X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=docs%2FGettingStarted.html;h=eed4547a7818ef78de98eef2c66f921590e77727;hb=0f4012f4759a6c6ca28f11ed1eb98feb8ab1481b;hp=e9a03a22fd7557a1fa3336510bba83a20528afde;hpb=c40eb5e0d23113fec92a39682e7ae3ca720f7e87;p=oota-llvm.git diff --git a/docs/GettingStarted.html b/docs/GettingStarted.html index e9a03a22fd7..eed4547a781 100644 --- a/docs/GettingStarted.html +++ b/docs/GettingStarted.html @@ -17,44 +17,42 @@
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 +level virtual machine. It contains an assembler, disassembler, bitcode +analyzer and bitcode optimizer. It also contains a test suite that can be used to test the LLVM tools and the GCC front end.
The second piece is the GCC front end. This component provides a version of -GCC that compiles C and C++ code into LLVM 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.
@@ -116,19 +114,19 @@ and performance.
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. @@ -385,9 +389,9 @@ href="CFEBuildInstrs.html">try to compile it on your platform.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 +successfully with them (however, see important notes below). Other versions +of GCC will probably work as well. GCC versions listed here are known to not work. If you are using one of these versions, please try to upgrade your GCC to something more recent. If you run into a problem with a version of GCC not listed here, please let @@ -512,19 +515,33 @@ 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 @@ -533,6 +550,23 @@ the "convert_from_eh_region_ranges_1" GCC function.
GCC 4.1.1: GCC fails to build LLVM with template concept check errors compiling some files. At the time of this writing, GCC mainline (4.2) did not share the problem.
+GCC 4.1.1 on X86-64/amd64: GCC + miscompiles portions of LLVM when compiling llvm itself into 64-bit + code. LLVM will appear to mostly work but will be buggy, e.g. failing + portions of its testsuite.
+GCC 4.1.2 on OpenSUSE: Seg faults during libstdc++ build and on x86_64 +platforms compiling md5.c gets a mangled constant.
+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).
+For the pre-built GCC front end binaries, the LLVMGCCDIR is - cfrontend/platform/llvm-gcc. + llvm-gcc/platform/llvm-gcc. @@ -604,11 +638,11 @@ In order to compile and use LLVM, you may need to set some environment variables.
It is also possible to download the sources of the llvm-gcc4 front end from a @@ -663,32 +689,39 @@ svn://anonsvn.opensource.apple.com/svn/llvm/trunk.
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 Subvresion 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:
+revision), you can checkout it from the 'tags' directory (instead of +'trunk'). The following releases are located in the following + subdirectories of the 'tags' directory:If you would like to get the LLVM test suite (a separate package as of 1.4), -you get it from the 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 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 3.4 front end source code, you can also get it from the CVS repository:
- -- cvs -z3 -d :pserver:anon@llvm.org:/var/cvs/llvm co llvm-gcc -+you run svn update. -
Please note that you must follow these -instructions to successfully build the LLVM GCC front-end.
+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.
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, you can optionally extract the +LLVM GCC front end from the binary distribution. It is used for running the +llvm-test testsuite and for compiling C/C++ programs. Note that you can optionally +build llvm-gcc yourself after building the +main LLVM repository.
To install the GCC front end, do the following:
Next, you will need to fix your system header files:
- -cd cfrontend/platform
- ./fixheaders
Once the binary is uncompressed, you should add a symlink for llvm-gcc and +llvm-g++ to some directory in your path. When you configure LLVM, it will +automatically detect llvm-gcc's presence (if it is in your path) enabling its +use in llvm-test. Note that you can always build or install llvm-gcc at any +pointer after building the main LLVM repository: just reconfigure llvm and +llvm-test will pick it up. +
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 @@ -751,8 +787,8 @@ 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.
+href="GCCFEBuildInstrs.html">building the GCC front end from source. This is +much easier now than it was in the past.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 @@ -805,7 +842,7 @@ 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.To configure LLVM, follow these steps:
Change directory into the object root directory:
-% cd OBJ_ROOT
Run the configure script located in the LLVM source + tree:
+ +% SRC_ROOT/configure --prefix=/install/path [other options]+
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.
@@ -918,7 +961,7 @@ 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:
@@ -948,8 +991,8 @@ source code:Change directory to where the LLVM object files should live:
-cd OBJ_ROOT
% cd OBJ_ROOT
Run the configure script found in the LLVM source directory:
-SRC_ROOT/configure
% SRC_ROOT/configure
The LLVM build will place files underneath OBJ_ROOT in directories @@ -1109,23 +1152,22 @@ 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::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 +This allows you to execute LLVM bitcode files directly. Thanks to Jack Cummings for pointing this out!
@@ -1147,13 +1189,6 @@ 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.
-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.
@@ -1283,13 +1318,16 @@ end to compile.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 +
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.
@@ -1320,30 +1358,29 @@ information is in the Command Guide. 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 + dependent libraries found in bitcode. This reduces the need to get the traditional -l<name> options right on the command line. Please note that this tool, while functional, is still experimental and not feature complete.---
-- 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.
-
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 instructiosn 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.
- #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 bitcode file:
-Next, compile the C file into a LLVM bytecode file:
-% llvm-gcc -O3 -emit-llvm hello.c -c -o hello.bc
+% 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.
Use the llvm-dis utility to take a look at the LLVM assembly code:
-% llvm-dis < hello.bc | less
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.
@@ -1578,66 +1593,6 @@ output.- #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