-
-
- Terminology and Notation -
- Setting Up Your Environment -
- Unpacking the LLVM Archives -
- Checkout LLVM from CVS -
- Install the GCC Front End -
- Local LLVM Configuration -
- Compiling the LLVM Suite Source Code -
- Cross-Compiling LLVM -
- The Location of LLVM Object Files -
- Optional Configuration Items +
- Terminology and Notation +
- Setting Up Your Environment +
- Unpacking the LLVM Archives +
- Checkout LLVM from Subversion +
- LLVM GIT mirror +
- Install the GCC Front End +
- Local LLVM Configuration +
- Compiling the LLVM Suite Source Code +
- Cross-Compiling LLVM +
- The Location of LLVM Object Files +
- Optional Configuration Items
-
-
- CVS directories -
- llvm/examples -
- llvm/include -
- llvm/lib -
- llvm/projects -
- llvm/runtime -
- llvm/test -
- llvm-test -
- llvm/tools -
- llvm/utils -
- llvm/win32 +
- llvm/examples +
- llvm/include +
- llvm/lib +
- llvm/projects +
- llvm/runtime +
- llvm/test +
- test-suite +
- llvm/tools +
- llvm/utils
Written by: John Criswell, Chris Lattner, - Misha Brukman, + Misha Brukman, Vikram Adve, and Guochun Shi.
@@ -72,30 +70,31 @@ -+ 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.
+First, LLVM comes in three 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 basic regression tests 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 +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 +There is a third, optional piece called Test Suite. It is a suite of programs with a testing harness that can be used to further test LLVM's functionality and performance.
@@ -103,12 +102,12 @@ and performance.+ Getting Started Quickly (A Summary) +
-Here's the short story for getting up and running quickly with LLVM:
@@ -116,19 +115,20 @@ and performance.- cd where-you-want-the-C-front-end-to-live -
- gunzip --stdout llvm-gcc.platform.tar.gz | tar -xvf - - -
- cd llvm-gcc3.4/platform (llvm-gcc3.4 only)
- ./fixheaders
- - Add llvm-gcc's "bin" directory to your PATH variable. +
- gunzip --stdout llvm-gcc-4.2-version-platform.tar.gz | tar -xvf - +
- install-binutils-binary-from-MinGW (Windows only) +
- Note: If the binary extension is ".bz" use bunzip2 instead of gunzip. +
- Note: On Windows, use 7-Zip or a similar archiving tool. +
- Add llvm-gcc's "bin" directory to your PATH environment variable.
-
-
- With the distributed files (or use CVS): +
- With the distributed files (or use SVN):
- cd where-you-want-llvm-to-live
- gunzip --stdout llvm-version.tar.gz | tar -xvf - @@ -138,11 +138,12 @@ and performance.
- [Optional] Get the Test Suite Source Code @@ -162,7 +163,8 @@ and performance.
- --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.
+ not specified, the PATH will be searched. This is only needed if you
+ want to run test-suite or do some special kinds of LLVM builds.
- --enable-spec2000=directory
Enable the SPEC2000 benchmarks for testing. The SPEC2000 benchmarks should be available in @@ -189,25 +191,23 @@ 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:
@@ -217,11 +217,21 @@ software you will need.Notes:
@@ -308,45 +325,53 @@ software you will need. upNote 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 disable them individually in llvm/tools/Makefile. The Release -build requires considerably less space.
+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 bytecode. Code +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.
+href="GCCFEBuildInstrs.html">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 @@ -362,34 +387,27 @@ href="CFEBuildInstrs.html">try to compile it on your platform.
(not 1.85 or 1.875)
+ 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 below). Other versions of GCC will -probably work as well. GCC versions listed +to compile LLVM. We routinely use GCC 4.2 (and higher) or Clang. +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 @@ -513,19 +529,33 @@ of GCC you are using. problems in the STL that effectively prevent it from compiling LLVM.
-GCC 3.2.2: This version of GCC fails to compile LLVM.
+GCC 3.2.2 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 + 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 @@ -538,22 +568,51 @@ the "convert_from_eh_region_ranges_1" GCC function.
