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+ <head>
+ <title>Creating an LLVM Project</title>
+ </head>
+
+ <body bgcolor=white>
+
+ <center><h1>Creating an LLVM Project<br></h1></center>
+
+ <!--===============================================================-->
+ <h2><a name="a">Overview</a><hr></h2>
+ <!--===============================================================-->
+
+ In order to set up a new project that uses the LLVM build system,
+ libraries, and header files, follow these steps:
+
+ <ol>
+ <li>
+ Copy the <tt>llvm/projects/sample</tt> directory to any place
+ of your choosing. You can place it anywhere you like, although
+ someplace underneath your home directory would work best.
+ <p>
+
+ <li>
+ Edit the <tt>Makefile.config</tt> and <tt>Makefile.common</tt>
+ files so that the LLVM_SRC_ROOT variable equals the absolute
+ pathname of the LLVM source tree and LLVM_OBJ_ROOT equals the
+ pathname of where LLVM was built.
+
+ <p>
+
+ For example, if the LLVM source tree is in
+ <tt>/usr/home/joe/src/llvm</tt>, and you configured it with
+ <tt>--with-objroot=/tmp</tt> when his home directory is
+ <tt>/usr/home/joe</tt>, then
+ LLVM_SRC_ROOT=<tt>/usr/home/joe/src/llvm</tt> and
+ LLVM_OBJ_ROOT=<tt>/tmp/src/llvm</tt>.
+ <p>
+
+ <li>
+ Add your source code to the source tree.
+ <p>
+
+ <li>
+ Modify the various Makefiles to contain the names of the
+ objects that you want to build.
+ </ol>
+
+ <!--===============================================================-->
+ <h2><a name="Source Tree Layout">Source Tree Layout</a><hr></h2>
+ <!--===============================================================-->
+
+ In order to use the LLVM build system, you will want to lay out 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.
+
+ Underneath your top level directory, you should have the following
+ directories:
+
+ <dl compact>
+ <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 good place for these as it
+ places them all in a directory from which they can be linked
+ later on.
+
+ <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.
+ </dl>
+
+ Typically, you will want to build your <b>lib</b> directory first
+ followed by your <b>tools</b> directory.
+
+ <!--===============================================================-->
+ <h2><a name="Makefile Variables">Makefile Variables</a><hr></h2>
+ <!--===============================================================-->
+ The LLVM build system provides several variables which you may
+ use.
+
+ <h3> Required Variables </h3>
+ <dl compact>
+ <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 /tmp/src, then the Makefile in
+ /tmp/src/jump/high would set LEVEL to "../..".
+ </dl>
+
+ <h3> Variables for Building Subdirectories</h3>
+ <dl compact>
+ <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>
+
+ <h3> Variables for Building Libraries</h3>
+ <dl compact>
+ <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. However, if you set the BUILD_ARCHIVE
+ variable, an archive library (sometimes known as a static
+ library) will be built instead.
+ <p>
+
+ <dt>SHARED_LIBRARY
+ <dd>
+ If SHARED_LIBRARY is defined in your Makefile, then the
+ Makefiles will generate a shared (or dynamic) library.
+ </dl>
+
+ <h3> Variables for Building Programs</h3>
+ <dl compact>
+ <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>
+ </dl>
+
+ <h3> Miscellaneous Variables</h3>
+ <dl compact>
+ <dt>ExtraSource
+ <dd>
+ This variable contains a space separated list of extra source
+ files that needs 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 these variable as
+ opposed to overwriting them. The master Makefiles may already
+ have useful options in them that you may not want to overwrite.
+ <p>
+ </dl>
+
+ <!--===============================================================-->
+ <h2><a name="Caveats">Caveats</a><hr></h2>
+ <!--===============================================================-->
+
+ Some caveats and known issues:
+ <ol>
+ <li>
+ The projects system currently uses the $HOME environment
+ variable in determining where object files should go. If $HOME
+ is not set, then your path relative to the root directory may
+ be used to determine where your object files go. It is
+ therefore advised that your source directory reside underneath
+ your home directory.
+ </ol>
+</body>
+</html>
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