmane7d923d2012-02-09 15:23:18 +0000[diff] [blame]222 python (path to llvm)\llvm\utils\lit\lit.py -sv
223 --param=build_mode=Win32 --param=build_config=Debug
224 --param=clang_site_config=(build dir)\tools\clang\test\lit.site.cfg
225 (path to llvm)\llvm\tools\clang\test
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]226</pre>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]227
Douglas Gregora71ef5d2011-01-24 18:04:58 +0000[diff] [blame]228 <p>For CMake builds e.g. on Windows with Visual Studio, you will need
229 to specify your build configuration (Debug, Release, etc.) via
Aaron Ballmane7d923d2012-02-09 15:23:18 +0000[diff] [blame]230 <tt>--param=build_config=(build config)</tt>. You may also need to specify
231 the build mode (Win32, etc) via <tt>--param=build_mode=(build mode)</tt>.</p>
232
233 <p>Additionally, you will need to specify the lit site configuration which
234 lives in (build dir)\tools\clang\test, via
235 <tt>--param=clang_site_config=(build dir)\tools\clang\test\lit.site.cfg</tt>.
236 </p>
Douglas Gregora71ef5d2011-01-24 18:04:58 +0000[diff] [blame]237
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]238 <p>To run a single test:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]239
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]240 <pre>
Aaron Ballmane7d923d2012-02-09 15:23:18 +0000[diff] [blame]241 python (path to llvm)\llvm\utils\lit\lit.py -sv
242 --param=build_mode=Win32 --param=build_config=Debug
243 --param=clang_site_config=(build dir)\tools\clang\test\lit.site.cfg
244 (path to llvm)\llvm\tools\clang\test\(dir)\(test)
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]245</pre>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]246
247 <p>For example:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]248
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]249 <pre>
Aaron Ballmane7d923d2012-02-09 15:23:18 +0000[diff] [blame]250 python C:\Tool\llvm\utils\lit\lit.py -sv
251 --param=build_mode=Win32 --param=build_config=Debug
252 --param=clang_site_config=c:\Tools\build\tools\clang\test\lit.site.cfg
253 C:\Tools\llvm\tools\clang\test\Sema\wchar.c
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]254</pre>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]255
256 <p>The -sv option above tells the runner to show the test output if
257 any tests failed, to help you determine the cause of failure.</p>
258
Aaron Ballmane7d923d2012-02-09 15:23:18 +0000[diff] [blame]259 <p>You can also pass in the --no-progress-bar option if you wish to disable
260 progress indications while the tests are running.</p>
261
Francois Pichetb2043d72010-09-11 21:16:11 +0000[diff] [blame]262 <p>Your output might look something like this:</p>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]263
Aaron Ballmane7d923d2012-02-09 15:23:18 +0000[diff] [blame]264 <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]265-- Testing: Testing: 2534 tests, 4 threads --
266Testing: 0 .. 10.. 20.. 30.. 40.. 50.. 60.. 70.. 80.. 90..
267Testing Time: 81.52s
268 Expected Passes : 2503
269 Expected Failures : 28
270 Unsupported Tests : 3
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]271</pre>
John Thompson99ff8da2009-11-06 00:06:29 +0000[diff] [blame]272
Francois Pichetb2043d72010-09-11 21:16:11 +0000[diff] [blame]273 <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]274
275 <!--=====================================================================-->
276 <h2 id="patches">Creating Patch Files</h2>
277 <!--=====================================================================-->
278
279 <p>To return changes to the Clang team, unless you have checkin
Chris Lattnerfc8f0e12011-04-15 05:22:18 +0000[diff] [blame]280 privileges, the preferred way is to send patch files to the
Douglas Gregor8b06d6b2011-11-19 19:14:26 +0000[diff] [blame]281 cfe-commits mailing list, with an explanation of what the patch is
282 for. If your patch requires a wider discussion (for example,
283 because it is an architectural change), you can use the cfe-dev
284 mailing list. </p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]285
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]286 <p>To create these patch files, change directory
287 to the llvm/tools/clang root and run:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]288
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]289 <pre>svn diff (relative path) >(patch file name)</pre>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]290
291 <p>For example, for getting the diffs of all of clang:</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]292
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]293 <pre>svn diff . >~/mypatchfile.patch</pre>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]294
295 <p>For example, for getting the diffs of a single file:</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 lib/Parse/ParseDeclCXX.cpp >~/ParseDeclCXX.patch</pre>
Eli Friedmand1e1ef32009-08-03 19:42:28 +0000[diff] [blame]298
299 <p>Note that the paths embedded in the patch depend on where you run it,
300 so changing directory to the llvm/tools/clang directory is recommended.</p>
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]301
302 <!--=====================================================================-->
303 <h2 id="irgen">LLVM IR Generation</h2>
304 <!--=====================================================================-->
305
306 <p>The LLVM IR generation part of clang handles conversion of the
307 AST nodes output by the Sema module to the LLVM Intermediate
308 Representation (IR). Historically, this was referred to as
309 "codegen", and the Clang code for this lives
310 in <tt>lib/CodeGen</tt>.</p>
NAKAMURA Takumi6975d072011-03-18 03:21:38 +0000[diff] [blame]311
Cedric Venet3d658642009-02-14 20:20:19 +0000[diff] [blame]312 <p>The output is most easily inspected using the <tt>-emit-llvm</tt>
313 option to clang (possibly in conjunction with <tt>-o -</tt>). You
314 can also use <tt>-emit-llvm-bc</tt> to write an LLVM bitcode file
315 which can be processed by the suite of LLVM tools
316 like <tt>llvm-dis</tt>, <tt>llvm-nm</tt>, etc. See the LLVM
317 <a href="http://llvm.org/docs/CommandGuide/">Command Guide</a>
318 for more information.</p>
319
320</div>
321</body>
322</html>