1=================== 2LLVM Makefile Guide 3=================== 4 5.. contents:: 6 :local: 7 8Introduction 9============ 10 11This document provides *usage* information about the LLVM makefile system. While 12loosely patterned after the BSD makefile system, LLVM has taken a departure from 13BSD in order to implement additional features needed by LLVM. Although makefile 14systems, such as ``automake``, were attempted at one point, it has become clear 15that the features needed by LLVM and the ``Makefile`` norm are too great to use 16a more limited tool. Consequently, LLVM requires simply GNU Make 3.79, a widely 17portable makefile processor. LLVM unabashedly makes heavy use of the features of 18GNU Make so the dependency on GNU Make is firm. If you're not familiar with 19``make``, it is recommended that you read the `GNU Makefile Manual 20<http://www.gnu.org/software/make/manual/make.html>`_. 21 22While this document is rightly part of the `LLVM Programmer's 23Manual <ProgrammersManual.html>`_, it is treated separately here because of the 24volume of content and because it is often an early source of bewilderment for 25new developers. 26 27General Concepts 28================ 29 30The LLVM Makefile System is the component of LLVM that is responsible for 31building the software, testing it, generating distributions, checking those 32distributions, installing and uninstalling, etc. It consists of a several files 33throughout the source tree. These files and other general concepts are described 34in this section. 35 36Projects 37-------- 38 39The LLVM Makefile System is quite generous. It not only builds its own software, 40but it can build yours too. Built into the system is knowledge of the 41``llvm/projects`` directory. Any directory under ``projects`` that has both a 42``configure`` script and a ``Makefile`` is assumed to be a project that uses the 43LLVM Makefile system. Building software that uses LLVM does not require the 44LLVM Makefile System nor even placement in the ``llvm/projects`` 45directory. However, doing so will allow your project to get up and running 46quickly by utilizing the built-in features that are used to compile LLVM. LLVM 47compiles itself using the same features of the makefile system as used for 48projects. 49 50For complete details on setting up your projects configuration, simply mimic the 51``llvm/projects/sample`` project. Or for further details, consult the 52`Projects <Projects.html>`_ page. 53 54Variable Values 55--------------- 56 57To use the makefile system, you simply create a file named ``Makefile`` in your 58directory and declare values for certain variables. The variables and values 59that you select determine what the makefile system will do. These variables 60enable rules and processing in the makefile system that automatically Do The 61Right Thing (C). 62 63Including Makefiles 64------------------- 65 66Setting variables alone is not enough. You must include into your Makefile 67additional files that provide the rules of the LLVM Makefile system. The various 68files involved are described in the sections that follow. 69 70``Makefile`` 71^^^^^^^^^^^^ 72 73Each directory to participate in the build needs to have a file named 74``Makefile``. This is the file first read by ``make``. It has three 75sections: 76 77#. Settable Variables --- Required that must be set first. 78#. ``include $(LEVEL)/Makefile.common`` --- include the LLVM Makefile system. 79#. Override Variables --- Override variables set by the LLVM Makefile system. 80 81.. _$(LEVEL)/Makefile.common: 82 83``Makefile.common`` 84^^^^^^^^^^^^^^^^^^^ 85 86Every project must have a ``Makefile.common`` file at its top source 87directory. This file serves three purposes: 88 89#. It includes the project's configuration makefile to obtain values determined 90 by the ``configure`` script. This is done by including the 91 `$(LEVEL)/Makefile.config`_ file. 92 93#. It specifies any other (static) values that are needed throughout the 94 project. Only values that are used in all or a large proportion of the 95 project's directories should be placed here. 96 97#. It includes the standard rules for the LLVM Makefile system, 98 `$(LLVM_SRC_ROOT)/Makefile.rules`_. This file is the *guts* of the LLVM 99 ``Makefile`` system. 100 101.. _$(LEVEL)/Makefile.config: 102 103``Makefile.config`` 104^^^^^^^^^^^^^^^^^^^ 105 106Every project must have a ``Makefile.config`` at the top of its *build* 107directory. This file is **generated** by the ``configure`` script from the 108pattern provided by the ``Makefile.config.in`` file located at the top of the 109project's *source* directory. The contents of this file depend largely on what 110configuration items the project uses, however most projects can get what they 111need by just relying on LLVM's configuration found in 112``$(LLVM_OBJ_ROOT)/Makefile.config``. 