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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 project to be configured with the <tt>configure</tt> script
93 then you need to edit <tt>autoconf/configure.ac</tt> as follows:
95 <li><b>AC_INIT</b>. Place the name of your project, its version number and
96 a contact email address for your project as the arguments to this macro</li>
97 <li><b>AC_CONFIG_AUC_DIR</b>. If your project isn't in the
98 <tt>llvm/projects</tt> directory then you might need to adjust this so that
99 it specifies a relative path to the <tt>llvm/autoconf</tt> directory.</li>
100 <li><b>LLVM_CONFIG_PROJECT</b>. Just leave this alone.</li>
101 <li><b>AC_CONFIG_SRCDIR</b>. Specify a path to a file name that identifies
102 your project; or just leave it at <tt>Makefile.config.in</tt></li>
103 <li><b>AC_CONFIG_FILES</b>. Do not change.</li>
104 <li><b>AC_CONFIG_MAKEFILE</b>. Use one of these macros for each Makefile
105 that your project uses. This macro arranges for your makefiles to be copied
106 from the source directory, unmodified, to the build directory.</li>
110 <li>After updating <tt>autoconf/configure.ac</tt>, regenerate the
111 configure script with these commands:
113 <div class="doc_code">
114 <p><tt>% cd autoconf<br>
115 % AutoRegen.sh</tt></p>
118 <p>You must be using Autoconf version 2.59 or later and your aclocal version
119 should 1.9 or later.</p></li>
121 <li>Run <tt>configure</tt> in the directory in which you want to place
122 object code. Use the following options to tell your project where it
126 <dt><tt>--with-llvmsrc=<directory></tt></dt>
127 <dd>Tell your project where the LLVM source tree is located.</dd>
128 <dt><br/><tt>--with-llvmobj=<directory></tt></dt>
129 <dd>Tell your project where the LLVM object tree is located.</dd>
130 <dt><br/><tt>--prefix=<directory></tt></dt>
131 <dd>Tell your project where it should get installed.</dd>
135 <p>That's it! Now all you have to do is type <tt>gmake</tt> (or <tt>make</tt>
136 if your on a GNU/Linux system) in the root of your object directory, and your
137 project should build.</p>
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142 <div class="doc_section">
143 <a name="source">Source Tree Layout</a>
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147 <div class="doc_text">
149 <p>In order to use the LLVM build system, you will want to organize your
150 source code so that it can benefit from the build system's features.
151 Mainly, you want your source tree layout to look similar to the LLVM
152 source tree layout. The best way to do this is to just copy the
153 project tree from <tt>llvm/projects/sample</tt> and modify it to meet
154 your needs, but you can certainly add to it if you want.</p>
156 <p>Underneath your top level directory, you should have the following
162 This subdirectory should contain all of your library source
163 code. For each library that you build, you will have one
164 directory in <b>lib</b> that will contain that library's source
168 Libraries can be object files, archives, or dynamic libraries.
169 The <b>lib</b> directory is just a convenient place for libraries
170 as it places them all in a directory from which they can be linked
175 This subdirectory should contain any header files that are
176 global to your project. By global, we mean that they are used
177 by more than one library or executable of your project.
179 By placing your header files in <b>include</b>, they will be
180 found automatically by the LLVM build system. For example, if
181 you have a file <b>include/jazz/note.h</b>, then your source
182 files can include it simply with <b>#include "jazz/note.h"</b>.
186 This subdirectory should contain all of your source
187 code for executables. For each program that you build, you
188 will have one directory in <b>tools</b> that will contain that
189 program's source code.
194 This subdirectory should contain tests that verify that your code
195 works correctly. Automated tests are especially useful.
197 Currently, the LLVM build system provides basic support for tests.
198 The LLVM system provides the following:
201 LLVM provides a tcl procedure that is used by Dejagnu to run
202 tests. It can be found in <tt>llvm/lib/llvm-dg.exp</tt>. This
203 test procedure uses RUN lines in the actual test case to determine
204 how to run the test. See the <a
205 href="TestingGuide.html">TestingGuide</a> for more details. You
206 can easily write Makefile support similar to the Makefiles in
207 <tt>llvm/test</tt> to use Dejagnu to run your project's tests.<br/></li>
209 LLVM contains an optional package called <tt>llvm-test</tt>
210 which provides benchmarks and programs that are known to compile with the
211 LLVM GCC front ends. You can use these
212 programs to test your code, gather statistics information, and
213 compare it to the current LLVM performance statistics.