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.
+GCC 4.3.5 and GCC 4.4.5 on ARM: These can miscompile value >> +1 even at -O0. A test failure in test/Assembler/alignstack.ll is +one symptom of the problem.
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.
@@ -563,14 +622,13 @@ href="#layout">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. -Throughout this manual, the following names are used to denote paths specific to the local system and working environment. These are not @@ -603,22 +661,22 @@ All these paths are absolute:
In order to compile and use LLVM, you may need to set some environment variables.
-
-
- LLVM_LIB_SEARCH_PATH=/path/to/your/bytecode/libs +
- LLVM_LIB_SEARCH_PATH=/path/to/your/bitcode/libs
- [Optional] This environment variable helps LLVM linking tools find the - locations of your bytecode libraries. It is provided only as a + 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 bytecode files + tools and the C/C++ front-end will automatically use the bitcode files installed in its lib directory.
If you have the LLVM distribution, you will need to unpack it before you @@ -643,60 +701,61 @@ 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.
- Source release for the LLVM libraries and tools.
- llvm-test-x.y.tar.gz -
- Source release for the LLVM test suite. +
- Source release for the LLVM test-suite. -
- llvm-gcc3.4-x.y.source.tar.gz -
- Source release of the LLVM GCC 3.4 front end.
- llvm-gcc3.4-x.y-platform.tar.gz -
- Binary release of the LLVM GCC 3.4 for a specific platform.
- 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-gcc4-x.y.source.tar.gz -
- Source release of the llvm-gcc4 front end. See README.LLVM in the root
- directory for build instructions.
- llvm-gcc4-x.y-platform.tar.gz -
- Binary release of the llvm-gcc4 front end for a specific platform.
- llvm-gcc-4.2-x.y-platform.tar.gz +
- Binary release of the llvm-gcc-4.2 front end for a specific platform.
It is also possible to download the sources of the llvm-gcc4 front end from a -read-only subversion mirror at -svn://anonsvn.opensource.apple.com/svn/llvm/trunk.
-+ Checkout LLVM from Subversion +
-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 +
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:
-
-
- cd where-you-want-llvm-to-live -
- cvs -d :pserver:anon@llvm.org:/var/cvs/llvm login -
- Hit the return key when prompted for the password. -
- cvs -z3 -d :pserver:anon@llvm.org:/var/cvs/llvm co - llvm +
- cd where-you-want-llvm-to-live +
- Read-Only: svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm +
- Read-Write:svn co https://user@llvm.org/svn/llvm-project/llvm/trunk + 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.
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:
+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:-
+
- Release 2.9: RELEASE_29/final +
- Release 2.8: RELEASE_28 +
- Release 2.7: RELEASE_27 +
- Release 2.6: RELEASE_26 +
- Release 2.5: RELEASE_25 +
- Release 2.4: RELEASE_24 +
- Release 2.3: RELEASE_23 +
- Release 2.2: RELEASE_22 +
- Release 2.1: RELEASE_21 +
- Release 2.0: RELEASE_20
- Release 1.9: RELEASE_19
- Release 1.8: RELEASE_18
- Release 1.7: RELEASE_17 @@ -710,70 +769,265 @@ 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:
+you get it from the Subversion repository: + +- cd llvm/projects - cvs -z3 -d :pserver:anon@llvm.org:/var/cvs/llvm co llvm-test +% cd llvm/projects +% svn co http://llvm.org/svn/llvm-project/test-suite/trunk test-suite+
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.
+you run svn update. -If you would like to get the GCC 3.4 front end source code, you can also get it from the CVS repository:
+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.
