X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=docs%2FGettingStarted.html;h=0a19841124109c6d5b103034d572b998891e0b8e;hb=838bce56d2643cb9a45a66c5f32264667f70a38c;hp=75048cbe6c06a7123dd51298e2a424c7b129f865;hpb=312a68c4ce08b7ce6e6312383bd1db4ed4cfefcb;p=oota-llvm.git diff --git a/docs/GettingStarted.html b/docs/GettingStarted.html index 75048cbe6c0..0a198411241 100644 --- a/docs/GettingStarted.html +++ b/docs/GettingStarted.html @@ -1,962 +1,1520 @@ - + - - Getting Started with LLVM System - + + + Getting Started with LLVM System + + + + +
+ Getting Started with the LLVM System +
+ + + +
+

Written by: + John Criswell, Chris Lattner, - John Criswell, and - Vikram Adve - - - -

Contents

- - - - - - -
-

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 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 code into LLVM bytecode. Currently, the C front end - is a modified version of GCC 3.4 (we track the GCC 3.4 development). - Once compiled into LLVM bytecode, a program can be manipulated with the - LLVM tools. - - -

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: - - - LLVM may compile on other platforms. The LLVM utilities should work - on other platforms, so it should be possible to generate and produce LLVM - bytecode on unsupported platforms (although bytecode generated on one - platform may not work on another platform). However, the code generators - and Just-In-Time (JIT) compilers only generate SparcV9 or x86 machine code. - - -

Software

- -

- - Unpacking the distribution requires the following tools: -

-
GNU Zip (gzip) -
GNU Tar -
- These tools are needed to uncompress and unarchive the software. - Regular Solaris tar may work for unpacking the TAR archive but - is untested. -
- - Compiling LLVM requires that you have several different software packages - installed: - -
-
GCC -
- The GNU Compiler Collection must be installed with C and C++ language - support. GCC 3.2.x works, and GCC 3.x is generally supported. - -

- Note that we currently do not support any other C++ compiler. -

- -
GNU Make -
- The LLVM build system relies upon GNU Make extensions. Therefore, you - will need GNU Make (sometimes known as gmake) to build LLVM. -

- -

Flex and Bison -
- The LLVM source code is built using flex and bison. You will not be - able to configure and compile LLVM without them. -

- -

GNU M4 -
- If you are installing Bison on your machine for the first time, you - will need GNU M4 (version 1.4 or higher). -
- -

- There are some additional tools that you may want to have when working with - LLVM: -

- - - - -

The next section 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 first subsection gives - a short summary for those who are already familiar with the system and - want to get started as quickly as possible. - -

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. - - -

-

Getting Started

-
- - - -

Getting Started Quickly (A Summary)

- - - Here's the short story for getting up and running quickly with LLVM: + 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, bytecode +analyzer, and bytecode 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 bytecode. Currently, the GCC front +end is a modified version of GCC 3.4 (we track the GCC 3.4 development). Once +compiled into LLVM bytecode, 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 GCC front end if you intend to compile C or C++:
      -
    1. Build the LLVM suite -
        -
      1. Find the path to the CVS repository containing LLVM (we'll call this CVSROOTDIR). -
      2. cd where-you-want-llvm-to-live -
      3. cvs -d CVSROOTDIR checkout llvm -
      4. cd llvm -
      5. Run configure to configure the Makefiles and header files. - Useful options include: -
          -
        • --with-objroot=directory -
          - Specify where object files should be placed during the build. - -
        • --with-llvmgccdir=directory -
          - Specify where the LLVM C frontend is going to be installed. -
        -
      6. Set your LLVM_LIB_SEARCH_PATH environment variable. -
      7. gmake -k |& tee gnumake.out -    # this is csh or tcsh syntax -
      -

      -

    2. Build the LLVM C Front End (optional) -
        -
      1. Create a directory for the object files to live. -
      2. cd object file directory -
      3. Run Pathname-to-where-the-source-code-lives/configure --prefix=LLVMGCCDIR to configure GCC. -
      4. make bootstrap -
      5. make install -
      -
    - -

