From f375e9a0924fd059792c6dccbb0412d5127bfc74 Mon Sep 17 00:00:00 2001 From: mike-m Date: Fri, 7 May 2010 00:28:04 +0000 Subject: Revert r103213. It broke several sections of live website. llvm-svn: 103219 --- llvm/docs/GettingStarted.html | 1679 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 1679 insertions(+) create mode 100644 llvm/docs/GettingStarted.html (limited to 'llvm/docs/GettingStarted.html') diff --git a/llvm/docs/GettingStarted.html b/llvm/docs/GettingStarted.html new file mode 100644 index 000000000000..8bb1ac41e4fd --- /dev/null +++ b/llvm/docs/GettingStarted.html @@ -0,0 +1,1679 @@ + + + + + Getting Started with LLVM System + + + + +
+ Getting Started with the LLVM System +
+ + + +
+

Written by: + John Criswell, + Chris Lattner, + Misha Brukman, + Vikram Adve, and + Guochun Shi. +

+
+ + + +
+ Overview +
+ + +
+ +

Welcome to LLVM! In order to get started, you first need to know some +basic information.

+ +

First, LLVM comes in two pieces. The first piece is the LLVM suite. This +contains all of the tools, libraries, and header files needed to use the low +level virtual machine. It contains an assembler, disassembler, bitcode +analyzer and bitcode optimizer. It also contains a test suite that can be +used to test the LLVM tools and the GCC front end.

+ +

The second piece is the GCC front end. This component provides a version of +GCC that compiles C and C++ code into LLVM bitcode. Currently, the GCC front +end uses the GCC parser to convert code to LLVM. Once +compiled into LLVM bitcode, a program can be manipulated with the LLVM tools +from the LLVM suite.

+ +

+There is a third, optional piece called llvm-test. It is a suite of programs +with a testing harness that can be used to further test LLVM's functionality +and performance. +

+ +
+ + +
+ Getting Started Quickly (A Summary) +
+ + +
+ +

Here's the short story for getting up and running quickly with LLVM:

+ +
    +
  1. Read the documentation.
    2. +
  2. Read the documentation.
    3. +
  3. Remember that you were warned twice about reading the documentation.
    4. +
  4. Install the llvm-gcc-4.2 front end if you intend to compile C or C++ + (see Install the GCC Front End for details):
    5. +
      +
    1. cd where-you-want-the-C-front-end-to-live
      2. +
    2. gunzip --stdout llvm-gcc-4.2-version-platform.tar.gz | tar -xvf -
      3. +
    3. install-binutils-binary-from-MinGW (Windows only)
      4. +
    4. Note: If the binary extension is ".bz" use bunzip2 instead of gunzip.
      5. +
    5. Note: On Windows, use 7-Zip or a similar archiving tool.
      6. +
    6. Add llvm-gcc's "bin" directory to your PATH environment variable.
      7. +
    + +
  5. Get the LLVM Source Code +
      +
    • With the distributed files (or use SVN): +
        +
      1. cd where-you-want-llvm-to-live +
      2. gunzip --stdout llvm-version.tar.gz | tar -xvf - +
      • + +
    6. + +
  6. [Optional] Get the Test Suite Source Code +
      +
    • With the distributed files (or use SVN): +
        +
      1. cd where-you-want-llvm-to-live +
      2. cd llvm/projects +
      3. gunzip --stdout llvm-test-version.tar.gz | tar -xvf - +
      • + +
    7. + + +
  7. Configure the LLVM Build Environment +
      +
    1. cd where-you-want-to-build-llvm
      2. +
    2. /path/to/llvm/configure [options]
      + Some common options: + +
        +
      • --prefix=directory +

        Specify for directory the full pathname of where you + want the LLVM tools and libraries to be installed (default + /usr/local).

        • +
      • --with-llvmgccdir=directory +

        Optionally, specify for directory the full pathname of the + C/C++ front end installation to use with this LLVM configuration. If + not specified, the PATH will be searched. This is only needed if you + want to run the testsuite or do some special kinds of LLVM builds.

        • +
      • --enable-spec2000=directory +

        Enable the SPEC2000 benchmarks for testing. The SPEC2000 + benchmarks should be available in + directory.

        • +
      +
    8. + +
  8. Build the LLVM Suite: +
      +
    1. gmake -k |& tee gnumake.out +    # this is csh or tcsh syntax
      2. +
    2. If you get an "internal compiler error (ICE)" or test failures, see + below.
      3. +
    + +
+ +

Consult the Getting Started with LLVM section for +detailed information on configuring and compiling LLVM. See Setting Up Your Environment for tips that simplify +working with the GCC front end and LLVM tools. Go to Program +Layout to learn about the layout of the source code tree.

+ +
+ + +
+ Requirements +
+ + +
+ +

Before you begin to use the LLVM system, review the requirements given below. +This may save you some trouble by knowing ahead of time what hardware and +software you will need.

