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  10 <h1>Creating an LLVM Project</h1>
  11
  12 <ol>
  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>
  17   <ol>
  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>
  23   </ol></li>
  24 <li><a href="#objcode">Placement of object code</a></li>
  25 <li><a href="#help">Further help</a></li>
  26 </ol>
  27
  28 <div class="doc_author">
  29   <p>Written by John Criswell</p>
  30 </div>
  31
  32 <!-- *********************************************************************** -->
  33 <h2><a name="overview">Overview</a></h2>
  34 <!-- *********************************************************************** -->
  35
  36 <div>
  37
  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>
  41
  42 <ol>
  43   <li>Set <tt>make</tt> variables. There are several variables that a Makefile
  44   needs to set to use the LLVM build system:
  45   <ul>
  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 ($PROJ_OBJ_ROOT).</li>
  54   </ul></li>
  55   <li>Include <tt>Makefile.config</tt> from <tt>$(LLVM_OBJ_ROOT)</tt>.</li>
  56   <li>Include <tt>Makefile.rules</tt> from <tt>$(LLVM_SRC_ROOT)</tt>.</li>
  57 </ol>
  58
  59 <p>There are two ways that you can set all of these variables:</p>
  60 <ol>
  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>
  66 </ol>
  67
  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>
  72
  73 </div>
  74
  75 <!-- *********************************************************************** -->
  76 <h2>
  77   <a name="create">Create a Project from the Sample Project</a>
  78 </h2>
  79 <!-- *********************************************************************** -->
  80
  81 <div>
  82
  83 <p>Follow these simple steps to start your project:</p>
  84
  85 <ol>
  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>
  89
  90 <li>
  91 If you downloaded LLVM using Subversion, remove all the directories named .svn
  92 (and all the files therein) from your project's new source tree.  This will
  93 keep Subversion from thinking that your project is inside
  94 <tt>llvm/trunk/projects/sample</tt>.</li>
  95
  96 <li>Add your source code and Makefiles to your source tree.</li>
  97
  98 <li>If you want your project to be configured with the <tt>configure</tt> script
  99 then you need to edit <tt>autoconf/configure.ac</tt> as follows:
 100   <ul>
 101     <li><b>AC_INIT</b>. Place the name of your project, its version number and
 102     a contact email address for your project as the arguments to this macro</li>
 103     <li><b>AC_CONFIG_AUX_DIR</b>. If your project isn't in the
 104     <tt>llvm/projects</tt> directory then you might need to adjust this so that
 105     it specifies a relative path to the <tt>llvm/autoconf</tt> directory.</li>
 106     <li><b>LLVM_CONFIG_PROJECT</b>. Just leave this alone.</li>
 107     <li><b>AC_CONFIG_SRCDIR</b>. Specify a path to a file name that identifies
 108     your project; or just leave it at <tt>Makefile.common.in</tt></li>
 109     <li><b>AC_CONFIG_FILES</b>. Do not change.</li>
 110     <li><b>AC_CONFIG_MAKEFILE</b>. Use one of these macros for each Makefile
 111     that your project uses. This macro arranges for your makefiles to be copied
 112     from the source directory, unmodified, to the build directory.</li>
 113   </ul>
 114 </li>
 115
 116 <li>After updating <tt>autoconf/configure.ac</tt>, regenerate the
 117 configure script with these commands:
 118
 119 <div class="doc_code">
 120 <p><tt>% cd autoconf<br>
 121        % ./AutoRegen.sh</tt></p>
 122 </div>
 123
 124 <p>You must be using Autoconf version 2.59 or later and your aclocal version
 125 should be 1.9 or later.</p></li>
 126
 127 <li>Run <tt>configure</tt> in the directory in which you want to place
 128 object code.  Use the following options to tell your project where it
 129 can find LLVM:
 130
 131   <dl>
 132     <dt><tt>--with-llvmsrc=&lt;directory&gt;</tt></dt>
 133     <dd>Tell your project where the LLVM source tree is located.</dd>
 134     <dt><br><tt>--with-llvmobj=&lt;directory&gt;</tt></dt>
 135     <dd>Tell your project where the LLVM object tree is located.</dd>
 136     <dt><br><tt>--prefix=&lt;directory&gt;</tt></dt>
 137     <dd>Tell your project where it should get installed.</dd>
 138   </dl>
 139 </ol>
 140
 141 <p>That's it!  Now all you have to do is type <tt>gmake</tt> (or <tt>make</tt>
 142 if your on a GNU/Linux system) in the root of your object directory, and your
 143 project should build.</p>
 144
 145 </div>
 146
 147 <!-- *********************************************************************** -->
 148 <h2>
 149   <a name="source">Source Tree Layout</a>
 150 </h2>
 151 <!-- *********************************************************************** -->
 152
 153 <div>
 154
 155 <p>In order to use the LLVM build system, you will want to organize your
 156 source code so that it can benefit from the build system's features.
