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<h1>LLVM Makefile Guide</h1>
<ol>
<li><a href="#introduction">Introduction</a></li>
<li><a href="#general">General Concepts</a>
<ol>
<li><a href="#projects">Projects</a></li>
<li><a href="#varvals">Variable Values</a></li>
<li><a href="#including">Including Makefiles</a>
<ol>
<li><a href="#Makefile">Makefile</a></li>
<li><a href="#Makefile.common">Makefile.common</a></li>
<li><a href="#Makefile.config">Makefile.config</a></li>
<li><a href="#Makefile.rules">Makefile.rules</a></li>
</ol>
</li>
<li><a href="#Comments">Comments</a></li>
</ol>
</li>
<li><a href="#tutorial">Tutorial</a>
<ol>
<li><a href="#libraries">Libraries</a>
<ol>
<li><a href="#BCModules">Bitcode Modules</a></li>
<li><a href="#LoadableModules">Loadable Modules</a></li>
</ol>
</li>
<li><a href="#tools">Tools</a>
<ol>
<li><a href="#JIT">JIT Tools</a></li>
</ol>
</li>
<li><a href="#projects">Projects</a></li>
</ol>
</li>
<li><a href="#targets">Targets Supported</a>
<ol>
<li><a href="#all">all</a></li>
<li><a href="#all-local">all-local</a></li>
<li><a href="#check">check</a></li>
<li><a href="#check-local">check-local</a></li>
<li><a href="#clean">clean</a></li>
<li><a href="#clean-local">clean-local</a></li>
<li><a href="#dist">dist</a></li>
<li><a href="#dist-check">dist-check</a></li>
<li><a href="#dist-clean">dist-clean</a></li>
<li><a href="#install">install</a></li>
<li><a href="#preconditions">preconditions</a></li>
<li><a href="#printvars">printvars</a></li>
<li><a href="#reconfigure">reconfigure</a></li>
<li><a href="#spotless">spotless</a></li>
<li><a href="#tags">tags</a></li>
<li><a href="#uninstall">uninstall</a></li>
</ol>
</li>
<li><a href="#variables">Using Variables</a>
<ol>
<li><a href="#setvars">Control Variables</a></li>
<li><a href="#overvars">Override Variables</a></li>
<li><a href="#getvars">Readable Variables</a></li>
<li><a href="#intvars">Internal Variables</a></li>
</ol>
</li>
</ol>
<div class="doc_author">
<p>Written by <a href="mailto:reid@x10sys.com">Reid Spencer</a></p>
</div>
<!-- *********************************************************************** -->
<h2><a name="introduction">Introduction</a></h2>
<!-- *********************************************************************** -->
<div>
<p>This document provides <em>usage</em> information about the LLVM makefile
system. While loosely patterned after the BSD makefile system, LLVM has taken
a departure from BSD in order to implement additional features needed by LLVM.
Although makefile systems such as automake were attempted at one point, it
has become clear that the features needed by LLVM and the Makefile norm are
too great to use a more limited tool. Consequently, LLVM requires simply GNU
Make 3.79, a widely portable makefile processor. LLVM unabashedly makes heavy
use of the features of GNU Make so the dependency on GNU Make is firm. If
you're not familiar with <tt>make</tt>, it is recommended that you read the
<a href="http://www.gnu.org/software/make/manual/make.html">GNU Makefile
Manual</a>.</p>
<p>While this document is rightly part of the
<a href="ProgrammersManual.html">LLVM Programmer's Manual</a>, it is treated
separately here because of the volume of content and because it is often an
early source of bewilderment for new developers.</p>
</div>
<!-- *********************************************************************** -->
<h2><a name="general">General Concepts</a></h2>
<!-- *********************************************************************** -->
<div>
<p>The LLVM Makefile System is the component of LLVM that is responsible for
building the software, testing it, generating distributions, checking those
distributions, installing and uninstalling, etc. It consists of a several
files throughout the source tree. These files and other general concepts are
described in this section.</p>
<!-- ======================================================================= -->
<h3><a name="projects">Projects</a></h3>
<div>
<p>The LLVM Makefile System is quite generous. It not only builds its own
software, but it can build yours too. Built into the system is knowledge of
the <tt>llvm/projects</tt> directory. Any directory under <tt>projects</tt>
that has both a <tt>configure</tt> script and a <tt>Makefile</tt> is assumed
to be a project that uses the LLVM Makefile system. Building software that
uses LLVM does not require the LLVM Makefile System nor even placement in the
<tt>llvm/projects</tt> directory. However, doing so will allow your project
to get up and running quickly by utilizing the built-in features that are used
to compile LLVM. LLVM compiles itself using the same features of the makefile
system as used for projects.</p>
<p>For complete details on setting up your projects configuration, simply
mimic the <tt>llvm/projects/sample</tt> project or for further details,
consult the <a href="Projects.html">Projects.html</a> page.</p>
</div>
<!-- ======================================================================= -->
<h3><a name="varvalues">Variable Values</a></h3>
<div>
<p>To use the makefile system, you simply create a file named
<tt>Makefile</tt> in your directory and declare values for certain variables.
The variables and values that you select determine what the makefile system
will do. These variables enable rules and processing in the makefile system
that automatically Do The Right Thing™.
</div>
<!-- ======================================================================= -->
<h3><a name="including">Including Makefiles</a></h3>
<div>
<p>Setting variables alone is not enough. You must include into your Makefile
additional files that provide the rules of the LLVM Makefile system. The
various files involved are described in the sections that follow.</p>
<!-- ======================================================================= -->
<h4><a name="Makefile">Makefile</a></h4>
<div>
<p>Each directory to participate in the build needs to have a file named
<tt>Makefile</tt>. This is the file first read by <tt>make</tt>. It has three
sections:</p>
<ol>
<li><a href="#setvars">Settable Variables</a> - Required that must be set
first.</li>
<li><a href="#Makefile.common">include <tt>$(LEVEL)/Makefile.common</tt></a>
- include the LLVM Makefile system.
<li><a href="#overvars">Override Variables</a> - Override variables set by
the LLVM Makefile system.