+ +
+ + +
+ Hardware +
+ +
+ +

LLVM is known to work on the following platforms:

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
OSArchCompilers
AuroraUXx861GCC
Linuxx861GCC
Linuxamd64GCC
SolarisV9 (Ultrasparc)GCC
FreeBSDx861GCC
MacOS X2PowerPCGCC
MacOS X2,9x86GCC
Cygwin/Win32x861,8, + 11GCC 3.4.X, binutils 2.20
MinGW/Win32x861,6, + 8, 10GCC 3.4.X, binutils 2.20
+ +

LLVM has partial support for the following platforms:

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
OSArchCompilers
Windowsx861Visual Studio 2005 SP1 or higher4,5
AIX3,4PowerPCGCC
Linux3,5PowerPCGCC
Linux7AlphaGCC
Linux7Itanium (IA-64)GCC
HP-UX7Itanium (IA-64)HP aCC
+ +

Notes:

+ +
+
    +
  1. Code generation supported for Pentium processors and +up
    2. +
  2. Code generation supported for 32-bit ABI only
    3. +
  3. No native code generation
    4. +
  4. Build is not complete: one or more tools do not link or function
    5. +
  5. The GCC-based C/C++ frontend does not build
    6. +
  6. The port is done using the MSYS shell.
    7. +
  7. Native code generation exists but is not complete.
    8. +
  8. Binutils 2.20 or later is required to build the assembler + generated by LLVM properly.
    9. +
  9. XCode 2.5 and gcc 4.0.1 (Apple Build 5370) will trip + internal LLVM assert messages when compiled for Release at optimization + levels greater than 0 (i.e., "-O1" and higher). + Add OPTIMIZE_OPTION="-O0" to the build command line + if compiling for LLVM Release or bootstrapping the LLVM toolchain.
    10. +
  10. For MSYS/MinGW on Windows, be sure to install the MSYS + version of the perl package, and be sure it appears in your path + before any Windows-based versions such as Strawberry Perl and + ActivePerl, as these have Windows-specifics that will cause the + build to fail.
    11. +
  11. In general, LLVM modules requiring dynamic linking can + not be built on Windows. However, you can build LLVM tools using + "make tools-only".
    12. +
+
+ +

Note that you will need about 1-3 GB of space for a full LLVM build in Debug +mode, depending on the system (it is so large because of all the debugging +information and the fact that the libraries are statically linked into multiple +tools). If you do not need many of the tools and you are space-conscious, you +can pass ONLY_TOOLS="tools you need" to make. The Release build +requires considerably less space.

+ +

The LLVM suite may compile on other platforms, but it is not +guaranteed to do so. If compilation is successful, the LLVM utilities should be +able to assemble, disassemble, analyze, and optimize LLVM bitcode. Code +generation should work as well, although the generated native code may not work +on your platform.

+ +

The GCC front end is not very portable at the moment. If you want to get it +to work on another platform, you can download a copy of the source and try to compile it on your platform.

+ +
+ + +
Software
+
+

Compiling LLVM requires that you have several software packages + installed. The table below lists those required packages. The Package column + is the usual name for the software package that LLVM depends on. The Version + column provides "known to work" versions of the package. The Notes column + describes how LLVM uses the package and provides other details.

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
PackageVersionNotes
GNU Make3.79, 3.79.1Makefile/build processor
GCC3.4.2C/C++ compiler1
TeXinfo4.5For building the CFE
SVN≥1.3Subversion access to LLVM2
DejaGnu1.4.2Automated test suite3
tcl8.3, 8.4Automated test suite3
expect5.38.0Automated test suite3
perl≥5.6.0Nightly tester, utilities
GNU M4 + 1.4Macro processor for configuration4
GNU Autoconf2.60Configuration script builder4
GNU Automake1.9.6aclocal macro generator4
libtool1.5.22Shared library manager4
+ +

Notes:

+
+
    +
  1. Only the C and C++ languages are needed so there's no + need to build the other languages for LLVM's purposes. See + below for specific version info.
    2. +
  2. You only need Subversion if you intend to build from the + latest LLVM sources. If you're working from a release distribution, you + don't need Subversion.
    3. +
  3. Only needed if you want to run the automated test + suite in the llvm/test directory.
    4. +
  4. If you want to make changes to the configure scripts, + you will need GNU autoconf (2.59), and consequently, GNU M4 (version 1.4 + or higher). You will also need automake (1.9.2). We only use aclocal + from that package.
    5. +
+
+ +

Additionally, your compilation host is expected to have the usual + plethora of Unix utilities. Specifically:

+ +
+ + +
+ Broken versions of GCC and other tools +
+ +
+ +

LLVM is very demanding of the host C++ compiler, and as such tends to expose +bugs in the compiler. In particular, several versions of GCC crash when trying +to compile LLVM. We routinely use GCC 3.3.3, 3.4.0, and Apple 4.0.1 +successfully with them (however, see important notes below). Other versions +of GCC will probably work as well. GCC versions listed +here are known to not work. If you are using one of these versions, please try +to upgrade your GCC to something more recent. If you run into a problem with a +version of GCC not listed here, please let +us know. Please use the "gcc -v" command to find out which version +of GCC you are using. +

+ +

GCC versions prior to 3.0: GCC 2.96.x and before had several +problems in the STL that effectively prevent it from compiling LLVM. +

+ +

GCC 3.2.2 and 3.2.3: These versions of GCC fails to compile LLVM with +a bogus template error. This was fixed in later GCCs.

+ +

GCC 3.3.2: This version of GCC suffered from a serious bug which causes it to crash in +the "convert_from_eh_region_ranges_1" GCC function.

+ +

Cygwin GCC 3.3.3: The version of GCC 3.3.3 commonly shipped with + Cygwin does not work. Please upgrade + to a newer version if possible.