 157 Mainly, you want your source tree layout to look similar to the LLVM
 158 source tree layout.  The best way to do this is to just copy the
 159 project tree from <tt>llvm/projects/sample</tt> and modify it to meet
 160 your needs, but you can certainly add to it if you want.</p>
 161
 162 <p>Underneath your top level directory, you should have the following
 163 directories:</p>
 164
 165 <dl>
 166   <dt><b>lib</b>
 167   <dd>
 168   This subdirectory should contain all of your library source
 169   code.  For each library that you build, you will have one
 170   directory in <b>lib</b> that will contain that library's source
 171   code.
 172
 173   <p>
 174   Libraries can be object files, archives, or dynamic libraries.
 175   The <b>lib</b> directory is just a convenient place for libraries
 176   as it places them all in a directory from which they can be linked
 177   later.
 178
 179   <dt><b>include</b>
 180   <dd>
 181   This subdirectory should contain any header files that are
 182   global to your project.  By global, we mean that they are used
 183   by more than one library or executable of your project.
 184   <p>
 185   By placing your header files in <b>include</b>, they will be
 186   found automatically by the LLVM build system.  For example, if
 187   you have a file <b>include/jazz/note.h</b>, then your source
 188   files can include it simply with <b>#include "jazz/note.h"</b>.
 189
 190   <dt><b>tools</b>
 191   <dd>
 192   This subdirectory should contain all of your source
 193   code for executables.  For each program that you build, you
 194   will have one directory in <b>tools</b> that will contain that
 195   program's source code.
 196   <p>
 197
 198   <dt><b>test</b>
 199   <dd>
 200   This subdirectory should contain tests that verify that your code
 201   works correctly.  Automated tests are especially useful.
 202   <p>
 203   Currently, the LLVM build system provides basic support for tests.
 204   The LLVM system provides the following:
 205   <ul>
 206     <li>
 207     LLVM provides a tcl procedure that is used by Dejagnu to run
 208     tests.  It can be found in <tt>llvm/lib/llvm-dg.exp</tt>.  This
 209     test procedure uses RUN lines in the actual test case to determine
 210     how to run the test.  See the <a
 211     href="TestingGuide.html">TestingGuide</a> for more details. You
 212     can easily write Makefile support similar to the Makefiles in
 213     <tt>llvm/test</tt> to use Dejagnu to run your project's tests.<br></li>
 214     <li>
 215     LLVM contains an optional package called <tt>llvm-test</tt>
 216     which provides benchmarks and programs that are known to compile with the
 217     LLVM GCC front ends.  You can use these
 218     programs to test your code, gather statistics information, and
 219     compare it to the current LLVM performance statistics.
 220     <br>Currently, there is no way to hook your tests directly into the
 221     <tt>llvm/test</tt> testing harness.  You will simply
 222     need to find a way to use the source provided within that directory
 223     on your own.
 224   </ul>
 225 </dl>
 226
 227 <p>Typically, you will want to build your <b>lib</b> directory first followed by
 228 your <b>tools</b> directory.</p>
 229
 230 </div>
 231
 232 <!-- *********************************************************************** -->
 233 <h2>
 234   <a name="makefiles">Writing LLVM Style Makefiles</a>
 235 </h2>
 236 <!-- *********************************************************************** -->
 237
 238 <div>
 239
 240 <p>The LLVM build system provides a convenient way to build libraries and
 241 executables.  Most of your project Makefiles will only need to define a few
 242 variables.  Below is a list of the variables one can set and what they can
 243 do:</p>
 244
 245 <!-- ======================================================================= -->
 246 <h3>
 247   <a name="reqVars">Required Variables</a>
 248 </h3>
 249
 250 <div>
 251
 252 <dl>
 253   <dt>LEVEL
 254   <dd>
 255   This variable is the relative path from this Makefile to the
 256   top directory of your project's source code.  For example, if
 257   your source code is in <tt>/tmp/src</tt>, then the Makefile in
 258   <tt>/tmp/src/jump/high</tt> would set <tt>LEVEL</tt> to <tt>"../.."</tt>.
