samedi 23 avril 2016

LLVM / C++

The LLVM compiler system for C and C++ includes the following:
  • Front-ends for C, C++, Objective-C, Fortran, etc based on the GCC 4.2 parsers. They support the ANSI-standard C and C++ languages to the same degree that GCC supports them. Additionally, many GCC extensions are supported.
  • A stable implementation of the LLVM instruction set, which serves as both the online and offline code representation, together with assembly (ASCII) and bytecode (binary) readers and writers, and a verifier.
  • A powerful pass-management system that automatically sequences passes (including analysis, transformation, and code-generation passes) based on their dependences, and pipelines them for efficiency.
  • A wide range of global scalar optimizations.
  • A link-time interprocedural optimization framework with a rich set of analyses and transformations, including sophisticated whole-program pointer analysis, call graph construction, and support for profile-guided optimizations.
  • An easily retargettable code generator, which currently supports X86, X86-64, PowerPC, PowerPC-64, ARM, Thumb, SPARC, Alpha, CellSPU, MIPS, MSP430, SystemZ, and XCore.
  • A Just-In-Time (JIT) code generation system, which currently supports X86, X86-64, ARM, AArch64, Mips, SystemZ, PowerPC, and PowerPC-64.
  • Support for generating DWARF debugging information.
  • A C back-end useful for testing and for generating native code on targets other than the ones listed above.
  • A profiling system similar to gprof.
  • A test framework with a number of benchmark codes and applications.
  • APIs and debugging tools to simplify rapid development of LLVM components.
Strengths of the LLVM System
  1. LLVM uses a simple low-level language with strictly defined semantics.
  2. It includes front-ends for C and C++. Front-ends for Java, Scheme, and other languages are in development.
  3. It includes an aggressive optimizer, including scalar, interprocedural, profile-driven, and some simple loop optimizations.
  4. It supports a life-long compilation model, including link-time, install-time, run-time, and offline optimization.
  5. LLVM has full support for accurate garbage collection.
  6. The LLVM code generator is relatively easy to retarget, and makes use of a powerful target description language.
  7. LLVM has extensive documentation and has hosted many projects of various sorts.
  8. Many third-party users have claimed that LLVM is easy to work with and develop for. For example, the (now removed) Stacker front-end was written in 4 days by someone who started knowing nothing about LLVM. Additionally, LLVM has tools to make development easier.
  9. LLVM is under active development and is constantly being extended, enhanced and improved. See the status updates on the left bar to see the rate of development.
  10. LLVM is freely available under an OSI-approved "three-clause BSD" license.
  11. LLVM is currently used by several commercial entities, who contribute many extensions and new features.
LLVM Audience
LLVM can be used in many different kinds of projects. You might be interested in LLVM if you are:
  • A compiler researcher interested in compile-time, link-time (interprocedural), and runtime transformations for C and C++ programs.
  • A virtual machine researcher/developer interested in a portable, language-independent instruction set and compilation framework.
  • An architecture researcher interested in compiler/hardware techniques.
  • A security researcher interested in static analysis or instrumentation.
  • An instructor or developer interested in a system for quick prototyping of compiler transformations.
  • An end-user who wants to get better performance out of your code.
Want to Know More?
You can browse the documentation online, try LLVM in your web browser, or download the source code.
 
LLVM Debian/Ubuntu nightly packages
Download
The goal is to provide Debian and Ubuntu nightly packages ready to be installed with minimal impact on the distribution.
Packages are available for amd64 and i386 and for both the stable, qualification and development branches (currently 3.7, 3.8 and 3.9).
The packages provide LLVM + Clang + compiler-rt + polly + LLDB
Debian
Jessie (Debian stable) - Last update : Sat, 23 Apr 2016 19:38:36 UTC / Revision: 267277 
deb http://llvm.org/apt/jessie/ llvm-toolchain-jessie main
deb-src http://llvm.org/apt/jessie/ llvm-toolchain-jessie main
# 3.7 
deb http://llvm.org/apt/jessie/ llvm-toolchain-jessie-3.7 main
deb-src http://llvm.org/apt/jessie/ llvm-toolchain-jessie-3.7 main
# 3.8 
deb http://llvm.org/apt/jessie/ llvm-toolchain-jessie-3.8 main
deb-src http://llvm.org/apt/jessie/ llvm-toolchain-jessie-3.8 main
sid (unstable) - Last update : Sat, 23 Apr 2016 03:22:23 UTC / Revision: 267209 
deb http://llvm.org/apt/unstable/ llvm-toolchain main
deb-src http://llvm.org/apt/unstable/ llvm-toolchain main
# 3.7 
deb http://llvm.org/apt/unstable/ llvm-toolchain-3.7 main
deb-src http://llvm.org/apt/unstable/ llvm-toolchain-3.7 main
# 3.8 
deb http://llvm.org/apt/unstable/ llvm-toolchain-3.8 main
deb-src http://llvm.org/apt/unstable/ llvm-toolchain-3.8 main
Ubuntu
gcc backport (ppa) is necessary on Precise (for libstdc++).
Quantal, Raring, Saucy and Utopic are no longer supported by Ubuntu.

