Llvm Makefile Guide

===================LLVM Makefile Guide===================

.. contents:: :local:

Introduction============

This document provides *usage* information about the LLVM makefile system. Whileloosely patterned after the BSD makefile system, LLVM has taken a departure fromBSD in order to implement additional features needed by LLVM. Although makefilesystems, such as ``automake``, were attempted at one point, it has become clearthat the features needed by LLVM and the ``Makefile`` norm are too great to usea more limited tool. Consequently, LLVM requires simply GNU Make 3.79, a widelyportable makefile processor. LLVM unabashedly makes heavy use of the features ofGNU Make so the dependency on GNU Make is firm. If you're not familiar with``make``, it is recommended that you read the `GNU Makefile Manual`_.

While this document is rightly part of the `LLVM Programmer'sManual `_, it is treated separately here because of thevolume of content and because it is often an early source of bewilderment fornew developers.

General Concepts================

The LLVM Makefile System is the component of LLVM that is responsible forbuilding the software, testing it, generating distributions, checking thosedistributions, installing and uninstalling, etc. It consists of a several filesthroughout the source tree. These files and other general concepts are describedin this section.

Projects--------

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``llvm/projects`` directory. Any directory under ``projects`` that has both a``configure`` script and a ``Makefile`` is assumed to be a project that uses theLLVM Makefile system. Building software that uses LLVM does not require theLLVM Makefile System nor even placement in the ``llvm/projects``directory. However, doing so will allow your project to get up and runningquickly by utilizing the built-in features that are used to compile LLVM. LLVMcompiles itself using the same features of the makefile system as used forprojects.

For complete details on setting up your projects configuration, simply mimic the``llvm/projects/sample`` project. Or for further details, consult the`Projects `_ page.

Variable Values---------------

To use the makefile system, you simply create a file named ``Makefile`` in yourdirectory and declare values for certain variables. The variables and valuesthat you select determine what the makefile system will do. These variablesenable rules and processing in the makefile system that automatically Do TheRight Thing (C).

Including Makefiles-------------------

Setting variables alone is not enough. You must include into your Makefileadditional files that provide the rules of the LLVM Makefile system. The variousfiles involved are described in the sections that follow.

``Makefile``^^^^^^^^^^^^

Each directory to participate in the build needs to have a file named``Makefile``. This is the file first read by ``make``. It has threesections:

#. Settable Variables --- Required that must be set first.#. ``include $(LEVEL)/Makefile.common`` --- include the LLVM Makefile system.#. Override Variables --- Override variables set by the LLVM Makefile system.

.. _$(LEVEL)/Makefile.common:

``Makefile.common``^^^^^^^^^^^^^^^^^^^

Every project must have a ``Makefile.common`` file at its top sourcedirectory. This file serves three purposes:

#. It includes the project's configuration makefile to obtain values determined by the ``configure`` script. This is done by including the `$(LEVEL)/Makefile.config`_ file.

#. 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.

#. It includes the standard rules for the LLVM Makefile system, `$(LLVM_SRC_ROOT)/Makefile.rules`_. This file is the *guts* of the LLVM ``Makefile`` system.

.. _$(LEVEL)/Makefile.config:

``Makefile.config``^^^^^^^^^^^^^^^^^^^

Every project must have a ``Makefile.config`` at the top of its *build*directory. This file is **generated** by the ``configure`` script from thepattern provided by the ``Makefile.config.in`` file located at the top of theproject's *source* directory. The contents of this file depend largely on whatconfiguration items the project uses, however most projects can get what they

need by just relying on LLVM's configuration found in``$(LLVM_OBJ_ROOT)/Makefile.config``.

.. _$(LLVM_SRC_ROOT)/Makefile.rules:

``Makefile.rules``^^^^^^^^^^^^^^^^^^

This file, located at ``$(LLVM_SRC_ROOT)/Makefile.rules`` is the heart of theLLVM Makefile System. It provides all the logic, dependencies, and rules forbuilding the targets supported by the system. What it does largely depends onthe values of ``make`` `variables`_ that have been set *before*``Makefile.rules`` is included.

Comments^^^^^^^^

User ``Makefile``\s need not have comments in them unless the construction isunusual or it does not strictly follow the rules and patterns of the LLVMmakefile system. Makefile comments are invoked with the pound (``#``) character.The ``#`` character and any text following it, to the end of the line, areignored by ``make``.