+

SuSE GCC 3.3.3: The version of GCC 3.3.3 shipped with SuSE 9.1 (and + possibly others) does not compile LLVM correctly (it appears that exception + handling is broken in some cases). Please download the FSF 3.3.3 or upgrade + to a newer version of GCC.

+

GCC 3.4.0 on linux/x86 (32-bit): GCC miscompiles portions of the + code generator, causing an infinite loop in the llvm-gcc build when built + with optimizations enabled (i.e. a release build).

+

GCC 3.4.2 on linux/x86 (32-bit): GCC miscompiles portions of the + code generator at -O3, as with 3.4.0. However gcc 3.4.2 (unlike 3.4.0) + correctly compiles LLVM at -O2. A work around is to build release LLVM + builds with "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 ..."

+

GCC 3.4.x on X86-64/amd64: GCC + miscompiles portions of LLVM.

+

GCC 3.4.4 (CodeSourcery ARM 2005q3-2): this compiler miscompiles LLVM + when building with optimizations enabled. It appears to work with + "make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O1" or build a debug + build.

+

IA-64 GCC 4.0.0: The IA-64 version of GCC 4.0.0 is known to + miscompile LLVM.

+

Apple Xcode 2.3: GCC crashes when compiling LLVM at -O3 (which is the + default with ENABLE_OPTIMIZED=1. To work around this, build with + "ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2".

+

GCC 4.1.1: GCC fails to build LLVM with template concept check errors + compiling some files. At the time of this writing, GCC mainline (4.2) + did not share the problem.

+

GCC 4.1.1 on X86-64/amd64: GCC + miscompiles portions of LLVM when compiling llvm itself into 64-bit + code. LLVM will appear to mostly work but will be buggy, e.g. failing + portions of its testsuite.

+

GCC 4.1.2 on OpenSUSE: Seg faults during libstdc++ build and on x86_64 +platforms compiling md5.c gets a mangled constant.

+

GCC 4.1.2 (20061115 (prerelease) (Debian 4.1.1-21)) on Debian: Appears +to miscompile parts of LLVM 2.4. One symptom is ValueSymbolTable complaining +about symbols remaining in the table on destruction.

+

GCC 4.1.2 20071124 (Red Hat 4.1.2-42): Suffers from the same symptoms +as the previous one. It appears to work with ENABLE_OPTIMIZED=0 (the default).

+

Cygwin GCC 4.3.2 20080827 (beta) 2: + Users reported various problems related + with link errors when using this GCC version.

+

Debian GCC 4.3.2 on X86: Crashes building some files in LLVM 2.6.

+

GCC 4.3.3 (Debian 4.3.3-10) on ARM: Miscompiles parts of LLVM 2.6 +when optimizations are turned on. The symptom is an infinite loop in +FoldingSetImpl::RemoveNode while running the code generator.

+

GNU ld 2.16.X. Some 2.16.X versions of the ld linker will produce very +long warning messages complaining that some ".gnu.linkonce.t.*" symbol was +defined in a discarded section. You can safely ignore these messages as they are +erroneous and the linkage is correct. These messages disappear using ld +2.17.

+ +

GNU binutils 2.17: Binutils 2.17 contains a bug which +causes huge link times (minutes instead of seconds) when building LLVM. We +recommend upgrading to a newer version (2.17.50.0.4 or later).

+ +

GNU Binutils 2.19.1 Gold: This version of Gold contained +a bug +which causes intermittent failures when building LLVM with position independent +code. The symptom is an error about cyclic dependencies. We recommend +upgrading to a newer version of Gold.

+ +
+ + + + +
+ Getting Started with LLVM +
+ + +
+ +

The remainder of this guide is meant to get you up and running with +LLVM and to give you some basic information about the LLVM environment.

+ +

The later sections of this guide describe the general layout of the the LLVM source tree, a simple example using the LLVM tool chain, and links to find more information about LLVM or to get +help via e-mail.

+
+ + +
+ Terminology and Notation +
+ +
+ +

Throughout this manual, the following names are used to denote paths +specific to the local system and working environment. These are not +environment variables you need to set but just strings used in the rest +of this document below. In any of the examples below, simply replace +each of these names with the appropriate pathname on your local system. +All these paths are absolute:

+ +
+
SRC_ROOT +
+ This is the top level directory of the LLVM source tree. +

+ +
OBJ_ROOT +
+ This is the top level directory of the LLVM object tree (i.e. the + tree where object files and compiled programs will be placed. It + can be the same as SRC_ROOT). +

+ +
LLVMGCCDIR +
+ This is where the LLVM GCC Front End is installed. +

+ For the pre-built GCC front end binaries, the LLVMGCCDIR is + llvm-gcc/platform/llvm-gcc. +

+ +
+ + +
+ Setting Up Your Environment +
+ +
+ +

+In order to compile and use LLVM, you may need to set some environment +variables. + +

+
LLVM_LIB_SEARCH_PATH=/path/to/your/bitcode/libs
+
[Optional] This environment variable helps LLVM linking tools find the + locations of your bitcode libraries. It is provided only as a + convenience since you can specify the paths using the -L options of the + tools and the C/C++ front-end will automatically use the bitcode files + installed in its + lib directory.
+
+ +
+ + +
+ Unpacking the LLVM Archives +
+ +
+ +