Precise (12.04) - Last update : Fri, 22 Apr 2016 15:52:37 UTC / Revision: 267128 
deb http://llvm.org/apt/precise/ llvm-toolchain-precise main
deb-src http://llvm.org/apt/precise/ llvm-toolchain-precise main
# 3.7 
deb http://llvm.org/apt/precise/ llvm-toolchain-precise-3.7 main
deb-src http://llvm.org/apt/precise/ llvm-toolchain-precise-3.7 main
# 3.8 
deb http://llvm.org/apt/precise/ llvm-toolchain-precise-3.8 main
deb-src http://llvm.org/apt/precise/ llvm-toolchain-precise-3.8 main

# Common
deb http://ppa.launchpad.net/ubuntu-toolchain-r/test/ubuntu precise main
Trusty (14.04) - Last update : Thu, 21 Apr 2016 21:08:54 UTC / Revision: 266994 
deb http://llvm.org/apt/trusty/ llvm-toolchain-trusty main
deb-src http://llvm.org/apt/trusty/ llvm-toolchain-trusty main
# 3.7 
deb http://llvm.org/apt/trusty/ llvm-toolchain-trusty-3.7 main
deb-src http://llvm.org/apt/trusty/ llvm-toolchain-trusty-3.7 main
# 3.8 
deb http://llvm.org/apt/trusty/ llvm-toolchain-trusty-3.8 main
deb-src http://llvm.org/apt/trusty/ llvm-toolchain-trusty-3.8 main
Wily (15.10) - Last update : Sat, 23 Apr 2016 11:08:55 UTC / Revision: 267280 
deb http://llvm.org/apt/wily/ llvm-toolchain-wily main
deb-src http://llvm.org/apt/wily/ llvm-toolchain-wily main
# 3.7 
deb http://llvm.org/apt/wily/ llvm-toolchain-wily-3.7 main
deb-src http://llvm.org/apt/wily/ llvm-toolchain-wily-3.7 main
# 3.8 
deb http://llvm.org/apt/wily/ llvm-toolchain-wily-3.8 main
deb-src http://llvm.org/apt/wily/ llvm-toolchain-wily-3.8 main
Xenial (15.10) - Last update : Sat, 23 Apr 2016 20:47:56 UTC / Revision: 267293 
deb http://llvm.org/apt/xenial/ llvm-toolchain-xenial main
deb-src http://llvm.org/apt/xenial/ llvm-toolchain-xenial main
# 3.7
deb http://llvm.org/apt/xenial/ llvm-toolchain-xenial-3.7 main
deb-src http://llvm.org/apt/xenial/ llvm-toolchain-xenial-3.7 main
# 3.8
deb http://llvm.org/apt/xenial/ llvm-toolchain-xenial-3.8 main
deb-src http://llvm.org/apt/xenial/ llvm-toolchain-xenial-3.8 main
Install
(stable branch)
To retrieve the archive signature:
wget -O - http://llvm.org/apt/llvm-snapshot.gpg.key|sudo apt-key add -

To install just clang and lldb (3.7 release):
apt-get install clang-3.7 lldb-3.7

To install all packages:
apt-get install clang-3.7 clang-3.7-doc libclang-common-3.7-dev libclang-3.7-dev libclang1-3.7 libclang1-3.7-dbg libllvm-3.7-ocaml-dev libllvm3.7 libllvm3.7-dbg lldb-3.7 llvm-3.7 llvm-3.7-dev llvm-3.7-doc llvm-3.7-examples llvm-3.7-runtime clang-modernize-3.7 clang-format-3.7 python-clang-3.7 lldb-3.7-dev
Install
(qualification branch)
To retrieve the archive signature:
wget -O - http://llvm.org/apt/llvm-snapshot.gpg.key|sudo apt-key add -

