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