</ol>
</div>
<!-- ======================================================================= -->
<h4><a name="Makefile.common">Makefile.common</a></h4>
<div>
<p>Every project must have a <tt>Makefile.common</tt> file at its top source
directory. This file serves three purposes:</p>
<ol>
<li>It includes the project's configuration makefile to obtain values
determined by the <tt>configure</tt> script. This is done by including the
<a href="#Makefile.config"><tt>$(LEVEL)/Makefile.config</tt></a> file.</li>
<li>It specifies any other (static) values that are needed throughout the
project. Only values that are used in all or a large proportion of the
project's directories should be placed here.</li>
<li>It includes the standard rules for the LLVM Makefile system,
<a href="#Makefile.rules"><tt>$(LLVM_SRC_ROOT)/Makefile.rules</tt></a>.
This file is the "guts" of the LLVM Makefile system.</li>
</ol>
</div>
<!-- ======================================================================= -->
<h4><a name="Makefile.config">Makefile.config</a></h4>
<div>
<p>Every project must have a <tt>Makefile.config</tt> at the top of its
<em>build</em> directory. This file is <b>generated</b> by the
<tt>configure</tt> script from the pattern provided by the
<tt>Makefile.config.in</tt> file located at the top of the project's
<em>source</em> directory. The contents of this file depend largely on what
configuration items the project uses, however most projects can get what they
need by just relying on LLVM's configuration found in
<tt>$(LLVM_OBJ_ROOT)/Makefile.config</tt>.
</div>
<!-- ======================================================================= -->
<h4><a name="Makefile.rules">Makefile.rules</a></h4>
<div>
<p>This file, located at <tt>$(LLVM_SRC_ROOT)/Makefile.rules</tt> is the heart
of the LLVM Makefile System. It provides all the logic, dependencies, and
rules for building the targets supported by the system. What it does largely
depends on the values of <tt>make</tt> <a href="#variables">variables</a> that
have been set <em>before</em> <tt>Makefile.rules</tt> is included.
</div>
</div>
<!-- ======================================================================= -->
<h3><a name="Comments">Comments</a></h3>
<div>
<p>User Makefiles need not have comments in them unless the construction is
unusual or it does not strictly follow the rules and patterns of the LLVM
makefile system. Makefile comments are invoked with the pound (#) character.
The # character and any text following it, to the end of the line, are ignored
by <tt>make</tt>.</p>
</div>
</div>
<!-- *********************************************************************** -->
<h2><a name="tutorial">Tutorial</a></h2>
<!-- *********************************************************************** -->
<div>
<p>This section provides some examples of the different kinds of modules you
can build with the LLVM makefile system. In general, each directory you
provide will build a single object although that object may be composed of
additionally compiled components.</p>
<!-- ======================================================================= -->
<h3><a name="libraries">Libraries</a></h3>
<div>
<p>Only a few variable definitions are needed to build a regular library.
Normally, the makefile system will build all the software into a single
<tt>libname.o</tt> (pre-linked) object. This means the library is not
searchable and that the distinction between compilation units has been
dissolved. Optionally, you can ask for a shared library (.so) or archive
library (.a) built. Archive libraries are the default. For example:</p>
<pre><tt>
LIBRARYNAME = mylib
SHARED_LIBRARY = 1
ARCHIVE_LIBRARY = 1
</tt></pre>
<p>says to build a library named "mylib" with both a shared library
(<tt>mylib.so</tt>) and an archive library (<tt>mylib.a</tt>) version. The
contents of all the
libraries produced will be the same, they are just constructed differently.
Note that you normally do not need to specify the sources involved. The LLVM
Makefile system will infer the source files from the contents of the source
directory.</p>
<p>The <tt>LOADABLE_MODULE=1</tt> directive can be used in conjunction with
<tt>SHARED_LIBRARY=1</tt> to indicate that the resulting shared library should
be openable with the <tt>dlopen</tt> function and searchable with the
<tt>dlsym</tt> function (or your operating system's equivalents). While this
isn't strictly necessary on Linux and a few other platforms, it is required
on systems like HP-UX and Darwin. You should use <tt>LOADABLE_MODULE</tt> for
any shared library that you intend to be loaded into an tool via the
<tt>-load</tt> option. See the
<a href="WritingAnLLVMPass.html#makefile">WritingAnLLVMPass.html</a> document
for an example of why you might want to do this.
<!-- ======================================================================= -->
<h4><a name="BCModules">Bitcode Modules</a></h4>
<div>
<p>In some situations, it is desirable to build a single bitcode module from
a variety of sources, instead of an archive, shared library, or bitcode
library. Bitcode modules can be specified in addition to any of the other
types of libraries by defining the <a href="#MODULE_NAME">MODULE_NAME</a>
variable. For example:</p>
<pre><tt>
LIBRARYNAME = mylib
BYTECODE_LIBRARY = 1
MODULE_NAME = mymod
</tt></pre>
<p>will build a module named <tt>mymod.bc</tt> from the sources in the
directory. This module will be an aggregation of all the bitcode modules
derived from the sources. The example will also build a bitcode archive
containing a bitcode module for each compiled source file. The difference is
subtle, but important depending on how the module or library is to be linked.