+If you have the LLVM distribution, you will need to unpack it before you +can begin to compile it. LLVM is distributed as a set of two files: the LLVM +suite and the LLVM GCC front end compiled for your platform. There is an +additional test suite that is optional. Each file is a TAR archive that is +compressed with the gzip program. +

+ +

The files are as follows, with x.y marking the version number: +

+
llvm-x.y.tar.gz
+
Source release for the LLVM libraries and tools.
+ +
llvm-test-x.y.tar.gz
+
Source release for the LLVM test suite.
+ +
llvm-gcc-4.2-x.y.source.tar.gz
+
Source release of the llvm-gcc-4.2 front end. See README.LLVM in the root + directory for build instructions.
+ +
llvm-gcc-4.2-x.y-platform.tar.gz
+
Binary release of the llvm-gcc-4.2 front end for a specific platform.
+ +
+ +
+ + +
+ Checkout LLVM from Subversion +
+ +
+ +

If you have access to our Subversion repository, you can get a fresh copy of +the entire source code. All you need to do is check it out from Subversion as +follows:

+ + + + +

This will create an 'llvm' directory in the current +directory and fully populate it with the LLVM source code, Makefiles, +test directories, and local copies of documentation files.

+ +

If you want to get a specific release (as opposed to the most recent +revision), you can checkout it from the 'tags' directory (instead of +'trunk'). The following releases are located in the following +subdirectories of the 'tags' directory:

+ + + +

If you would like to get the LLVM test suite (a separate package as of 1.4), +you get it from the Subversion repository:

+ +
+
+% cd llvm/projects
+% svn co http://llvm.org/svn/llvm-project/test-suite/trunk llvm-test
+
+
+ +

By placing it in the llvm/projects, it will be automatically +configured by the LLVM configure script as well as automatically updated when +you run svn update.

+ +

If you would like to get the GCC front end source code, you can also get it +and build it yourself. Please follow these +instructions to successfully get and build the LLVM GCC front-end.

+ +
+ + +
+ Install the GCC Front End +
+ +
+ +

Before configuring and compiling the LLVM suite (or if you want to use just the LLVM +GCC front end) you can optionally extract the front end from the binary distribution. +It is used for running the llvm-test testsuite and for compiling C/C++ programs. Note that +you can optionally build llvm-gcc yourself after building the +main LLVM repository.

+ +

To install the GCC front end, do the following (on Windows, use an archival tool +like 7-zip that understands gzipped tars):

+ +
    +
  1. cd where-you-want-the-front-end-to-live
    2. +
  2. gunzip --stdout llvm-gcc-4.2-version-platform.tar.gz | tar -xvf + -
    3. +
+ +

Once the binary is uncompressed, if you're using a *nix-based system, add a symlink for +llvm-gcc and llvm-g++ to some directory in your path. If you're using a +Windows-based system, add the bin subdirectory of your front end installation directory +to your PATH environment variable. For example, if you uncompressed the binary to +c:\llvm-gcc, add c:\llvm-gcc\bin to your PATH.

+ +

If you now want to build LLVM from source, when you configure LLVM, it will +automatically detect llvm-gcc's presence (if it is in your path) enabling its +use in llvm-test. Note that you can always build or install llvm-gcc at any +point after building the main LLVM repository: just reconfigure llvm and +llvm-test will pick it up. +

+ +

As a convenience for Windows users, the front end binaries for MinGW/x86 include +versions of the required w32api and mingw-runtime binaries. The last remaining step for +Windows users is to simply uncompress the binary binutils package from +MinGW into your front end installation directory. While the +front end installation steps are not quite the same as a typical manual MinGW installation, +they should be similar enough to those who have previously installed MinGW on Windows systems.

+ +

To install binutils on Windows:

+ +
    +
  1. download GNU Binutils from MinGW Downloads
    2. +
  2. cd where-you-uncompressed-the-front-end
    3. +
  3. uncompress archived binutils directories (not the tar file) into the current directory
    4. +
+ +

The binary versions of the LLVM GCC front end may not suit all of your needs. For +example, the binary distribution may include an old version of a system header +file, not "fix" a header file that needs to be fixed for GCC, or it may be linked with +libraries not available on your system. In cases like these, you may want to try +building the GCC front end from source. Thankfully, +this is much easier now than it was in the past.

+ +

We also do not currently support updating of the GCC front end by manually overlaying +newer versions of the w32api and mingw-runtime binary packages that may become available +from MinGW. At this time, it's best to think of the MinGW LLVM GCC front end binary as +a self-contained convenience package that requires Windows users to simply download and +uncompress the GNU Binutils binary package from the MinGW project.

+ +

Regardless of your platform, if you discover that installing the LLVM GCC front end +binaries is not as easy as previously described, or you would like to suggest improvements, +please let us know how you would like to see things improved by dropping us a note on our +mailing list.

+ +
+ + +
+ Local LLVM Configuration +
+ +
+ +

Once checked out from the Subversion repository, the LLVM suite source + code must be +configured via the configure script. This script sets variables in the +various *.in files, most notably llvm/Makefile.config and +llvm/include/Config/config.h. It also populates OBJ_ROOT with +the Makefiles needed to begin building LLVM.