113 114.. _$(LLVM_SRC_ROOT)/Makefile.rules: 115 116``Makefile.rules`` 117^^^^^^^^^^^^^^^^^^ 118 119This file, located at ``$(LLVM_SRC_ROOT)/Makefile.rules`` is the heart of the 120LLVM Makefile System. It provides all the logic, dependencies, and rules for 121building the targets supported by the system. What it does largely depends on 122the values of ``make`` `variables`_ that have been set *before* 123``Makefile.rules`` is included. 124 125Comments 126^^^^^^^^ 127 128User ``Makefile``\s need not have comments in them unless the construction is 129unusual or it does not strictly follow the rules and patterns of the LLVM 130makefile system. Makefile comments are invoked with the pound (``#``) character. 131The ``#`` character and any text following it, to the end of the line, are 132ignored by ``make``. 133 134Tutorial 135======== 136 137This section provides some examples of the different kinds of modules you can 138build with the LLVM makefile system. In general, each directory you provide will 139build a single object although that object may be composed of additionally 140compiled components. 141 142Libraries 143--------- 144 145Only a few variable definitions are needed to build a regular library. 146Normally, the makefile system will build all the software into a single 147``libname.o`` (pre-linked) object. This means the library is not searchable and 148that the distinction between compilation units has been dissolved. Optionally, 149you can ask for a shared library (.so) or archive library (.a) built. Archive 150libraries are the default. For example: 151 152.. code-block:: makefile 153 154 LIBRARYNAME = mylib 155 SHARED_LIBRARY = 1 156 ARCHIVE_LIBRARY = 1 157 158says to build a library named ``mylib`` with both a shared library 159(``mylib.so``) and an archive library (``mylib.a``) version. The contents of all 160the libraries produced will be the same, they are just constructed differently. 161Note that you normally do not need to specify the sources involved. The LLVM 162Makefile system will infer the source files from the contents of the source 163directory. 164 165The ``LOADABLE_MODULE=1`` directive can be used in conjunction with 166``SHARED_LIBRARY=1`` to indicate that the resulting shared library should be 167openable with the ``dlopen`` function and searchable with the ``dlsym`` function 168(or your operating system's equivalents). While this isn't strictly necessary on 169Linux and a few other platforms, it is required on systems like HP-UX and 170Darwin. You should use ``LOADABLE_MODULE`` for any shared library that you 171intend to be loaded into an tool via the ``-load`` option. `Pass documentation 172<writing-an-llvm-pass-makefile>`_ has an example of why you might want to do 173this. 174 175Bitcode Modules 176^^^^^^^^^^^^^^^ 177 178In some situations, it is desirable to build a single bitcode module from a 179variety of sources, instead of an archive, shared library, or bitcode 180library. Bitcode modules can be specified in addition to any of the other types 181of libraries by defining the `MODULE_NAME`_ variable. For example: 182 183.. code-block:: makefile 184 185 LIBRARYNAME = mylib 186 BYTECODE_LIBRARY = 1 187 MODULE_NAME = mymod 188 189will build a module named ``mymod.bc`` from the sources in the directory. This 190module will be an aggregation of all the bitcode modules derived from the 191sources. The example will also build a bitcode archive containing a bitcode 192module for each compiled source file. The difference is subtle, but important 193depending on how the module or library is to be linked. 194 195Loadable Modules 196^^^^^^^^^^^^^^^^ 197 198In some situations, you need to create a loadable module. Loadable modules can 199be loaded into programs like ``opt`` or ``llc`` to specify additional passes to 200run or targets to support. Loadable modules are also useful for debugging a 201pass or providing a pass with another package if that pass can't be included in 202LLVM. 203 204LLVM provides complete support for building such a module. All you need to do is 205use the ``LOADABLE_MODULE`` variable in your ``Makefile``. For example, to build 206a loadable module named ``MyMod`` that uses the LLVM libraries ``LLVMSupport.a`` 207and ``LLVMSystem.a``, you would specify: 208 209.. code-block:: makefile 210 211 LIBRARYNAME := MyMod 212 LOADABLE_MODULE := 1 213 LINK_COMPONENTS := support system 214 215Use of the ``LOADABLE_MODULE`` facility implies several things: 216 217#. There will be no "``lib``" prefix on the module. This differentiates it from 218 a standard shared library of the same name. 219 220#. The `SHARED_LIBRARY`_ variable is turned on. 221 222#. The `LINK_LIBS_IN_SHARED`_ variable is turned on. 223 224A loadable module is loaded by LLVM via the facilities of libtool's libltdl 225library which is part of ``lib/System`` implementation. 