Tutorial========

This section provides some examples of the different kinds of modules you canbuild with the LLVM makefile system. In general, each directory you provide willbuild a single object although that object may be composed of additionallycompiled components.

Libraries---------

Only a few variable definitions are needed to build a regular library.Normally, the makefile system will build all the software into a single``libname.o`` (pre-linked) object. This means the library is not searchable andthat the distinction between compilation units has been dissolved.

Optionally,you can ask for a shared library (.so) or archive library (.a) built. Archivelibraries are the default. For example:

.. code-block:: makefile

LIBRARYNAME = mylib SHARED_LIBRARY = 1 ARCHIVE_LIBRARY = 1

says to build a library named ``mylib`` with both a shared library(``mylib.so``) and an archive library (``mylib.a``) version. The contents of allthe libraries produced will be the same, they are just constructed differently.Note that you normally do not need to specify the sources involved. The LLVMMakefile system will infer the source files from the contents of the sourcedirectory.

The ``LOADABLE_MODULE=1`` directive can be used in conjunction with``SHARED_LIBRARY=1`` to indicate that the resulting shared library should beopenable with the ``dlopen`` function and searchable with the ``dlsym`` function(or your operating system's equivalents). While this isn't strictly necessary onLinux and a few other platforms, it is required on systems like HP-UX andDarwin. You should use ``LOADABLE_MODULE`` for any shared library that youintend to be loaded into an tool via the ``-load`` option. `Pass documentation`_ has an example of why you might want to dothis.

Bitcode Modules^^^^^^^^^^^^^^^

In some situations, it is desirable to build a single bitcode module from avariety of sources, instead of an archive, shared library, or bitcodelibrary. Bitcode modules can be specified in addition to any of the other typesof libraries by defining the `MODULE_NAME`_ variable. For example:

.. code-block:: makefile

LIBRARYNAME = mylib

BYTECODE_LIBRARY = 1 MODULE_NAME = mymod

will build a module named ``mymod.bc`` from the sources in the directory. Thismodule will be an aggregation of all the bitcode modules derived from thesources. The example will also build a bitcode archive containing a bitcodemodule for each compiled source file. The difference is subtle, but importantdepending on how the module or library is to be linked.

Loadable Modules^^^^^^^^^^^^^^^^

In some situations, you need to create a loadable module. Loadable modules canbe loaded into programs like ``opt`` or ``llc`` to specify additional passes torun or targets to support. Loadable modules are also useful for debugging apass or providing a pass with another package if that pass can't be included inLLVM.

LLVM provides complete support for building such a module. All you need to do isuse the ``LOADABLE_MODULE`` variable in your ``Makefile``. For example, to builda loadable module named ``MyMod`` that uses the LLVM libraries ``LLVMSupport.a``and ``LLVMSystem.a``, you would specify:

.. code-block:: makefile

LIBRARYNAME := MyMod LOADABLE_MODULE := 1 LINK_COMPONENTS := support system

Use of the ``LOADABLE_MODULE`` facility implies several things:

#. There will be no "``lib``" prefix on the module. This differentiates it from a standard shared library of the same name.

#. The `SHARED_LIBRARY`_ variable is turned on.

#. The `LINK_LIBS_IN_SHARED`_ variable is turned on.

A loadable module is loaded by LLVM via the facilities of libtool's libltdllibrary which is part of ``lib/System`` implementation.

Tools-----

For building executable programs (tools), you must provide the name of the tooland the names of the libraries you wish to link with the tool. For example:

.. code-block:: makefile

TOOLNAME = mytool USEDLIBS = mylib LINK_COMPONENTS = support system

says that we are to build a tool name ``mytool`` and that it requires threelibraries: ``mylib``, ``LLVMSupport.a`` and ``LLVMSystem.a``.

Note that two different variables are used to indicate which libraries arelinked: ``USEDLIBS`` and ``LLVMLIBS``. This distinction is necessary to supportprojects. ``LLVMLIBS`` refers to the LLVM libraries found in the LLVM objectdirectory. ``USEDLIBS`` refers to the libraries built by your project. In thecase of building LLVM tools, ``USEDLIBS`` and ``LLVMLIBS`` can be usedinterchangeably since the "project" is LLVM itself and ``USEDLIBS`` refers tothe same place as ``LLVMLIBS``.

