HLVM Developer's Guide

CAUTION: This document is a work in progress.
  1. Introduction
  2. Contributions
    1. Copyright
    2. License
    3. Patches
  3. Build System
    1. About SCONS
    2. Configuring
    3. Build Rules
    4. Sane Build Environment
  4. Coding Style
  5. Appendices
    1. Lesser General Public License

Author: Reid Spencer.

Introduction

This document is a manual for developers who wish to contribute to the HLVM project. It covers topics such as copyright assignment, license, coding style, the build system and project rules.

Contributions

Contributions to the HLVM source base are very much appreciated. If you are able to contribute source code, this section provides details about how your contributions will be handled.

Copyright

The founders of the HLVM project intend for a formal non-profit legal entity to be incorporated that will hold the copyright of all HLVM software. This legal entity has not yet been incorporated. When there is sufficient software to warrant the incorporation, the founders of the project will form the corporation and at that time all software contributed to the project will become the property of that corporation.

By contributing software to the HLVM project, you agree to the following terms:

  • Before incorporation, you may retain copyright for any file you initially contribute or develop.
  • After incorporation, you agree to transfer copyright of any files you have contributed or developed into the name of the corporation formed.
  • You agree that both before and after incorporation that all your contributions may be distributed under the terms of the Lesser General Public License (LGPL).

License

It is the intention of the HLVM project to release the HLVM software for distribution under the terms of the Lesser General Public License (LGPL). This license was chosen by the founds for the following reasons:

  • The LGPL is well understood by the Open Source community.
  • Unlike the GPL, the LGPL does not prevent unmodified releases of HLVM from being incorporated into commercial and proprietary products. The founders wish to encourage HLVM's use both in open source and proprietary projects.
  • The LGPL protects the contributors by ensuring that distributions of HLVM retain copyright and the LGPL license for any modifications to HLVM.
  • The LGPL ensures that modifications to HLVM will be distributed in source form so that they can be available for incorporation back into the main project.

See below for the complete text of the LGPL license

Patches

The HLVM group welcomes your patches. If you find something wrong with the HLVM software or you wish to make a contribution to extend HLVM, you may send your patches to hlvm-dev@hlvm.org. To make things easier for everyone, please follow these guidelines when submitting patches:

  • Patches should be attached to your email, not placed inline
  • Patches should be generated by svn diff from the SVN HEAD.
  • Your patch may not be applied for one or more of the following reasons:
    • Coding style requirements were not met.
    • There were technical errors in the patch
    • The patch is not relevant to HLVM's purpose/goal/target.
    If your patch is not accepted, we will tell you why in a private response email.
  • If you are making significant contributions, you may ask for write access to the SVN repository. Permission to update the repository directly will be granted on a case-by-case basis.

Build System

This section describes the HLVM build system.

About SCONS

The HLVM project uses the scons software construction tool to orchestrate its builds. This gives us superior dependency checking and a much more flexible tool for developing the build system. We started with "make" but were convinced of SCons superiority after trying it for a week. If you're not familiar with it, please read up on it and get a general understanding. You don't need detailed understanding because all you will most likely need to do is follow the instructions in this section.

Configuring

Configuration On Every Build

Unlike some other build systems (e.g. autoconf/automake), the configuration and construction phases of building are not separated with scons. The configuration parameters are checked every time you build. While you might think that will slow things down, it doesn't. The configuration information is cached and proceeds quite quickly once your configuration is stable. If something changes in your environment, only those pieces affected will get re-configured. This saves a lot of time and hassle by telling you of any configuration errors on the very next build.

The Options Cache

Configuration parameters are specified on the scons command line. The values of these parameters are stored in the options cache which is simply a file named .options_cache in the root source directory. If the file doesn't exist, it will be created the first time you run scons. On subsequent runs, the values are loaded from this cache and used unless new values are given on the command line. In this way, you only need to specify your options once and then they "stick" from that point forward.

Configuration Options

HLVM has a variety of options to assist with configuring HLVM for your environment and build choices. Each option has a default that will work in many environments but might need adjusting for your environment. The default assumes various software packages are in /usr/local and that a fully debuggable version of HLVM should be built. The table below provides the full list of options.

