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+
+======================
+LLVM 3.2 Release Notes
+======================
+
+.. contents::
+    :local:
+
+Written by the `LLVM Team <http://llvm.org/>`_
+
+:red:`These are in-progress notes for the upcoming LLVM 3.2 release.  You may
+prefer the` `LLVM 3.1 Release Notes <http://llvm.org/releases/3.1/docs
+/ReleaseNotes.html>`_.
+
+Introduction
+============
+
+This document contains the release notes for the LLVM Compiler Infrastructure,
+release 3.2.  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/>`_.
+
+Sub-project Status Update
+=========================
+
+The LLVM 3.2 distribution currently consists of code from the core LLVM
+repository, which roughly includes the LLVM optimizers, code generators and
+supporting tools, and the Clang repository.  In addition to this code, the LLVM
+Project includes other sub-projects that are in development.  Here we include
+updates on these subprojects.
+
+Clang: C/C++/Objective-C Frontend Toolkit
+-----------------------------------------
+
+`Clang <http://clang.llvm.org/>`_ is an LLVM front end for the C, C++, and
+Objective-C languages.  Clang aims to provide a better user experience through
+expressive diagnostics, a high level of conformance to language standards, fast
+compilation, and low memory use.  Like LLVM, Clang provides a modular,
+library-based architecture that makes it suitable for creating or integrating
+with other development tools.  Clang is considered a production-quality
+compiler for C, Objective-C, C++ and Objective-C++ on x86 (32- and 64-bit), and
+for Darwin/ARM targets.
+
+In the LLVM 3.2 time-frame, the Clang team has made many improvements.
+Highlights include:
+
+#. ...
+
+For more details about the changes to Clang since the 3.1 release, see the
+`Clang release notes. <http://clang.llvm.org/docs/ReleaseNotes.html>`_
+
+If Clang rejects your code but another compiler accepts it, please take a look
+at the `language compatibility <http://clang.llvm.org/compatibility.html>`_
+guide to make sure this is not intentional or a known issue.
+
+DragonEgg: GCC front-ends, LLVM back-end
+----------------------------------------
+
+`DragonEgg <http://dragonegg.llvm.org/>`_ is a `gcc plugin
+<http://gcc.gnu.org/wiki/plugins>`_ that replaces GCC's optimizers and code
+generators with LLVM's.  It works with gcc-4.5 and gcc-4.6 (and partially with
+gcc-4.7), can target the x86-32/x86-64 and ARM processor families, and has been
+successfully used on the Darwin, FreeBSD, KFreeBSD, Linux and OpenBSD
+platforms.  It fully supports Ada, C, C++ and Fortran.  It has partial support
+for Go, Java, Obj-C and Obj-C++.
+
+The 3.2 release has the following notable changes:
+
+#. ...
+
+compiler-rt: Compiler Runtime Library
+-------------------------------------
+
+The new LLVM `compiler-rt project <http://compiler-rt.llvm.org/>`_ is a simple
+library that provides an implementation of the low-level target-specific hooks
+required by code generation and other runtime components.  For example, when
+compiling for a 32-bit target, converting a double to a 64-bit unsigned integer
+is compiled into a runtime call to the ``__fixunsdfdi`` function.  The
+``compiler-rt`` library provides highly optimized implementations of this and
+other low-level routines (some are 3x faster than the equivalent libgcc
+routines).
+
+The 3.2 release has the following notable changes:
+
+#. ...
+
+LLDB: Low Level Debugger
+------------------------
+
+`LLDB <http://lldb.llvm.org>`_ is a ground-up implementation of a command line
+debugger, as well as a debugger API that can be used from other applications.
+LLDB makes use of the Clang parser to provide high-fidelity expression parsing
+(particularly for C++) and uses the LLVM JIT for target support.
+
+The 3.2 release has the following notable changes:
+
+#. ...
+
+libc++: C++ Standard Library
+----------------------------
+
+Like compiler_rt, libc++ is now :ref:`dual licensed
+<copyright-license-patents>` under the MIT and UIUC license, allowing it to be
+used more permissively.
+
+Within the LLVM 3.2 time-frame there were the following highlights:
+
+#. ...
+
+VMKit
+-----
+
+The `VMKit project <http://vmkit.llvm.org/>`_ is an implementation of a Java
+Virtual Machine (Java VM or JVM) that uses LLVM for static and just-in-time
+compilation.
+
+The 3.2 release has the following notable changes:
+
+#. ...