</p>
</div>
<!-- ======================================================================= -->
<h4>
<a name="LoadableModules">Loadable Modules</a>
</h4>
<div>
<p>In some situations, you need to create a loadable module. Loadable modules
can be loaded into programs like <tt>opt</tt> or <tt>llc</tt> to specify
additional passes to run or targets to support. Loadable modules are also
useful for debugging a pass or providing a pass with another package if that
pass can't be included in LLVM.</p>
<p>LLVM provides complete support for building such a module. All you need to
do is use the LOADABLE_MODULE variable in your Makefile. For example, to
build a loadable module named <tt>MyMod</tt> that uses the LLVM libraries
<tt>LLVMSupport.a</tt> and <tt>LLVMSystem.a</tt>, you would specify:</p>
<pre><tt>
LIBRARYNAME := MyMod
LOADABLE_MODULE := 1
LINK_COMPONENTS := support system
</tt></pre>
<p>Use of the <tt>LOADABLE_MODULE</tt> facility implies several things:</p>
<ol>
<li>There will be no "lib" prefix on the module. This differentiates it from
a standard shared library of the same name.</li>
<li>The <a href="#SHARED_LIBRARY">SHARED_LIBRARY</a> variable is turned
on.</li>
<li>The <a href="#LINK_LIBS_IN_SHARED">LINK_LIBS_IN_SHARED</a> variable
is turned on.</li>
</ol>
<p>A loadable module is loaded by LLVM via the facilities of libtool's libltdl
library which is part of <tt>lib/System</tt> implementation.</p>
</div>
</div>
<!-- ======================================================================= -->
<h3><a name="tools">Tools</a></h3>
<div>
<p>For building executable programs (tools), you must provide the name of the
tool and the names of the libraries you wish to link with the tool. For
example:</p>
<pre><tt>
TOOLNAME = mytool
USEDLIBS = mylib
LINK_COMPONENTS = support system
</tt></pre>
<p>says that we are to build a tool name <tt>mytool</tt> and that it requires
three libraries: <tt>mylib</tt>, <tt>LLVMSupport.a</tt> and
<tt>LLVMSystem.a</tt>.</p>
<p>Note that two different variables are use to indicate which libraries are
linked: <tt>USEDLIBS</tt> and <tt>LLVMLIBS</tt>. This distinction is necessary
to support projects. <tt>LLVMLIBS</tt> refers to the LLVM libraries found in
the LLVM object directory. <tt>USEDLIBS</tt> refers to the libraries built by
your project. In the case of building LLVM tools, <tt>USEDLIBS</tt> and
<tt>LLVMLIBS</tt> can be used interchangeably since the "project" is LLVM
itself and <tt>USEDLIBS</tt> refers to the same place as <tt>LLVMLIBS</tt>.
</p>
<p>Also note that there are two different ways of specifying a library: with a
<tt>.a</tt> suffix and without. Without the suffix, the entry refers to the
re-linked (.o) file which will include <em>all</em> symbols of the library.
This is useful, for example, to include all passes from a library of passes.
If the <tt>.a</tt> suffix is used then the library is linked as a searchable
library (with the <tt>-l</tt> option). In this case, only the symbols that are
unresolved <em>at that point</em> will be resolved from the library, if they
exist. Other (unreferenced) symbols will not be included when the <tt>.a</tt>
syntax is used. Note that in order to use the <tt>.a</tt> suffix, the library
in question must have been built with the <tt>ARCHIVE_LIBRARY</tt> option set.
</p>
<!-- ======================================================================= -->
<h4><a name="JIT">JIT Tools</a></h4>
<div>
<p>Many tools will want to use the JIT features of LLVM. To do this, you
simply specify that you want an execution 'engine', and the makefiles will
automatically link in the appropriate JIT for the host or an interpreter
if none is available:</p>
<pre><tt>
TOOLNAME = my_jit_tool
USEDLIBS = mylib
LINK_COMPONENTS = engine
</tt></pre>
<p>Of course, any additional libraries may be listed as other components. To
get a full understanding of how this changes the linker command, it is
recommended that you:</p>
<pre><tt>
cd examples/Fibonacci
make VERBOSE=1
</tt></pre>
</div>
</div>
</div>
<!-- *********************************************************************** -->
<h2><a name="targets">Targets Supported</a></h2>
<!-- *********************************************************************** -->
<div>
<p>This section describes each of the targets that can be built using the LLVM
Makefile system. Any target can be invoked from any directory but not all are
applicable to a given directory (e.g. "check", "dist" and "install" will
always operate as if invoked from the top level directory).</p>
<table style="text-align:left">
<tr>
<th>Target Name</th><th>Implied Targets</th><th>Target Description</th>
</tr>
<tr><td><a href="#all"><tt>all</tt></a></td><td></td>
<td>Compile the software recursively. Default target.
</td></tr>
<tr><td><a href="#all-local"><tt>all-local</tt></a></td><td></td>
<td>Compile the software in the local directory only.
</td></tr>
<tr><td><a href="#check"><tt>check</tt></a></td><td></td>
<td>Change to the <tt>test</tt> directory in a project and run the
test suite there.
</td></tr>
<tr><td><a href="#check-local"><tt>check-local</tt></a></td><td></td>
<td>Run a local test suite. Generally this is only defined in the
<tt>Makefile</tt> of the project's <tt>test</tt> directory.
</td></tr>
<tr><td><a href="#clean"><tt>clean</tt></a></td><td></td>
<td>Remove built objects recursively.
</td></tr>
<tr><td><a href="#clean-local"><tt>clean-local</tt></a></td><td></td>
<td>Remove built objects from the local directory only.
</td></tr>
<tr><td><a href="#dist"><tt>dist</tt></a></td><td>all</td>
<td>Prepare a source distribution tarball.
</td></tr>
<tr><td><a href="#dist-check"><tt>dist-check</tt></a></td><td>all</td>
<td>Prepare a source distribution tarball and check that it builds.
</td></tr>
<tr><td><a href="#dist-clean"><tt>dist-clean</tt></a></td><td>clean</td>
<td>Clean source distribution tarball temporary files.
</td></tr>
<tr><td><a href="#install"><tt>install</tt></a></td><td>all</td>
<td>Copy built objects to installation directory.
</td></tr>
<tr><td><a href="#preconditions"><tt>preconditions</tt></a></td><td>all</td>
<td>Check to make sure configuration and makefiles are up to date.
</td></tr>
<tr><td><a href="#printvars"><tt>printvars</tt></a></td><td>all</td>
<td>Prints variables defined by the makefile system (for debugging).
</td></tr>
<tr><td><a href="#tags"><tt>tags</tt></a></td><td></td>
<td>Make C and C++ tags files for emacs and vi.
</td></tr>
<tr><td><a href="#uninstall"><tt>uninstall</tt></a></td><td></td>
<td>Remove built objects from installation directory.