    See Setting up your environment on tips to - simplify working with the LLVM front-end and compiled tools. See the - other sub-sections below for other useful details in working with LLVM, - or go straight to Program Layout to learn about the - layout of the source code tree. - - -

    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:

    -
    -
    CVSROOTDIR -
    - This is the path for the CVS repository containing the LLVM source - code. Ask the person responsible for your local LLVM installation to - give you this path. -

    - -

    OBJ_ROOT -
    - This is the top level directory for where the LLVM suite object files - will be placed during the build. -

    - -

    LLVMGCCDIR -
    - This is the pathname to the location where the LLVM C Front End will - be installed. Note that the C front end does not need to be installed - during the LLVM suite build; you will just need to know where it will - go for configuring the build system and running the test suite later. -

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

    GCCSRC -
    - This is the pathname of the directory where the LLVM C front end source - code can be found. -

    - -

    GCCOBJ -
    - This is the pathname of the directory where the LLVM C front end object - code will be placed during the build. It can be safely removed once - the build is complete. -
    - - -

    Setting up your environment

    - - -

    - In order to compile and use LLVM, you will need to set some environment - variables. There are also some shell aliases which you may find useful. - You can set these on the command line, or better yet, set them in your - .cshrc or .profile. - -

    -
    LLVM_LIB_SEARCH_PATH=LLVMGCCDIR/llvm-gcc/bytecode-libs -
    - This environment variable helps the LLVM C front end find bytecode - libraries that it will need for compilation. -

    - -

    PATH=${PATH}:OBJ_ROOT/llvm/tools/Debug -
    - Adding this directory to the end of your path will allow the - compilation of the C front end to find the LLVM tools. The LLVM tools - are needed for the C front end compile. -

    - -

    CC=Pathname to your GCC compiler -
    - The GCC compiler that you want to use must be the first C compiler in - your PATH. Otherwise, set this variable so that - configure will use the GCC compiler that you want to use. -

    - -

    CXX=Pathname to your GCC C++ compiler -
    - The GCC compiler that you want to use must be the first C++ compiler in - your PATH. Otherwise, set this variable so that - configure will use the GCC compiler that you want to use. -

    - -

    CVSROOT=CVSROOT -
    - This environment variable tells CVS where to find the CVS repository. -

    - -

    alias llvmgcc LLVMGCCDIR/bin/llvm-gcc -
    - This alias allows you to use the LLVM C front end without putting it in - your PATH or typing in its complete pathname. -
    - - -

    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 four files. Each - file is a TAR archive that is compressed with the gzip program. -

    - -

    The four files are the following: -

    -
    llvm.tar.gz -
    This is the source code to the LLVM suite. -

    - -

    cfrontend.sparc.tar.gz -
    This is the binary release of the C front end for Solaris/Sparc. -

    - -

    cfrontend.x86.tar.gz -
    This is the binary release of the C front end for Linux/x86. -

    - -

    cfrontend-src.tar.gz -
    This is the source code release of the C front end. -

    -

    - -

    - To unpack the files, take each one, unzip it, and then untar it. A fast - way to do that is with the following: -

    - - gunzip --stdout name of file | tar -xvf - - -

    - For example, to extract the LLVM source code, use the following command: -

    - - gunzip --stdout llvm.tar.gz | tar -xvf - - - -

    Checkout LLVM from CVS

    - - -

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

      -
    • cd where-you-want-llvm-to-live -
    • cvs -d CVSROOTDIR checkout llvm

      -
    - -

    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.