OptionDescriptionDefault
assertions Include assertions in the code. This can be enabled or disabled separate from the setting for debug. 1
debug Build with debug options turned on. This includes #ifdef/#endif code as well as instructing the compiler to include debug information (-g) 1
inline Cause inline code to be inline. This causes inline functions to really be inline. Its off by default for better debuggability.0
optimize Build object files with optimization. This turns on compiler optimization (-O3) to make the code efficient.0
profile Generate profiling aware code. This causes the compiler to construct the code so that it can be profiled (-pg on Unix).0
small Generate smaller code rather than faster. Instructs the code to favor smaller object files and executables than faster ones. Might be useful for memory constrained platforms. 0
strip Strip executables of their symbols. This can significantly reduce the size of the executable. Useful for release preparation when trying to minimize the size of a tarball or RPM package. 0
prefix Specify where to install HLVM. This is the root directory of where HLVM will be installed when you run scons install /usr/local
confpath Specify additional configuration dirs to search. This is a unix style path (colon separate) of directories to include in the search for software packages. These directories will be searched first. If you put your software in a non-standard place like /proj (Reid) or /more (Saem) then you'll want to use this option. {empty}
with_llvm Specify where LLVM is installed. /usr/local
with_apr Specify where apr is installed. /usr/local/apr
with_apru Specify where apr-utils is installed. /usr/local/apr
with_libxml2 Specify where LibXml2 is installed. /usr/local
with_gperf Specify where the gperf program is installed. /usr/local/bin/gperf
with_llc Specify where the LLVM compiler is installed. /usr/local/bin/llc
with_llvmdis Specify where the LLVM disassembler is installed. /usr/local/bin/llvm-dis
with_llvmas Specify where the LLVM assembler is installed. /usr/local/bin/llvm-as
with_llvmgcc Specify where the LLVM C compiler is installed. /usr/local/bin/llvm-gcc
with_llvmgxx Specify where the LLVM C++ compiler is installed. /usr/local/bin/llvm-g++
with_llvmar Specify where the LLVM bytecode archiver is installed. /usr/local/bin/llvm-g++
with_llvm2cpp Specify where the LLVM llvm2cpp program is installed. /usr/local/bin/llvm2cpp
with_runtest Specify where DejaGnu runtest program is installed. /usr/local/bin/runtest
with_doxygen Specify where the doxygen program is installed. /usr/local/bin/doxygen
with_xsltproc Specify where the XSLT processor is installed. /usr/local/bin/xsltproc

Configuration Prompts

When you first run scons against HLVM, if you did not specify the confpath option or the configuration code cannot otherwise find a package it needs, you will be prompted to enter the applicable path names manually. You only need to do this once as the values you enter will be remembered in the .options_cache file. These prompts will repeat until you enter a path in which the package is properly recognized. If you wish to abort this, just enter exit or quit at any prompt.

Build Rules

This subsection describes the various build rules and extensions to SCons that HLVM uses.

The build python module

For convenience, and to unclutter the SConscript files, the top level build directory contains a python module that provides the build facilities for HLVM. This module manipulates an SCons environment to set the variables and define the builder rules for HLVM. The public interface to this library is in the hlvm.py module. No other module should be imported into the SConscript files.

HLVM Builder Rules

HLVM requires some specialized build rules beyond what SCons provides. While general construction of static libraries, shared libraries, and executables use the standard SCons builders, several more are defined in the build python module. The table below describes the HLVM specific builders.

BuilderSourceTargetDescription
RNGTokenizer Relax/NG Schema (.rng) *Tokenizer.h, *Tokenizer.cpp, *TokenHash.cpp This builder scans a Relax/NG Schema for element, attribute, and enumerated value names. It then uses these tokens to build a perfect hash function (via gperf) for quickly recognizing the tokens and converting it to an enumeration value. This is provided to make recognizing the element and attributes names of an XML document faster.
RNGQuoteSource Relax/NG Schema (.rng) C++ Strings For Inclusion (.inc) This builder converts a Relax/NG schema into a set of strings that can be #included into a C++ program as a literal string. It strips out comments, annotations, and converts special characters into the C++ equivalent. The purpose here is to allow a single source for the schema to be incorporated directly into the software so that no file I/O is necessaroy to access the schema.
Bytecode C++ Source (.cpp) LLVM Bytecode (.bc) This builder compiles a C++ source file and produces an equivalent LLVM bytecode file. This allows us to incorporate C++ source into the Runtime as linkable bytecode.
BytecodeArchive LLVM Bytecode (.bc) LLVM Bytecode Archive (.bca) This builder collects a group of LLVM Bytecode files together and creates a bytecode archive from them using llvm-ar
Cpp2LLVMCpp C++ Source (.cxx) C++ Source (.cpp) This builder uses the llvm2cpp to turn source C++ into equivalent C++ calls against the LLVM Intermediate Representation (IR) to construct the same program or program fragment. The construction environment variable LLVM2CPPFLAGS can be set to control what options are passed to llvm2cpp. See the llvm2cpp manual page for details. Examples are in the hlvm/CodeGen/SConscript file.
Check n/a n/a This builder is a little special. It is used to run the DejaGnu test suite. It is aliased on the command line as the target "check" so that the scons check command will invoke this build.
Doxygen n/a doxygen.tar.gz This builder runs the doxygen documentation generator on the source code and builds a gzipped tar file containing doxygen's output. This allows the HLVM API documentation, generated from source code comments, to be packged into a single file.

