These are in-progress notes for the upcoming LLVM 3.3 release. You may prefer the LLVM 3.2 Release Notes.
This document contains the release notes for the LLVM Compiler Infrastructure, release 3.3. Here we describe the status of LLVM, including major improvements from the previous release, improvements in various subprojects of LLVM, and some of the current users of the code. 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 release, please see the releases page.
We’ve added support for AArch64, ARM’s 64-bit architecture. Development is still in fairly early stages, but we expect successful compilation when:
Some additional functionality is also implemented, notably DWARF debugging, GNU-style thread local storage and inline assembly.
We’ve continued the work on the loop vectorizer. The loop vectorizer now has the following features:
The loop vectorizer is now enabled by default for -O3.
LLVM now has a new SLP vectorizer. The new SLP vectorizer is not enabled by default but can be enabled using the clang flag -fslp-vectorize. The BB-vectorizer can also be enabled using the command line flag -fslp-vectorize-aggressive.
The R600 backend was added in this release, it supports AMD GPUs (HD2XXX - HD7XXX). This backend is used in AMD’s Open Source graphics / compute drivers which are developed as part of the Mesa3D project.
An exciting aspect of LLVM is that it is used as an enabling technology for a lot of other language and tools projects. This section lists some of the projects that have already been updated to work with LLVM 3.3.
In addition to producing an easily portable open source OpenCL implementation, another major goal of pocl is improving performance portability of OpenCL programs with compiler optimizations, reducing the need for target-dependent manual optimizations. An important part of pocl is a set of LLVM passes used to statically parallelize multiple work-items with the kernel compiler, even in the presence of work-group barriers. This enables static parallelization of the fine-grained static concurrency in the work groups in multiple ways.
TCE is a toolset for designing new processors based on the Transport triggered architecture (TTA). The toolset provides a complete co-design flow from C/C++ programs down to synthesizable VHDL/Verilog and parallel program binaries. Processor customization points include the register files, function units, supported operations, and the interconnection network.
TCE uses Clang and LLVM for C/C++/OpenCL C language support, target independent optimizations and also for parts of code generation. It generates new LLVM-based code generators “on the fly” for the designed TTA processors and loads them in to the compiler backend as runtime libraries to avoid per-target recompilation of larger parts of the compiler chain.
Jade (Just-in-time Adaptive Decoder Engine) is a generic video decoder engine using LLVM for just-in-time compilation of video decoder configurations. Those configurations are designed by MPEG Reconfigurable Video Coding (RVC) committee. MPEG RVC standard is built on a stream-based dataflow representation of decoders. It is composed of a standard library of coding tools written in RVC-CAL language and a dataflow configuration — block diagram — of a decoder.
Jade project is hosted as part of the Open RVC-CAL Compiler (Orcc) and requires it to translate the RVC-CAL standard library of video coding tools into an LLVM assembly code.
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/docs/ directory in the LLVM tree.
If you have any questions or comments about LLVM, please feel free to contact us via the mailing lists.