    - -

    - Note that the C front end is not included in the CVS repository. You - should have either downloaded the source, or better yet, downloaded the - binary distribution for your platform. -

    - - -

    Local LLVM Configuration

    - - -

    Once checked out from the CVS repository, the LLVM suite source code - must be configured via the configure script. This script sets - variables in llvm/Makefile.config and - llvm/include/Config/config.h. - -

    - The following environment variables are used by configure to - configure Makefile.config: -

    - -
      -

    • CXX = Pathname of the C++ compiler to use. -

    • CC = Pathname of the C compiler to use. -
    +
  5. cd where-you-want-the-C-front-end-to-live
    6. +
  6. gunzip --stdout cfrontend.platform.tar.gz | tar -xvf - +
    7. +
  7. cd cfrontend/platform
    + ./fixheaders
    8. +
  8. Add the cfrontend's "bin" directory to your PATH variable.
    9. +
+ +
  • Get the LLVM Source Code +
    • -
    -
    --with-objroot=OBJ_ROOT -
    - Path to the directory where - object files, libraries, and executables should be placed. - If this is set to ., then the object files will be placed - within the source code tree. If left unspecified, the default value is - .. - (See the Section on - The location for LLVM object files - for more information.) -

    -

    --with-llvmgccdir=LLVMGCCDIR -
    - Path to the location where the LLVM C front end binaries and - associated libraries will be installed. -

    -

    --enable-optimized -
    - Enables optimized compilation (debugging symbols are removed and GCC - optimization flags are enabled). The default is to use an unoptimized - build (also known as a debug build). -

    -

    --enable-jit +
  • [Optional] Get the Test Suite Source Code +
      +
    • With the distributed files (or use CVS): +
        +
      1. cd where-you-want-llvm-to-live +
      2. cd llvm/projects +
      3. gunzip --stdout llvm-test-version.tar.gz | tar -xvf - +
      • + +
    • + + +
  • 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.

        • +
      • --enable-spec2000=directory +

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

        • +
      +
    • + +
  • 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)" 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
    Linuxx861GCC
    SolarisV9 (Ultrasparc)GCC
    FreeBSDx861GCC
    MacOS X2PowerPCGCC
    Cygwin/Win32x861GCC 3.4.X, binutils 2.15
    MinGW/Win32x861,6GCC 3.4.X, binutils 2.15
    Linuxamd643GCC
    + +

    LLVM has partial support for the following platforms:

    + + + + + + + + + + + + + + + + + + + + + +
    OSArchCompilers
    Windowsx861Visual Studio .NET4,5
    AIX3,4PowerPCGCC
    Linux3,5PowerPCGCC
    + +

    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 don't link
      5. +
    5. The GCC-based C/C++ frontend does not build
      6. +
    6. The port is done using the MSYS shell. +Download and install +bison (excl. M4.exe) and flex in that order. Build binutils-2.15 from source, +if necessary.
      7. +
    +
    + +

    Note that you will need about 1-3 GB of space for a full LLVM build in Debug +mode, depending on the system (because of all the debug info), and the libraries +appear in more than one of the tools that get linked, so there is some +duplication. If you do not need many of the tools and you are space-conscious, +you can disable them individually in llvm/tools/Makefile. 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 bytecode. 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
    Flex2.5.4LEX compiler
    Bison1.35YACC compiler
    CVS≥1.11CVS 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 Autoconf2.59Configuration script builder4
    GNU Automake1.9.2aclocal macro generator4
    libtool1.5.10Shared 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 CVS if you intend to build from the + latest LLVM sources. If you're working from a release distribution, you + don't need CVS.
      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 +
    + +
    + +

    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 and GCC 3.4.0 and have had success +with them (however, see 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: This version of GCC fails to compile LLVM.

    + +

    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.

    +
    + + + + +
    + 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
    - Compile the Just In Time (JIT) 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. -
    - - In addition to running configure, you must set the - LLVM_LIB_SEARCH_PATH environment variable in your startup scripts. - This environment variable is used to locate "system" libraries like - "-lc" and "-lm" when linking. This variable should be set - to the absolute path for the bytecode-libs subdirectory of the C front-end - install, or LLVMGCCDIR/llvm-gcc/bytecode-libs. For example, one might - set LLVM_LIB_SEARCH_PATH to - /home/vadve/lattner/local/x86/llvm-gcc/bytecode-libs for the X86 - version of the C front-end on our research machines.

