LLVM 1.9 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 1.9. Here we describe the status of LLVM, including any known problems and major improvements from the previous release. The most up-to-date version of this document (corresponding to LLVM CVS) can be found on the LLVM releases web site. If you are not reading this on the LLVM web pages, you should probably go there because this document may be updated after the release.

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 tenth public release of the LLVM Compiler Infrastructure. This release incorporates a large number of enhancements, new features, and bug fixes. We recommend that all users of previous LLVM versions upgrade.

New Features in LLVM 1.9
New X86-64 Backend

LLVM 1.9 now fully supports the x86-64 instruction set on Mac OS/X, and supports it on Linux (and other operating systems) when compiling in -static mode. LLVM includes JIT support for X86-64, and supports both Intel EMT-64T and AMD-64 architectures. The X86-64 instruction set permits addressing a 64-bit addressing space and provides the compiler with twice the number of integer registers to use.

Link-Time Optimization integration with native linkers

LLVM now includes liblto which can be used to integrate LLVM Link-Time Optimization support into a native linker. This allows LLVM .bc to transparently participate with linking an application, even when some .o files are in LLVM form and some are not.

DWARF debugging support for Linux, Cygwin and MinGW on X86

llvm-gcc4 now supports generating debugging info for Linux, Cygwin and MinGW. This extends the PPC/Darwin and X86/Darwin debugging support available in the 1.8 release. DWARF is a standard debugging format used on many platforms.

Optimizer Improvements

The mid-level optimizer is now faster and produces better code in many cases. Significant changes include:

Code Generator Enhancements

The LLVM Target-Independent code generator now supports more target features and optimizes many cases more aggressively. New features include:

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

Further, several significant target-specific enhancements are included in LLVM 1.9:

Other Improvements

This release includes many other improvements, including improvements to the optimizers and code generators (improving the generated code) changes to speed up the compiler in many ways (improving algorithms and fine tuning code), and changes to reduce the code size of the compiler itself.

More specific changes include:

Significant API Changes in LLVM 1.9

Several significant API changes have been made. If you are maintaining out-of-tree code, please be aware that:

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 SPARC back-end
Known problems with the C back-end
Known problems with the Alpha back-end
Known problems with the IA64 back-end
Known problems with the ARM back-end
Known problems with the LLVM Core
Known problems with the C front-end

llvm-gcc4 is far more stable and produces better code than llvm-gcc3, but does not currently support Link-Time Optimization or C++ Exception Handling, which llvm-gcc3 does.

llvm-gcc4 does not support the GCC indirect goto extension, but llvm-gcc3 does.


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

For this release, the C++ front-end is considered to be fully tested and works for a number of non-trivial programs, including LLVM itself.

Additional Information

A wide variety of additional information is available on the LLVM web page, including documentation and publications describing algorithms and components implemented in LLVM. 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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