Also note that there are two different ways of specifying a library: with a``.a`` suffix and without. Without the suffix, the entry refers to the re-linked(.o) file which will include *all* symbols of the library. This isuseful, for example, to include all passes from a library of passes. If the``.a`` suffix is used then the library is linked as a searchable library (withthe ``-l`` option). In this case, only the symbols that are unresolved *atthat point* will be resolved from the library, if they exist. Other(unreferenced) symbols will not be included when the ``.a`` syntax is used. Notethat in order to use the ``.a`` suffix, the library in question must have been

built with the ``ARCHIVE_LIBRARY`` option set.

JIT Tools^^^^^^^^^

Many tools will want to use the JIT features of LLVM. To do this, you simplyspecify that you want an execution 'engine', and the makefiles willautomatically link in the appropriate JIT for the host or an interpreter if noneis available:

.. code-block:: makefile

TOOLNAME = my_jit_tool USEDLIBS = mylib LINK_COMPONENTS = engine

Of course, any additional libraries may be listed as other components. To get afull understanding of how this changes the linker command, it is recommendedthat you:

.. code-block:: bash

% cd examples/Fibonacci % make VERBOSE=1

Targets Supported=================

This section describes each of the targets that can be built using the LLVMMakefile system. Any target can be invoked from any directory but not all areapplicable to a given directory (e.g. "check", "dist" and "install" will alwaysoperate as if invoked from the top level directory).

================= =============== ==================Target Name Implied Targets Target Description================= =============== ==================``all`` \ Compile the software recursively. Default target.``all-local`` \ Compile the software in the local directory only.

``check`` \ Change to the ``test`` directory in a project and run the test suite there.``check-local`` \ Run a local test suite. Generally this is only defined in the ``Makefile`` of the project's ``test`` directory.``clean`` \ Remove built objects recursively.``clean-local`` \ Remove built objects from the local directory only.``dist`` ``all`` Prepare a source distribution tarball.``dist-check`` ``all`` Prepare a source distribution tarball and check that it builds.``dist-clean`` ``clean`` Clean source distribution tarball temporary files.``install`` ``all`` Copy built objects to installation directory.``preconditions`` ``all`` Check to make sure configuration and makefiles are up to date.``printvars`` ``all`` Prints variables defined by the makefile system (for debugging).``tags`` \ Make C and C++ tags files for emacs and vi.``uninstall`` \ Remove built objects from installation directory.================= =============== ==================

.. _all:

``all`` (default)-----------------

When you invoke ``make`` with no arguments, you are implicitly instructing it toseek the ``all`` target (goal). This target is used for building the softwarerecursively and will do different things in different directories. For example,in a ``lib`` directory, the ``all`` target will compile source files andgenerate libraries. But, in a ``tools`` directory, it will link libraries andgenerate executables.

``all-local``-------------

This target is the same as `all`_ but it operates only on the current directoryinstead of recursively.

``check``---------

This target can be invoked from anywhere within a project's directories butalways invokes the `check-local`_ target in the project's ``test`` directory, ifit exists and has a ``Makefile``. A warning is produced otherwise. If`TESTSUITE`_ is defined on the ``make`` command line, it will be passed down tothe invocation of ``make check-local`` in the ``test`` directory. The intendedusage for this is to assist in running specific suites of tests. If``TESTSUITE`` is not set, the implementation of ``check-local`` should run allnormal tests. It is up to the project to define what different values for``TESTSUTE`` will do. See the :doc:`Testing Guide ` for furtherdetails.

``check-local``---------------

This target should be implemented by the ``Makefile`` in the project's ``test``directory. It is invoked by the ``check`` target elsewhere. Each project isfree to define the actions of ``check-local`` as appropriate for thatproject. The LLVM project itself uses the :doc:`Lit ` testingtool to run a suite of feature and regression tests. Other projects may chooseto use :program:`lit` or any other testing mechanism.

``clean``---------

This target cleans the build directory, recursively removing all things that theMakefile builds. The cleaning rules have been made guarded so they shouldn't goawry (via ``rm -f $(UNSET_VARIABLE)/*`` which will attempt to erase the entire

directory structure).

``clean-local``---------------

This target does the same thing as ``clean`` but only for the current (local)directory.

``dist``--------

This target builds a distribution tarball. It first builds the entire projectusing the ``all`` target and then tars up the necessary files and compressesit. The generated tarball is sufficient for a casual source distribution, butprobably not for a release (see ``dist-check``).

