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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>
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29 <div class="doc_section"><a name="overview">Overview</a></div>
30 <!-- *********************************************************************** -->
32 <div class="doc_text">
34 <p>The LLVM build system is designed to facilitate the building of third party
35 projects that use LLVM header files, libraries, and tools. In order to use
36 these facilities, a Makefile from a project must do the following things:</p>
39 <li>Set environment variables.There are several environment variables that a
40 Makefile needs to set to use the LLVM build system:
43 <li><tt>LLVM_SRC_ROOT</tt> - The root of the LLVM source tree.</li>
44 <li><tt>LLVM_OBJ_ROOT</tt> - The root of the LLVM object tree.</li>
45 <li><tt>BUILD_SRC_ROOT</tt> - The root of the project's source tree.</li>
46 <li><tt>BUILD_OBJ_ROOT</tt> - The root of the project's object tree.</li>
47 <li><tt>BUILD_SRC_DIR</tt> - The directory containing the current source to be
49 <li><tt>BUILD_OBJ_DIR</tt> - The directory where the current source will place
50 the new object files. This should always be the current directory.</li>
51 <li><tt>LEVEL</tt> - The relative path from the current directory to the root
52 of the object tree.</li>
54 <li>Include <tt>Makefile.config</tt> from <tt>$(LLVM_OBJ_ROOT)</tt>.</li>
55 <li>Include <tt>Makefile.rules</tt> from <tt>$(LLVM_SRC_ROOT)</tt>.</li>
58 <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>
63 <li> You can use the pre-made LLVM sample project. This sample project includes
64 Makefiles, a configure script that can be used to configure the location of
65 LLVM, and the ability to support multiple object directories from a single
66 source directory.</li>
69 <p>This document assumes that you will base your project off of the LLVM sample
70 project found in <tt>llvm/projects/sample</tt>. If you want to devise your own
71 build system, studying the sample project and LLVM Makefiles will probably
72 provide enough information on how to write your own Makefiles.</p>
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77 <div class="doc_section">
78 <a name="create">Create a Project from the Sample Project</a>
80 <!-- *********************************************************************** -->
82 <div class="doc_text">
84 <p>Follow these simple steps to start your project:</p>
87 <li>Copy the <tt>llvm/projects/sample</tt> directory to any place of your
88 choosing. You can place it anywhere you like. Rename the directory to match
89 the name of your project.</li>
91 <li>Add your source code and Makefiles to your source tree.</li>
93 <li>If you want your Makefiles to be configured by the <tt>configure</tt>
94 script, or if you want to support multiple object directories, add your
95 Makefiles to the <tt>configure</tt> script by adding them into the
96 <tt>autoconf/configure.ac</tt> file. The macro <tt>AC_CONFIG_MAKEFILE</tt> will
97 copy a file, unmodified, from the source directory to the object directory.</li>
99 <li>After updating <tt>autoconf/configure.ac</tt>, regenerate the
100 configure script with these commands:
102 <div class="doc_code">
103 <p><tt>% cd autoconf<br>
104 % autoconf -o ../configure</tt></p>
107 <p>You must be using Autoconf version 2.57 or higher.</p></li>
109 <li>Run <tt>configure</tt> in the directory in which you want to place
110 object code. Use the following options to tell your project where it
114 <dt><tt>--with-llvmsrc=<directory></tt>
116 Tell your project where the LLVM source tree is located.
118 <dt><tt>--with-llvmobj=<directory></tt>
120 Tell your project where the LLVM object tree is located.
124 <p>That's it! Now all you have to do is type <tt>gmake</tt> in the root of
125 your object directory, and your project should build.</p>
129 <!-- *********************************************************************** -->
130 <div class="doc_section">
131 <a name="source">Source Tree Layout</a>
133 <!-- *********************************************************************** -->
135 <div class="doc_text">
137 <p>In order to use the LLVM build system, you will want to organize your
138 source code so that it can benefit from the build system's features.
139 Mainly, you want your source tree layout to look similar to the LLVM
140 source tree layout. The best way to do this is to just copy the
141 project tree from <tt>llvm/projects/sample</tt> and modify it to meet
142 your needs, but you can certainly add to it if you want.</p>
144 <p>Underneath your top level directory, you should have the following
150 This subdirectory should contain all of your library source
151 code. For each library that you build, you will have one
152 directory in <b>lib</b> that will contain that library's source
156 Libraries can be object files, archives, or dynamic libraries.
157 The <b>lib</b> directory is just a convenient place for libraries
158 as it places them all in a directory from which they can be linked
163 This subdirectory should contain any header files that are
164 global to your project. By global, we mean that they are used
165 by more than one library or executable of your project.
167 By placing your header files in <b>include</b>, they will be
168 found automatically by the LLVM build system. For example, if
169 you have a file <b>include/jazz/note.h</b>, then your source
170 files can include it simply with <b>#include "jazz/note.h"</b>.
174 This subdirectory should contain all of your source
175 code for executables. For each program that you build, you
176 will have one directory in <b>tools</b> that will contain that
177 program's source code.
182 This subdirectory should contain tests that verify that your code
183 works correctly. Automated tests are especially useful.
185 Currently, the LLVM build system provides little support for tests,
186 although some exists. Expanded support for tests will hopefully
187 occur in the future. In the meantime, the LLVM system does provide the
191 LLVM provides several QMTest test classes that can be used to
192 create tests. They can be found in
193 <tt>llvm/test/QMTest/llvm.py</tt>. These test classes perform a
194 variety of functions, including code optimization tests, assembly
195 tests, and code analysis tests. The Makefile in
196 <tt>llvm/test</tt> provides the QMTest context needed by LLVM test
201 The LLVM source tree provides benchmarks and programs which are
202 known to compile with the LLVM GCC front ends. You can use these
203 programs to test your code, gather statistics information, and
204 compare it to the current LLVM performance statistics. These
205 programs are found in the <tt>llvm/test/Programs</tt> directory.