    - - -

    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. They compile the tools and libraries - with debugging information. -

    - -

    Release (Optimized) Builds -
    - These builds are enabled with the --enable-optimized option to - configure. They compile the tools and libraries with GCC - optimizer flags on and strip debugging information from the libraries - and executables it generates. -

    - -

    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 setting variables on the - make command line. -
    - - Once you have LLVM configured, you can build it by entering the top level - llvm directory and issuing the following command: + This is the top level directory of the LLVM source tree.

    - make - -

    - 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: -

    +
    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).

    - make -j2 +

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

    - There are several other targets which are useful when working with the LLVM - source code: - -

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

    - -

    make distclean -
    - Removes everything that make 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. -

    -

    - - It is also possible to override default values from configure by - declaring variables on the command line. The following are some examples: - -
    -
    make ENABLE_OPTIMIZED=1 -
    - Perform a Release (Optimized) build. -

    - -

    make ENABLE_PROFILING=1 -
    - Perform a Profiling build. -

    - -

    make VERBOSE=1 -
    - Print what make is doing on standard output. -

    -

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

    Building the LLVM C Front End

    - - - + For the pre-built GCC front end binaries, the LLVMGCCDIR is + cfrontend/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/bytecode/libs
    +
    [Optional] This environment variable helps LLVM linking tools find the + locations of your bytecode libraries. It is provided only a + convenience since you can specify the paths using the -L options of the + tools and the C/C++ front-end will use the bytecode 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.
    + +
    cfrontend-x.y.source.tar.gz
    +
    Source release of the GCC front end.
    + +
    cfrontend-x.y.sparc-sun-solaris2.8.tar.gz
    +
    Binary release of the GCC front end for Solaris/Sparc. +
    + +
    cfrontend-x.y.i686-redhat-linux-gnu.tar.gz
    +
    Binary release of the GCC front end for Linux/x86.
    + +
    cfrontend-x.y.i386-unknown-freebsd5.1.tar.gz
    +
    Binary release of the GCC front end for FreeBSD/x86.
    + +
    cfrontend-x.y.powerpc-apple-darwin7.6.0.tar.gz
    +
    Binary release of the GCC front end for MacOS X/PPC.
    +
    + +
    + + +
    + Checkout LLVM from CVS +
    + +
    + +

    If you have access to our CVS repository, you can get a fresh copy of +the entire source code. All you need to do is check it out from CVS 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 specify a label. The following releases have the following +labels:

    + + + +

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

    +
    +  cd llvm/projects
+  cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm co 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 cvs update.

    + +

    If you would like to get the GCC front end source code, you can also get it +from the CVS repository:

    + +
    +  cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm co llvm-gcc
+
    + +

    Please note that you must follow these +instructions to successfully build the LLVM GCC front-end.

    + +
    + + +
    + LLVM CVS Mirrors +
    + +
    + +

    If the main CVS server is overloaded or inaccessible, you can try one of +these user-hosted mirrors:

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

    Before configuring and compiling the LLVM suite, you need to extract the LLVM +GCC front end from the binary distribution. It is used for building the +bytecode libraries later used by the GCC front end for linking programs, and its +location must be specified when the LLVM suite is configured.

    + +

    To install the GCC front end, do the following:

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

    Next, you will need to fix your system header files:

    + +

    cd cfrontend/platform
    + ./fixheaders

    + +

    The binary versions of the 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. This is +not for the faint of heart, so be forewarned.