-- cvs -z3 -d :pserver:anon@llvm.org:/var/cvs/llvm co llvm-gcc +
+ GIT mirror +
+ +GIT mirrors are available for a number of LLVM subprojects. These mirrors + sync automatically with each Subversion commit and contain all necessary + git-svn marks (so, you can recreate git-svn metadata locally). Note that right + now mirrors reflect only trunk for each project. You can do the + read-only GIT clone of LLVM via:
+ ++git clone http://llvm.org/git/llvm.git ++ +
If you want to check out clang too, run:
+ ++git clone http://llvm.org/git/llvm.git +cd llvm/tools +git clone http://llvm.org/git/clang.git ++ +
+Since the upstream repository is in Subversion, you should use +"git pull --rebase" +instead of "git pull" to avoid generating a non-linear +history in your clone. +To configure "git pull" to pass --rebase by default +on the master branch, run the following command: +
+ ++git config branch.master.rebase true-
Please note that you must follow these -instructions to successfully build the LLVM GCC front-end.
+Sending patches with Git
++Please read Developer Policy, too. +
+ ++Assume master points the upstream and mybranch points your +working branch, and mybranch is rebased onto master. +At first you may check sanity of whitespaces: +
+ ++git diff --check master..mybranch ++ +
+The easiest way to generate a patch is as below: +
+ ++git diff master..mybranch > /path/to/mybranch.diff ++ +
+It is a little different from svn-generated diff. git-diff-generated diff has +prefixes like a/ and b/. Don't worry, most developers might +know it could be accepted with patch -p1 -N. +
+ ++But you may generate patchset with git-format-patch. It generates +by-each-commit patchset. To generate patch files to attach to your article: +
+ ++git format-patch --no-attach master..mybranch -o /path/to/your/patchset ++ +
+If you would like to send patches directly, you may use git-send-email or +git-imap-send. Here is an example to generate the patchset in Gmail's [Drafts]. +
+ ++git format-patch --attach master..mybranch --stdout | git imap-send ++ +
+Then, your .git/config should have [imap] sections. +
+ ++[imap] + host = imaps://imap.gmail.com + user = your.gmail.account@gmail.com + pass = himitsu! + port = 993 + sslverify = false +; in English + folder = "[Gmail]/Drafts" +; example for Japanese, "Modified UTF-7" encoded. + folder = "[Gmail]/&Tgtm+DBN-" +; example for Traditional Chinese + folder = "[Gmail]/&g0l6Pw-" ++ +
For developers to work with git-svn
+To set up clone from which you can submit code using + git-svn, run:
+ ++git clone http://llvm.org/git/llvm.git +cd llvm +git svn init https://llvm.org/svn/llvm-project/llvm/trunk --username=<username> +git config svn-remote.svn.fetch :refs/remotes/origin/master +git svn rebase -l # -l avoids fetching ahead of the git mirror. + +# If you have clang too: +cd tools +git clone http://llvm.org/git/clang.git +cd clang +git svn init https://llvm.org/svn/llvm-project/cfe/trunk --username=<username> +git config svn-remote.svn.fetch :refs/remotes/origin/master +git svn rebase -l ++ +
To update this clone without generating git-svn tags that conflict +with the upstream git repo, run:
+ ++git fetch && (cd tools/clang && git fetch) # Get matching revisions of both trees. +git checkout master +git svn rebase -l +(cd tools/clang && + git checkout master && + git svn rebase -l) ++ +
This leaves your working directories on their master branches, so +you'll need to checkout each working branch individually and +rebase it on top of its parent branch. (Note: This script is +intended for relative newbies to git. If you have more experience, +you can likely improve on it.)
+ +The git-svn metadata can get out of sync after you mess around with
+branches and dcommit. When that happens, git svn
+dcommit stops working, complaining about files with uncommitted
+changes. The fix is to rebuild the metadata:
+rm -rf .git/svn +git svn rebase -l ++ +
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.
+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-suite 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:
+To install the GCC front end, do the following (on Windows, use an archival tool +like 7-zip that understands gzipped tars):
- cd where-you-want-the-front-end-to-live -
- gunzip --stdout llvmgcc-version.platform.tar.gz | tar -xvf
+
- gunzip --stdout llvm-gcc-4.2-version-platform.tar.gz | tar -xvf -
Next, you will need to fix your system header files (llvm-gcc3.4 only):
+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 test-suite. Note that you can always build or install llvm-gcc at any +point after building the main LLVM repository: just reconfigure llvm and +test-suite will pick it up. +
-cd llvm-gcc3.4/platform
- ./fixheaders
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.
