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 |   <title>Creating an LLVM Project</title> | 
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 | <body> | 
 |  | 
 | <div class="doc_title">Creating an LLVM Project</div> | 
 |  | 
 | <ol> | 
 | <li><a href="#overview">Overview</a></li> | 
 | <li><a href="#create">Create a project from the Sample Project</a></li> | 
 | <li><a href="#source">Source tree layout</a></li> | 
 | <li><a href="#makefiles">Writing LLVM-style Makefiles</a> | 
 |   <ol> | 
 |   <li><a href="#reqVars">Required Variables</a></li> | 
 |   <li><a href="#varsBuildDir">Variables for Building Subdirectories</a></li> | 
 |   <li><a href="#varsBuildLib">Variables for Building Libraries</a></li> | 
 |   <li><a href="#varsBuildProg">Variables for Building Programs</a></li> | 
 |   <li><a href="#miscVars">Miscellaneous Variables</a></li> | 
 |   </ol></li> | 
 | <li><a href="#objcode">Placement of object code</a></li> | 
 | <li><a href="#help">Further help</a></li> | 
 | </ol> | 
 |  | 
 | <div class="doc_author"> | 
 |   <p>Written by John Criswell</p> | 
 | </div> | 
 |  | 
 | <!-- *********************************************************************** --> | 
 | <div class="doc_section"><a name="overview">Overview</a></div> | 
 | <!-- *********************************************************************** --> | 
 |  | 
 | <div class="doc_text"> | 
 |  | 
 | <p>The LLVM build system is designed to facilitate the building of third party | 
 | projects that use LLVM header files, libraries, and tools.  In order to use | 
 | these facilities, a Makefile from a project must do the following things:</p> | 
 |  | 
 | <ol> | 
 | <li>Set environment variables.There are several environment variables that a | 
 | Makefile needs to set to use the LLVM build system: | 
 |  | 
 | <ul> | 
 |   <li><tt>LLVM_SRC_ROOT</tt> - The root of the LLVM source tree.</li> | 
 |   <li><tt>LLVM_OBJ_ROOT</tt> - The root of the LLVM object tree.</li> | 
 |   <li><tt>BUILD_SRC_ROOT</tt> - The root of the project's source tree.</li> | 
 |   <li><tt>BUILD_OBJ_ROOT</tt> - The root of the project's object tree.</li> | 
 |   <li><tt>BUILD_SRC_DIR</tt> - The directory containing the current source to be | 
 |   compiled.</li> | 
 |   <li><tt>BUILD_OBJ_DIR</tt> - The directory where the current source will place | 
 |   the new object files.  This should always be the current directory.</li> | 
 |   <li><tt>LEVEL</tt> - The relative path from the current directory to the root | 
 |   of the object tree.</li> | 
 | </ul></li> | 
 | <li>Include <tt>Makefile.config</tt> from <tt>$(LLVM_OBJ_ROOT)</tt>.</li> | 
 | <li>Include <tt>Makefile.rules</tt> from <tt>$(LLVM_SRC_ROOT)</tt>.</li> | 
 | </ol> | 
 |  | 
 | <p>There are two ways that you can set all of these variables:</p> | 
 |  | 
 | <ol> | 
 | <li>You can write your own Makefiles which hard-code these values.</li> | 
 |  | 
 | <li> You can use the pre-made LLVM sample project.  This sample project includes | 
 | Makefiles, a configure script that can be used to configure the location of | 
 | LLVM, and the ability to support multiple object directories from a single | 
 | source directory.</li> | 
 | </ol> | 
 |  | 
 | <p>This document assumes that you will base your project off of the LLVM sample | 
 | project found in <tt>llvm/projects/sample</tt>.  If you want to devise your own | 
 | build system, studying the sample project and LLVM Makefiles will probably | 
 | provide enough information on how to write your own Makefiles.</p> | 
 |  | 
 | </div> | 
 |  | 
 | <!-- *********************************************************************** --> | 
 | <div class="doc_section"> | 
 |   <a name="create">Create a Project from the Sample Project</a> | 
 | </div> | 
 | <!-- *********************************************************************** --> | 
 |  | 
 | <div class="doc_text"> | 
 |  | 
 | <p>Follow these simple steps to start your project:</p> | 
 |  | 
 | <ol> | 
 | <li>Copy the <tt>llvm/projects/sample</tt> directory to any place of your | 
 | choosing.  You can place it anywhere you like.  Rename the directory to match | 
 | the name of your project.</li> | 
 |  | 
 | <li>Add your source code and Makefiles to your source tree.</li> | 
 |  | 
 | <li>If you want your Makefiles to be configured by the <tt>configure</tt> | 