A Sane Build Environment

Building HLVM is no small feat. It depends on a lot of software that is quite version dependent. To bring a little sanity to the process, here is a step-by-step procedure we know to work.

Build Separation

In building HLVM, you'll be installing compilers and library that may already exist on your system. You don't want to overwrite your system versions of these things or it will wreak havoc on your system. So, we suggest that you start with a fresh directory. In the discussion that follows, we'll call it /proj (that's what Reid uses). But, it could be anything you want, as long as its new. ~/hlvm would work just as well.

IMPORTANT: Choosing the disk location for these builds should not be taken lightly. You will need upwards of 40GB of storage on a 32-bit machine to build all this software. Don't assume your home directory has enough space!

Once you've found a suitable location for HLVM, create the following directory structure:

  cd /proj
  mkdir gcc llvm llvm-gcc4 libxml2 apr apru hlvm gperf scons install

In the following sections you will build each of these packages and install them into /proj/install which will keep it separate from anything else in your system.

Build GCC 3.4.6

First, start with obtaining GCC 3.4.6. This will be the compiler that you use for all the remaining compilations. Use the following commands to obtain, build and install GCC 3.4.6:

  cd /proj/gcc
  mkdir build
  svn co svn://gcc.gnu.org/svn/gcc/tags/gcc_3_4_6_release src
  cd ../build
  ../src/configure  --prefix=/proj/install
  make 
  make install

Set Environment

Now that you have gcc installed in a separate location, you will need to change your environment to ensure that that version of gcc is the one used in subsequent builds. Details vary from platform to platform, but on Linux, the following should work:

  export PATH=/proj/install/bin:$PATH
  export LD_LIBRARY_PATH=/proj/install/lib:$LD_LIBRARY_PATH

The essential point is to change your environment so that programs and libraries installed into /proj/install will be found first. You should do this in any shell environment in which you'll be building HLVM related software.

Build gperf

This package is used for generating perfect hash functions. It is used by HLVM for fast recognition of XML element and attribute names. Its easy and fast to build:

  cd /proj/gperf
  wget http://mirrors.kernel.org/gnu/gperf/gperf-2.7.2.tar.gz
  tar zxf gperf-2.7.2.tar.gz
  mkdir build
  cd build
  ../gperf-2.7.2/configure --prefix=/proj/install
  make
  make install

You can probably use any version after 2.7. We know it works with 2.7.2 and 3.0.1.

Build libxml2

This package provides all XML services for HLVM. It is part of GNome and many other packages and quite stable. It should build quickly and easily for you. Use these commands:

  cd /proj/libxml2
  wget ftp://xmlsoft.org/libxml2/libxml2-2.6.24.tar.gz
  tar zxf libxml2-2.6.24.tar.gz
  mkdir build
  cd build
  ../libxml2-2.6.24/configure --prefix=/proj/install
  make
  make install

Build apr

The Apache Portable Runtime is a portability layer used within the Apache HTTP Server. Although it is still undergoing active development, stable releases are available. HLVM uses APR for portability in the runtime. Build APR with the following commands:

  cd /proj/apr
  wget http://mirror.olnevhost.net/pub/apache/apr/apr-1.2.7.tar.gz
  tar zxf apr-1.2.7.tar.gz
  mkdir build
  cd apr-1.2.7
  ./buildconf
  cd ../build
  ../apr-1.2.7/configure --prefix=/proj/install --enable-debug \
    --enable-threads --enable-other-child
  make
  make install

Build apr-util

The apr-util package is some additional utilities that go with APR. Build apr-util with the following commands:

  cd /proj/apru
  wget http://mirror.olnevhost.net/pub/apache/apr/apr-util-1.2.7.tar.gz
  tar zxf apr-1.2.7.tar.gz
  mkdir build
  cd apr-util-1.2.7
  ./buildconf
  cd ../build
  ../apr-util-1.2.7/configure --prefix=/proj/install --enable-debug \
    --enable-threads --enable-other-child
  make
  make install

Build LLVM

For now, you must build LLVM from the CVS repository. Although LLVM is actively being developed, it is generally stable and this is safe. If you get tempted to use a release tarball, it will fail. HLVM depends on post-1.7 features of LLVM. When you build LLVM, use the "tools-only" target. This will avoid building the "runtime" portion of LLVM which was necessary for an older version of llvm-gcc (v3). Since we'll be using llvm-gcc4, this is unnecessary and will eliminate some chicken-and-egg type problems.