``dist-check``--------------

This target does the same thing as the ``dist`` target but also checks thedistribution tarball. The check is made by unpacking the tarball to a newdirectory, configuring it, building it, installing it, and then verifying thatthe installation results are correct (by comparing to the original build). Thistarget can take a long time to run but should be done before a release goes outto make sure that the distributed tarball can actually be built into a workingrelease.

``dist-clean``--------------

This is a special form of the ``clean`` clean target. It performs a normal``clean`` but also removes things pertaining to building the distribution.

``install``-----------

This target finalizes shared objects and executables and copies all libraries,

headers, executables and documentation to the directory given with the``--prefix`` option to ``configure``. When completed, the prefix directory willhave everything needed to **use** LLVM.

The LLVM makefiles can generate complete **internal** documentation for all theclasses by using ``doxygen``. By default, this feature is **not** enabledbecause it takes a long time and generates a massive amount of data (>100MB). Ifyou want this feature, you must configure LLVM with the --enable-doxygen switchand ensure that a modern version of doxygen (1.3.7 or later) is available inyour ``PATH``. You can download doxygen from `here`_.

``preconditions``-----------------

This utility target checks to see if the ``Makefile`` in the object directory isolder than the ``Makefile`` in the source directory and copies it if so. It alsoreruns the ``configure`` script if that needs to be done and rebuilds the``Makefile.config`` file similarly. Users may overload this target to ensurethat sanity checks are run *before* any building of targets as all the targetsdepend on ``preconditions``.

``printvars``-------------

This utility target just causes the LLVM makefiles to print out some of themakefile variables so that you can double check how things are set.

``reconfigure``---------------

This utility target will force a reconfigure of LLVM or your project. It simplyruns ``$(PROJ_OBJ_ROOT)/config.status --recheck`` to rerun the configurationtests and rebuild the configured files. This isn't generally useful as themakefiles will reconfigure themselves whenever its necessary.

``spotless``

------------

.. warning::

Use with caution!

This utility target, only available when ``$(PROJ_OBJ_ROOT)`` is not the same as``$(PROJ_SRC_ROOT)``, will completely clean the ``$(PROJ_OBJ_ROOT)`` directoryby removing its content entirely and reconfiguring the directory. This returnsthe ``$(PROJ_OBJ_ROOT)`` directory to a completely fresh state. All content inthe directory except configured files and top-level makefiles will be lost.

``tags``--------

This target will generate a ``TAGS`` file in the top-level source directory. Itis meant for use with emacs, XEmacs, or ViM. The TAGS file provides an index ofsymbol definitions so that the editor can jump you to the definitionquickly.

``uninstall``-------------

This target is the opposite of the ``install`` target. It removes the header,library and executable files from the installation directories. Note that thedirectories themselves are not removed because it is not guaranteed that LLVM isthe only thing installing there (e.g. ``--prefix=/usr``).

.. _variables:

Variables=========

Variables are used to tell the LLVM Makefile System what to do and to obtaininformation from it. Variables are also used internally by the LLVM MakefileSystem. Variable names that contain only the upper case alphabetic letters

andunderscore are intended for use by the end user. All other variables areinternal to the LLVM Makefile System and should not be relied upon normodified. The sections below describe how to use the LLVM Makefilevariables.

Control Variables-----------------

Variables listed in the table below should be set *before* the inclusion of`$(LEVEL)/Makefile.common`_. These variables provide input to the LLVM makesystem that tell it what to do for the current directory.

``BUILD_ARCHIVE`` If set to any value, causes an archive (.a) library to be built.

``BUILT_SOURCES`` 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.

``BYTECODE_LIBRARY`` If set to any value, causes a bitcode library (.bc) to be built.

``CONFIG_FILES`` Specifies a set of configuration files to be installed.

``DEBUG_SYMBOLS`` 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.

``DIRS`` 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.

``DISABLE_AUTO_DEPENDENCIES`` If set to any value, causes the makefiles to **not** automatically generate dependencies when running the compiler. Use of this feature is

discouraged and it may be removed at a later date.

``ENABLE_OPTIMIZED`` 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.

``ENABLE_PROFILING`` 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 ``gprof`` tool to analyze the output from the profiled tools (``gmon.out``).