226 227Tools 228----- 229 230For building executable programs (tools), you must provide the name of the tool 231and the names of the libraries you wish to link with the tool. For example: 232 233.. code-block:: makefile 234 235 TOOLNAME = mytool 236 USEDLIBS = mylib 237 LINK_COMPONENTS = support system 238 239says that we are to build a tool name ``mytool`` and that it requires three 240libraries: ``mylib``, ``LLVMSupport.a`` and ``LLVMSystem.a``. 241 242Note that two different variables are used to indicate which libraries are 243linked: ``USEDLIBS`` and ``LLVMLIBS``. This distinction is necessary to support 244projects. ``LLVMLIBS`` refers to the LLVM libraries found in the LLVM object 245directory. ``USEDLIBS`` refers to the libraries built by your project. In the 246case of building LLVM tools, ``USEDLIBS`` and ``LLVMLIBS`` can be used 247interchangeably since the "project" is LLVM itself and ``USEDLIBS`` refers to 248the same place as ``LLVMLIBS``. 249 250Also note that there are two different ways of specifying a library: with a 251``.a`` suffix and without. Without the suffix, the entry refers to the re-linked 252(.o) file which will include *all* symbols of the library. This is 253useful, for example, to include all passes from a library of passes. If the 254``.a`` suffix is used then the library is linked as a searchable library (with 255the ``-l`` option). In this case, only the symbols that are unresolved *at 256that point* will be resolved from the library, if they exist. Other 257(unreferenced) symbols will not be included when the ``.a`` syntax is used. Note 258that in order to use the ``.a`` suffix, the library in question must have been 259built with the ``ARCHIVE_LIBRARY`` option set. 260 261JIT Tools 262^^^^^^^^^ 263 264Many tools will want to use the JIT features of LLVM. To do this, you simply 265specify that you want an execution 'engine', and the makefiles will 266automatically link in the appropriate JIT for the host or an interpreter if none 267is available: 268 269.. code-block:: makefile 270 271 TOOLNAME = my_jit_tool 272 USEDLIBS = mylib 273 LINK_COMPONENTS = engine 274 275Of course, any additional libraries may be listed as other components. To get a 276full understanding of how this changes the linker command, it is recommended 277that you: 278 279.. code-block:: bash 280 281 % cd examples/Fibonacci 282 % make VERBOSE=1 283 284Targets Supported 285================= 286 287This section describes each of the targets that can be built using the LLVM 288Makefile system. Any target can be invoked from any directory but not all are 289applicable to a given directory (e.g. "check", "dist" and "install" will always 290operate as if invoked from the top level directory). 291 292================= =============== ================== 293Target Name Implied Targets Target Description 294================= =============== ================== 295``all`` \ Compile the software recursively. Default target. 296``all-local`` \ Compile the software in the local directory only. 297``check`` \ Change to the ``test`` directory in a project and run the test suite there. 298``check-local`` \ Run a local test suite. Generally this is only defined in the ``Makefile`` of the project's ``test`` directory. 299``clean`` \ Remove built objects recursively. 300``clean-local`` \ Remove built objects from the local directory only. 301``dist`` ``all`` Prepare a source distribution tarball. 302``dist-check`` ``all`` Prepare a source distribution tarball and check that it builds. 303``dist-clean`` ``clean`` Clean source distribution tarball temporary files. 304``install`` ``all`` Copy built objects to installation directory. 305``preconditions`` ``all`` Check to make sure configuration and makefiles are up to date. 306``printvars`` ``all`` Prints variables defined by the makefile system (for debugging). 307``tags`` \ Make C and C++ tags files for emacs and vi. 308``uninstall`` \ Remove built objects from installation directory. 