</td></tr>
</table>
<!-- ======================================================================= -->
<h3><a name="all">all (default)</a></h3>
<div>
<p>When you invoke <tt>make</tt> with no arguments, you are implicitly
instructing it to seek the "all" target (goal). This target is used for
building the software recursively and will do different things in different
directories. For example, in a <tt>lib</tt> directory, the "all" target will
compile source files and generate libraries. But, in a <tt>tools</tt>
directory, it will link libraries and generate executables.</p>
</div>
<!-- ======================================================================= -->
<h3><a name="all-local">all-local</a></h3>
<div>
<p>This target is the same as <a href="#all">all</a> but it operates only on
the current directory instead of recursively.</p>
</div>
<!-- ======================================================================= -->
<h3><a name="check">check</a></h3>
<div>
<p>This target can be invoked from anywhere within a project's directories
but always invokes the <a href="#check-local"><tt>check-local</tt></a> target
in the project's <tt>test</tt> directory, if it exists and has a
<tt>Makefile</tt>. A warning is produced otherwise. If
<a href="#TESTSUITE"><tt>TESTSUITE</tt></a> is defined on the <tt>make</tt>
command line, it will be passed down to the invocation of
<tt>make check-local</tt> in the <tt>test</tt> directory. The intended usage
for this is to assist in running specific suites of tests. If
<tt>TESTSUITE</tt> is not set, the implementation of <tt>check-local</tt>
should run all normal tests. It is up to the project to define what
different values for <tt>TESTSUTE</tt> will do. See the
<a href="TestingGuide.html">TestingGuide</a> for further details.</p>
</div>
<!-- ======================================================================= -->
<h3><a name="check-local">check-local</a></h3>
<div>
<p>This target should be implemented by the <tt>Makefile</tt> in the project's
<tt>test</tt> directory. It is invoked by the <tt>check</tt> target elsewhere.
Each project is free to define the actions of <tt>check-local</tt> as
appropriate for that project. The LLVM project itself uses dejagnu to run a
suite of feature and regresson tests. Other projects may choose to use
dejagnu or any other testing mechanism.</p>
</div>
<!-- ======================================================================= -->
<h3><a name="clean">clean</a></h3>
<div>
<p>This target cleans the build directory, recursively removing all things
that the Makefile builds. The cleaning rules have been made guarded so they
shouldn't go awry (via <tt>rm -f $(UNSET_VARIABLE)/*</tt> which will attempt
to erase the entire directory structure.</p>
</div>
<!-- ======================================================================= -->
<h3><a name="clean-local">clean-local</a></h3>
<div>
<p>This target does the same thing as <tt>clean</tt> but only for the current
(local) directory.</p>
</div>
<!-- ======================================================================= -->
<h3><a name="dist">dist</a></h3>
<div>
<p>This target builds a distribution tarball. It first builds the entire
project using the <tt>all</tt> target and then tars up the necessary files and
compresses it. The generated tarball is sufficient for a casual source
distribution, but probably not for a release (see <tt>dist-check</tt>).</p>
</div>
<!-- ======================================================================= -->
<h3><a name="dist-check">dist-check</a></h3>
<div>
<p>This target does the same thing as the <tt>dist</tt> target but also checks
the distribution tarball. The check is made by unpacking the tarball to a new
directory, configuring it, building it, installing it, and then verifying that
the installation results are correct (by comparing to the original build).
This target can take a long time to run but should be done before a release
goes out to make sure that the distributed tarball can actually be built into
a working release.</p>
</div>
<!-- ======================================================================= -->
<h3><a name="dist-clean">dist-clean</a></h3>
<div>
<p>This is a special form of the <tt>clean</tt> clean target. It performs a
normal <tt>clean</tt> but also removes things pertaining to building the
distribution.</p>
</div>
<!-- ======================================================================= -->
<h3><a name="install">install</a></h3>
<div>
<p>This target finalizes shared objects and executables and copies all
libraries, headers, executables and documentation to the directory given
with the <tt>--prefix</tt> option to <tt>configure</tt>. When completed,
the prefix directory will have everything needed to <b>use</b> LLVM. </p>
<p>The LLVM makefiles can generate complete <b>internal</b> documentation
for all the classes by using <tt>doxygen</tt>. By default, this feature is
<b>not</b> enabled because it takes a long time and generates a massive
amount of data (>100MB). If you want this feature, you must configure LLVM
with the --enable-doxygen switch and ensure that a modern version of doxygen
(1.3.7 or later) is available in your <tt>PATH</tt>. You can download
doxygen from
<a href="http://www.stack.nl/~dimitri/doxygen/download.html#latestsrc">
here</a>.
</div>
<!-- ======================================================================= -->
<h3><a name="preconditions">preconditions</a></h3>
<div>
<p>This utility target checks to see if the <tt>Makefile</tt> in the object
directory is older than the <tt>Makefile</tt> in the source directory and
copies it if so. It also reruns the <tt>configure</tt> script if that needs to
be done and rebuilds the <tt>Makefile.config</tt> file similarly. Users may
overload this target to ensure that sanity checks are run <em>before</em> any
building of targets as all the targets depend on <tt>preconditions</tt>.</p>
</div>
<!-- ======================================================================= -->
<h3><a name="printvars">printvars</a></h3>
<div>
<p>This utility target just causes the LLVM makefiles to print out some of
the makefile variables so that you can double check how things are set. </p>
</div>
<!-- ======================================================================= -->
<h3><a name="reconfigure">reconfigure</a></h3>
<div>
<p>This utility target will force a reconfigure of LLVM or your project. It
simply runs <tt>$(PROJ_OBJ_ROOT)/config.status --recheck</tt> to rerun the
configuration tests and rebuild the configured files. This isn't generally
useful as the makefiles will reconfigure themselves whenever its necessary.