+ +

The following environment variables are used by the configure +script to configure the build system:

+ + + + + + + + + + + +
VariablePurpose
CCTells configure which C compiler to use. By default, + configure will look for the first GCC C compiler in + PATH. Use this variable to override + configure's default behavior.
CXXTells configure which C++ compiler to use. By default, + configure will look for the first GCC C++ compiler in + PATH. Use this variable to override + configure's default behavior.
+ +

The following options can be used to set or enable LLVM specific options:

+ +
+
--with-llvmgccdir
+
Path to the LLVM C/C++ FrontEnd to be used with this LLVM configuration. + The value of this option should specify the full pathname of the C/C++ Front + End to be used. If this option is not provided, the PATH will be searched for + a program named llvm-gcc and the C/C++ FrontEnd install directory will + be inferred from the path found. If the option is not given, and no llvm-gcc + can be found in the path then a warning will be produced by + configure indicating this situation. LLVM may still be built with + the tools-only target but attempting to build the runtime libraries + will fail as these libraries require llvm-gcc and llvm-g++. See + Install the GCC Front End for details on installing + the C/C++ Front End. See + Bootstrapping the LLVM C/C++ Front-End + for details on building the C/C++ Front End.
+
--with-tclinclude
+
Path to the tcl include directory under which tclsh can be + found. Use this if you have multiple tcl installations on your machine and you + want to use a specific one (8.x) for LLVM. LLVM only uses tcl for running the + dejagnu based test suite in llvm/test. If you don't specify this + option, the LLVM configure script will search for the tcl 8.4 and 8.3 + releases. +

+
+
--enable-optimized
+
+ Enables optimized compilation (debugging symbols are removed + and GCC optimization flags are enabled). Note that this is the default + setting if you are using the LLVM distribution. The default behavior + of an Subversion checkout is to use an unoptimized build (also known as a + debug build). +

+
+
--enable-debug-runtime
+
+ Enables debug symbols in the runtime libraries. The default is to strip + debug symbols from the runtime libraries. +
+
--enable-jit
+
+ Compile the Just In Time (JIT) compiler functionality. This is not + available + on all platforms. The default is dependent on platform, so it is best + to explicitly enable it if you want it. +

+
+
--enable-targets=target-option
+
Controls which targets will be built and linked into llc. The default + value for target_options is "all" which builds and links all + available targets. The value "host-only" can be specified to build only a + native compiler (no cross-compiler targets available). The "native" target is + selected as the target of the build host. You can also specify a comma + separated list of target names that you want available in llc. The target + names use all lower case. The current set of targets is:
+ alpha, ia64, powerpc, skeleton, sparc, x86. +

+
--enable-doxygen
+
Look for the doxygen program and enable construction of doxygen based + documentation from the source code. This is disabled by default because + generating the documentation can take a long time and producess 100s of + megabytes of output.
+
--with-udis86
+
LLVM can use external disassembler library for various purposes (now it's + used only for examining code produced by JIT). This option will enable usage + of udis86 x86 (both 32 and 64 + bits) disassembler library.
+
+ +

To configure LLVM, follow these steps:

+ +
    +

  1. Change directory into the object root directory:

    + + 
    % cd OBJ_ROOT
    2. + +

  2. Run the configure script located in the LLVM source + tree:

    + +
    + 
    % SRC_ROOT/configure --prefix=/install/path [other options]
    +
    3. +
+ +
+ + +
+ Compiling the LLVM Suite Source Code +
+ +
+ +

Once you have configured LLVM, you can build it. There are three types of +builds:

+ +
+
Debug Builds +
+ These builds are the default when one is using an Subversion checkout and + types gmake (unless the --enable-optimized option was + used during configuration). The build system will compile the tools and + libraries with debugging information. To get a Debug Build using the + LLVM distribution the --disable-optimized option must be passed + to configure. +

+ +
Release (Optimized) Builds +
+ These builds are enabled with the --enable-optimized option to + configure or by specifying ENABLE_OPTIMIZED=1 on the + gmake command line. For these builds, the build system will + compile the tools and libraries with GCC optimizations enabled and strip + debugging information from the libraries and executables it generates. + Note that Release Builds are default when using an LLVM distribution. +

+ +
Profile Builds +
+ These builds are for use with profiling. They compile profiling + information into the code for use with programs like gprof. + Profile builds must be started by specifying ENABLE_PROFILING=1 + on the gmake command line. +
+ +

Once you have LLVM configured, you can build it by entering the +OBJ_ROOT directory and issuing the following command:

+ +
% gmake
+ +

If the build fails, please check here to see if you +are using a version of GCC that is known not to compile LLVM.

+ +

+If you have multiple processors in your machine, you may wish to use some of +the parallel build options provided by GNU Make. For example, you could use the +command:

+ +
% gmake -j2
+ +

There are several special targets which are useful when working with the LLVM +source code:

+ +
+
gmake clean +
+ Removes all files generated by the build. This includes object files, + generated C/C++ files, libraries, and executables. +

+ +
gmake dist-clean +
+ Removes everything that gmake clean does, but also removes files + generated by configure. It attempts to return the source tree to the + original state in which it was shipped. +

+ +
gmake install +
+ Installs LLVM header files, libraries, tools, and documentation in a + hierarchy + under $PREFIX, specified with ./configure --prefix=[dir], which + defaults to /usr/local. +

+ +
gmake -C runtime install-bytecode +
+ Assuming you built LLVM into $OBJDIR, when this command is run, it will + install bitcode libraries into the GCC front end's bitcode library + directory. If you need to update your bitcode libraries, + this is the target to use once you've built them. +

+
+ +

Please see the Makefile Guide for further +details on these make targets and descriptions of other targets +available.

