This document is intended to explain the process of building the LLVM C/C++ front-end, based on GCC 3.4, from its source code. You would have to do this, for example, if you are porting LLVM to a new architecture or operating system.
NOTE: This is currently a somewhat fragile, error-prone process, and you should only try to do it if:
We welcome patches to help make this process simpler.
If you are building LLVM and the GCC front-end under Cygwin, please note that the LLVM and GCC makefiles do not correctly handle spaces in paths. To deal with this issue, make sure that your LLVM and GCC source and build trees are located in a top-level directory (like /cygdrive/c/llvm and /cygdrive/c/llvm-cfrontend), not in a directory that contains a space (which includes your "home directory", because it lives under the "Documents and Settings" directory). We welcome patches to fix this issue.
If you are building LLVM and the GCC front-end under AIX, do NOT use GNU Binutils. They are not stable under AIX and may produce incorrect and/or invalid code. Instead, use the system assembler and linker.
Configure and build the LLVM libraries and tools using:
% cd llvm % ./configure --prefix=/some/path/you/can/install/to [options...] % gmake tools-only
This will build all of the LLVM tools and libraries. The --prefix option defaults to /usr/local (per configure standards) but unless you are a system administrator, you probably won't be able to install LLVM there because of permissions. Specify a path into which LLVM can be installed (e.g. --prefix=/home/user/llvm).
Add the directory containing the tools to your PATH.
% set path = ( `cd llvm/Debug/bin && pwd` $path )
Unpack the C/C++ front-end source into cfrontend/src.
Make "build" and "install" directories as siblings of the "src" tree.
% pwd /usr/local/example/cfrontend/src % cd .. % mkdir build install % set CFEINSTALL = `pwd`/install
Configure, build, and install the GCC front-end:
MacOS X/PowerPC (requires dlcompat library):
% cd build % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \ --disable-shared --enable-languages=c,c++ % gmake % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc % gmake all; gmake install
% cd build % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \ --disable-shared --enable-languages=c,c++ --disable-c-mbchar % gmake % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc % gmake all; gmake install
For Solaris/SPARC, LLVM only supports the SPARC V9 architecture. Therefore, the configure command line should specify sparcv9, as shown below. Also, note that Solaris has trouble with various wide (multibyte) character functions from C as referenced from C++, so we typically configure with --disable-c-mbchar (cf. Bug 206).
% cd build % ../src/configure --prefix=$CFEINSTALL --disable-threads --disable-nls \ --disable-shared --enable-languages=c,c++ --host=sparcv9-sun-solaris2.8 \ --disable-c-mbchar % gmake % setenv LLVM_LIB_SEARCH_PATH `pwd`/gcc % gmake all; gmake install
Common Problem: You may get error messages regarding the fact that LLVM does not support inline assembly. Here are two common fixes:
Fix 1: If you have system header files that include
inline assembly, you may have to modify them to remove the inline
assembly and install the modified versions in
src/libstdc++-v3/config/cpu/name-of-cpu/atomicity.hand apply a patch so that it does not use inline assembly.
Porting to a new architecture: If you are porting the front-end to a new architecture or compiling in a configuration that we have not tried previously, there are probably several changes you will have to make to the GCC target to get it to work correctly. These include:
Go back into the LLVM source tree proper. Rerun configure, using
--with-llvmgccdir=$CFEINSTALL option to specify the path
to the newly built GCC front-end.
If you edited header files during the C/C++ front-end build as
described in "Fix 1" above, you must now copy those header files from
(This should be the "include" directory in the same directory as the
libgcc.a library, which you can find by running
Rebuild your CVS tree. This shouldn't cause the whole thing to be rebuilt, but it should build the runtime libraries. After the tree is built, install the runtime libraries into your GCC front-end build tree. These are the commands you need.
% gmake % mkdir $CFEINSTALL/bytecode-libs % gmake -C runtime install-bytecode % setenv LLVM_LIB_SEARCH_PATH $CFEINSTALL/bytecode-libs
Optionally, build a symbol table for the newly installed runtime libraries. Although this step is optional, you are encouraged to do this as the symbol tables will make a significant difference in your link times. Use the llvm-ranlib tool to do this, as follows:
% cd $CFEINSTALL/lib % llvm-ranlib libiberty.a % llvm-ranlib libstdc++.a % llvm-ranlib libsupc++.a % cd $CFEINSTALL/lib/target-triplet/3.4-llvm % llvm-ranlib libgcc.a % llvm-ranlib libgcov.a
Test the newly-installed C frontend by one or more of the following means:
The LLVM GCC frontend is licensed to you under the GNU General Public License and the GNU Lesser General Public License. Please see the files COPYING and COPYING.LIB for more details.
The software also has the following additional copyrights:
Copyright (c) 2003, 2004 University of Illinois at Urbana-Champaign. All rights reserved. Developed by: LLVM Team University of Illinois at Urbana-Champaign http://llvm.cs.uiuc.edu THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE SOFTWARE. Copyright (c) 1994 Hewlett-Packard Company Permission to use, copy, modify, distribute and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation. Hewlett-Packard Company makes no representations about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty. Copyright (c) 1996, 1997, 1998, 1999 Silicon Graphics Computer Systems, Inc. Permission to use, copy, modify, distribute and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation. Silicon Graphics makes no representations about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty.