LLVM 2.1 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 2.1. 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 twelfth public release of the LLVM Compiler Infrastructure. It includes many features and refinements from LLVM 2.0.

New Frontends

LLVM 2.1 brings two new beta C front-ends. First, a new version of llvm-gcc based on GCC 4.2, innovatively called "llvm-gcc-4.2". This promises to bring FORTRAN and Ada support to LLVM as well as features like atomic builtins and OpenMP. None of these actually work yet, but don't let that stop you checking it out!

Second, LLVM now includes its own native C and Objective-C front-end (C++ is in progress, but is not very far along) code named "clang". This front-end has a number of great features, primarily aimed at source-level analysis and speeding up compile-time. At this point though, the LLVM Code Generator component is still very early in development, so it's mostly useful for people looking to build source-level analysis tools or source-to-source translators.

Optimizer Improvements

Some of the most noticable feature improvements this release have been in the optimizer, speeding it up and making it more aggressive. For example:

Code Generator Improvements

One of the main focuses of this release was performance tuning and bug fixing. In addition to these, several new major changes occurred:

Target Specific Improvements

New features include:

llvm-gcc Improvements

New features include:

LLVM Core Improvements

New 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-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 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: 2007/09/27 05:55:55 $