+ +

It is also possible to override default values from configure by +declaring variables on the command line. The following are some examples:

+ +
+
gmake ENABLE_OPTIMIZED=1 +
+ Perform a Release (Optimized) build. +

+ +
gmake ENABLE_OPTIMIZED=1 DISABLE_ASSERTIONS=1 +
+ Perform a Release (Optimized) build without assertions enabled. +

+ +
gmake ENABLE_OPTIMIZED=0 +
+ Perform a Debug build. +

+ +
gmake ENABLE_PROFILING=1 +
+ Perform a Profiling build. +

+ +
gmake VERBOSE=1 +
+ Print what gmake is doing on standard output. +

+ +
gmake TOOL_VERBOSE=1
+
Ask each tool invoked by the makefiles to print out what it is doing on + the standard output. This also implies VERBOSE=1. +

+
+ +

Every directory in the LLVM object tree includes a Makefile to build +it and any subdirectories that it contains. Entering any directory inside the +LLVM object tree and typing gmake should rebuild anything in or below +that directory that is out of date.

+ +
+ + +
+ Cross-Compiling LLVM +
+ +
+

It is possible to cross-compile LLVM itself. That is, you can create LLVM + executables and libraries to be hosted on a platform different from the + platform where they are build (a Canadian Cross build). To configure a + cross-compile, supply the configure script with --build and + --host options that are different. The values of these options must + be legal target triples that your GCC compiler supports.

+ +

The result of such a build is executables that are not runnable on + on the build host (--build option) but can be executed on the compile host + (--host option).

+
+ + +
+ The Location of LLVM Object Files +
+ +
+ +

The LLVM build system is capable of sharing a single LLVM source tree among +several LLVM builds. Hence, it is possible to build LLVM for several different +platforms or configurations using the same source tree.

+ +

This is accomplished in the typical autoconf manner:

+ + + +

The LLVM build will place files underneath OBJ_ROOT in directories +named after the build type:

+ +
+
Debug Builds +
+
+
Tools +
OBJ_ROOT/Debug/bin +
Libraries +
OBJ_ROOT/Debug/lib +
+

+ +
Release Builds +
+
+
Tools +
OBJ_ROOT/Release/bin +
Libraries +
OBJ_ROOT/Release/lib +
+

+ +
Profile Builds +
+
+
Tools +
OBJ_ROOT/Profile/bin +
Libraries +
OBJ_ROOT/Profile/lib +
+
+ +
+ + +
+ Optional Configuration Items +
+ +
+ +

+If you're running on a Linux system that supports the "binfmt_misc" +module, and you have root access on the system, you can set your system up to +execute LLVM bitcode files directly. To do this, use commands like this (the +first command may not be required if you are already using the module):

+ +
+
+$ mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
+$ echo ':llvm:M::BC::/path/to/lli:' > /proc/sys/fs/binfmt_misc/register
+$ chmod u+x hello.bc   (if needed)
+$ ./hello.bc
+
+
+ +

+This allows you to execute LLVM bitcode files directly. On Debian, you +can also use this command instead of the 'echo' command above:

+

+ +
+
+$ sudo update-binfmts --install llvm /path/to/lli --magic 'BC'
+
+
+ +
+ + +
+ Program Layout +
+ + +
+ +

One useful source of information about the LLVM source base is the LLVM doxygen documentation available at http://llvm.org/doxygen/. +The following is a brief introduction to code layout:

+ +
+ + +
llvm/examples
+
+

This directory contains some simple examples of how to use the LLVM IR and + JIT.

+
+ + +
llvm/include
+
+ +

This directory contains public header files exported from the LLVM +library. The three main subdirectories of this directory are:

+ +
+
llvm/include/llvm
+
This directory contains all of the LLVM specific header files. This + directory also has subdirectories for different portions of LLVM: + Analysis, CodeGen, Target, Transforms, + etc...
+ +
llvm/include/llvm/Support
+
This directory contains generic support libraries that are provided with + LLVM but not necessarily specific to LLVM. For example, some C++ STL utilities + and a Command Line option processing library store their header files here. +
+ +
llvm/include/llvm/Config
+
This directory contains header files configured by the configure + script. They wrap "standard" UNIX and C header files. Source code can + include these header files which automatically take care of the conditional + #includes that the configure script generates.
+
+
+ + +
llvm/lib
+
+ +

This directory contains most of the source files of the LLVM system. In LLVM, +almost all code exists in libraries, making it very easy to share code among the +different tools.