309================= =============== ================== 310 311.. _all: 312 313``all`` (default) 314----------------- 315 316When you invoke ``make`` with no arguments, you are implicitly instructing it to 317seek the ``all`` target (goal). This target is used for building the software 318recursively and will do different things in different directories. For example, 319in a ``lib`` directory, the ``all`` target will compile source files and 320generate libraries. But, in a ``tools`` directory, it will link libraries and 321generate executables. 322 323``all-local`` 324------------- 325 326This target is the same as `all`_ but it operates only on the current directory 327instead of recursively. 328 329``check`` 330--------- 331 332This target can be invoked from anywhere within a project's directories but 333always invokes the `check-local`_ target in the project's ``test`` directory, if 334it exists and has a ``Makefile``. A warning is produced otherwise. If 335`TESTSUITE`_ is defined on the ``make`` command line, it will be passed down to 336the invocation of ``make check-local`` in the ``test`` directory. The intended 337usage for this is to assist in running specific suites of tests. If 338``TESTSUITE`` is not set, the implementation of ``check-local`` should run all 339normal tests. It is up to the project to define what different values for 340``TESTSUTE`` will do. See the :doc:`Testing Guide <TestingGuide>` for further 341details. 342 343``check-local`` 344--------------- 345 346This target should be implemented by the ``Makefile`` in the project's ``test`` 347directory. It is invoked by the ``check`` target elsewhere. Each project is 348free to define the actions of ``check-local`` as appropriate for that 349project. The LLVM project itself uses the :doc:`Lit <CommandGuide/lit>` testing 350tool to run a suite of feature and regression tests. Other projects may choose 351to use :program:`lit` or any other testing mechanism. 352 353``clean`` 354--------- 355 356This target cleans the build directory, recursively removing all things that the 357Makefile builds. The cleaning rules have been made guarded so they shouldn't go 358awry (via ``rm -f $(UNSET_VARIABLE)/*`` which will attempt to erase the entire 359directory structure). 360 361``clean-local`` 362--------------- 363 364This target does the same thing as ``clean`` but only for the current (local) 365directory. 366 367``dist`` 368-------- 369 370This target builds a distribution tarball. It first builds the entire project 371using the ``all`` target and then tars up the necessary files and compresses 372it. The generated tarball is sufficient for a casual source distribution, but 373probably not for a release (see ``dist-check``). 374 375``dist-check`` 376-------------- 377 378This target does the same thing as the ``dist`` target but also checks the 379distribution tarball. The check is made by unpacking the tarball to a new 380directory, configuring it, building it, installing it, and then verifying that 381the installation results are correct (by comparing to the original build). This 382target can take a long time to run but should be done before a release goes out 383to make sure that the distributed tarball can actually be built into a working 384release. 385 386``dist-clean`` 387-------------- 388 389This is a special form of the ``clean`` clean target. It performs a normal 390``clean`` but also removes things pertaining to building the distribution. 391 392``install`` 393----------- 394 395This target finalizes shared objects and executables and copies all libraries, 396headers, executables and documentation to the directory given with the 397``--prefix`` option to ``configure``. When completed, the prefix directory will 398have everything needed to **use** LLVM. 399 400The LLVM makefiles can generate complete **internal** documentation for all the 401classes by using ``doxygen``. By default, this feature is **not** enabled 402because it takes a long time and generates a massive amount of data (>100MB). If 403you want this feature, you must configure LLVM with the --enable-doxygen switch 404and ensure that a modern version of doxygen (1.3.7 or later) is available in 405your ``PATH``. You can download doxygen from `here 406<http://www.stack.nl/~dimitri/doxygen/download.html#latestsrc>`_. 407 408``preconditions`` 409----------------- 410 411This utility target checks to see if the ``Makefile`` in the object directory is 412older than the ``Makefile`` in the source directory and copies it if so. It also 413reruns the ``configure`` script if that needs to be done and rebuilds the 414``Makefile.config`` file similarly. Users may overload this target to ensure 415that sanity checks are run *before* any building of targets as all the targets 416depend on ``preconditions``. 