LLVM 2.2 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 2.2. 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 a Subversion checkout or the main LLVM web page, this document applies to the next release, not the current one. To see the release notes for a specific releases, please see the releases page.

What's New?

This is the thirteenth public release of the LLVM Compiler Infrastructure. It includes many features and refinements from LLVM 2.1.

Deprecated features in LLVM 2.2

This is the last LLVM release to support llvm-gcc 4.0, llvm-upgrade, and llvmc in its current form. llvm-gcc 4.0 has been replaced with llvm-gcc 4.2. llvm-upgrade is useful for upgrading llvm 1.9 files to llvm 2.x syntax, but you can always use an old release to do this. llvmc is currently mostly useless in llvm 2.2, and will be redesigned or removed in llvm 2.3.

llvm-gcc 4.0, llvm-gcc 4.2, and clang

LLVM 2.2 fully supports both the llvm-gcc 4.0 and llvm-gcc 4.2 front-ends (in LLVM 2.1, llvm-gcc 4.2 was beta). Since LLVM 2.1, the llvm-gcc 4.2 front-end has made leaps and bounds and is now at least as good as 4.0 in virtually every area, and is better in several areas (for example, exception handling correctness, support for Ada and Fortran, better ABI compatibility, etc). We strongly recommend that you migrate from llvm-gcc 4.0 to llvm-gcc 4.2 in this release cycle because LLVM 2.2 is the last release that will support llvm-gcc 4.0: LLVM 2.3 will only support the llvm-gcc 4.2 front-end.

The clang project is an effort to build a set of new 'llvm native' front-end technologies for the LLVM optimizer and code generator. Currently, its C and Objective-C support is maturing nicely, and it has advanced source-to-source analysis and transformation capabilities. If you are interested in building source-level tools for C and Objective-C (and eventually C++), you should take a look. However, note that clang is not an official part of the LLVM 2.2 release. If you are interested in this project, please see its web site.

Major New Features

LLVM 2.2 includes several major new capabilities:

LLVM Core Improvements

New features include:

Code Generator Improvements

We put a significant amount of work into the code generator infrastructure, which allows us to implement more aggressive algorithms and make it run faster:

Optimizer Improvements

In addition to a huge array of bug fixes and minor performance tweaks, the LLVM 2.2 optimizers support a few major enhancements:

Target Specific Improvements

New target-specific features include:

Other Improvements

New features include:

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-gcc 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.

Known problems with the Ada front-end
The llvm-gcc 4.2 Ada compiler works fairly well, however this is not a mature technology and problems should be expected.
Known problems with the Fortran front-end
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 Subversion 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: 2008/02/15 19:06:44 $