-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.
+To install binutils on Windows:
+ +-
+
- download GNU Binutils from MinGW Downloads +
- cd where-you-uncompressed-the-front-end +
- uncompress archived binutils directories (not the tar file) into the current directory +
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.
+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.
Once checked out from the CVS repository, the LLVM suite source code must be +
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 @@ -815,7 +1069,7 @@ script to configure the build system:
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 + Bootstrapping the LLVM C/C++ Front-End for details on building the C/C++ Front End.+ names use all lower case. The current set of targets is:
alpha, ia64, powerpc, skeleton, sparc, x86.
To configure LLVM, follow these steps:
-
-
- Change directory into the object root directory:
-
- cd OBJ_ROOT -
+ Change directory into the object root directory:
-- Run the configure script located in the LLVM source tree:
-
- SRC_ROOT/configure --prefix=/install/path [other options] -
+% cd OBJ_ROOT
+
+ Run the configure script located in the LLVM source + tree:
+ ++% SRC_ROOT/configure --prefix=/install/path [other options]
+
Once you have configured LLVM, you can build it. There are three types of builds:
@@ -892,10 +1154,12 @@ 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.
+ 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
@@ -905,6 +1169,7 @@ builds:
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 @@ -918,7 +1183,7 @@ builds:
Once you have LLVM configured, you can build it by entering the OBJ_ROOT directory and issuing the following command:
-gmake
+% 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.
@@ -928,7 +1193,7 @@ 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
+% gmake -j2
There are several special targets which are useful when working with the LLVM source code:
@@ -958,8 +1223,8 @@ source code:- gmake -C runtime install-bytecode
- Profile Builds @@ -918,7 +1183,7 @@ builds:
-
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,
+ 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.
+ +
It is possible to cross-compile LLVM. That is, you can create LLVM - executables and libraries for a platform different than the one one which you - are compiling. To do this, a few additional steps are - required. 1 To cross-compile LLVM, use - these instructions:
--
-
- Configure and build LLVM as a native compiler. You will need
- just TableGen from that build.
-
-
-
- If you have $LLVM_OBJ_ROOT=$LLVM_SRC_ROOT just execute - make -C utils/TableGen after configuring. -
- Otherwise you will need to monitor building process and terminate - it just after TableGen was built. -
- - Copy the TableGen binary to somewhere safe (out of your build tree). - -
- Configure LLVM to build with a cross-compiler. To do this, 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. -
- Put the saved TableGen executable into the - into $LLVM_OBJ_ROOT/{BUILD_TYPE}/bin directory (e.g. into - .../Release/bin for a Release build). -
- Build LLVM as usual. -
The result of such a build will produce executables that are not executable - on your build host (--build option) but can be executed on your compile host + + +
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).
-Notes:
--
-
- Cross-compiling was tested only with Linux as - build platform and Windows as host using mingw32 cross-compiler. Other - combinations have not been tested. -
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 @@ -1066,25 +1309,25 @@ platforms or configurations using the same source tree.
Change directory to where the LLVM object files should live:
-cd OBJ_ROOT
+ Run the configure script found in the LLVM source directory:
-SRC_ROOT/configure
+
% cd OBJ_ROOT
% SRC_ROOT/configure
The LLVM build will place files underneath OBJ_ROOT in directories named after the build type:
-
-
- Debug Builds
+
- Debug Builds with assertions enabled (the default)
-
- Tools -
- OBJ_ROOT/Debug/bin
+
- OBJ_ROOT/Debug+Asserts/bin
- Libraries -
- OBJ_ROOT/Debug/lib
+
- OBJ_ROOT/Debug+Asserts/lib
@@ -1111,69 +1354,72 @@ named after the build type:
If you're running on a Linux system that supports the " - binfmt_misc" +href="http://www.tat.physik.uni-tuebingen.de/~rguenth/linux/binfmt_misc.html">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 +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::llvm::/path/to/lli:' > /proc/sys/fs/binfmt_misc/register - $ chmod u+x hello.bc (if needed) - $ ./hello.bc +$ 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 bytecode files directly. Thanks to Jack -Cummings for pointing this out! +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 doxygen documentation available at http://llvm.org/doxygen/. The following is a brief introduction to code layout:
-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:
@@ -1200,8 +1446,11 @@ library. The three main subdirectories of this directory are:+ 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 @@ -1216,8 +1465,8 @@ different tools.