214 <br/>Currently, there is no way to hook your tests directly into the
215 <tt>llvm/test</tt> testing harness. You will simply
216 need to find a way to use the source provided within that directory
221 <p>Typically, you will want to build your <b>lib</b> directory first followed by
222 your <b>tools</b> directory.</p>
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227 <div class="doc_section">
228 <a name="makefiles">Writing LLVM Style Makefiles</a>
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232 <div class="doc_text">
234 <p>The LLVM build system provides a convenient way to build libraries and
235 executables. Most of your project Makefiles will only need to define a few
236 variables. Below is a list of the variables one can set and what they can
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242 <div class="doc_subsection">
243 <a name="reqVars">Required Variables</a>
246 <div class="doc_text">
251 This variable is the relative path from this Makefile to the
252 top directory of your project's source code. For example, if
253 your source code is in <tt>/tmp/src</tt>, then the Makefile in
254 <tt>/tmp/src/jump/high</tt> would set <tt>LEVEL</tt> to <tt>"../.."</tt>.
259 <!-- ======================================================================= -->
260 <div class="doc_subsection">
261 <a name="varsBuildDir">Variables for Building Subdirectories</a>
264 <div class="doc_text">
269 This is a space separated list of subdirectories that should be
270 built. They will be built, one at a time, in the order
276 This is a list of directories that can be built in parallel.
277 These will be built after the directories in DIRS have been
283 This is a list of directories that can be built if they exist,
284 but will not cause an error if they do not exist. They are
285 built serially in the order in which they are listed.
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291 <div class="doc_subsection">
292 <a name="varsBuildLib">Variables for Building Libraries</a>
295 <div class="doc_text">
300 This variable contains the base name of the library that will
301 be built. For example, to build a library named
302 <tt>libsample.a</tt>, LIBRARYNAME should be set to
308 By default, a library is a <tt>.o</tt> file that is linked
309 directly into a program. To build an archive (also known as
310 a static library), set the BUILD_ARCHIVE variable.
315 If SHARED_LIBRARY is defined in your Makefile, a shared
316 (or dynamic) library will be built.
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322 <div class="doc_subsection">
323 <a name="varsBuildProg">Variables for Building Programs</a>
326 <div class="doc_text">
331 This variable contains the name of the program that will
332 be built. For example, to build an executable named
333 <tt>sample</tt>, TOOLNAME should be set to <tt>sample</tt>.
338 This variable holds a space separated list of libraries that
339 should be linked into the program. These libraries must either
340 be LLVM libraries or libraries that come from your <b>lib</b>
341 directory. The libraries must be specified by their base name.
342 For example, to link libsample.a, you would set USEDLIBS to
345 Note that this works only for statically linked libraries.
350 To link dynamic libraries, add <tt>-l<library base name></tt> to
351 the LIBS variable. The LLVM build system will look in the same places
352 for dynamic libraries as it does for static libraries.
354 For example, to link <tt>libsample.so</tt>, you would have the
355 following line in your <tt>Makefile</tt>:
364 <!-- ======================================================================= -->
365 <div class="doc_subsection">
366 <a name="miscVars">Miscellaneous Variables</a>
369 <div class="doc_text">
374 This variable contains a space separated list of extra source
375 files that need to be built. It is useful for including the
376 output of Lex and Yacc programs.
382 This variable can be used to add options to the C and C++
383 compiler, respectively. It is typically used to add options
384 that tell the compiler the location of additional directories
385 to search for header files.
387 It is highly suggested that you append to CFLAGS and CPPFLAGS as
388 opposed to overwriting them. The master Makefiles may already
389 have useful options in them that you may not want to overwrite.
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396 <div class="doc_section">
397 <a name="objcode">Placement of Object Code</a>
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401 <div class="doc_text">
403 <p>The final location of built libraries and executables will depend upon
404 whether you do a Debug, Release, or Profile build.</p>
409 All libraries (static and dynamic) will be stored in
410 <tt>PROJ_OBJ_ROOT/<type>/lib</tt>, where type is <tt>Debug</tt>,
411 <tt>Release</tt>, or <tt>Profile</tt> for a debug, optimized, or
412 profiled build, respectively.<p>
415 <dd>All executables will be stored in
416 <tt>PROJ_OBJ_ROOT/<type>/bin</tt>, where type is <tt>Debug</tt>,
417 <tt>Release</tt>, or <tt>Profile</tt> for a debug, optimized, or profiled
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424 <div class="doc_section">
425 <a name="help">Further Help</a>
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429 <div class="doc_text">
431 <p>If you have any questions or need any help creating an LLVM project,
432 the LLVM team would be more than happy to help. You can always post your
434 href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developers
435 Mailing List</a>.</p>
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447 <a href="mailto:criswell@uiuc.edu">John Criswell</a><br>
448 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a>
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