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5 <title>Creating an LLVM Project</title>
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10 <div class="doc_title">Creating an LLVM Project</div>
13 <li><a href="#overview">Overview</a></li>
14 <li><a href="#create">Create a project from the Sample Project</a></li>
15 <li><a href="#source">Source tree layout</a></li>
16 <li><a href="#makefiles">Writing LLVM-style Makefiles</a>
18 <li><a href="#reqVars">Required Variables</a></li>
19 <li><a href="#varsBuildDir">Variables for Building Subdirectories</a></li>
20 <li><a href="#varsBuildLib">Variables for Building Libraries</a></li>
21 <li><a href="#varsBuildProg">Variables for Building Programs</a></li>
22 <li><a href="#miscVars">Miscellaneous Variables</a></li>
24 <li><a href="#objcode">Placement of object code</a></li>
25 <li><a href="#help">Further help</a></li>
28 <div class="doc_author">
29 <p>Written by John Criswell</p>
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33 <div class="doc_section"><a name="overview">Overview</a></div>
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36 <div class="doc_text">
38 <p>The LLVM build system is designed to facilitate the building of third party
39 projects that use LLVM header files, libraries, and tools. In order to use
40 these facilities, a Makefile from a project must do the following things:</p>
43 <li>Set <tt>make</tt> variables. There are several variables that a Makefile
44 needs to set to use the LLVM build system:
46 <li><tt>PROJECT_NAME</tt> - The name by which your project is known.</li>
47 <li><tt>LLVM_SRC_ROOT</tt> - The root of the LLVM source tree.</li>
48 <li><tt>LLVM_OBJ_ROOT</tt> - The root of the LLVM object tree.</li>
49 <li><tt>PROJ_SRC_ROOT</tt> - The root of the project's source tree.</li>
50 <li><tt>PROJ_OBJ_ROOT</tt> - The root of the project's object tree.</li>
51 <li><tt>PROJ_INSTALL_ROOT</tt> - The root installation directory.</li>
52 <li><tt>LEVEL</tt> - The relative path from the current directory to the
53 project's root ($PROJ_OBJ_ROOT).</li>
55 <li>Include <tt>Makefile.config</tt> from <tt>$(LLVM_OBJ_ROOT)</tt>.</li>
56 <li>Include <tt>Makefile.rules</tt> from <tt>$(LLVM_SRC_ROOT)</tt>.</li>
59 <p>There are two ways that you can set all of these variables:</p>
61 <li>You can write your own Makefiles which hard-code these values.</li>
62 <li>You can use the pre-made LLVM sample project. This sample project
63 includes Makefiles, a configure script that can be used to configure the
64 location of LLVM, and the ability to support multiple object directories
65 from a single source directory.</li>
68 <p>This document assumes that you will base your project on the LLVM sample
69 project found in <tt>llvm/projects/sample</tt>. If you want to devise your own
70 build system, studying the sample project and LLVM Makefiles will probably
71 provide enough information on how to write your own Makefiles.</p>
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76 <div class="doc_section">
77 <a name="create">Create a Project from the Sample Project</a>
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81 <div class="doc_text">
83 <p>Follow these simple steps to start your project:</p>
86 <li>Copy the <tt>llvm/projects/sample</tt> directory to any place of your
87 choosing. You can place it anywhere you like. Rename the directory to match
88 the name of your project.</li>
90 <li>Add your source code and Makefiles to your source tree.</li>
92 <li>If you want your Makefiles to be configured by the <tt>configure</tt>
93 script, or if you want to support multiple object directories, add your
94 Makefiles to the <tt>configure</tt> script by adding them into the
95 <tt>autoconf/configure.ac</tt> file. The macro <tt>AC_CONFIG_MAKEFILE</tt> will
96 copy a file, unmodified, from the source directory to the object directory.</li>
98 <li>After updating <tt>autoconf/configure.ac</tt>, regenerate the
99 configure script with these commands:
101 <div class="doc_code">
102 <p><tt>% cd autoconf<br>
103 % autoconf -o ../configure</tt></p>
106 <p>You must be using Autoconf version 2.57 or higher.</p></li>
108 <li>Run <tt>configure</tt> in the directory in which you want to place
109 object code. Use the following options to tell your project where it
113 <dt><tt>--with-llvmsrc=<directory></tt>
115 Tell your project where the LLVM source tree is located.
117 <dt><tt>--with-llvmobj=<directory></tt>
119 Tell your project where the LLVM object tree is located.
123 <p>That's it! Now all you have to do is type <tt>gmake</tt> in the root of
124 your object directory, and your project should build.</p>
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129 <div class="doc_section">
130 <a name="source">Source Tree Layout</a>
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134 <div class="doc_text">
136 <p>In order to use the LLVM build system, you will want to organize your
137 source code so that it can benefit from the build system's features.
138 Mainly, you want your source tree layout to look similar to the LLVM
139 source tree layout. The best way to do this is to just copy the
140 project tree from <tt>llvm/projects/sample</tt> and modify it to meet
141 your needs, but you can certainly add to it if you want.</p>
143 <p>Underneath your top level directory, you should have the following
149 This subdirectory should contain all of your library source
150 code. For each library that you build, you will have one
151 directory in <b>lib</b> that will contain that library's source
155 Libraries can be object files, archives, or dynamic libraries.
156 The <b>lib</b> directory is just a convenient place for libraries
157 as it places them all in a directory from which they can be linked
162 This subdirectory should contain any header files that are
163 global to your project. By global, we mean that they are used
164 by more than one library or executable of your project.
166 By placing your header files in <b>include</b>, they will be
167 found automatically by the LLVM build system. For example, if
168 you have a file <b>include/jazz/note.h</b>, then your source
169 files can include it simply with <b>#include "jazz/note.h"</b>.
173 This subdirectory should contain all of your source
174 code for executables. For each program that you build, you
175 will have one directory in <b>tools</b> that will contain that
176 program's source code.
181 This subdirectory should contain tests that verify that your code
182 works correctly. Automated tests are especially useful.
184 Currently, the LLVM build system provides basic support for tests.
185 The LLVM system provides the following:
188 LLVM provides a tcl procedure that is used by Dejagnu to run
189 tests. It can be found in <tt>llvm/lib/llvm-dg.exp</tt>. This
190 test procedure uses RUN lines in the actual test case to determine
191 how to run the test. See the <a
192 href="TestingGuide.html">TestingGuide</a> for more details. You
193 can easily write Makefile support similar to the Makefiles in <tt>llvm/test</tt>
194 to use Dejagnu to run your project's tests.</li>
199 LLVM contains an optional package called <tt>llvm-test</tt>
200 which provides benchmarks and programs that are known to compile with the
201 LLVM GCC front ends. You can use these
202 programs to test your code, gather statistics information, and
203 compare it to the current LLVM performance statistics.
205 Currently, there is no way to hook your tests directly into the
206 <tt>llvm/test</tt> testing harness. You will simply
207 need to find a way to use the source provided within that directory
212 <p>Typically, you will want to build your <b>lib</b> directory first followed by
213 your <b>tools</b> directory.</p>
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218 <div class="doc_section">
219 <a name="makefiles">Writing LLVM Style Makefiles</a>
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223 <div class="doc_text">
225 <p>The LLVM build system provides a convenient way to build libraries and
226 executables. Most of your project Makefiles will only need to define a few
227 variables. Below is a list of the variables one can set and what they can
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233 <div class="doc_subsection">
234 <a name="reqVars">Required Variables</a>
237 <div class="doc_text">
242 This variable is the relative path from this Makefile to the
243 top directory of your project's source code. For example, if
244 your source code is in <tt>/tmp/src</tt>, then the Makefile in
245 <tt>/tmp/src/jump/high</tt> would set <tt>LEVEL</tt> to <tt>"../.."</tt>.