 259 </dl>
 260
 261 </div>
 262
 263 <!-- ======================================================================= -->
 264 <h3>
 265   <a name="varsBuildDir">Variables for Building Subdirectories</a>
 266 </h3>
 267
 268 <div>
 269
 270 <dl>
 271   <dt>DIRS
 272   <dd>
 273   This is a space separated list of subdirectories that should be
 274   built.  They will be built, one at a time, in the order
 275   specified.
 276   <p>
 277
 278   <dt>PARALLEL_DIRS
 279   <dd>
 280   This is a list of directories that can be built in parallel.
 281   These will be built after the directories in DIRS have been
 282   built.
 283   <p>
 284
 285   <dt>OPTIONAL_DIRS
 286   <dd>
 287   This is a list of directories that can be built if they exist,
 288   but will not cause an error if they do not exist.  They are
 289   built serially in the order in which they are listed.
 290 </dl>
 291
 292 </div>
 293
 294 <!-- ======================================================================= -->
 295 <h3>
 296   <a name="varsBuildLib">Variables for Building Libraries</a>
 297 </h3>
 298
 299 <div>
 300
 301 <dl>
 302   <dt>LIBRARYNAME
 303   <dd>
 304   This variable contains the base name of the library that will
 305   be built.  For example, to build a library named
 306   <tt>libsample.a</tt>, LIBRARYNAME should be set to
 307   <tt>sample</tt>.
 308   <p>
 309
 310   <dt>BUILD_ARCHIVE
 311   <dd>
 312   By default, a library is a <tt>.o</tt> file that is linked
 313   directly into a program.  To build an archive (also known as
 314   a static library), set the BUILD_ARCHIVE variable.
 315   <p>
 316
 317   <dt>SHARED_LIBRARY
 318   <dd>
 319   If SHARED_LIBRARY is defined in your Makefile, a shared
 320   (or dynamic) library will be built.
 321 </dl>
 322
 323 </div>
 324
 325 <!-- ======================================================================= -->
 326 <h3>
 327   <a name="varsBuildProg">Variables for Building Programs</a>
 328 </h3>
 329
 330 <div>
 331
 332 <dl>
 333   <dt>TOOLNAME
 334   <dd>
 335   This variable contains the name of the program that will
 336   be built.  For example, to build an executable named
 337   <tt>sample</tt>, TOOLNAME should be set to <tt>sample</tt>.
 338   <p>
 339
 340   <dt>USEDLIBS
 341   <dd>
 342   This variable holds a space separated list of libraries that should
 343   be linked into the program.  These libraries must be libraries that
 344   come from your <b>lib</b> directory.  The libraries must be
 345   specified without their "lib" prefix.  For example, to link
 346   libsample.a, you would set USEDLIBS to
 347   <tt>sample.a</tt>.
 348   <p>
 349   Note that this works only for statically linked libraries.
 350   <p>
 351
 352   <dt>LLVMLIBS
 353   <dd>
 354   This variable holds a space separated list of libraries that should
 355   be linked into the program.  These libraries must be LLVM libraries.
 356   The libraries must be specified without their "lib" prefix.  For
 357   example, to link with a driver that performs an IR transformation
 358   you might set LLVMLIBS to this minimal set of libraries
 359   <tt>LLVMSupport.a LLVMCore.a LLVMBitReader.a LLVMAsmParser.a LLVMAnalysis.a LLVMTransformUtils.a LLVMScalarOpts.a LLVMTarget.a</tt>.