</p>
</div>
<!-- ======================================================================= -->
<h3><a name="spotless">spotless</a></h3>
<div>
<p>This utility target, only available when <tt>$(PROJ_OBJ_ROOT)</tt> is not
the same as <tt>$(PROJ_SRC_ROOT)</tt>, will completely clean the
<tt>$(PROJ_OBJ_ROOT)</tt> directory by removing its content entirely and
reconfiguring the directory. This returns the <tt>$(PROJ_OBJ_ROOT)</tt>
directory to a completely fresh state. All content in the directory except
configured files and top-level makefiles will be lost.</p>
<div class="doc_warning"><p>Use with caution.</p></div>
</div>
<!-- ======================================================================= -->
<h3><a name="tags">tags</a></h3>
<div>
<p>This target will generate a <tt>TAGS</tt> file in the top-level source
directory. It is meant for use with emacs, XEmacs, or ViM. The TAGS file
provides an index of symbol definitions so that the editor can jump you to the
definition quickly. </p>
</div>
<!-- ======================================================================= -->
<h3><a name="uninstall">uninstall</a></h3>
<div>
<p>This target is the opposite of the <tt>install</tt> target. It removes the
header, library and executable files from the installation directories. Note
that the directories themselves are not removed because it is not guaranteed
that LLVM is the only thing installing there (e.g. --prefix=/usr).</p>
</div>
</div>
<!-- *********************************************************************** -->
<h2><a name="variables">Variables</a></h2>
<!-- *********************************************************************** -->
<div>
<p>Variables are used to tell the LLVM Makefile System what to do and to
obtain information from it. Variables are also used internally by the LLVM
Makefile System. Variable names that contain only the upper case alphabetic
letters and underscore are intended for use by the end user. All other
variables are internal to the LLVM Makefile System and should not be relied
upon nor modified. The sections below describe how to use the LLVM Makefile
variables.</p>
<!-- ======================================================================= -->
<h3><a name="setvars">Control Variables</a></h3>
<div>
<p>Variables listed in the table below should be set <em>before</em> the
inclusion of <a href="#Makefile.common"><tt>$(LEVEL)/Makefile.common</tt></a>.
These variables provide input to the LLVM make system that tell it what to do
for the current directory.</p>
<dl>
<dt><a name="BUILD_ARCHIVE"><tt>BUILD_ARCHIVE</tt></a></dt>
<dd>If set to any value, causes an archive (.a) library to be built.</dd>
<dt><a name="BUILT_SOURCES"><tt>BUILT_SOURCES</tt></a></dt>
<dd>Specifies a set of source files that are generated from other source
files. These sources will be built before any other target processing to
ensure they are present.</dd>
<dt><a name="BYTECODE_LIBRARY"><tt>BYTECODE_LIBRARY</tt></a></dt>
<dd>If set to any value, causes a bitcode library (.bc) to be built.</dd>
<dt><a name="CONFIG_FILES"><tt>CONFIG_FILES</tt></a></dt>
<dd>Specifies a set of configuration files to be installed.</dd>
<dt><a name="DEBUG_SYMBOLS"><tt>DEBUG_SYMBOLS</tt></a></dt>
<dd>If set to any value, causes the build to include debugging
symbols even in optimized objects, libraries and executables. This
alters the flags specified to the compilers and linkers. Debugging
isn't fun in an optimized build, but it is possible.</dd>
<dt><a name="DIRS"><tt>DIRS</tt></a></dt>
<dd>Specifies a set of directories, usually children of the current
directory, that should also be made using the same goal. These directories
will be built serially.</dd>
<dt><a name="DISABLE_AUTO_DEPENDENCIES"><tt>DISABLE_AUTO_DEPENDENCIES</tt></a></dt>
<dd>If set to any value, causes the makefiles to <b>not</b> automatically
generate dependencies when running the compiler. Use of this feature is
discouraged and it may be removed at a later date.</dd>
<dt><a name="ENABLE_OPTIMIZED"><tt>ENABLE_OPTIMIZED</tt></a></dt>
<dd>If set to 1, causes the build to generate optimized objects,
libraries and executables. This alters the flags specified to the compilers
and linkers. Generally debugging won't be a fun experience with an optimized
build.</dd>
<dt><a name="ENABLE_PROFILING"><tt>ENABLE_PROFILING</tt></a></dt>
<dd>If set to 1, causes the build to generate both optimized and
profiled objects, libraries and executables. This alters the flags specified
to the compilers and linkers to ensure that profile data can be collected
from the tools built. Use the <tt>gprof</tt> tool to analyze the output from
the profiled tools (<tt>gmon.out</tt>).</dd>
<dt><a name="DISABLE_ASSERTIONS"><tt>DISABLE_ASSERTIONS</tt></a></dt>
<dd>If set to 1, causes the build to disable assertions, even if
building a debug or profile build. This will exclude all assertion check
code from the build. LLVM will execute faster, but with little help when
things go wrong.</dd>
<dt><a name="EXPERIMENTAL_DIRS"><tt>EXPERIMENTAL_DIRS</tt></a></dt>
<dd>Specify a set of directories that should be built, but if they fail, it
should not cause the build to fail. Note that this should only be used
temporarily while code is being written.</dd>
<dt><a name="EXPORTED_SYMBOL_FILE"><tt>EXPORTED_SYMBOL_FILE</tt></a></dt>
<dd>Specifies the name of a single file that contains a list of the
symbols to be exported by the linker. One symbol per line.</dd>
<dt><a name="EXPORTED_SYMBOL_LIST"><tt>EXPORTED_SYMBOL_LIST</tt></a></dt>
<dd>Specifies a set of symbols to be exported by the linker.</dd>
<dt><a name="EXTRA_DIST"><tt>EXTRA_DIST</tt></a></dt>
<dd>Specifies additional files that should be distributed with LLVM. All
source files, all built sources, all Makefiles, and most documentation files
will be automatically distributed. Use this variable to distribute any
files that are not automatically distributed.</dd>
<dt><a name="KEEP_SYMBOLS"><tt>KEEP_SYMBOLS</tt></a></dt>
<dd>If set to any value, specifies that when linking executables the
makefiles should retain debug symbols in the executable. Normally, symbols
are stripped from the executable.</dd>
<dt><a name="LEVEL"><tt>LEVEL</tt></a><small>(required)</small></dt>
<dd>Specify the level of nesting from the top level. This variable must be
set in each makefile as it is used to find the top level and thus the other
makefiles.</dd>
<dt><a name="LIBRARYNAME"><tt>LIBRARYNAME</tt></a></dt>
<dd>Specify the name of the library to be built. (Required For
Libraries)</dd>
<dt><a name="LINK_COMPONENTS"><tt>LINK_COMPONENTS</tt></a></dt>
<dd>When specified for building a tool, the value of this variable will be
passed to the <tt>llvm-config</tt> tool to generate a link line for the
tool. Unlike <tt>USEDLIBS</tt> and <tt>LLVMLIBS</tt>, not all libraries need
to be specified. The <tt>llvm-config</tt> tool will figure out the library
dependencies and add any libraries that are needed. The <tt>USEDLIBS</tt>
variable can still be used in conjunction with <tt>LINK_COMPONENTS</tt> so
that additional project-specific libraries can be linked with the LLVM
libraries specified by <tt>LINK_COMPONENTS</tt></dd>
<dt><a name="LINK_LIBS_IN_SHARED"><tt>LINK_LIBS_IN_SHARED</tt></a></dt>
<dd>By default, shared library linking will ignore any libraries specified
with the <a href="LLVMLIBS">LLVMLIBS</a> or <a href="USEDLIBS">USEDLIBS</a>.