417 418``printvars`` 419------------- 420 421This utility target just causes the LLVM makefiles to print out some of the 422makefile variables so that you can double check how things are set. 423 424``reconfigure`` 425--------------- 426 427This utility target will force a reconfigure of LLVM or your project. It simply 428runs ``$(PROJ_OBJ_ROOT)/config.status --recheck`` to rerun the configuration 429tests and rebuild the configured files. This isn't generally useful as the 430makefiles will reconfigure themselves whenever its necessary. 431 432``spotless`` 433------------ 434 435.. warning:: 436 437 Use with caution! 438 439This utility target, only available when ``$(PROJ_OBJ_ROOT)`` is not the same as 440``$(PROJ_SRC_ROOT)``, will completely clean the ``$(PROJ_OBJ_ROOT)`` directory 441by removing its content entirely and reconfiguring the directory. This returns 442the ``$(PROJ_OBJ_ROOT)`` directory to a completely fresh state. All content in 443the directory except configured files and top-level makefiles will be lost. 444 445``tags`` 446-------- 447 448This target will generate a ``TAGS`` file in the top-level source directory. It 449is meant for use with emacs, XEmacs, or ViM. The TAGS file provides an index of 450symbol definitions so that the editor can jump you to the definition 451quickly. 452 453``uninstall`` 454------------- 455 456This target is the opposite of the ``install`` target. It removes the header, 457library and executable files from the installation directories. Note that the 458directories themselves are not removed because it is not guaranteed that LLVM is 459the only thing installing there (e.g. ``--prefix=/usr``). 460 461.. _variables: 462 463Variables 464========= 465 466Variables are used to tell the LLVM Makefile System what to do and to obtain 467information from it. Variables are also used internally by the LLVM Makefile 468System. Variable names that contain only the upper case alphabetic letters and 469underscore are intended for use by the end user. All other variables are 470internal to the LLVM Makefile System and should not be relied upon nor 471modified. The sections below describe how to use the LLVM Makefile 472variables. 473 474Control Variables 475----------------- 476 477Variables listed in the table below should be set *before* the inclusion of 478`$(LEVEL)/Makefile.common`_. These variables provide input to the LLVM make 479system that tell it what to do for the current directory. 480 481``BUILD_ARCHIVE`` 482 If set to any value, causes an archive (.a) library to be built. 483 484``BUILT_SOURCES`` 485 Specifies a set of source files that are generated from other source 486 files. These sources will be built before any other target processing to 487 ensure they are present. 488 489``BYTECODE_LIBRARY`` 490 If set to any value, causes a bitcode library (.bc) to be built. 491 492``CONFIG_FILES`` 493 Specifies a set of configuration files to be installed. 494 495``DEBUG_SYMBOLS`` 496 If set to any value, causes the build to include debugging symbols even in 497 optimized objects, libraries and executables. This alters the flags 498 specified to the compilers and linkers. Debugging isn't fun in an optimized 499 build, but it is possible. 500 501``DIRS`` 502 Specifies a set of directories, usually children of the current directory, 503 that should also be made using the same goal. These directories will be 504 built serially. 505 506``DISABLE_AUTO_DEPENDENCIES`` 507 If set to any value, causes the makefiles to **not** automatically generate 508 dependencies when running the compiler. Use of this feature is discouraged 509 and it may be removed at a later date. 510 511``ENABLE_OPTIMIZED`` 512 If set to 1, causes the build to generate optimized objects, libraries and 513 executables. This alters the flags specified to the compilers and 514 linkers. Generally debugging won't be a fun experience with an optimized 515 build. 516 517``ENABLE_PROFILING`` 518 If set to 1, causes the build to generate both optimized and profiled 519 objects, libraries and executables. This alters the flags specified to the 520 compilers and linkers to ensure that profile data can be collected from the 521 tools built. Use the ``gprof`` tool to analyze the output from the profiled 522 tools (``gmon.out``). 523 524``DISABLE_ASSERTIONS`` 525 If set to 1, causes the build to disable assertions, even if building a 526 debug or profile build. This will exclude all assertion check code from the 527 build. LLVM will execute faster, but with little help when things go 528 wrong. 