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

    Once checked out from the CVS 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 the 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 tcl 8.4 and 8.3 releases. +

    +
    +
    --enable-optimized
    +
    + Enables optimized compilation by default (debugging symbols are removed + and GCC optimization flags are enabled). The default is to use an + unoptimized build (also known as a debug build). +

    +
    +
    --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 is 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.
    +
    + +

    To configure LLVM, follow these steps:

    + +
      +
    1. Change directory into the object root directory: +
      + cd OBJ_ROOT

      - This step is optional if you have the C front end binary distrubtion for - your platform. -

      -       - Now that you have the LLVM Suite built, you can build the C front end. For - those of you that have built GCC before, the process is very similar. +
    2. Run the configure script located in the LLVM source tree: +
      + SRC_ROOT/configure --prefix=/install/path [other options]

      - Be forewarned, though: the build system for the C front end is not as - polished as the rest of the LLVM code, so there will be many warnings and - errors that you will need to ignore for now: - -

        -
      1. Ensure that OBJ_ROOT/llvm/tools/Debug is at the - end of your PATH environment variable. - -
      2. cd GCCOBJ - -
      3. Configure the source code: -
          -
        • On Linux/x86, use -
            -
          • GCCSRC/configure --prefix=LLVMGCCDIR - --enable-languages=c -
          - -
        • On Solaris/Sparc, use -
            -
          • GCCSRC/configure --prefix=LLVMGCCDIR - --enable-languages=c --target=sparcv9-sun-solaris2 -
          -
        +
      -
    3. make bootstrap +
    -
  • The build will eventually fail. Don't worry; chances are good that - everything that needed to build is built. + +
    + Compiling the LLVM Suite Source Code +
    -
  • make install - +
    - At this point, you should have a working copy of the LLVM C front end - installed in LLVMGCCDIR. - - -

    The location for LLVM object files

    - - -

    The LLVM build system sends most output files generated during the build - into the directory defined by the variable OBJ_ROOT in - llvm/Makefile.config, which is set by the --with-objroot - option in configure. This can be either just your normal LLVM - source tree or some other directory writable by you. You may wish to put - object files on a different filesystem either to keep them from being backed - up or to speed up local builds. +

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

    +
    +
    Debug Builds +
    + These builds are the default when one types gmake (unless the + --enable-optimized option was used during configuration). The + build system will compile the tools and libraries with debugging + information.

    - If OBJ_ROOT is specified, then the build system will create a - directory tree underneath it that resembles the source code's pathname - relative to your home directory. -

    +
    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.

    - For example, suppose that OBJ_ROOT is set to /tmp and the - LLVM suite source code is located in /usr/home/joe/src/llvm, where - /usr/home/joe is the home directory of a user named Joe. Then, - the object files will be placed in /tmp/src/llvm. -

    - -

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

    - -
    -
    Debug Builds -
    -
    -
    Tools -
    OBJ_ROOT/llvm/tools/Debug -
    Libraries -
    OBJ_ROOT/llvm/lib/Debug -
    -

    - -

    Release Builds -
    -
    -
    Tools -
    OBJ_ROOT/llvm/tools/Release -
    Libraries -
    OBJ_ROOT/llvm/lib/Release -
    -

    - -

    Profile Builds -
    -
    -
    Tools -
    OBJ_ROOT/llvm/tools/Profile -
    Libraries -
    OBJ_ROOT/llvm/lib/Profile -
    -
    - - -
    -

    Program Layout

    -
    - - -

    One useful source of information about the LLVM source base is the LLVM doxygen documentation, available at http://llvm.cs.uiuc.edu/doxygen/. The - following is a brief introduction to code layout:

    - - - -

    CVS directories

    - - - Every directory checked out of CVS will contain a CVS directory; - for the most part these can just be ignored. - - - -

    llvm/include

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

    - -

      -
    1. 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, - Reoptimizer, Target, Transforms, etc... - -
    2. llvm/include/Support - This directory contains generic - support libraries that are independent of LLVM, but are used by LLVM. - For example, some C++ STL utilities and a Command Line option processing - library. - -
    3. llvm/include/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/ByteCode/
    This directory holds code for reading - and write LLVM bytecode. - -
    llvm/lib/CWriter/
    This directory implements the LLVM to C - converter. - -
    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 - Invarient Code Motion, Dead Global Elimination, Pool Allocation, and many - others... - -
    llvm/lib/Target/
    This directory contains files that - describe various target architectures for code generation. For example, - the llvm/lib/Target/Sparc directory holds the Sparc machine - description.
    - -
    llvm/lib/CodeGen/
    This directory contains the major parts - of the code generator: Instruction Selector, Instruction Scheduling, and - Register Allocation. - -
    llvm/lib/Reoptimizer/
    This directory holds code related - to the runtime reoptimizer framework that is currently under development. - -
    llvm/lib/Support/
    This directory contains the source code - that corresponds to the header files located in - llvm/include/Support/. -
    - - -

    llvm/test

    - - -

    This directory contains regression tests and source code that is used to - test the LLVM infrastructure...

    - - -

    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.

    - -
    -
    as
    The assembler transforms the human readable - LLVM assembly to LLVM bytecode.

    - -

    dis
    The disassembler transforms the LLVM bytecode - to human readable LLVM assembly. Additionally it can convert LLVM - bytecode to C, which is enabled with the -c option.

    - -

    lli
    lli is the LLVM interpreter, which - can directly execute LLVM bytecode (although very slowly...). In addition - to a simple interpreter, lli is also has debugger and tracing - modes (entered by specifying -debug or -trace on the - command line, respectively). Finally, for architectures that support it - (currently only x86 and Sparc), 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 bytecode to a SPARC or x86 assembly file.

    - -

    llvmgcc
    llvmgcc is a GCC based C frontend - that has been retargeted to emit LLVM code as the machine code output. It - works just like any other GCC compiler, taking the typical -c, -S, -E, - -o options that are typically used. The source code for the - llvmgcc tool is currently not included in the LLVM cvs tree - because it is quite large and not very interesting.

    - -

      -
      gccas
      This tool is invoked by the - llvmgcc frontend as the "assembler" part of the compiler. This - tool actually assembles LLVM assembly to LLVM bytecode, - performs a variety of optimizations, - and outputs LLVM bytecode. Thus when you invoke llvmgcc -c x.c -o - x.o, you are causing gccas to be run, which writes the - x.o file (which is an LLVM bytecode file that can be - disassembled or manipulated just like any other bytecode file). The - command line interface to gccas is designed to be as close as - possible to the system 'as' utility so that the gcc - frontend itself did not have to be modified to interface to a "weird" - assembler.

      - -

      gccld
      gccld links together several LLVM - bytecode files into one bytecode file and does some optimization. It is - the linker invoked by the gcc frontend when multiple .o files need to be - linked together. Like gccas the command line interface of - gccld is designed to match the system linker, to aid - interfacing with the GCC frontend.

      -

    - -
    opt
    opt reads LLVM bytecode, applies a - series of LLVM to LLVM transformations (which are specified on the command - line), and then outputs the resultant bytecode. The 'opt --help' - command is a good way to get a list of the program transformations - available in LLVM.

    - - -

    analyze
    analyze is used to run a specific - analysis on an input LLVM bytecode file and print out the results. It is - primarily useful for debugging analyses, or familiarizing yourself with - what an analysis does.

    +

    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 bytecode libraries into the GCC front end's bytecode library + directory. If you need to update your bytecode 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_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.

    + +
    + + +
    + 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 bytecode 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::llvm::/path/to/lli:' > /proc/sys/fs/binfmt_misc/register
+   $ chmod u+x hello.bc                (if needed)
+   $ ./hello.bc
+
    +
    + +

    +This allows you to execute LLVM bytecode files directly. Thanks to Jack +Cummings for pointing this out! +

    + +
    + + + +
    + Program Layout +
    + + +
    + +

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

    + +
    + + +
    CVS directories
    +
    +

    Every directory checked out of CVS will contain a CVS directory; for +the most part these can just be ignored.

