forked from OSchip/llvm-project
194 lines
7.6 KiB
ReStructuredText
194 lines
7.6 KiB
ReStructuredText
======================
|
|
LLVM 3.3 Release Notes
|
|
======================
|
|
|
|
.. contents::
|
|
:local:
|
|
|
|
.. warning::
|
|
These are in-progress notes for the upcoming LLVM 3.3 release. You may
|
|
prefer the `LLVM 3.2 Release Notes <http://llvm.org/releases/3.2/docs
|
|
/ReleaseNotes.html>`_.
|
|
|
|
|
|
Introduction
|
|
============
|
|
|
|
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 <http://llvm.org/releases/>`_.
|
|
|
|
For more information about LLVM, including information about the latest
|
|
release, please check out the `main LLVM web site <http://llvm.org/>`_. If you
|
|
have questions or comments, the `LLVM Developer's Mailing List
|
|
<http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev>`_ 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 <http://llvm.org/releases/>`_.
|
|
|
|
Non-comprehensive list of changes in this release
|
|
=================================================
|
|
|
|
.. NOTE
|
|
For small 1-3 sentence descriptions, just add an entry at the end of
|
|
this list. If your description won't fit comfortably in one bullet
|
|
point (e.g. maybe you would like to give an example of the
|
|
functionality, or simply have a lot to talk about), see the `NOTE` below
|
|
for adding a new subsection.
|
|
|
|
* The CellSPU port has been removed. It can still be found in older versions.
|
|
|
|
* The IR-level extended linker APIs (for example, to link bitcode files out of
|
|
archives) have been removed. Any existing clients of these features should
|
|
move to using a linker with integrated LTO support.
|
|
|
|
* LLVM and Clang's documentation has been migrated to the `Sphinx
|
|
<http://sphinx-doc.org/>`_ documentation generation system which uses
|
|
easy-to-write reStructuredText. See `llvm/docs/README.txt` for more
|
|
information.
|
|
|
|
* TargetTransformInfo (TTI) is a new interface that can be used by IR-level
|
|
passes to obtain target-specific information, such as the costs of
|
|
instructions. Only "Lowering" passes such as LSR and the vectorizer are
|
|
allowed to use the TTI infrastructure.
|
|
|
|
* We've improved the X86 and ARM cost model.
|
|
|
|
* The Attributes classes have been completely rewritten and expanded. They now
|
|
support not only enumerated attributes and alignments, but "string"
|
|
attributes, which are useful for passing information to code generation. See
|
|
:doc:`HowToUseAttributes` for more details.
|
|
|
|
* TableGen's syntax for instruction selection patterns has been simplified.
|
|
Instead of specifying types indirectly with register classes, you should now
|
|
specify types directly in the input patterns. See ``SparcInstrInfo.td`` for
|
|
examples of the new syntax. The old syntax using register classes still
|
|
works, but it will be removed in a future LLVM release.
|
|
|
|
* MCJIT now supports exception handling. Support for it in the old jit will be
|
|
removed in the 3.4 release.
|
|
|
|
* ... next change ...
|
|
|
|
.. NOTE
|
|
If you would like to document a larger change, then you can add a
|
|
subsection about it right here. You can copy the following boilerplate
|
|
and un-indent it (the indentation causes it to be inside this comment).
|
|
|
|
Special New Feature
|
|
-------------------
|
|
|
|
Makes programs 10x faster by doing Special New Thing.
|
|
|
|
AArch64 target
|
|
--------------
|
|
|
|
We've added support for AArch64, ARM's 64-bit architecture. Development is still
|
|
in fairly early stages, but we expect successful compilation when:
|
|
|
|
- compiling standard compliant C99 and C++03 with Clang;
|
|
- using Linux as a target platform;
|
|
- where code + static data doesn't exceed 4GB in size (heap allocated data has
|
|
no limitation).
|
|
|
|
Some additional functionality is also implemented, notably DWARF debugging,
|
|
GNU-style thread local storage and inline assembly.
|
|
|
|
Hexagon Target
|
|
--------------
|
|
|
|
- Removed support for legacy hexagonv2 and hexagonv3 processor
|
|
architectures which are no longer in use. Currently supported
|
|
architectures are hexagonv4 and hexagonv5.
|
|
|
|
Loop Vectorizer
|
|
---------------
|
|
|
|
We've continued the work on the loop vectorizer. The loop vectorizer now
|
|
has the following features:
|
|
|
|
- Loops with unknown trip counts.
|
|
- Runtime checks of pointers.
|
|
- Reductions, Inductions.
|
|
- Min/Max reductions of integers.
|
|
- If Conversion.
|
|
- Pointer induction variables.
|
|
- Reverse iterators.
|
|
- Vectorization of mixed types.
|
|
- Vectorization of function calls.
|
|
- Partial unrolling during vectorization.
|
|
|
|
The loop vectorizer is now enabled by default for -O3.
|
|
|
|
SLP Vectorizer
|
|
--------------
|
|
|
|
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.
|
|
|
|
R600 Backend
|
|
------------
|
|
|
|
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
|
|
<http://www.mesa3d.org>`_ project.
|
|
|
|
|
|
External Open Source Projects Using LLVM 3.3
|
|
============================================
|
|
|
|
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.
|
|
|
|
|
|
Portable Computing Language (pocl)
|
|
----------------------------------
|
|
|
|
In addition to producing an easily portable open source OpenCL
|
|
implementation, another major goal of `pocl <http://pocl.sourceforge.net/>`_
|
|
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.
|
|
|
|
TTA-based Co-design Environment (TCE)
|
|
-------------------------------------
|
|
|
|
`TCE <http://tce.cs.tut.fi/>`_ 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.
|
|
|
|
|
|
Additional Information
|
|
======================
|
|
|
|
A wide variety of additional information is available on the `LLVM web page
|
|
<http://llvm.org/>`_, in particular in the `documentation
|
|
<http://llvm.org/docs/>`_ 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 <http://llvm.org/docs/#maillist>`_.
|
|
|