 360   <p>
 361   Note that this works only for statically linked libraries. LLVM is
 362   split into a large number of static libraries, and the list of libraries you
 363   require may be much longer than the list above. To see a full list
 364   of libraries use:
 365   <tt>llvm-config --libs all</tt>.
 366   Using LINK_COMPONENTS as described below, obviates the need to set LLVMLIBS.
 367   <p>
 368
 369   <dt>LINK_COMPONENTS
 370   <dd>This variable holds a space separated list of components that
 371   the LLVM Makefiles pass to the <tt>llvm-config</tt> tool to generate
 372   a link line for the program. For example, to link with all LLVM
 373   libraries use
 374   <tt>LINK_COMPONENTS = all</tt>.
 375   <p>
 376
 377   <dt>LIBS
 378   <dd>
 379   To link dynamic libraries, add <tt>-l&lt;library base name&gt;</tt> to
 380   the LIBS variable.  The LLVM build system will look in the same places
 381   for dynamic libraries as it does for static libraries.
 382   <p>
 383   For example, to link <tt>libsample.so</tt>, you would have the
 384   following line in your <tt>Makefile</tt>:
 385   <p>
 386   <tt>
 387   LIBS += -lsample
 388   </tt>
 389   <p>
 390   Note that LIBS must occur in the Makefile after the inclusion of Makefile.common.
 391   <p>
 392 </dl>
 393
 394 </div>
 395
 396 <!-- ======================================================================= -->
 397 <h3>
 398   <a name="miscVars">Miscellaneous Variables</a>
 399 </h3>
 400
 401 <div>
 402
 403 <dl>
 404   <dt>ExtraSource
 405   <dd>
 406   This variable contains a space separated list of extra source
 407   files that need to be built.  It is useful for including the
 408   output of Lex and Yacc programs.
 409   <p>
 410
 411   <dt>CFLAGS
 412   <dt>CPPFLAGS
 413   <dd>
 414   This variable can be used to add options to the C and C++
 415   compiler, respectively.  It is typically used to add options
 416   that tell the compiler the location of additional directories
 417   to search for header files.
 418   <p>
 419   It is highly suggested that you append to CFLAGS and CPPFLAGS as
 420   opposed to overwriting them.  The master Makefiles may already
 421   have useful options in them that you may not want to overwrite.
 422   <p>
 423 </dl>
 424
 425 </div>
 426
 427 </div>
 428
 429 <!-- *********************************************************************** -->
 430 <h2>
 431   <a name="objcode">Placement of Object Code</a>
 432 </h2>
 433 <!-- *********************************************************************** -->
 434
 435 <div>
 436
 437 <p>The final location of built libraries and executables will depend upon
 438 whether you do a Debug, Release, or Profile build.</p>
 439
 440 <dl>
 441   <dt>Libraries
 442   <dd>
 443   All libraries (static and dynamic) will be stored in
 444   <tt>PROJ_OBJ_ROOT/&lt;type&gt;/lib</tt>, where type is <tt>Debug</tt>,
 445   <tt>Release</tt>, or <tt>Profile</tt> for a debug, optimized, or
 446   profiled build, respectively.<p>
 447
 448   <dt>Executables
 449   <dd>All executables will be stored in
 450   <tt>PROJ_OBJ_ROOT/&lt;type&gt;/bin</tt>, where type is <tt>Debug</tt>,
 451   <tt>Release</tt>, or <tt>Profile</tt> for a debug, optimized, or profiled
 452   build, respectively.
 453 </dl>
 454
 455 </div>
 456
 457 <!-- *********************************************************************** -->
 458 <h2>
 459   <a name="help">Further Help</a>
 460 </h2>
 461 <!-- *********************************************************************** -->
 462
 463 <div>
 464
 465 <p>If you have any questions or need any help creating an LLVM project,
 466 the LLVM team would be more than happy to help.  You can always post your
 467 questions to the <a
 468 href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developers
 469 Mailing List</a>.</p>
 470
 471 </div>
 472
 473 <!-- *********************************************************************** -->
 474 <hr>
 475 <address>
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 480
 481   <a href="mailto:criswell@uiuc.edu">John Criswell</a><br>
 482   <a href="http://llvm.org/">The LLVM Compiler Infrastructure</a>
 483   <br>
 484   Last modified: $Date$
 485 </address>
 486
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