+ 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.
+ to set up your own project.+ llvm/runtime +
+ +This directory contains libraries which are compiled into LLVM bytecode and +
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.
@@ -1285,33 +1540,45 @@ 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.
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 +
+ 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 CVS module because not every LLVM user is + 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 +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.
@@ -1325,35 +1592,24 @@ information is in the Command Guide. href="HowToSubmitABug.html">HowToSubmitABug.html for more information on using bugpoint. ----
-- 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.
-
+ the resultant bitcode. 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 @@ -1432,14 +1665,6 @@ are code generators for parts of LLVM infrastructure.
assuming that the other generates correct output. For the full user manual, run `perldoc codegen-diff'.-
-
-
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. -
This section gives an example of using LLVM. Since we are currently -transitioning from llvm-gcc3 to llvm-gcc4, we include examples for both. +
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 bytecode by default: gcc4 produces native code. As the example below illustrates, -the '--emit-llvm' flag is needed to produce LLVM bytecode output. For makefiles and -configure scripts, the CFLAGS variable needs '--emit-llvm' to produce bytecode +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 +
--
-
- First, create a simple C file, name it 'hello.c':
-
- #include <stdio.h> - int main() { - printf("hello world\n"); - return 0; - } -
+ First, create a simple C file, name it 'hello.c':
+ +++#include <stdio.h> + +int main() { + printf("hello world\n"); + return 0; +} +Next, compile the C file into a native executable:
-% llvm-gcc hello.c -o hello
+% 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).
+ respectively).
- Next, compile the C file into a LLVM bytecode file:
-% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc
+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 bytecode file.
+ the bitcode file.Unlike llvm-gcc3, llvm-gcc4 correctly responds to -O[0123] arguments.
Run the program in both forms. To run the program, use:
-% ./hello
+% ./hello
and
-% lli hello.bc
+% lli hello.bc
The second examples shows how to invoke the LLVM JIT, lli.
@@ -1564,21 +1788,28 @@ output.
Use the llvm-dis utility to take a look at the LLVM assembly code:
-% llvm-dis < hello.bc | less
+Compile the program to native assembly using the LLC code generator:
-% llc hello.bc -o hello.s
+% llc hello.bc -o hello.s
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
+++Solaris: % /opt/SUNWspro/bin/cc -xarch=v9 hello.s -o hello.native + +Others: % gcc hello.s -o hello.native +
+Execute the native code program:
-% ./hello.native
+% ./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.
@@ -1588,74 +1819,15 @@ output.
llvm-dis < hello.bc | less+
-
-
- First, create a simple C file, name it 'hello.c':
-
- #include <stdio.h> - int main() { - printf("hello world\n"); - return 0; - } -
-
- Next, compile the C file into a LLVM bytecode file:
-% llvm-gcc 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 - 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. Note that - all LLVM optimizations are enabled by default, so there is no need for a - "-O3" switch.
-
- Run the program. To make sure the program ran, execute one of the - following commands:
- -% ./hello
- -or
- -% lli hello.bc
-
- Use the llvm-dis utility to take a look at the LLVM assembly - code:
- -% llvm-dis < hello.bc | less
-
- Compile the program to native assembly using the LLC code - generator:
- -% llc hello.bc -o hello.s
- -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
- -Execute the native code program:
- -% ./hello.native
-
-
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 @@ -1664,14 +1836,14 @@ Asked Questions page.
Links -
This document is just an introduction to how to use LLVM to do +
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 @@ -1691,13 +1863,13 @@ out:
+ src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS">
Reid Spencer
- The LLVM Compiler Infrastructure
+ The LLVM Compiler Infrastructure
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