 | script, or if you want to support multiple object directories, add your | 
 | Makefiles to the <tt>configure</tt> script by adding them into the | 
 | <tt>autoconf/configure.ac</tt> file.  The macro <tt>AC_CONFIG_MAKEFILE</tt> will | 
 | copy a file, unmodified, from the source directory to the object directory.</li> | 
 |  | 
 | <li>After updating <tt>autoconf/configure.ac</tt>, regenerate the | 
 | configure script with these commands: | 
 |  | 
 | <div class="doc_code"> | 
 | <p><tt>% cd autoconf<br> | 
 |        % autoconf -o ../configure</tt></p> | 
 | </div> | 
 |  | 
 | <p>You must be using Autoconf version 2.57 or higher.</p></li> | 
 |  | 
 | <li>Run <tt>configure</tt> in the directory in which you want to place | 
 | object code.  Use the following options to tell your project where it | 
 | can find LLVM: | 
 |  | 
 |   <dl> | 
 |     <dt><tt>--with-llvmsrc=<directory></tt> | 
 |     <dd> | 
 |     Tell your project where the LLVM source tree is located. | 
 |     <p> | 
 |     <dt><tt>--with-llvmobj=<directory></tt> | 
 |     <dd> | 
 |     Tell your project where the LLVM object tree is located. | 
 |   </dl> | 
 | </ol> | 
 |  | 
 | <p>That's it!  Now all you have to do is type <tt>gmake</tt> in the root of | 
 | your object directory, and your project should build.</p> | 
 |  | 
 | </div> | 
 |  | 
 | <!-- *********************************************************************** --> | 
 | <div class="doc_section"> | 
 |   <a name="source">Source Tree Layout</a> | 
 | </div> | 
 | <!-- *********************************************************************** --> | 
 |  | 
 | <div class="doc_text"> | 
 |  | 
 | <p>In order to use the LLVM build system, you will want to organize your | 
 | source code so that it can benefit from the build system's features. | 
 | Mainly, you want your source tree layout to look similar to the LLVM | 
 | source tree layout.  The best way to do this is to just copy the | 
 | project tree from <tt>llvm/projects/sample</tt> and modify it to meet | 
 | your needs, but you can certainly add to it if you want.</p> | 
 |  | 
 | <p>Underneath your top level directory, you should have the following | 
 | directories:</p> | 
 |  | 
 | <dl> | 
 |   <dt><b>lib</b> | 
 |   <dd> | 
 |   This subdirectory should contain all of your library source | 
 |   code.  For each library that you build, you will have one | 
 |   directory in <b>lib</b> that will contain that library's source | 
 |   code. | 
 |  | 
 |   <p> | 
 |   Libraries can be object files, archives, or dynamic libraries. | 
 |   The <b>lib</b> directory is just a convenient place for libraries | 
 |   as it places them all in a directory from which they can be linked | 
 |   later. | 
 |  | 
 |   <dt><b>include</b> | 
 |   <dd> | 
 |   This subdirectory should contain any header files that are | 
 |   global to your project.  By global, we mean that they are used | 
 |   by more than one library or executable of your project. | 
 |   <p> | 
 |   By placing your header files in <b>include</b>, they will be | 
 |   found automatically by the LLVM build system.  For example, if | 
 |   you have a file <b>include/jazz/note.h</b>, then your source | 
 |   files can include it simply with <b>#include "jazz/note.h"</b>. | 
 |  | 
 |   <dt><b>tools</b> | 
 |   <dd> | 
 |   This subdirectory should contain all of your source | 
 |   code for executables.  For each program that you build, you | 
 |   will have one directory in <b>tools</b> that will contain that | 
 |   program's source code. | 
 |   <p> | 
 |  | 
 |   <dt><b>test</b> | 
 |   <dd> | 
 |   This subdirectory should contain tests that verify that your code | 
 |   works correctly.  Automated tests are especially useful. | 
 |   <p> | 
 |   Currently, the LLVM build system provides little support for tests, | 
 |   although some exists.  Expanded support for tests will hopefully | 
 |   occur in the future.  In the meantime, the LLVM system does provide the | 
 |   following: | 
 |   <ul> | 
 |     <li> | 
 |     LLVM provides several QMTest test classes that can be used to | 
 |     create tests.  They can be found in | 
 |     <tt>llvm/test/QMTest/llvm.py</tt>.  These test classes perform a | 
 |     variety of functions, including code optimization tests, assembly | 
 |     tests,  and code analysis tests.  The Makefile in | 