529 530``EXPERIMENTAL_DIRS`` 531 Specify a set of directories that should be built, but if they fail, it 532 should not cause the build to fail. Note that this should only be used 533 temporarily while code is being written. 534 535``EXPORTED_SYMBOL_FILE`` 536 Specifies the name of a single file that contains a list of the symbols to 537 be exported by the linker. One symbol per line. 538 539``EXPORTED_SYMBOL_LIST`` 540 Specifies a set of symbols to be exported by the linker. 541 542``EXTRA_DIST`` 543 Specifies additional files that should be distributed with LLVM. All source 544 files, all built sources, all Makefiles, and most documentation files will 545 be automatically distributed. Use this variable to distribute any files that 546 are not automatically distributed. 547 548``KEEP_SYMBOLS`` 549 If set to any value, specifies that when linking executables the makefiles 550 should retain debug symbols in the executable. Normally, symbols are 551 stripped from the executable. 552 553``LEVEL`` (required) 554 Specify the level of nesting from the top level. This variable must be set 555 in each makefile as it is used to find the top level and thus the other 556 makefiles. 557 558``LIBRARYNAME`` 559 Specify the name of the library to be built. (Required For Libraries) 560 561``LINK_COMPONENTS`` 562 When specified for building a tool, the value of this variable will be 563 passed to the ``llvm-config`` tool to generate a link line for the 564 tool. Unlike ``USEDLIBS`` and ``LLVMLIBS``, not all libraries need to be 565 specified. The ``llvm-config`` tool will figure out the library dependencies 566 and add any libraries that are needed. The ``USEDLIBS`` variable can still 567 be used in conjunction with ``LINK_COMPONENTS`` so that additional 568 project-specific libraries can be linked with the LLVM libraries specified 569 by ``LINK_COMPONENTS``. 570 571.. _LINK_LIBS_IN_SHARED: 572 573``LINK_LIBS_IN_SHARED`` 574 By default, shared library linking will ignore any libraries specified with 575 the `LLVMLIBS`_ or `USEDLIBS`_. This prevents shared libs from including 576 things that will be in the LLVM tool the shared library will be loaded 577 into. However, sometimes it is useful to link certain libraries into your 578 shared library and this option enables that feature. 579 580.. _LLVMLIBS: 581 582``LLVMLIBS`` 583 Specifies the set of libraries from the LLVM ``$(ObjDir)`` that will be 584 linked into the tool or library. 585 586``LOADABLE_MODULE`` 587 If set to any value, causes the shared library being built to also be a 588 loadable module. Loadable modules can be opened with the dlopen() function 589 and searched with dlsym (or the operating system's equivalent). Note that 590 setting this variable without also setting ``SHARED_LIBRARY`` will have no 591 effect. 592 593.. _MODULE_NAME: 594 595``MODULE_NAME`` 596 Specifies the name of a bitcode module to be created. A bitcode module can 597 be specified in conjunction with other kinds of library builds or by 598 itself. It constructs from the sources a single linked bitcode file. 599 600``NO_INSTALL`` 601 Specifies that the build products of the directory should not be installed 602 but should be built even if the ``install`` target is given. This is handy 603 for directories that build libraries or tools that are only used as part of 604 the build process, such as code generators (e.g. ``tblgen``). 605 606``OPTIONAL_DIRS`` 607 Specify a set of directories that may be built, if they exist, but it is 608 not an error for them not to exist. 609 610``PARALLEL_DIRS`` 611 Specify a set of directories to build recursively and in parallel if the 612 ``-j`` option was used with ``make``. 613 614.. _SHARED_LIBRARY: 615 616``SHARED_LIBRARY`` 617 If set to any value, causes a shared library (``.so``) to be built in 618 addition to any other kinds of libraries. Note that this option will cause 619 all source files to be built twice: once with options for position 620 independent code and once without. Use it only where you really need a 621 shared library. 622 623``SOURCES`` (optional) 624 Specifies the list of source files in the current directory to be 625 built. Source files of any type may be specified (programs, documentation, 626 config files, etc.). If not specified, the makefile system will infer the 627 set of source files from the files present in the current directory. 628 629``SUFFIXES`` 630 Specifies a set of filename suffixes that occur in suffix match rules. Only 631 set this if your local ``Makefile`` specifies additional suffix match 632 rules. 