+ +
+
llvm/lib/VMCore/
+
This directory holds the core LLVM source files that implement core + classes like Instruction and BasicBlock.
+ +
llvm/lib/AsmParser/
+
This directory holds the source code for the LLVM assembly language parser + library.
+ +
llvm/lib/BitCode/
+
This directory holds code for reading and write LLVM bitcode.
+ +
llvm/lib/Analysis/
This directory contains a variety of + different program analyses, such as Dominator Information, Call Graphs, + Induction Variables, Interval Identification, Natural Loop Identification, + etc.
+ +
llvm/lib/Transforms/
+
This directory contains the source code for the LLVM to LLVM program + transformations, such as Aggressive Dead Code Elimination, Sparse Conditional + Constant Propagation, Inlining, Loop Invariant Code Motion, Dead Global + Elimination, and many others.
+ +
llvm/lib/Target/
+
This directory contains files that describe various target architectures + for code generation. For example, the llvm/lib/Target/X86 + directory holds the X86 machine description while + llvm/lib/Target/CBackend implements the LLVM-to-C converter.
+ +
llvm/lib/CodeGen/
+
This directory contains the major parts of the code generator: Instruction + Selector, Instruction Scheduling, and Register Allocation.
+ +
llvm/lib/Debugger/
+
This directory contains the source level debugger library that makes + it possible to instrument LLVM programs so that a debugger could identify + source code locations at which the program is executing.
+ +
llvm/lib/ExecutionEngine/
+
This directory contains libraries for executing LLVM bitcode directly + at runtime in both interpreted and JIT compiled fashions.
+ +
llvm/lib/Support/
+
This directory contains the source code that corresponds to the header + files located in llvm/include/Support/.
+ +
llvm/lib/System/
+
This directory contains the operating system abstraction layer that + shields LLVM from platform-specific coding.
+
+ +
+ + +
llvm/projects
+
+

This directory contains projects that are not strictly part of LLVM but are + shipped with LLVM. This is also the directory where you should create your own + LLVM-based projects. See llvm/projects/sample for an example of how + to set up your own project.

+
+ + +
llvm/runtime
+
+ +

This directory contains libraries which are compiled into LLVM bitcode and +used when linking programs with the GCC front end. Most of these libraries are +skeleton versions of real libraries; for example, libc is a stripped down +version of glibc.

+ +

Unlike the rest of the LLVM suite, this directory needs the LLVM GCC front +end to compile.

+ +
+ + +
llvm/test
+
+

This directory contains feature and regression tests and other basic sanity + checks on the LLVM infrastructure. These are intended to run quickly and cover + a lot of territory without being exhaustive.

+
+ + +
test-suite
+
+

This is not a directory in the normal llvm module; it is a separate + Subversion + module that must be checked out (usually to projects/test-suite). + This + module contains a comprehensive correctness, performance, and benchmarking + test + suite for LLVM. It is a separate Subversion module because not every LLVM + user is + interested in downloading or building such a comprehensive test suite. For + further details on this test suite, please see the + Testing Guide document.

+
+ + +
llvm/tools
+
+ +

The tools directory contains the executables built out of the +libraries above, which form the main part of the user interface. You can +always get help for a tool by typing tool_name -help. The +following is a brief introduction to the most important tools. More detailed +information is in the Command Guide.

+ +
+ +
bugpoint
+
bugpoint is used to debug + optimization passes or code generation backends by narrowing down the + given test case to the minimum number of passes and/or instructions that + still cause a problem, whether it is a crash or miscompilation. See HowToSubmitABug.html for more information + on using bugpoint.
+ +
llvmc
+
The LLVM Compiler Driver. This program can + be configured to utilize both LLVM and non-LLVM compilation tools to enable + pre-processing, translation, optimization, assembly, and linking of programs + all from one command line. llvmc also takes care of processing the + dependent libraries found in bitcode. This reduces the need to get the + traditional -l<name> options right on the command line. Please + note that this tool, while functional, is still experimental and not feature + complete.
+ +
llvm-ar
+
The archiver produces an archive containing + the given LLVM bitcode files, optionally with an index for faster + lookup.
+ +
llvm-as
+
The assembler transforms the human readable LLVM assembly to LLVM + bitcode.
+ +
llvm-dis
+
The disassembler transforms the LLVM bitcode to human readable + LLVM assembly.
+ +
llvm-ld
+
llvm-ld is a general purpose and extensible linker for LLVM. + This is the linker invoked by llvmc. It performsn standard link time + optimizations and allows optimization modules to be loaded and run so that + language specific optimizations can be applied at link time.
+ +
llvm-link
+
llvm-link, not surprisingly, links multiple LLVM modules into + a single program.
+ +
lli
+
lli is the LLVM interpreter, which + can directly execute LLVM bitcode (although very slowly...). For architectures + that support it (currently x86, Sparc, and PowerPC), by default, lli + will function as a Just-In-Time compiler (if the functionality was compiled + in), and will execute the code much faster than the interpreter.
+ +
llc
+
llc is the LLVM backend compiler, which + translates LLVM bitcode to a native code assembly file or to C code (with + the -march=c option).
+ +
llvm-gcc
+
llvm-gcc is a GCC-based C frontend that has been retargeted to + use LLVM as its backend instead of GCC's RTL backend. It can also emit LLVM + bitcode or assembly (with the -emit-llvm option) instead of the + usual machine code output. It works just like any other GCC compiler, + taking the typical -c, -S, -E, -o options that are typically used. + Additionally, the the source code for llvm-gcc is available as a + separate Subversion module.
+ +
opt
+
opt reads LLVM bitcode, applies a series of LLVM to LLVM + transformations (which are specified on the command line), and then outputs + the resultant bitcode. The 'opt -help' command is a good way to + get a list of the program transformations available in LLVM.
+
opt can also be used to run a specific analysis on an input + LLVM bitcode file and print out the results. It is primarily useful for + debugging analyses, or familiarizing yourself with what an analysis does.
+
+
+ + +
llvm/utils
+
+ +

This directory contains utilities for working with LLVM source code, and some +of the utilities are actually required as part of the build process because they +are code generators for parts of LLVM infrastructure.