 |     <tt>llvm/test</tt> provides the QMTest context needed by LLVM test | 
 |     classes. | 
 |     <p> | 
 |  | 
 |     <li> | 
 |     The LLVM source tree provides benchmarks and programs which are | 
 |     known to compile with the LLVM GCC front ends.  You can use these | 
 |     programs to test your code, gather statistics information, and | 
 |     compare it to the current LLVM performance statistics.  These | 
 |     programs are found in the <tt>llvm/test/Programs</tt> directory. | 
 |     <p> | 
 |     Currently, there is no way to hook your tests directly into the | 
 |     <tt>llvm/test/Programs</tt> testing harness.  You will simply | 
 |     need to find a way to use the source provided within that directory | 
 |     on your own. | 
 |   </ul> | 
 | </dl> | 
 |  | 
 | <p>Typically, you will want to build your <b>lib</b> directory first followed by | 
 | your <b>tools</b> directory.</p> | 
 |  | 
 | </div> | 
 |  | 
 | <!-- *********************************************************************** --> | 
 | <div class="doc_section"> | 
 |   <a name="makefiles">Writing LLVM Style Makefiles</a> | 
 | </div> | 
 | <!-- *********************************************************************** --> | 
 |  | 
 | <div class="doc_text"> | 
 |  | 
 | <p>The LLVM build system provides a convenient way to build libraries and | 
 | executables.  Most of your project Makefiles will only need to define a few | 
 | variables.  Below is a list of the variables one can set and what they can | 
 | do:</p> | 
 |  | 
 | </div> | 
 |  | 
 | <!-- ======================================================================= --> | 
 | <div class="doc_subsection"> | 
 |   <a name="reqVars">Required Variables</a> | 
 | </div> | 
 |  | 
 | <div class="doc_text"> | 
 |  | 
 | <dl> | 
 |   <dt>LEVEL | 
 |   <dd> | 
 |   This variable is the relative path from this Makefile to the | 
 |   top directory of your project's source code.  For example, if | 
 |   your source code is in <tt>/tmp/src</tt>, then the Makefile in | 
 |   <tt>/tmp/src/jump/high</tt> would set <tt>LEVEL</tt> to <tt>"../.."</tt>. | 
 | </dl> | 
 |  | 
 | </div> | 
 |  | 
 | <!-- ======================================================================= --> | 
 | <div class="doc_subsection"> | 
 |   <a name="varsBuildDir">Variables for Building Subdirectories</a> | 
 | </div> | 
 |  | 
 | <div class="doc_text"> | 
 |  | 
 | <dl> | 
 |   <dt>DIRS | 
 |   <dd> | 
 |   This is a space separated list of subdirectories that should be | 
 |   built.  They will be built, one at a time, in the order | 
 |   specified. | 
 |   <p> | 
 |  | 
 |   <dt>PARALLEL_DIRS | 
 |   <dd> | 
 |   This is a list of directories that can be built in parallel. | 
 |   These will be built after the directories in DIRS have been | 
 |   built. | 
 |   <p> | 
 |  | 
 |   <dt>OPTIONAL_DIRS | 
 |   <dd> | 
 |   This is a list of directories that can be built if they exist, | 
 |   but will not cause an error if they do not exist.  They are | 
 |   built serially in the order in which they are listed. | 
 | </dl> | 
 |  | 
 | </div> | 
 |  | 
 | <!-- ======================================================================= --> | 
 | <div class="doc_subsection"> | 
 |   <a name="varsBuildLib">Variables for Building Libraries</a> | 
 | </div> | 
 |  | 
 | <div class="doc_text"> | 
 |  | 
 | <dl> | 
 |   <dt>LIBRARYNAME | 
 |   <dd> | 
 |   This variable contains the base name of the library that will | 
 |   be built.  For example, to build a library named | 
 |   <tt>libsample.a</tt>, LIBRARYNAME should be set to | 
 |   <tt>sample</tt>. | 
 |   <p> | 
 |  | 
 |   <dt>BUILD_ARCHIVE | 
 |   <dd> | 
 |   By default, a library is a <tt>.o</tt> file that is linked | 
 |   directly into a program.  To build an archive (also known as | 
 |   a static library), set the BUILD_ARCHIVE variable. | 
 |   <p> | 
 |  | 
 |   <dt>SHARED_LIBRARY | 
 |   <dd> | 
 |   If SHARED_LIBRARY is defined in your Makefile, a shared | 
 |   (or dynamic) library will be built. | 
 | </dl> | 
 |  | 
 | </div> | 
 |  | 
 | <!-- ======================================================================= --> | 
 | <div class="doc_subsection"> | 
 |   <a name="varsBuildProg">Variables for Building Programs</a> | 
 | </div> | 
 |  | 
 | <div class="doc_text"> | 
 |  | 
 | <dl> | 