To install just clang and lldb (3.8 release):
apt-get install clang-3.8 lldb-3.8

To install all packages:
apt-get install clang-3.8 clang-3.8-doc libclang-common-3.8-dev libclang-3.8-dev libclang1-3.8 libclang1-3.8-dbg libllvm-3.8-ocaml-dev libllvm3.8 libllvm3.8-dbg lldb-3.8 llvm-3.8 llvm-3.8-dev llvm-3.8-doc llvm-3.8-examples llvm-3.8-runtime clang-modernize-3.8 clang-format-3.8 python-clang-3.8 lldb-3.8-dev liblldb-3.8-dbg
Install
(development branch)
To retrieve the archive signature:
wget -O - http://llvm.org/apt/llvm-snapshot.gpg.key|sudo apt-key add -

To install just clang and lldb (3.9 release):
apt-get install clang-3.9 lldb-3.9

To install all packages:
apt-get install clang-3.9 clang-3.9-doc libclang-common-3.9-dev libclang-3.9-dev libclang1-3.9 libclang1-3.9-dbg libllvm-3.9-ocaml-dev libllvm3.9 libllvm3.9-dbg lldb-3.9 llvm-3.9 llvm-3.9-dev llvm-3.9-doc llvm-3.9-examples llvm-3.9-runtime clang-modernize-3.9 clang-format-3.9 python-clang-3.9 lldb-3.9-dev liblldb-3.9-dbg
Technical aspects
Packages are rebuilt against the trunk of the various LLVM projects.
They are rebuild through a Jenkins instance:
http://llvm-jenkins.debian.net

Bugs

Bugs should be reported on the LLVM bug tracker (deb packages).

Workflow

Twice a day, each jenkins job will checkout the debian/ directory necessary to build the packages. The repository is available on the Debian hosting infrastructure: http://anonscm.debian.org/viewvc/pkg-llvm/llvm-toolchain/branches/. In the llvm-toolchain-*-source, the following tasks will be performed:
  • upstream sources will be checkout
  • tarballs will be created. They are named:
    • llvm-toolchain_X.Y~svn123456.orig-lldb.tar.bz2
    • llvm-toolchain_X.Y~svn123456.orig-compiler-rt.tar.bz2
    • llvm-toolchain_X.Y~svn123456.orig.tar.bz2
    • llvm-toolchain_X.Y~svn123456.orig-clang.tar.bz2
    • llvm-toolchain_X.Y~svn123456.orig-polly.tar.bz2
  • Debian .dsc package description is created
  • Start the jenkins job llvm-toolchain-X-binary
Then, the job llvm-toolchain-X-binary will:
  • Create a chroot using cowbuilder or update it is already existing
  • Build all the packages
  • Launch lintian, the Debian static analyzer
  • Publish the result on the LLVM repository
Note that a few patches are applied over the LLVM tarballs (and should be merged upstream at some point).
Extra
With the Jenkins instance, several reports are produced:

Overview

Warning
If you are using a released version of LLVM, see the download page to find your documentation.
The LLVM compiler infrastructure supports a wide range of projects, from industrial strength compilers to specialized JIT applications to small research projects.
Similarly, documentation is broken down into several high-level groupings targeted at different audiences:

LLVM Design & Overview

Several introductory papers and presentations.
LLVM Language Reference Manual
Defines the LLVM intermediate representation.
Introduction to the LLVM Compiler
Presentation providing a users introduction to LLVM.
Intro to LLVM
Book chapter providing a compiler hacker’s introduction to LLVM.
LLVM: A Compilation Framework for Lifelong Program Analysis & Transformation
Design overview.
LLVM: An Infrastructure for Multi-Stage Optimization
More details (quite old now).
Publications mentioning LLVM