633 634``TARGET`` 635 Specifies the name of the LLVM code generation target that the current 636 directory builds. Setting this variable enables additional rules to build 637 ``.inc`` files from ``.td`` files. 638 639.. _TESTSUITE: 640 641``TESTSUITE`` 642 Specifies the directory of tests to run in ``llvm/test``. 643 644``TOOLNAME`` 645 Specifies the name of the tool that the current directory should build. 646 647``TOOL_VERBOSE`` 648 Implies ``VERBOSE`` and also tells each tool invoked to be verbose. This is 649 handy when you're trying to see the sub-tools invoked by each tool invoked 650 by the makefile. For example, this will pass ``-v`` to the GCC compilers 651 which causes it to print out the command lines it uses to invoke sub-tools 652 (compiler, assembler, linker). 653 654.. _USEDLIBS: 655 656``USEDLIBS`` 657 Specifies the list of project libraries that will be linked into the tool or 658 library. 659 660``VERBOSE`` 661 Tells the Makefile system to produce detailed output of what it is doing 662 instead of just summary comments. This will generate a LOT of output. 663 664Override Variables 665------------------ 666 667Override variables can be used to override the default values provided by the 668LLVM makefile system. These variables can be set in several ways: 669 670* In the environment (e.g. setenv, export) --- not recommended. 671* On the ``make`` command line --- recommended. 672* On the ``configure`` command line. 673* In the Makefile (only *after* the inclusion of `$(LEVEL)/Makefile.common`_). 674 675The override variables are given below: 676 677``AR`` (defaulted) 678 Specifies the path to the ``ar`` tool. 679 680``PROJ_OBJ_DIR`` 681 The directory into which the products of build rules will be placed. This 682 might be the same as `PROJ_SRC_DIR`_ but typically is not. 683 684.. _PROJ_SRC_DIR: 685 686``PROJ_SRC_DIR`` 687 The directory which contains the source files to be built. 688 689``BUILD_EXAMPLES`` 690 If set to 1, build examples in ``examples`` and (if building Clang) 691 ``tools/clang/examples`` directories. 692 693``BZIP2`` (configured) 694 The path to the ``bzip2`` tool. 695 696``CC`` (configured) 697 The path to the 'C' compiler. 698 699``CFLAGS`` 700 Additional flags to be passed to the 'C' compiler. 701 702``CPPFLAGS`` 703 Additional flags passed to the C/C++ preprocessor. 704 705``CXX`` 706 Specifies the path to the C++ compiler. 707 708``CXXFLAGS`` 709 Additional flags to be passed to the C++ compiler. 710 711``DATE`` (configured) 712 Specifies the path to the ``date`` program or any program that can generate 713 the current date and time on its standard output. 714 715``DOT`` (configured) 716 Specifies the path to the ``dot`` tool or ``false`` if there isn't one. 717 718``ECHO`` (configured) 719 Specifies the path to the ``echo`` tool for printing output. 720 721``EXEEXT`` (configured) 722 Provides the extension to be used on executables built by the makefiles. 723 The value may be empty on platforms that do not use file extensions for 724 executables (e.g. Unix). 725 726``INSTALL`` (configured) 727 Specifies the path to the ``install`` tool. 728 729``LDFLAGS`` (configured) 730 Allows users to specify additional flags to pass to the linker. 731 732``LIBS`` (configured) 733 The list of libraries that should be linked with each tool. 734 735``LIBTOOL`` (configured) 736 Specifies the path to the ``libtool`` tool. This tool is renamed ``mklib`` 737 by the ``configure`` script. 738 739``LLVMAS`` (defaulted) 740 Specifies the path to the ``llvm-as`` tool. 741 742``LLVMCC`` 743 Specifies the path to the LLVM capable compiler. 744 745``LLVMCXX`` 746 Specifies the path to the LLVM C++ capable compiler. 747 748``LLVMGCC`` (defaulted) 749 Specifies the path to the LLVM version of the GCC 'C' Compiler. 750 751``LLVMGXX`` (defaulted) 752 Specifies the path to the LLVM version of the GCC C++ Compiler. 753 754``LLVMLD`` (defaulted) 755 Specifies the path to the LLVM bitcode linker tool 756 757``LLVM_OBJ_ROOT`` (configured) 758 Specifies the top directory into which the output of the build is placed. 759 760``LLVM_SRC_ROOT`` (configured) 761 Specifies the top directory in which the sources are found. 762 763``LLVM_TARBALL_NAME`` (configured) 764 Specifies the name of the distribution tarball to create. This is configured 765 from the name of the project and its version number. 766 767``MKDIR`` (defaulted) 768 Specifies the path to the ``mkdir`` tool that creates directories. 769 770``ONLY_TOOLS`` 771 If set, specifies the list of tools to build. 772 773``PLATFORMSTRIPOPTS`` 774 The options to provide to the linker to specify that a stripped (no symbols) 775 executable should be built. 