 |   <dt>TOOLNAME | 
 |   <dd> | 
 |   This variable contains the name of the program that will | 
 |   be built.  For example, to build an executable named | 
 |   <tt>sample</tt>, TOOLNAME should be set to <tt>sample</tt>. | 
 |   <p> | 
 |  | 
 |   <dt>USEDLIBS | 
 |   <dd> | 
 |   This variable holds a space separated list of libraries that | 
 |   should be linked into the program.  These libraries must either | 
 |   be LLVM libraries or libraries that come from your <b>lib</b> | 
 |   directory.  The libraries must be specified by their base name. | 
 |   For example, to link libsample.a, you would set USEDLIBS to | 
 |   <tt>sample</tt>. | 
 |   <p> | 
 |   Note that this works only for statically linked libraries. | 
 |   <p> | 
 |  | 
 |   <dt>LIBS | 
 |   <dd> | 
 |   To link dynamic libraries, add <tt>-l<library base name></tt> to | 
 |   the LIBS variable.  The LLVM build system will look in the same places | 
 |   for dynamic libraries as it does for static libraries. | 
 |   <p> | 
 |   For example, to link <tt>libsample.so</tt>, you would have the | 
 |   following line in your <tt>Makefile</tt>: | 
 |   <p> | 
 |   <tt> | 
 |   LIBS += -lsample | 
 |   </tt> | 
 | </dl> | 
 |  | 
 | </div> | 
 |  | 
 | <!-- ======================================================================= --> | 
 | <div class="doc_subsection"> | 
 |   <a name="miscVars">Miscellaneous Variables</a> | 
 | </div> | 
 |  | 
 | <div class="doc_text"> | 
 |  | 
 | <dl> | 
 |   <dt>ExtraSource | 
 |   <dd> | 
 |   This variable contains a space separated list of extra source | 
 |   files that need to be built.  It is useful for including the | 
 |   output of Lex and Yacc programs. | 
 |   <p> | 
 |  | 
 |   <dt>CFLAGS | 
 |   <dt>CPPFLAGS | 
 |   <dd> | 
 |   This variable can be used to add options to the C and C++ | 
 |   compiler, respectively.  It is typically used to add options | 
 |   that tell the compiler the location of additional directories | 
 |   to search for header files. | 
 |   <p> | 
 |   It is highly suggested that you append to CFLAGS and CPPFLAGS as | 
 |   opposed to overwriting them.  The master Makefiles may already | 
 |   have useful options in them that you may not want to overwrite. | 
 |   <p> | 
 | </dl> | 
 |  | 
 | </div> | 
 |  | 
 | <!-- *********************************************************************** --> | 
 | <div class="doc_section"> | 
 |   <a name="objcode">Placement of Object Code</a> | 
 | </div> | 
 | <!-- *********************************************************************** --> | 
 |  | 
 | <div class="doc_text"> | 
 |  | 
 | <p>The final location of built libraries and executables will depend upon | 
 | whether you do a Debug, Release, or Profile build.</p> | 
 |  | 
 | <dl> | 
 |   <dt>Libraries | 
 |   <dd> | 
 |   All libraries (static and dynamic) will be stored in | 
 |   <tt>BUILD_OBJ_ROOT/lib/<type></tt>, where type is <tt>Debug</tt>, | 
 |   <tt>Release</tt>, or <tt>Profile</tt> for a debug, optimized, or | 
 |   profiled build, respectively.<p> | 
 |  | 
 |   <dt>Executables | 
 |   <dd>All executables will be stored in | 
 |   <tt>BUILD_OBJ_ROOT/tools/<type></tt>, where type is <tt>Debug</tt>, | 
 |   <tt>Release</tt>, or <tt>Profile</tt> for a debug, optimized, or profiled | 
 |   build, respectively. | 
 | </dl> | 
 |  | 
 | </div> | 
 |  | 
 | <!-- *********************************************************************** --> | 
 | <div class="doc_section"> | 
 |   <a name="help">Further Help</a> | 
 | </div> | 
 | <!-- *********************************************************************** --> | 
 |  | 
 | <div class="doc_text"> | 
 |  | 
 | <p>If you have any questions or need any help creating an LLVM project, | 
 | the LLVM team would be more than happy to help.  You can always post your | 
 | questions to the <a | 
 | href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM Developers | 
 | Mailing List</a>.</p> | 
 |  | 
 | </div> | 
 |    | 
 | <!-- *********************************************************************** --> | 
 | <hr> | 
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 |  | 
 |   <a href="mailto:criswell@uiuc.edu">John Criswell</a><br> | 
 |   <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a> | 
 |   <br> | 
 |   Last modified: $Date$ | 
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