This prevents shared libs from including things that will be in the LLVM
tool the shared library will be loaded into. However, sometimes it is useful
to link certain libraries into your shared library and this option enables
that feature.</dd>
<dt><a name="LLVMLIBS"><tt>LLVMLIBS</tt></a></dt>
<dd>Specifies the set of libraries from the LLVM $(ObjDir) that will be
linked into the tool or library.</dd>
<dt><a name="LOADABLE_MODULE"><tt>LOADABLE_MODULE</tt></a></dt>
<dd>If set to any value, causes the shared library being built to also be
a loadable module. Loadable modules can be opened with the dlopen() function
and searched with dlsym (or the operating system's equivalent). Note that
setting this variable without also setting <tt>SHARED_LIBRARY</tt> will have
no effect.</dd>
<dt><a name="MODULE_NAME"><tt>MODULE_NAME</tt></a></dt>
<dd>Specifies the name of a bitcode module to be created. A bitcode
module can be specified in conjunction with other kinds of library builds
or by itself. It constructs from the sources a single linked bitcode
file.</dd>
<dt><a name="NO_INSTALL"><tt>NO_INSTALL</tt></a></dt>
<dd>Specifies that the build products of the directory should not be
installed but should be built even if the <tt>install</tt> target is given.
This is handy for directories that build libraries or tools that are only
used as part of the build process, such as code generators (e.g.
<tt>tblgen</tt>).</dd>
<dt><a name="OPTIONAL_DIRS"><tt>OPTIONAL_DIRS</tt></a></dt>
<dd>Specify a set of directories that may be built, if they exist, but its
not an error for them not to exist.</dd>
<dt><a name="PARALLEL_DIRS"><tt>PARALLEL_DIRS</tt></a></dt>
<dd>Specify a set of directories to build recursively and in parallel if
the -j option was used with <tt>make</tt>.</dd>
<dt><a name="SHARED_LIBRARY"><tt>SHARED_LIBRARY</tt></a></dt>
<dd>If set to any value, causes a shared library (.so) to be built in
addition to any other kinds of libraries. Note that this option will cause
all source files to be built twice: once with options for position
independent code and once without. Use it only where you really need a
shared library.</dd>
<dt><a name="SOURCES"><tt>SOURCES</tt><small>(optional)</small></a></dt>
<dd>Specifies the list of source files in the current directory to be
built. Source files of any type may be specified (programs, documentation,
config files, etc.). If not specified, the makefile system will infer the
set of source files from the files present in the current directory.</dd>
<dt><a name="SUFFIXES"><tt>SUFFIXES</tt></a></dt>
<dd>Specifies a set of filename suffixes that occur in suffix match rules.
Only set this if your local <tt>Makefile</tt> specifies additional suffix
match rules.</dd>
<dt><a name="TARGET"><tt>TARGET</tt></a></dt>
<dd>Specifies the name of the LLVM code generation target that the
current directory builds. Setting this variable enables additional rules to
build <tt>.inc</tt> files from <tt>.td</tt> files. </dd>
<dt><a name="TESTSUITE"><tt>TESTSUITE</tt></a></dt>
<dd>Specifies the directory of tests to run in <tt>llvm/test</tt>.</dd>
<dt><a name="TOOLNAME"><tt>TOOLNAME</tt></a></dt>
<dd>Specifies the name of the tool that the current directory should
build.</dd>
<dt><a name="TOOL_VERBOSE"><tt>TOOL_VERBOSE</tt></a></dt>
<dd>Implies VERBOSE and also tells each tool invoked to be verbose. This is
handy when you're trying to see the sub-tools invoked by each tool invoked
by the makefile. For example, this will pass <tt>-v</tt> to the GCC
compilers which causes it to print out the command lines it uses to invoke
sub-tools (compiler, assembler, linker).</dd>
<dt><a name="USEDLIBS"><tt>USEDLIBS</tt></a></dt>
<dd>Specifies the list of project libraries that will be linked into the
tool or library.</dd>
<dt><a name="VERBOSE"><tt>VERBOSE</tt></a></dt>
<dd>Tells the Makefile system to produce detailed output of what it is doing
instead of just summary comments. This will generate a LOT of output.</dd>
</dl>
</div>
<!-- ======================================================================= -->
<h3><a name="overvars">Override Variables</a></h3>
<div>
<p>Override variables can be used to override the default
values provided by the LLVM makefile system. These variables can be set in
several ways:</p>
<ul>
<li>In the environment (e.g. setenv, export) -- not recommended.</li>
<li>On the <tt>make</tt> command line -- recommended.</li>
<li>On the <tt>configure</tt> command line</li>
<li>In the Makefile (only <em>after</em> the inclusion of <a
href="#Makefile.common"><tt>$(LEVEL)/Makefile.common</tt></a>).</li>
</ul>
<p>The override variables are given below:</p>
<dl>
<dt><a name="AR"><tt>AR</tt></a> <small>(defaulted)</small></dt>
<dd>Specifies the path to the <tt>ar</tt> tool.</dd>
<dt><a name="PROJ_OBJ_DIR"><tt>PROJ_OBJ_DIR</tt></a></dt>
<dd>The directory into which the products of build rules will be placed.