``DISABLE_ASSERTIONS`` 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.

``EXPERIMENTAL_DIRS`` 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.

``EXPORTED_SYMBOL_FILE`` Specifies the name of a single file that contains a list of the symbols to be exported by the linker. One symbol per line.

``EXPORTED_SYMBOL_LIST`` Specifies a set of symbols to be exported by the linker.

``EXTRA_DIST`` 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.

``KEEP_SYMBOLS`` 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.

``LEVEL`` (required) 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.

``LIBRARYNAME`` Specify the name of the library to be built. (Required For Libraries)

``LINK_COMPONENTS`` When specified for building a tool, the value of this variable will be passed to the ``llvm-config`` tool to generate a link line for the tool. Unlike ``USEDLIBS`` and ``LLVMLIBS``, not all libraries need to be specified. The ``llvm-config`` tool will figure out the library dependencies and add any libraries that are needed. The ``USEDLIBS`` variable can still be used in conjunction with ``LINK_COMPONENTS`` so that additional project-specific libraries can be linked with the LLVM libraries specified by ``LINK_COMPONENTS``.

.. _LINK_LIBS_IN_SHARED:

``LINK_LIBS_IN_SHARED`` By default, shared library linking will ignore any libraries specified with the `LLVMLIBS`_ or `USEDLIBS`_. 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.

.. _LLVMLIBS:

``LLVMLIBS`` Specifies the set of libraries from the LLVM ``$(ObjDir)`` that will be linked into the tool or library.

``LOADABLE_MODULE`` 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 ``SHARED_LIBRARY`` will have no effect.

.. _MODULE_NAME:

``MODULE_NAME`` 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.

``NO_INSTALL`` Specifies that the build products of the directory should not be installed but should be built even if the ``install`` 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. ``tblgen``).

``OPTIONAL_DIRS`` Specify a set of directories that may be built, if they exist, but it is not an error for them not to exist.

``PARALLEL_DIRS`` Specify a set of directories to build recursively and in parallel if the ``-j`` option was used with ``make``.

.. _SHARED_LIBRARY:

``SHARED_LIBRARY`` 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.

``SOURCES`` (optional) 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.

``SUFFIXES`` Specifies a set of filename suffixes that occur in suffix match rules. Only set this if your local ``Makefile`` specifies additional suffix match rules.

``TARGET`` Specifies the name of the LLVM code generation target that the current directory builds. Setting this variable enables additional rules to build ``.inc`` files from ``.td`` files.

.. _TESTSUITE:

``TESTSUITE`` Specifies the directory of tests to run in ``llvm/test``.

``TOOLNAME`` Specifies the name of the tool that the current directory should build.

``TOOL_VERBOSE`` 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 ``-v`` to the GCC compilers which causes it to print out the command lines it uses to invoke sub-tools (compiler, assembler, linker).

.. _USEDLIBS:

``USEDLIBS``

Specifies the list of project libraries that will be linked into the tool or library.

``VERBOSE`` 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.

Override Variables------------------

Override variables can be used to override the default values provided by theLLVM makefile system. These variables can be set in several ways:

* In the environment (e.g. setenv, export) --- not recommended.* On the ``make`` command line --- recommended.* On the ``configure`` command line.* In the Makefile (only *after* the inclusion of `$(LEVEL)/Makefile.common`_).

The override variables are given below:

``AR`` (defaulted) Specifies the path to the ``ar`` tool.

``PROJ_OBJ_DIR`` The directory into which the products of build rules will be placed. This might be the same as `PROJ_SRC_DIR`_ but typically is not.

.. _PROJ_SRC_DIR:

``PROJ_SRC_DIR`` The directory which contains the source files to be built.

``BUILD_EXAMPLES`` If set to 1, build examples in ``examples`` and (if building Clang) ``tools/clang/examples`` directories.

``BZIP2`` (configured) The path to the ``bzip2`` tool.

``CC`` (configured) The path to the 'C' compiler.

``CFLAGS`` Additional flags to be passed to the 'C' compiler.

``CPPFLAGS`` Additional flags passed to the C/C++ preprocessor.

``CXX`` Specifies the path to the C++ compiler.

``CXXFLAGS`` Additional flags to be passed to the C++ compiler.

``DATE`` (configured) Specifies the path to the ``date`` program or any program that can generate the current date and time on its standard output.