207 Currently, there is no way to hook your tests directly into the
208 <tt>llvm/test/Programs</tt> testing harness. You will simply
209 need to find a way to use the source provided within that directory
214 <p>Typically, you will want to build your <b>lib</b> directory first followed by
215 your <b>tools</b> directory.</p>
219 <!-- *********************************************************************** -->
220 <div class="doc_section">
221 <a name="makefiles">Writing LLVM Style Makefiles</a>
223 <!-- *********************************************************************** -->
225 <div class="doc_text">
227 <p>The LLVM build system provides a convenient way to build libraries and
228 executables. Most of your project Makefiles will only need to define a few
229 variables. Below is a list of the variables one can set and what they can
234 <!-- ======================================================================= -->
235 <div class="doc_subsection">
236 <a name="reqVars">Required Variables</a>
239 <div class="doc_text">
244 This variable is the relative path from this Makefile to the
245 top directory of your project's source code. For example, if
246 your source code is in <tt>/tmp/src</tt>, then the Makefile in
247 <tt>/tmp/src/jump/high</tt> would set <tt>LEVEL</tt> to <tt>"../.."</tt>.
252 <!-- ======================================================================= -->
253 <div class="doc_subsection">
254 <a name="varsBuildDir">Variables for Building Subdirectories</a>
257 <div class="doc_text">
262 This is a space separated list of subdirectories that should be
263 built. They will be built, one at a time, in the order
269 This is a list of directories that can be built in parallel.
270 These will be built after the directories in DIRS have been
276 This is a list of directories that can be built if they exist,
277 but will not cause an error if they do not exist. They are
278 built serially in the order in which they are listed.
283 <!-- ======================================================================= -->
284 <div class="doc_subsection">
285 <a name="varsBuildLib">Variables for Building Libraries</a>
288 <div class="doc_text">
293 This variable contains the base name of the library that will
294 be built. For example, to build a library named
295 <tt>libsample.a</tt>, LIBRARYNAME should be set to
301 By default, a library is a <tt>.o</tt> file that is linked
302 directly into a program. To build an archive (also known as
303 a static library), set the BUILD_ARCHIVE variable.
308 If SHARED_LIBRARY is defined in your Makefile, a shared
309 (or dynamic) library will be built.
314 <!-- ======================================================================= -->
315 <div class="doc_subsection">
316 <a name="varsBuildProg">Variables for Building Programs</a>
319 <div class="doc_text">
324 This variable contains the name of the program that will
325 be built. For example, to build an executable named
326 <tt>sample</tt>, TOOLNAME should be set to <tt>sample</tt>.
331 This variable holds a space separated list of libraries that
332 should be linked into the program. These libraries must either
333 be LLVM libraries or libraries that come from your <b>lib</b>
334 directory. The libraries must be specified by their base name.
335 For example, to link libsample.a, you would set USEDLIBS to
338 Note that this works only for statically linked libraries.
343 To link dynamic libraries, add <tt>-l<library base name></tt> to
344 the LIBS variable. The LLVM build system will look in the same places
345 for dynamic libraries as it does for static libraries.
347 For example, to link <tt>libsample.so</tt>, you would have the
348 following line in your <tt>Makefile</tt>:
357 <!-- ======================================================================= -->
358 <div class="doc_subsection">
359 <a name="miscVars">Miscellaneous Variables</a>
362 <div class="doc_text">
367 This variable contains a space separated list of extra source
368 files that need to be built. It is useful for including the
369 output of Lex and Yacc programs.
375 This variable can be used to add options to the C and C++
376 compiler, respectively. It is typically used to add options
377 that tell the compiler the location of additional directories
378 to search for header files.
380 It is highly suggested that you append to CFLAGS and CPPFLAGS as
381 opposed to overwriting them. The master Makefiles may already
382 have useful options in them that you may not want to overwrite.
388 <!-- *********************************************************************** -->
389 <div class="doc_section">
390 <a name="objcode">Placement of Object Code</a>
392 <!-- *********************************************************************** -->
394 <div class="doc_text">
396 <p>The final location of built libraries and executables will depend upon
397 whether you do a Debug, Release, or Profile build.</p>
402 All libraries (static and dynamic) will be stored in
403 <tt>BUILD_OBJ_ROOT/lib/<type></tt>, where type is <tt>Debug</tt>,
404 <tt>Release</tt>, or <tt>Profile</tt> for a debug, optimized, or
405 profiled build, respectively.<p>
408 <dd>All executables will be stored in
409 <tt>BUILD_OBJ_ROOT/tools/<type></tt>, where type is <tt>Debug</tt>,
410 <tt>Release</tt>, or <tt>Profile</tt> for a debug, optimized, or profiled
416 <!-- *********************************************************************** -->
417 <div class="doc_section">
418 <a name="help">Further Help</a>
420 <!-- *********************************************************************** -->
422 <div class="doc_text">
424 <p>If you have any questions or need any help creating an LLVM project,
425 the LLVM team would be more than happy to help. You can always post your
427 href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developers
428 Mailing List</a>.</p>
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440 <a href="mailto:criswell@uiuc.edu">John Criswell</a><br>
441 <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a>
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