User Guides

For those new to the LLVM system.
NOTE: If you are a user who is only interested in using LLVM-based compilers, you should look into Clang or DragonEgg instead. The documentation here is intended for users who have a need to work with the intermediate LLVM representation.
Getting Started with the LLVM System
Discusses how to get up and running quickly with the LLVM infrastructure. Everything from unpacking and compilation of the distribution to execution of some tools.
Building LLVM with CMake
An addendum to the main Getting Started guide for those using the CMake build system.
How To Build On ARM
Notes on building and testing LLVM/Clang on ARM.
How To Cross-Compile Clang/LLVM using Clang/LLVM
Notes on cross-building and testing LLVM/Clang.
Getting Started with the LLVM System using Microsoft Visual Studio
An addendum to the main Getting Started guide for those using Visual Studio on Windows.
LLVM Tutorial: Table of Contents
Tutorials about using LLVM. Includes a tutorial about making a custom language with LLVM.
LLVM Command Guide
A reference manual for the LLVM command line utilities (“man” pages for LLVM tools).
LLVM’s Analysis and Transform Passes
A list of optimizations and analyses implemented in LLVM.
Frequently Asked Questions (FAQ)
A list of common questions and problems and their solutions.
Release notes for the current release
This describes new features, known bugs, and other limitations.
How to submit an LLVM bug report
Instructions for properly submitting information about any bugs you run into in the LLVM system.
Sphinx Quickstart Template
A template + tutorial for writing new Sphinx documentation. It is meant to be read in source form.
LLVM Testing Infrastructure Guide
A reference manual for using the LLVM testing infrastructure.
How to build the C, C++, ObjC, and ObjC++ front end
Instructions for building the clang front-end from source.
The LLVM Lexicon
Definition of acronyms, terms and concepts used in LLVM.
How To Add Your Build Configuration To LLVM Buildbot Infrastructure
Instructions for adding new builder to LLVM buildbot master.
YAML I/O
A reference guide for using LLVM’s YAML I/O library.
The Often Misunderstood GEP Instruction
Answers to some very frequent questions about LLVM’s most frequently misunderstood instruction.
Performance Tips for Frontend Authors
A collection of tips for frontend authors on how to generate IR which LLVM is able to effectively optimize.

Programming Documentation

For developers of applications which use LLVM as a library.
LLVM Language Reference Manual
Defines the LLVM intermediate representation and the assembly form of the different nodes.
LLVM Atomic Instructions and Concurrency Guide
Information about LLVM’s concurrency model.
LLVM Programmer’s Manual
Introduction to the general layout of the LLVM sourcebase, important classes and APIs, and some tips & tricks.
LLVM Extensions
LLVM-specific extensions to tools and formats LLVM seeks compatibility with.
CommandLine 2.0 Library Manual
Provides information on using the command line parsing library.
LLVM Coding Standards
Details the LLVM coding standards and provides useful information on writing efficient C++ code.
How to set up LLVM-style RTTI for your class hierarchy
How to make isa<>, dyn_cast<>, etc. available for clients of your class hierarchy.
Extending LLVM: Adding instructions, intrinsics, types, etc.
Look here to see how to add instructions and intrinsics to LLVM.
Doxygen generated documentation
(classes) (tarball)
Documentation for Go bindings
ViewVC Repository Browser

Architecture & Platform Information for Compiler Writers
A list of helpful links for compiler writers.
LibFuzzer – a library for coverage-guided fuzz testing.
A library for writing in-process guided fuzzers.