    +
    + + +
    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/ByteCode/
    +
    This directory holds code for reading and write LLVM bytecode.
    + +
    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/SparcV9 + directory holds the Sparc 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 bytecode 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. See llvm/projects/Stacker for a fully + functional example of a compiler front end.

    +
    + + +
    llvm/runtime
    +
    + +

    This directory contains libraries which are compiled into LLVM bytecode 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.

    +
    + + +
    llvm-test
    +
    +

    This is not a directory in the normal llvm module; it is a separate CVS + module that must be checked out (usually to projects/llvm-test). This + module contains a comprehensive correctness, performance, and benchmarking + test + suite for LLVM. It is a separate CVS 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.

    + +
    +
    analyze
    +
    analyze is used to run a specific + analysis on an input LLVM bytecode file and print out the results. It is + primarily useful for debugging analyses, or familiarizing yourself with + what an analysis does.
    + +
    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 bytecode. This reduces the need to get the + traditional -l<name> options right on the command line. Please + note that this tool is new in 1.4 and considered experimental. It will be + fully supported in 1.5.
    + +
    llvm-ar
    +
    The archiver produces an archive containing + the given LLVM bytecode files, optionally with an index for faster + lookup.
    + +
    llvm-as
    +
    The assembler transforms the human readable LLVM assembly to LLVM + bytecode.
    + +
    llvm-dis
    +
    The disassembler transforms the LLVM bytecode to human readable + LLVM assembly.
    + +
    llvm-ld
    +
    llvm-ld is very similar to gccld and provides a general purpose + and extensible linker for LLVM. This is the linker invoked by llvmc. + It allows optimization modules to be loaded so that language specific + optimizations can be applied at link time. Please note that this tool is new + in LLVM 1.4 and still considered experimental. It will be fully supported in + LLVM 1.5.
    + +
    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 bytecode (although very slowly...). In addition + to a simple interpreter, lli also has a tracing mode (entered by + specifying -trace on the command line). Finally, 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 bytecode to a SPARC or x86 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 emit LLVM code as the machine code output. It + works just like any other GCC compiler, taking the typical -c, -S, -E, + -o options that are typically used. The source code for the + llvm-gcc tool is currently not included in the LLVM CVS tree + because it is quite large and not very interesting. +
    +
    +
    gccas
    +
    This tool is invoked by the llvm-gcc frontend as the + "assembler" part of the compiler. This tool actually assembles LLVM + assembly to LLVM bytecode, performs a variety of optimizations, and + outputs LLVM bytecode. Thus when you invoke + llvm-gcc -c x.c -o x.o, you are causing gccas to be + run, which writes the x.o file (which is an LLVM bytecode file + that can be disassembled or manipulated just like any other bytecode + file). The command line interface to gccas is designed to be + as close as possible to the system `as' utility so that + the gcc frontend itself did not have to be modified to interface to + a "weird" assembler.
    + +
    gccld
    +
    gccld links together several LLVM bytecode files into one + bytecode file and does some optimization. It is the linker invoked by + the GCC frontend when multiple .o files need to be linked together. + Like gccas, the command line interface of gccld is + designed to match the system linker, to aid interfacing with the GCC + frontend.
    - - -

    An example using the LLVM tool chain

    - - -
      -
    1. First, create a simple C file, name it 'hello.c': +
    +
    + +
    opt
    +
    opt reads LLVM bytecode, applies a + series of LLVM to LLVM transformations (which are specified on the command + line), and then outputs the resultant bytecode. The 'opt --help' + command is a good way to get a list of the program transformations + available in LLVM.
    +
    +
    + + +
    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.

    + +
    +
    Burg/
    Burg is an instruction selector + generator -- it builds trees on which it then performs pattern-matching to + select instructions according to the patterns the user has specified. Burg + is currently used in the Sparc V9 backend.

    + +

    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'.