``DOT`` (configured) Specifies the path to the ``dot`` tool or ``false`` if there isn't one.

``ECHO`` (configured) Specifies the path to the ``echo`` tool for printing output.

``EXEEXT`` (configured) 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).

``INSTALL`` (configured) Specifies the path to the ``install`` tool.

``LDFLAGS`` (configured) Allows users to specify additional flags to pass to the linker.

``LIBS`` (configured) The list of libraries that should be linked with each tool.

``LIBTOOL`` (configured) Specifies the path to the ``libtool`` tool. This tool is renamed ``mklib`` by the ``configure`` script.

``LLVMAS`` (defaulted) Specifies the path to the ``llvm-as`` tool.

``LLVMCC`` Specifies the path to the LLVM capable compiler.

``LLVMCXX`` Specifies the path to the LLVM C++ capable compiler.

``LLVMGCC`` (defaulted) Specifies the path to the LLVM version of the GCC 'C' Compiler.

``LLVMGXX`` (defaulted) Specifies the path to the LLVM version of the GCC C++ Compiler.

``LLVMLD`` (defaulted) Specifies the path to the LLVM bitcode linker tool

``LLVM_OBJ_ROOT`` (configured) Specifies the top directory into which the output of the build is placed.

``LLVM_SRC_ROOT`` (configured) Specifies the top directory in which the sources are found.

``LLVM_TARBALL_NAME`` (configured) Specifies the name of the distribution tarball to create. This is configured from the name of the project and its version number.

``MKDIR`` (defaulted) Specifies the path to the ``mkdir`` tool that creates directories.

``ONLY_TOOLS`` If set, specifies the list of tools to build.

``PLATFORMSTRIPOPTS`` The options to provide to the linker to specify that a stripped (no symbols) executable should be built.

``RANLIB`` (defaulted) Specifies the path to the ``ranlib`` tool.

``RM`` (defaulted) Specifies the path to the ``rm`` tool.

``SED`` (defaulted) Specifies the path to the ``sed`` tool.

``SHLIBEXT`` (configured) Provides the filename extension to use for shared libraries.

``TBLGEN`` (defaulted) Specifies the path to the ``tblgen`` tool.

``TAR`` (defaulted) Specifies the path to the ``tar`` tool.

``ZIP`` (defaulted) Specifies the path to the ``zip`` tool.

Readable Variables------------------

Variables listed in the table below can be used by the user's Makefile butshould not be changed. Changing the value will generally cause the build to gowrong, so don't do it.

``bindir`` The directory into which executables will ultimately be installed. This value is derived from the ``--prefix`` option given to ``configure``.

``BuildMode`` The name of the type of build being performed: Debug, Release, or Profile.

``bytecode_libdir`` The directory into which bitcode libraries will ultimately be installed. This value is derived from the ``--prefix`` option given to ``configure``.

``ConfigureScriptFLAGS`` Additional flags given to the ``configure`` script when reconfiguring.

``DistDir`` The *current* directory for which a distribution copy is being made.

.. _Echo:

``Echo``

The LLVM Makefile System output command. This provides the ``llvm[n]`` prefix and starts with ``@`` so the command itself is not printed by ``make``.

``EchoCmd`` Same as `Echo`_ but without the leading ``@``.

``includedir`` The directory into which include files will ultimately be installed. This value is derived from the ``--prefix`` option given to ``configure``.

``libdir`` The directory into which native libraries will ultimately be installed. This value is derived from the ``--prefix`` option given to ``configure``.

``LibDir`` The configuration specific directory into which libraries are placed before installation.

``MakefileConfig`` Full path of the ``Makefile.config`` file.

``MakefileConfigIn`` Full path of the ``Makefile.config.in`` file.

``ObjDir`` The configuration and directory specific directory where build objects (compilation results) are placed.

``SubDirs`` The complete list of sub-directories of the current directory as specified by other variables.

``Sources`` The complete list of source files.

``sysconfdir`` The directory into which configuration files will ultimately be installed. This value is derived from the ``--prefix`` option given to ``configure``.

``ToolDir``

The configuration specific directory into which executables are placed before they are installed.

``TopDistDir`` The top most directory into which the distribution files are copied.

``Verb`` 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).

Internal Variables------------------

Variables listed below are used by the LLVM Makefile System and consideredinternal. You should not use these variables under any circumstances.

.. code-block:: makefile

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