This might be the same as
<a href="#PROJ_SRC_DIR"><tt>PROJ_SRC_DIR</tt></a> but typically is
not.</dd>
<dt><a name="PROJ_SRC_DIR"><tt>PROJ_SRC_DIR</tt></a></dt>
<dd>The directory which contains the source files to be built.</dd>
<dt><a name="BUILD_EXAMPLES"><tt>BUILD_EXAMPLES</tt></a></dt>
<dd>If set to 1, build examples in <tt>examples</tt> and (if building
Clang) <tt>tools/clang/examples</tt> directories.</dd>
<dt><a name="BZIP2"><tt>BZIP2</tt></a><small>(configured)</small></dt>
<dd>The path to the <tt>bzip2</tt> tool.</dd>
<dt><a name="CC"><tt>CC</tt></a><small>(configured)</small></dt>
<dd>The path to the 'C' compiler.</dd>
<dt><a name="CFLAGS"><tt>CFLAGS</tt></a></dt>
<dd>Additional flags to be passed to the 'C' compiler.</dd>
<dt><a name="CXX"><tt>CXX</tt></a></dt>
<dd>Specifies the path to the C++ compiler.</dd>
<dt><a name="CXXFLAGS"><tt>CXXFLAGS</tt></a></dt>
<dd>Additional flags to be passed to the C++ compiler.</dd>
<dt><a name="DATE"><tt>DATE<small>(configured)</small></tt></a></dt>
<dd>Specifies the path to the <tt>date</tt> program or any program that can
generate the current date and time on its standard output</dd>
<dt><a name="DOT"><tt>DOT</tt></a><small>(configured)</small></dt>
<dd>Specifies the path to the <tt>dot</tt> tool or <tt>false</tt> if there
isn't one.</dd>
<dt><a name="ECHO"><tt>ECHO</tt></a><small>(configured)</small></dt>
<dd>Specifies the path to the <tt>echo</tt> tool for printing output.</dd>
<dt><a name="EXEEXT"><tt>EXEEXT</tt></a><small>(configured)</small></dt>
<dd>Provides the extension to be used on executables built by the makefiles.
The value may be empty on platforms that do not use file extensions for
executables (e.g. Unix).</dd>
<dt><a name="INSTALL"><tt>INSTALL</tt></a><small>(configured)</small></dt>
<dd>Specifies the path to the <tt>install</tt> tool.</dd>
<dt><a name="LDFLAGS"><tt>LDFLAGS</tt></a><small>(configured)</small></dt>
<dd>Allows users to specify additional flags to pass to the linker.</dd>
<dt><a name="LIBS"><tt>LIBS</tt></a><small>(configured)</small></dt>
<dd>The list of libraries that should be linked with each tool.</dd>
<dt><a name="LIBTOOL"><tt>LIBTOOL</tt></a><small>(configured)</small></dt>
<dd>Specifies the path to the <tt>libtool</tt> tool. This tool is renamed
<tt>mklib</tt> by the <tt>configure</tt> script and always located in the
<dt><a name="LLVMAS"><tt>LLVMAS</tt></a><small>(defaulted)</small></dt>
<dd>Specifies the path to the <tt>llvm-as</tt> tool.</dd>
<dt><a name="LLVMCC"><tt>LLVMCC</tt></a></dt>
<dd>Specifies the path to the LLVM capable compiler.</dd>
<dt><a name="LLVMCXX"><tt>LLVMCXX</tt></a></dt>
<dd>Specifies the path to the LLVM C++ capable compiler.</dd>
<dt><a name="LLVMGCC"><tt>LLVMGCC</tt></a><small>(defaulted)</small></dt>
<dd>Specifies the path to the LLVM version of the GCC 'C' Compiler</dd>
<dt><a name="LLVMGXX"><tt>LLVMGXX</tt></a><small>(defaulted)</small></dt>
<dd>Specifies the path to the LLVM version of the GCC C++ Compiler</dd>
<dt><a name="LLVMLD"><tt>LLVMLD</tt></a><small>(defaulted)</small></dt>
<dd>Specifies the path to the LLVM bitcode linker tool</dd>
<dt><a name="LLVM_OBJ_ROOT"><tt>LLVM_OBJ_ROOT</tt></a><small>(configured)
</small></dt>
<dd>Specifies the top directory into which the output of the build is
placed.</dd>
<dt><a name="LLVM_SRC_ROOT"><tt>LLVM_SRC_ROOT</tt></a><small>(configured)
</small></dt>
<dd>Specifies the top directory in which the sources are found.</dd>
<dt><a name="LLVM_TARBALL_NAME"><tt>LLVM_TARBALL_NAME</tt></a>
<small>(configured)</small></dt>
<dd>Specifies the name of the distribution tarball to create. This is
configured from the name of the project and its version number.</dd>
<dt><a name="MKDIR"><tt>MKDIR</tt></a><small>(defaulted)</small></dt>
<dd>Specifies the path to the <tt>mkdir</tt> tool that creates
directories.</dd>
<dt><a name="ONLY_TOOLS"><tt>ONLY_TOOLS</tt></a></dt>
<dd>If set, specifies the list of tools to build.</dd>
<dt><a name="PLATFORMSTRIPOPTS"><tt>PLATFORMSTRIPOPTS</tt></a></dt>
<dd>The options to provide to the linker to specify that a stripped (no
symbols) executable should be built.</dd>
<dt><a name="RANLIB"><tt>RANLIB</tt></a><small>(defaulted)</small></dt>
<dd>Specifies the path to the <tt>ranlib</tt> tool.</dd>
<dt><a name="RM"><tt>RM</tt></a><small>(defaulted)</small></dt>
<dd>Specifies the path to the <tt>rm</tt> tool.</dd>
<dt><a name="SED"><tt>SED</tt></a><small>(defaulted)</small></dt>
<dd>Specifies the path to the <tt>sed</tt> tool.</dd>
<dt><a name="SHLIBEXT"><tt>SHLIBEXT</tt></a><small>(configured)</small></dt>
<dd>Provides the filename extension to use for shared libraries.</dd>
<dt><a name="TBLGEN"><tt>TBLGEN</tt></a><small>(defaulted)</small></dt>
<dd>Specifies the path to the <tt>tblgen</tt> tool.</dd>
<dt><a name="TAR"><tt>TAR</tt></a><small>(defaulted)</small></dt>
<dd>Specifies the path to the <tt>tar</tt> tool.</dd>