+
+Polly: Polyhedral Optimizer
+---------------------------
+
+`Polly <http://polly.llvm.org/>`_ is an *experimental* optimizer for data
+locality and parallelism.  It provides high-level loop optimizations and
+automatic parallelisation.
+
+Within the LLVM 3.2 time-frame there were the following highlights:
+
+#. isl, the integer set library used by Polly, was relicensed to the MIT license
+#. isl based code generation
+#. MIT licensed replacement for CLooG (LGPLv2)
+#. Fine grained option handling (separation of core and border computations,
+   control overhead vs. code size)
+#. Support for FORTRAN and dragonegg
+#. OpenMP code generation fixes
+
+External Open Source Projects Using LLVM 3.2
+============================================
+
+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 3.2.
+
+Crack
+-----
+
+`Crack <http://code.google.com/p/crack-language/>`_ aims to provide the ease of
+development of a scripting language with the performance of a compiled
+language.  The language derives concepts from C++, Java and Python,
+incorporating object-oriented programming, operator overloading and strong
+typing.
+
+FAUST
+-----
+
+`FAUST <http://faust.grame.fr/>`_ is a compiled language for real-time audio
+signal processing.  The name FAUST stands for Functional AUdio STream.  Its
+programming model combines two approaches: functional programming and block
+diagram composition.  In addition with the C, C++, Java, JavaScript output
+formats, the Faust compiler can generate LLVM bitcode, and works with LLVM
+2.7-3.1.
+
+Glasgow Haskell Compiler (GHC)
+------------------------------
+
+`GHC <http://www.haskell.org/ghc/>`_ is an open source compiler and programming
+suite for Haskell, a lazy functional programming language.  It includes an
+optimizing static compiler generating good code for a variety of platforms,
+together with an interactive system for convenient, quick development.
+
+GHC 7.0 and onwards include an LLVM code generator, supporting LLVM 2.8 and
+later.
+
+Julia
+-----
+
+`Julia <https://github.com/JuliaLang/julia>`_ is a high-level, high-performance
+dynamic language for technical computing.  It provides a sophisticated
+compiler, distributed parallel execution, numerical accuracy, and an extensive
+mathematical function library.  The compiler uses type inference to generate
+fast code without any type declarations, and uses LLVM's optimization passes
+and JIT compiler.  The `Julia Language <http://julialang.org/>`_ is designed
+around multiple dispatch, giving programs a large degree of flexibility.  It is
+ready for use on many kinds of problems.
+
+LLVM D Compiler
+---------------
+
+`LLVM D Compiler <https://github.com/ldc-developers/ldc>`_ (LDC) is a compiler
+for the D programming Language.  It is based on the DMD frontend and uses LLVM
+as backend.
+
+Open Shading Language
+---------------------
+
+`Open Shading Language (OSL)
+<https://github.com/imageworks/OpenShadingLanguage/>`_ is a small but rich
+language for programmable shading in advanced global illumination renderers and
+other applications, ideal for describing materials, lights, displacement, and
+pattern generation.  It uses LLVM to JIT complex shader networks to x86 code at
+runtime.
+
+OSL was developed by Sony Pictures Imageworks for use in its in-house renderer
+used for feature film animation and visual effects, and is distributed as open
+source software with the "New BSD" license.
+
+Portable OpenCL (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 (SIMD, VLIW, superscalar, ...).
+
+Pure
+----
+
+`Pure <http://pure-lang.googlecode.com/>`_ is an algebraic/functional
+programming language based on term rewriting.  Programs are collections of
+equations which are used to evaluate expressions in a symbolic fashion.  The
+interpreter uses LLVM as a backend to JIT-compile Pure programs to fast native
+code.  Pure offers dynamic typing, eager and lazy evaluation, lexical closures,
+a hygienic macro system (also based on term rewriting), built-in list and
+matrix support (including list and matrix comprehensions) and an easy-to-use
+interface to C and other programming languages (including the ability to load
+LLVM bitcode modules, and inline C, C++, Fortran and Faust code in Pure
+programs if the corresponding LLVM-enabled compilers are installed).
+
+Pure version 0.54 has been tested and is known to work with LLVM 3.1 (and
+continues to work with older LLVM releases >= 2.5).
+
+TTA-based Co-design Environment (TCE)
+-------------------------------------
+
+`TCE <http://tce.cs.tut.fi/>`_ is a toolset for designing application-specific
+processors (ASP) 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++ 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.
+
+Installation Instructions
+=========================
+
+See :doc:`GettingStarted`.
+
+What's New in LLVM 3.2?
+=======================
+
+This release includes a huge number of bug fixes, performance tweaks and minor
+improvements.  Some of the major improvements and new features are listed in
+this section.