776 777``RANLIB`` (defaulted) 778 Specifies the path to the ``ranlib`` tool. 779 780``RM`` (defaulted) 781 Specifies the path to the ``rm`` tool. 782 783``SED`` (defaulted) 784 Specifies the path to the ``sed`` tool. 785 786``SHLIBEXT`` (configured) 787 Provides the filename extension to use for shared libraries. 788 789``TBLGEN`` (defaulted) 790 Specifies the path to the ``tblgen`` tool. 791 792``TAR`` (defaulted) 793 Specifies the path to the ``tar`` tool. 794 795``ZIP`` (defaulted) 796 Specifies the path to the ``zip`` tool. 797 798Readable Variables 799------------------ 800 801Variables listed in the table below can be used by the user's Makefile but 802should not be changed. Changing the value will generally cause the build to go 803wrong, so don't do it. 804 805``bindir`` 806 The directory into which executables will ultimately be installed. This 807 value is derived from the ``--prefix`` option given to ``configure``. 808 809``BuildMode`` 810 The name of the type of build being performed: Debug, Release, or 811 Profile. 812 813``bytecode_libdir`` 814 The directory into which bitcode libraries will ultimately be installed. 815 This value is derived from the ``--prefix`` option given to ``configure``. 816 817``ConfigureScriptFLAGS`` 818 Additional flags given to the ``configure`` script when reconfiguring. 819 820``DistDir`` 821 The *current* directory for which a distribution copy is being made. 822 823.. _Echo: 824 825``Echo`` 826 The LLVM Makefile System output command. This provides the ``llvm[n]`` 827 prefix and starts with ``@`` so the command itself is not printed by 828 ``make``. 829 830``EchoCmd`` 831 Same as `Echo`_ but without the leading ``@``. 832 833``includedir`` 834 The directory into which include files will ultimately be installed. This 835 value is derived from the ``--prefix`` option given to ``configure``. 836 837``libdir`` 838 The directory into which native libraries will ultimately be installed. 839 This value is derived from the ``--prefix`` option given to 840 ``configure``. 841 842``LibDir`` 843 The configuration specific directory into which libraries are placed before 844 installation. 845 846``MakefileConfig`` 847 Full path of the ``Makefile.config`` file. 848 849``MakefileConfigIn`` 850 Full path of the ``Makefile.config.in`` file. 851 852``ObjDir`` 853 The configuration and directory specific directory where build objects 854 (compilation results) are placed. 855 856``SubDirs`` 857 The complete list of sub-directories of the current directory as 858 specified by other variables. 859 860``Sources`` 861 The complete list of source files. 862 863``sysconfdir`` 864 The directory into which configuration files will ultimately be 865 installed. This value is derived from the ``--prefix`` option given to 866 ``configure``. 867 868``ToolDir`` 869 The configuration specific directory into which executables are placed 870 before they are installed. 871 872``TopDistDir`` 873 The top most directory into which the distribution files are copied. 874 875``Verb`` 876 Use this as the first thing on your build script lines to enable or disable 877 verbose mode. It expands to either an ``@`` (quiet mode) or nothing (verbose 878 mode). 879 880Internal Variables 881------------------ 882 883Variables listed below are used by the LLVM Makefile System and considered 884internal. You should not use these variables under any circumstances. 885 886.. code-block:: makefile 887 888 Archive 889 AR.Flags 890 BaseNameSources 891 BCCompile.C 892 BCCompile.CXX 893 BCLinkLib 894 C.Flags 895 Compile.C 896 CompileCommonOpts 897 Compile.CXX 898 ConfigStatusScript 899 ConfigureScript 900 CPP.Flags 901 CPP.Flags 902 CXX.Flags 903 DependFiles 904 DestArchiveLib 905 DestBitcodeLib 906 DestModule 907 DestSharedLib 908 DestTool 909 DistAlways 910 DistCheckDir 911 DistCheckTop 912 DistFiles 913 DistName 914 DistOther 915 DistSources 916 DistSubDirs 917 DistTarBZ2 918 DistTarGZip 919 DistZip 920 ExtraLibs 921 FakeSources 922 INCFiles 923 InternalTargets 924 LD.Flags 925 LibName.A 926 LibName.BC 927 LibName.LA 928 LibName.O 929 LibTool.Flags 930 Link 931 LinkModule 932 LLVMLibDir 933 LLVMLibsOptions 934 LLVMLibsPaths 935 LLVMToolDir 936 LLVMUsedLibs 937 LocalTargets 938 Module 939 ObjectsBC 940 ObjectsLO 941 ObjectsO 942 ObjMakefiles 943 ParallelTargets 944 PreConditions 945 ProjLibsOptions 946 ProjLibsPaths 947 ProjUsedLibs 948 Ranlib 949 RecursiveTargets 950 SrcMakefiles 951 Strip 952 StripWarnMsg 953 TableGen 954 TDFiles 955 ToolBuildPath 956 TopLevelTargets 957 UserTargets 958