250 <!-- ======================================================================= -->
251 <div class="doc_subsection">
252 <a name="varsBuildDir">Variables for Building Subdirectories</a>
255 <div class="doc_text">
260 This is a space separated list of subdirectories that should be
261 built. They will be built, one at a time, in the order
267 This is a list of directories that can be built in parallel.
268 These will be built after the directories in DIRS have been
274 This is a list of directories that can be built if they exist,
275 but will not cause an error if they do not exist. They are
276 built serially in the order in which they are listed.
281 <!-- ======================================================================= -->
282 <div class="doc_subsection">
283 <a name="varsBuildLib">Variables for Building Libraries</a>
286 <div class="doc_text">
291 This variable contains the base name of the library that will
292 be built. For example, to build a library named
293 <tt>libsample.a</tt>, LIBRARYNAME should be set to
299 By default, a library is a <tt>.o</tt> file that is linked
300 directly into a program. To build an archive (also known as
301 a static library), set the BUILD_ARCHIVE variable.
306 If SHARED_LIBRARY is defined in your Makefile, a shared
307 (or dynamic) library will be built.
312 <!-- ======================================================================= -->
313 <div class="doc_subsection">
314 <a name="varsBuildProg">Variables for Building Programs</a>
317 <div class="doc_text">
322 This variable contains the name of the program that will
323 be built. For example, to build an executable named
324 <tt>sample</tt>, TOOLNAME should be set to <tt>sample</tt>.
329 This variable holds a space separated list of libraries that
330 should be linked into the program. These libraries must either
331 be LLVM libraries or libraries that come from your <b>lib</b>
332 directory. The libraries must be specified by their base name.
333 For example, to link libsample.a, you would set USEDLIBS to
336 Note that this works only for statically linked libraries.
341 To link dynamic libraries, add <tt>-l<library base name></tt> to
342 the LIBS variable. The LLVM build system will look in the same places
343 for dynamic libraries as it does for static libraries.
345 For example, to link <tt>libsample.so</tt>, you would have the
346 following line in your <tt>Makefile</tt>:
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356 <div class="doc_subsection">
357 <a name="miscVars">Miscellaneous Variables</a>
360 <div class="doc_text">
365 This variable contains a space separated list of extra source
366 files that need to be built. It is useful for including the
367 output of Lex and Yacc programs.
373 This variable can be used to add options to the C and C++
374 compiler, respectively. It is typically used to add options
375 that tell the compiler the location of additional directories
376 to search for header files.
378 It is highly suggested that you append to CFLAGS and CPPFLAGS as
379 opposed to overwriting them. The master Makefiles may already
380 have useful options in them that you may not want to overwrite.
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387 <div class="doc_section">
388 <a name="objcode">Placement of Object Code</a>
390 <!-- *********************************************************************** -->
392 <div class="doc_text">
394 <p>The final location of built libraries and executables will depend upon
395 whether you do a Debug, Release, or Profile build.</p>
400 All libraries (static and dynamic) will be stored in
401 <tt>PROJ_OBJ_ROOT/<type>/lib</tt>, where type is <tt>Debug</tt>,
402 <tt>Release</tt>, or <tt>Profile</tt> for a debug, optimized, or
403 profiled build, respectively.<p>
406 <dd>All executables will be stored in
407 <tt>PROJ_OBJ_ROOT/<type>/bin</tt>, where type is <tt>Debug</tt>,
408 <tt>Release</tt>, or <tt>Profile</tt> for a debug, optimized, or profiled
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415 <div class="doc_section">
416 <a name="help">Further Help</a>
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420 <div class="doc_text">
422 <p>If you have any questions or need any help creating an LLVM project,
423 the LLVM team would be more than happy to help. You can always post your
425 href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developers
426 Mailing List</a>.</p>
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438 <a href="mailto:criswell@uiuc.edu">John Criswell</a><br>
439 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a>
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