Subsystem Documentation

For API clients and LLVM developers.
Writing an LLVM Pass
Information on how to write LLVM transformations and analyses.
Writing an LLVM Backend
Information on how to write LLVM backends for machine targets.
The LLVM Target-Independent Code Generator
The design and implementation of the LLVM code generator. Useful if you are working on retargetting LLVM to a new architecture, designing a new codegen pass, or enhancing existing components.
Machine IR (MIR) Format Reference Manual
A reference manual for the MIR serialization format, which is used to test LLVM’s code generation passes.
TableGen
Describes the TableGen tool, which is used heavily by the LLVM code generator.
LLVM Alias Analysis Infrastructure
Information on how to write a new alias analysis implementation or how to use existing analyses.
Garbage Collection with LLVM
The interfaces source-language compilers should use for compiling GC’d programs.
Source Level Debugging with LLVM
This document describes the design and philosophy behind the LLVM source-level debugger.
Auto-Vectorization in LLVM
This document describes the current status of vectorization in LLVM.
Exception Handling in LLVM
This document describes the design and implementation of exception handling in LLVM.
LLVM bugpoint tool: design and usage
Automatic bug finder and test-case reducer description and usage information.
LLVM Bitcode File Format
This describes the file format and encoding used for LLVM “bc” files.
System Library
This document describes the LLVM System Library (lib/System) and how to keep LLVM source code portable
LLVM Link Time Optimization: Design and Implementation
This document describes the interface between LLVM intermodular optimizer and the linker and its design
The LLVM gold plugin
How to build your programs with link-time optimization on Linux.
Debugging JIT-ed Code With GDB
How to debug JITed code with GDB.
MCJIT Design and Implementation
Describes the inner workings of MCJIT execution engine.
LLVM Branch Weight Metadata
Provides information about Branch Prediction Information.
LLVM Block Frequency Terminology
Provides information about terminology used in the BlockFrequencyInfo analysis pass.
Segmented Stacks in LLVM
This document describes segmented stacks and how they are used in LLVM.
LLVM’s Optional Rich Disassembly Output
This document describes the optional rich disassembly output syntax.
How To Use Attributes
Answers some questions about the new Attributes infrastructure.
User Guide for NVPTX Back-end
This document describes using the NVPTX back-end to compile GPU kernels.
User Guide for AMDGPU Back-end
This document describes how to use the AMDGPU back-end.
Stack maps and patch points in LLVM
LLVM support for mapping instruction addresses to the location of values and allowing code to be patched.
Using ARM NEON instructions in big endian mode
LLVM’s support for generating NEON instructions on big endian ARM targets is somewhat nonintuitive. This document explains the implementation and rationale.
LLVM Code Coverage Mapping Format
This describes the format and encoding used for LLVM’s code coverage mapping.
Garbage Collection Safepoints in LLVM
This describes a set of experimental extensions for garbage collection support.
MergeFunctions pass, how it works
Describes functions merging optimization.
Design and Usage of the InAlloca Attribute
Description of the inalloca argument attribute.
FaultMaps and implicit checks
LLVM support for folding control flow into faulting machine instructions.
Compiling CUDA C/C++ with LLVM
LLVM support for CUDA.

Development Process Documentation

Information about LLVM’s development process.
LLVM Developer Policy
The LLVM project’s policy towards developers and their contributions.
Creating an LLVM Project
How-to guide and templates for new projects that use the LLVM infrastructure. The templates (directory organization, Makefiles, and test tree) allow the project code to be located outside (or inside) the llvm/ tree, while using LLVM header files and libraries.
LLVMBuild Guide
Describes the LLVMBuild organization and files used by LLVM to specify component descriptions.
How To Release LLVM To The Public
This is a guide to preparing LLVM releases. Most developers can ignore it.
How To Validate a New Release
This is a guide to validate a new release, during the release process. Most developers can ignore it.
Advice on Packaging LLVM
Advice on packaging LLVM into a distribution.
Code Reviews with Phabricator
Describes how to use the Phabricator code review tool hosted on http://reviews.llvm.org/ and its command line interface, Arcanist.

Community

LLVM has a thriving community of friendly and helpful developers. The two primary communication mechanisms in the LLVM community are mailing lists and IRC.

Mailing Lists

If you can’t find what you need in these docs, try consulting the mailing lists.
Developer’s List (llvm-dev)
This list is for people who want to be included in technical discussions of LLVM. People post to this list when they have questions about writing code for or using the LLVM tools. It is relatively low volume.
Commits Archive (llvm-commits)
This list contains all commit messages that are made when LLVM developers commit code changes to the repository. It also serves as a forum for patch review (i.e. send patches here). It is useful for those who want to stay on the bleeding edge of LLVM development. This list is very high volume.
Bugs & Patches Archive (llvm-bugs)
This list gets emailed every time a bug is opened and closed. It is higher volume than the LLVM-dev list.
Test Results Archive (llvm-testresults)
A message is automatically sent to this list by every active nightly tester when it completes. As such, this list gets email several times each day, making it a high volume list.
LLVM Announcements List (llvm-announce)
This is a low volume list that provides important announcements regarding LLVM. It gets email about once a month.

IRC

Users and developers of the LLVM project (including subprojects such as Clang) can be found in #llvm on irc.oftc.net.
This channel has several bots.
  • Buildbot reporters
  • robot - Bugzilla linker. %bug <number>
  • clang-bot - A geordi instance running near-trunk clang instead of gcc.

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