  cd /proj/llvm
  cvs -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm login
  <return>
  cvs -z3 -d :pserver:anon@llvm-cvs.cs.uiuc.edu:/var/cvs/llvm co llvm
  mkdir build
  cd build
  ../llvm/configure --prefix=/proj/install
  make tools-only
  make install
  make ENABLE_OPTIMIZED=1 OPTIMIZE_OPTION=-O2 tools-only

Build llvm-gcc4

Apple provides a Subversion repository for llvm-gcc4. You need this latest version because HLVM depends on some of the features. You might find this one a bit tricky. See the README.LLVM file in the top source directory for additional help and late breaking news.

  cd /proj/llvm-gcc4
  svn co svn://anonsvn.opensource.apple.com/svn/llvm cfe
  mkdir build install
  cd build
  ../cfe/configure --prefix=/proj/llvm-gcc4/cfe/install \
    --enable-llvm=/proj/llvm/build --enable-languages=c,c++ --disable-threads \
    --program-prefix=llvm-
  make
  make install

Note that the --disable-threads option is a temporary workaround until LLVM's PR822 (supporting weak-external linkage) is implemented. This should be fixed by September, 2006 at which time --disable-threads won't be needed any more.

IMPORTANT: You MUST install llvm-gcc4 into its own installation area. Do NOT be tempted to install it into /proj/install. If you do, it will overwrite your gcc 3.4.6 installation and you will have corrupted your build environment. You've been warned.

Install SCons

As noted earlier, HLVM uses the SCons tool for its builds. You need version 0.96.92. Install it like this:

  cd /proj/scons
  wget http://internap.dl.sourceforge.net/sourceforge/scons/scons-0.96.92.tar.gz
  tar zxf scons-0.96.92.tar.gz
  python config.py install

Alternatively, you could use one of the SCons packages, such as:

  cd /proj/scons
  wget http://internap.dl.sourceforge.net/sourceforge/scons/scons-0.96.92-1.noarch.rpm
  rpm --install scons-0.96.92-1.noarch.rpm

Build HLVM

Note in the following that if you've actually used /proj as your build area then you don't need to provide any arguments to make as these paths are the default. Also note that the arguments are only needed the first time you build HLVM. Subsequently, these options will be remembered. See the description of SCons above.

  cd /proj/hlvm
  svn co svn://hlvm.org/hlvm hlvm
  cd hlvm
  make debug MYMODE=Debug MYPREFIX=/proj/install MYPATH=/proj/install \
    MYLLVMGCC=/proj/llvm/cfe/install/bin

Coding Style

Contributions to HLVM must meet the following Coding Style requirements:

  • Each file must start with the comment section common to other files in HLVM. This comment section starts with a line describing the file, followed by the HLVM title line, a copyright line, and the LGPL license text.
  • Source code that is to be part of an HLVM library or executable must be written in C++. We know this isn't the greatest language in the world, but it is the most compatible for meeting HLVM's integration and platform support requirements.
  • Utility programs should be written in python, especially if they are build related.
  • Files must not exceed 80 columns in width
  • Indentation is 2 spaces (no tabs).
  • Doxygen documentation must be provided in header files.

Appendices

 

Lesser General Public License

		  GNU LESSER GENERAL PUBLIC LICENSE
		       Version 2.1, February 1999

 Copyright (C) 1991, 1999 Free Software Foundation, Inc.
 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.

[This is the first released version of the Lesser GPL.  It also counts
 as the successor of the GNU Library Public License, version 2, hence
 the version number 2.1.]

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           How to Apply These Terms to Your New Libraries

  If you develop a new library, and you want it to be of the greatest
possible use to the public, we recommend making it free software that
everyone can redistribute and change.  You can do so by permitting
redistribution under these terms (or, alternatively, under the terms of the
ordinary General Public License).

  To apply these terms, attach the following notices to the library.  It is
safest to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least the
"copyright" line and a pointer to where the full notice is found.

    {one line to give the library's name and a brief idea of what it does.}
    Copyright (C) {year}  {name of author}

    This library is free software; you can redistribute it and/or
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    This library is distributed in the hope that it will be useful,
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Also add information on how to contact you by electronic and paper mail.

You should also get your employer (if you work as a programmer) or your
school, if any, to sign a "copyright disclaimer" for the library, if
necessary.  Here is a sample; alter the names:

  Yoyodyne, Inc., hereby disclaims all copyright interest in the
  library `Frob' (a library for tweaking knobs) written by James Random Hacker.

  {signature of Ty Coon}, 1 April 1990
  Ty Coon, President of Vice

That's all there is to it!