+
+Major New Features
+------------------
+
+..
+
+  Features that need text if they're finished for 3.2:
+   ARM EHABI
+   combiner-aa?
+   strong phi elim
+   loop dependence analysis
+   CorrelatedValuePropagation
+   lib/Transforms/IPO/MergeFunctions.cpp => consider for 3.2.
+   Integrated assembler on by default for arm/thumb?
+
+  Near dead:
+   Analysis/RegionInfo.h + Dom Frontiers
+   SparseBitVector: used in LiveVar.
+   llvm/lib/Archive - replace with lib object?
+
+
+LLVM 3.2 includes several major changes and big features:
+
+#. New NVPTX back-end (replacing existing PTX back-end) based on NVIDIA sources
+#. ...
+
+LLVM IR and Core Improvements
+-----------------------------
+
+LLVM IR has several new features for better support of new targets and that
+expose new optimization opportunities:
+
+#. Thread local variables may have a specified TLS model.  See the :ref:`Language
+   Reference Manual <globalvars>`.
+#. ...
+
+Optimizer Improvements
+----------------------
+
+In addition to many minor performance tweaks and bug fixes, this release
+includes a few major enhancements and additions to the optimizers:
+
+Loop Vectorizer - We've added a loop vectorizer and we are now able to
+vectorize small loops.  The loop vectorizer is disabled by default and can be
+enabled using the ``-mllvm -vectorize-loops`` flag.  The SIMD vector width can
+be specified using the flag ``-mllvm -force-vector-width=4``.  The default
+value is ``0`` which means auto-select.
+
+We can now vectorize this function:
+
+.. code-block:: c++
+
+  unsigned sum_arrays(int *A, int *B, int start, int end) {
+    unsigned sum = 0;
+    for (int i = start; i < end; ++i)
+      sum += A[i] + B[i] + i;
+    return sum;
+  }
+
+We vectorize under the following loops:
+
+#. The inner most loops must have a single basic block.
+#. The number of iterations are known before the loop starts to execute.
+#. The loop counter needs to be incremented by one.
+#. The loop trip count **can** be a variable.
+#. Loops do **not** need to start at zero.
+#. The induction variable can be used inside the loop.
+#. Loop reductions are supported.
+#. Arrays with affine access pattern do **not** need to be marked as
+   '``noalias``' and are checked at runtime.
+#. ...
+
+SROA - We've re-written SROA to be significantly more powerful.
+
+#. Branch weight metadata is preseved through more of the optimizer.
+#. ...
+
+MC Level Improvements
+---------------------
+
+The LLVM Machine Code (aka MC) subsystem was created to solve a number of
+problems in the realm of assembly, disassembly, object file format handling,
+and a number of other related areas that CPU instruction-set level tools work
+in.  For more information, please see the `Intro to the LLVM MC Project Blog
+Post <http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html>`_.
+
+#. ...
+
+.. _codegen:
+
+Target Independent Code Generator Improvements
+----------------------------------------------
+
+Stack Coloring - We have implemented a new optimization pass to merge stack
+objects which are used in disjoin areas of the code.  This optimization reduces
+the required stack space significantly, in cases where it is clear to the
+optimizer that the stack slot is not shared.  We use the lifetime markers to
+tell the codegen that a certain alloca is used within a region.
+
+We now merge consecutive loads and stores.
+
+We have put a significant amount of work into the code generator
+infrastructure, which allows us to implement more aggressive algorithms and
+make it run faster:
+
+#. ...
+
+We added new TableGen infrastructure to support bundling for Very Long
+Instruction Word (VLIW) architectures.  TableGen can now automatically generate
+a deterministic finite automaton from a VLIW target's schedule description
+which can be queried to determine legal groupings of instructions in a bundle.
+
+We have added a new target independent VLIW packetizer based on the DFA
+infrastructure to group machine instructions into bundles.
+
+Basic Block Placement
+^^^^^^^^^^^^^^^^^^^^^
+
+A probability based block placement and code layout algorithm was added to
+LLVM's code generator.  This layout pass supports probabilities derived from
+static heuristics as well as source code annotations such as
+``__builtin_expect``.
+
+X86-32 and X86-64 Target Improvements
+-------------------------------------
+
+New features and major changes in the X86 target include:
+
+#. ...
+
+.. _ARM:
+
+ARM Target Improvements
+-----------------------
+
+New features of the ARM target include:
+
+#. ...