+ +
+
codegen-diff
codegen-diff is a script + that finds differences between code that LLC generates and code that LLI + generates. This is a useful tool if you are debugging one of them, + assuming that the other generates correct output. For the full user + manual, run `perldoc codegen-diff'.

+ +
emacs/
The emacs directory contains + syntax-highlighting files which will work with Emacs and XEmacs editors, + providing syntax highlighting support for LLVM assembly files and TableGen + description files. For information on how to use the syntax files, consult + the README file in that directory.

+ +
getsrcs.sh
The getsrcs.sh script finds + and outputs all non-generated source files, which is useful if one wishes + to do a lot of development across directories and does not want to + individually find each file. One way to use it is to run, for example: + xemacs `utils/getsources.sh` from the top of your LLVM source + tree.

+ +
llvmgrep
+
This little tool performs an "egrep -H -n" on each source file in LLVM and + passes to it a regular expression provided on llvmgrep's command + line. This is a very efficient way of searching the source base for a + particular regular expression.
+ +
makellvm
The makellvm script compiles all + files in the current directory and then compiles and links the tool that + is the first argument. For example, assuming you are in the directory + llvm/lib/Target/Sparc, if makellvm is in your path, + simply running makellvm llc will make a build of the current + directory, switch to directory llvm/tools/llc and build it, + causing a re-linking of LLC.

+ +
NewNightlyTest.pl and + NightlyTestTemplate.html
These files are used in a + cron script to generate nightly status reports of the functionality of + tools, and the results can be seen by following the appropriate link on + the LLVM homepage.

+ +
TableGen/
The TableGen directory contains + the tool used to generate register descriptions, instruction set + descriptions, and even assemblers from common TableGen description + files.

+ +
vim/
The vim directory contains + syntax-highlighting files which will work with the VIM editor, providing + syntax highlighting support for LLVM assembly files and TableGen + description files. For information on how to use the syntax files, consult + the README file in that directory.

+ +
+ +
+ + +
llvm/win32
+
+

This directory contains build scripts and project files for use with + Visual C++. This allows developers on Windows to build LLVM without the need + for Cygwin. The contents of this directory should be considered experimental + at this time. +

+
+ +
+ An Example Using the LLVM Tool Chain +
+ + +
+

This section gives an example of using LLVM. llvm-gcc3 is now obsolete, +so we only include instructions for llvm-gcc4. +

+ +

Note: The gcc4 frontend's invocation is considerably different +from the previous gcc3 frontend. In particular, the gcc4 frontend does not +create bitcode by default: gcc4 produces native code. As the example below illustrates, +the '--emit-llvm' flag is needed to produce LLVM bitcode output. For makefiles and +configure scripts, the CFLAGS variable needs '--emit-llvm' to produce bitcode +output.

+
+ + +
Example with llvm-gcc4
+ +
+ +
    +

  1. First, create a simple C file, name it 'hello.c':

    + +
    +
    +#include <stdio.h>
+
+int main() {
+  printf("hello world\n");
+  return 0;
+}
+
    2. + +

  2. Next, compile the C file into a native executable:

    + + 
    % llvm-gcc hello.c -o hello
    + +

    Note that llvm-gcc works just like GCC by default. The standard -S and + -c arguments work as usual (producing a native .s or .o file, + respectively).

    3. + +

  3. Next, compile the C file into a LLVM bitcode file:

    + +
    + 
    % llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc
    + +

    The -emit-llvm option can be used with the -S or -c options to emit an + LLVM ".ll" or ".bc" file (respectively) for the code. This allows you + to use the standard LLVM tools on + the bitcode file.

    + +

    Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments. +

    4. + +

  4. Run the program in both forms. To run the program, use:

    + + 
    % ./hello
    + +

    and

    + + 
    % lli hello.bc
    + +

    The second examples shows how to invoke the LLVM JIT, lli.

    5. + +

  5. Use the llvm-dis utility to take a look at the LLVM assembly + code:

    + +
    +
    llvm-dis < hello.bc | less
    +
    6. + +

  6. Compile the program to native assembly using the LLC code + generator:

    + + 
    % llc hello.bc -o hello.s
    7. + +

  7. Assemble the native assembly language file into a program:

    + +
    +
    +Solaris: % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native
+
+Others:  % gcc hello.s -o hello.native
+
    +
    8. + +

  8. Execute the native code program:

    + + 
    % ./hello.native
    + +

    Note that using llvm-gcc to compile directly to native code (i.e. when + the -emit-llvm option is not present) does steps 6/7/8 for you.

    +
    9. + +
+ +
+ + + +
+ Common Problems +
+ + +
+ +

If you are having problems building or using LLVM, or if you have any other +general questions about LLVM, please consult the Frequently +Asked Questions page.

+ +
+ + +
+ Links +
+ + +
+ +

This document is just an introduction on how to use LLVM to do +some simple things... there are many more interesting and complicated things +that you can do that aren't documented here (but we'll gladly accept a patch +if you want to write something up!). For more information about LLVM, check +out:

+ + + +
+ + + +
+
+ Valid CSS + Valid HTML 4.01 + + Chris Lattner
+ Reid Spencer
+ The LLVM Compiler Infrastructure
+ Last modified: $Date$ +
+ + -- cgit v1.2.3