    + +

    cvsupdate
    cvsupdate is a script that will + update your CVS tree, but produce a much cleaner and more organized output + than simply running `cvs -z3 up -dP' will. For example, it will group + together all the new and updated files and modified files in separate + sections, so you can see at a glance what has changed. If you are at the + top of your LLVM CVS tree, running utils/cvsupdate is the + preferred way of updating the tree.

    + +

    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.

    + +

    NightlyTest.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 +
    + + +
    + +
      +
    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 LLVM bytecode file:

      +

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

      +

      % llvm-gcc hello.c -o hello

      - % llvmgcc hello.c -o hello

      +

      Note that you should have already built the tools and they have to be + in your path, at least gccas and gccld.

      - This will create two result files: hello and +

      This will create two result files: hello and hello.bc. The hello.bc is the LLVM bytecode that corresponds the the compiled program and the library facilities that it required. hello is a simple shell script that runs the bytecode - file with lli, making the result directly executable.

      + file with lli, making the result directly executable. Note that + all LLVM optimizations are enabled by default, so there is no need for a + "-O3" switch.

      4. -
    4. Run the program. To make sure the program ran, execute one of the - following commands:

      +

    5. Run the program. To make sure the program ran, execute one of the + following commands:

      - % ./hello

      +

      % ./hello

      - or

      +

      or

      - % lli hello.bc

      +

      % lli hello.bc

      6. -
    6. Use the dis utility to take a look at the LLVM assembly - code:

      +

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

      - % dis < hello.bc | less

      +

      % llvm-dis < hello.bc | less

      8. -
    8. Compile the program to native Sparc assembly using the code - generator (assuming you are currently on a Sparc system):

      +

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

      - % llc hello.bc -o hello.s

      +

      % llc hello.bc -o hello.s

      -
    10. Assemble the native sparc assemble file into a program:

      +

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

      - % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.sparc

      +

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

      +

      Others:% gcc hello.s -o hello.native

      -
    12. Execute the native sparc program:

      +

    13. Execute the native code program:

      - % ./hello.sparc

      +

      % ./hello.native

      14. -
    + +
    - -

    Common Problems

    - + +
    + Common Problems +
    + - Below are common problems and their remedies: +
    -
    -
    When I run configure, it finds the wrong C compiler. -
    - The configure script attempts to locate first gcc and - then cc, unless it finds compiler paths set in CC and - CXX for the C and C++ compiler, respectively. +

    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.

    - If configure finds the wrong compiler, either adjust your - PATH environment variable or set CC and CXX - explicitly. -

    +

    -
    I compile the code, and I get some error about /localhome. -
    - There are several possible causes for this. The first is that you - didn't set a pathname properly when using configure, and it - defaulted to a pathname that we use on our research machines. -

    - Another possibility is that we hardcoded a path in our Makefiles. If - you see this, please email the LLVM bug mailing list with the name of - the offending Makefile and a description of what is wrong with it. + +

    + Links +
    + -
    The configure script finds the right C compiler, but it - uses the LLVM linker from a previous build. What do I do? -
    - The configure script uses the PATH to find - executables, so if it's grabbing the wrong linker/assembler/etc, there - are two ways to fix it: -
      -
    1. Adjust your PATH environment variable so that the - correct program appears first in the PATH. This may work, - but may not be convenient when you want them first in your - path for other work. -

      +

      -
    2. Run configure with an alternative PATH that - is correct. In a Borne compatible shell, the syntax would be: -

      - PATH= ./configure ... -

      - This is still somewhat inconvenient, but it allows - configure to do its work without having to adjust your - PATH permanently. -

    - +

    This document is just an introduction to 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! - -

    Links

    - - -

    This document is just an introduction to 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:

    - - - -
    - - If you have any questions or run into any snags (or you have any - additions...), please send an email to - Chris Lattner.

    - - - -Last modified: Tue Jun 3 22:06:43 CDT 2003 - - + Chris Lattner
    + Reid Spencer
    + The LLVM Compiler Infrastructure
    + Last modified: $Date$ +
    +