+
+.. _armintegratedassembler:
+
+ARM Integrated Assembler
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+The ARM target now includes a full featured macro assembler, including
+direct-to-object module support for clang.  The assembler is currently enabled
+by default for Darwin only pending testing and any additional necessary
+platform specific support for Linux.
+
+Full support is included for Thumb1, Thumb2 and ARM modes, along with subtarget
+and CPU specific extensions for VFP2, VFP3 and NEON.
+
+The assembler is Unified Syntax only (see ARM Architecural Reference Manual for
+details).  While there is some, and growing, support for pre-unfied (divided)
+syntax, there are still significant gaps in that support.
+
+MIPS Target Improvements
+------------------------
+
+New features and major changes in the MIPS target include:
+
+#. ...
+
+PowerPC Target Improvements
+---------------------------
+
+Many fixes and changes across LLVM (and Clang) for better compliance with the
+64-bit PowerPC ELF Application Binary Interface, interoperability with GCC, and
+overall 64-bit PowerPC support.  Some highlights include:
+
+#. MCJIT support added.
+#. PPC64 relocation support and (small code model) TOC handling added.
+#. Parameter passing and return value fixes (alignment issues, padding, varargs
+   support, proper register usage, odd-sized structure support, float support,
+   extension of return values for i32 return values).
+#. Fixes in spill and reload code for vector registers.
+#. C++ exception handling enabled.
+#. Changes to remediate double-rounding compatibility issues with respect to
+   GCC behavior.
+#. Refactoring to disentangle ``ppc64-elf-linux`` ABI from Darwin ppc64 ABI
+   support.
+#. Assorted new test cases and test case fixes (endian and word size issues).
+#. Fixes for big-endian codegen bugs, instruction encodings, and instruction
+   constraints.
+#. Implemented ``-integrated-as`` support.
+#. Additional support for Altivec compare operations.
+#. IBM long double support.
+
+There have also been code generation improvements for both 32- and 64-bit code.
+Instruction scheduling support for the Freescale e500mc and e5500 cores has
+been added.
+
+PTX/NVPTX Target Improvements
+-----------------------------
+
+The PTX back-end has been replaced by the NVPTX back-end, which is based on the
+LLVM back-end used by NVIDIA in their CUDA (nvcc) and OpenCL compiler.  Some
+highlights include:
+
+#. Compatibility with PTX 3.1 and SM 3.5.
+#. Support for NVVM intrinsics as defined in the NVIDIA Compiler SDK.
+#. Full compatibility with old PTX back-end, with much greater coverage of LLVM
+   SIR.
+
+Please submit any back-end bugs to the LLVM Bugzilla site.
+
+Other Target Specific Improvements
+----------------------------------
+
+#. ...
+
+Major Changes and Removed Features
+----------------------------------
+
+If you're already an LLVM user or developer with out-of-tree changes based on
+LLVM 3.2, this section lists some "gotchas" that you may run into upgrading
+from the previous release.
+
+#. The CellSPU port has been removed.  It can still be found in older versions.
+#. ...
+
+Internal API Changes
+--------------------
+
+In addition, many APIs have changed in this release.  Some of the major LLVM
+API changes are:
+
+We've added a new interface for allowing IR-level passes to access
+target-specific information.  A new IR-level pass, called
+``TargetTransformInfo`` provides a number of low-level interfaces.  LSR and
+LowerInvoke already use the new interface.
+
+The ``TargetData`` structure has been renamed to ``DataLayout`` and moved to
+``VMCore`` to remove a dependency on ``Target``.
+
+#. ...
+
+Tools Changes
+-------------
+
+In addition, some tools have changed in this release.  Some of the changes are:
+
+#. ...
+
+Python Bindings
+---------------
+
+Officially supported Python bindings have been added!  Feature support is far
+from complete.  The current bindings support interfaces to:
+
+#. ...
+
+Known Problems
+==============
+
+LLVM is generally a production quality compiler, and is used by a broad range
+of applications and shipping in many products.  That said, not every subsystem
+is as mature as the aggregate, particularly the more obscure1 targets.  If you
+run into a problem, please check the `LLVM bug database
+<http://llvm.org/bugs/>`_ and submit a bug if there isn't already one or ask on
+the `LLVMdev list <http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev>`_.
+
+Known problem areas include:
+
+#. The CellSPU, MSP430, and XCore backends are experimental.
+
+#. The integrated assembler, disassembler, and JIT is not supported by several
+   targets.  If an integrated assembler is not supported, then a system
+   assembler is required.  For more details, see the
+   :ref:`target-feature-matrix`.
+
+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>`_.
+