LLVM 2.0 Release Notes
  1. Introduction
  2. What's New?
  3. Installation Instructions
  4. Portability and Supported Platforms
  5. Known Problems
  6. Additional Information

Written by the LLVM Team


This document contains the release notes for the LLVM compiler infrastructure, release 2.0. Here we describe the status of LLVM, including major improvements from the previous release and any known problems. All LLVM releases may be downloaded from the LLVM releases web site.

For more information about LLVM, including information about the latest release, please check out the main LLVM web site. If you have questions or comments, the LLVM developer's mailing list is a good place to send them.

Note that if you are reading this file from CVS or the main LLVM web page, this document applies to the next release, not the current one. To see the release notes for the current or previous releases, see the releases page.

What's New?

This is the eleventh public release of the LLVM Compiler Infrastructure. Being the first major release since 1.0, this release is different in several ways from our previous releases:

  1. We took this as an opportunity to break backwards compatibility with the LLVM 1.x bytecode and .ll file format. If you have LLVM 1.9 .ll files that you would like to upgrade to LLVM 2.x, we recommend the use of the stand alone llvm-upgrade tool (which is included with 2.0). We intend to keep compatibility with .ll and .bc formats within the 2.x release series, like we did within the 1.x series.
  2. There are several significant change to the LLVM IR and internal APIs, such as a major overhaul of the type system, the completely new bitcode file format, etc (described below).
  3. We designed the release around a 6 month release cycle instead of the usual 3-month cycle. This gave us extra time to develop and test some of the more invasive features in this release.
  4. LLVM 2.0 no longer supports the llvm-gcc3 front-end. Users are required to upgrade to llvm-gcc4. llvm-gcc4 includes many features over llvm-gcc3, is faster, and is much easier to build from source.

Note that while this is a major version bump, this release has been extensively tested on a wide range of software. It is easy to say that this is our best release yet, in terms of both features and correctness. This is the first LLVM release to correctly compile and optimize major software like LLVM itself, Mozilla/Seamonkey, Qt 4.3rc1, kOffice, etc out of the box on linux/x86.

New Features in LLVM 2.0
Major Changes

Changes to the LLVM IR itself:

Major new features:

llvm-gcc Improvements

New features include:

Optimizer Improvements

New features include:

Code Generator Enhancements

New features include:

Other improvements include:

In addition, the LLVM target description format has itself been extended in several ways:

Target-Specific Improvements

X86-specific Code Generator Enhancements:

ARM-specific Code Generator Enhancements:

PowerPC-specific Code Generator Enhancements:

Other Improvements

More specific changes include:

API Changes

LLVM 2.0 contains a revamp of the type system and several other significant internal changes. If you are programming to the C++ API, be aware of the following major changes:

Portability and Supported Platforms

LLVM is known to work on the following platforms:

The core LLVM infrastructure uses GNU autoconf to adapt itself to the machine and operating system on which it is built. However, minor porting may be required to get LLVM to work on new platforms. We welcome your portability patches and reports of successful builds or error messages.

Known Problems

This section contains all known problems with the LLVM system, listed by component. As new problems are discovered, they will be added to these sections. If you run into a problem, please check the LLVM bug database and submit a bug if there isn't already one.

Experimental features included with this release

The following components of this LLVM release are either untested, known to be broken or unreliable, or are in early development. These components should not be relied on, and bugs should not be filed against them, but they may be useful to some people. In particular, if you would like to work on one of these components, please contact us on the LLVMdev list.

Known problems with the X86 back-end
Known problems with the PowerPC back-end
Known problems with the ARM back-end
Known problems with the SPARC back-end
Known problems with the Alpha back-end
Known problems with the IA64 back-end
Known problems with the C back-end
Known problems with the C front-end

llvm-gcc4 does not currently support Link-Time Optimization on most platforms "out-of-the-box". Please inquire on the llvmdev mailing list if you are interested.


If you run into GCC extensions which have not been included in any of these lists, please let us know (also including whether or not they work).

Known problems with the C++ front-end

The C++ front-end is considered to be fully tested and works for a number of non-trivial programs, including LLVM itself, Qt, Mozilla, etc.

Additional Information

A wide variety of additional information is available on the LLVM web page, in particular in the documentation section. The web page also contains versions of the API documentation which is up-to-date with the CVS version of the source code. You can access versions of these documents specific to this release by going into the "llvm/doc/" directory in the LLVM tree.

If you have any questions or comments about LLVM, please feel free to contact us via the mailing lists.

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Last modified: $Date: 2007/05/23 18:10:20 $