<dt><a name="ZIP"><tt>ZIP</tt></a><small>(defaulted)</small></dt>
<dd>Specifies the path to the <tt>zip</tt> tool.</dd>
</dl>
</div>
<!-- ======================================================================= -->
<h3><a name="getvars">Readable Variables</a></h3>
<div>
<p>Variables listed in the table below can be used by the user's Makefile but
should not be changed. Changing the value will generally cause the build to go
wrong, so don't do it.</p>
<dl>
<dt><a name="bindir"><tt>bindir</tt></a></dt>
<dd>The directory into which executables will ultimately be installed. This
value is derived from the <tt>--prefix</tt> option given to
<tt>configure</tt>.</dd>
<dt><a name="BuildMode"><tt>BuildMode</tt></a></dt>
<dd>The name of the type of build being performed: Debug, Release, or
Profile</dd>
<dt><a name="bitcode_libdir"><tt>bytecode_libdir</tt></a></dt>
<dd>The directory into which bitcode libraries will ultimately be
installed. This value is derived from the <tt>--prefix</tt> option given to
<tt>configure</tt>.</dd>
<dt><a name="ConfigureScriptFLAGS"><tt>ConfigureScriptFLAGS</tt></a></dt>
<dd>Additional flags given to the <tt>configure</tt> script when
reconfiguring.</dd>
<dt><a name="DistDir"><tt>DistDir</tt></a></dt>
<dd>The <em>current</em> directory for which a distribution copy is being
made.</dd>
<dt><a name="Echo"><tt>Echo</tt></a></dt>
<dd>The LLVM Makefile System output command. This provides the
<tt>llvm[n]</tt> prefix and starts with @ so the command itself is not
printed by <tt>make</tt>.</dd>
<dt><a name="EchoCmd"><tt>EchoCmd</tt></a></dt>
<dd> Same as <a href="#Echo"><tt>Echo</tt></a> but without the leading @.
</dd>
<dt><a name="includedir"><tt>includedir</tt></a></dt>
<dd>The directory into which include files will ultimately be installed.
This value is derived from the <tt>--prefix</tt> option given to
<tt>configure</tt>.</dd>
<dt><a name="libdir"><tt>libdir</tt></a></dt><dd></dd>
<dd>The directory into which native libraries will ultimately be installed.
This value is derived from the <tt>--prefix</tt> option given to
<tt>configure</tt>.</dd>
<dt><a name="LibDir"><tt>LibDir</tt></a></dt>
<dd>The configuration specific directory into which libraries are placed
before installation.</dd>
<dt><a name="MakefileConfig"><tt>MakefileConfig</tt></a></dt>
<dd>Full path of the <tt>Makefile.config</tt> file.</dd>
<dt><a name="MakefileConfigIn"><tt>MakefileConfigIn</tt></a></dt>
<dd>Full path of the <tt>Makefile.config.in</tt> file.</dd>
<dt><a name="ObjDir"><tt>ObjDir</tt></a></dt>
<dd>The configuration and directory specific directory where build objects
(compilation results) are placed.</dd>
<dt><a name="SubDirs"><tt>SubDirs</tt></a></dt>
<dd>The complete list of sub-directories of the current directory as
specified by other variables.</dd>
<dt><a name="Sources"><tt>Sources</tt></a></dt>
<dd>The complete list of source files.</dd>
<dt><a name="sysconfdir"><tt>sysconfdir</tt></a></dt>
<dd>The directory into which configuration files will ultimately be
installed. This value is derived from the <tt>--prefix</tt> option given to
<tt>configure</tt>.</dd>
<dt><a name="ToolDir"><tt>ToolDir</tt></a></dt>
<dd>The configuration specific directory into which executables are placed
before they are installed.</dd>
<dt><a name="TopDistDir"><tt>TopDistDir</tt></a></dt>
<dd>The top most directory into which the distribution files are copied.
</dd>
<dt><a name="Verb"><tt>Verb</tt></a></dt>
<dd>Use this as the first thing on your build script lines to enable or
disable verbose mode. It expands to either an @ (quiet mode) or nothing
(verbose mode). </dd>
</dl>
</div>
<!-- ======================================================================= -->
<h3><a name="intvars">Internal Variables</a></h3>
<div>
<p>Variables listed below are used by the LLVM Makefile System
and considered internal. You should not use these variables under any
circumstances.</p>
<p><tt>
Archive
AR.Flags
BaseNameSources
BCCompile.C
BCCompile.CXX
BCLinkLib
C.Flags
Compile.C
CompileCommonOpts
Compile.CXX
ConfigStatusScript
ConfigureScript
CPP.Flags
CPP.Flags
CXX.Flags
DependFiles
DestArchiveLib
DestBitcodeLib
DestModule
DestSharedLib
DestTool
DistAlways
DistCheckDir
DistCheckTop
DistFiles
DistName
DistOther
DistSources
DistSubDirs
DistTarBZ2
DistTarGZip
DistZip
ExtraLibs
FakeSources
INCFiles
InternalTargets
LD.Flags
LibName.A
LibName.BC
LibName.LA
LibName.O
LibTool.Flags
Link
LinkModule
LLVMLibDir
LLVMLibsOptions
LLVMLibsPaths
LLVMToolDir
LLVMUsedLibs
LocalTargets
Module
ObjectsBC
ObjectsLO
ObjectsO
ObjMakefiles
ParallelTargets
PreConditions
ProjLibsOptions
ProjLibsPaths
ProjUsedLibs
Ranlib
RecursiveTargets
SrcMakefiles
Strip
StripWarnMsg
TableGen
TDFiles
ToolBuildPath
TopLevelTargets
UserTargets
</tt></p>
</div>
</div>
<!-- *********************************************************************** -->
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