Prep for merging 3.4: Undo changes from 3.3 branch

docs/ReleaseNotes.rst

 ======================
 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 ...
 
-* Command line options can now be grouped into categories which are shown in
-  the output of ``-help``. See :ref:`grouping options into categories`.
+.. 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).
 
-* The appearance of command line options in ``-help`` that are inherited by
-  linking with libraries that use the LLVM Command line support library can now
-  be modified at runtime. See :ref:`cl::getRegisteredOptions`.
+   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.
-
-Mips target
---------------
-
-New features and improvements:
-
-- Clang driver
- - Support for Sourcery CodeBench Mips toolchain directories tree.
- - Support for new command line options including:
-  - -mxgot/-mno-xgot
-  - -EL / -EB
-  - -mmicromips / -mno-micromips
-  - -msingle-float / -mdouble-float
-  - -mabi=32 (o32 abi) and -mabi=64 (n64 abi)
- - Previously, options such as -mips16, -mmicromips, -mdsp and -mdspr2 were
-   not passed to the assembler. This issue has been fixed.
-
-- A number of changes have been made to improve the quality of DSP-ASE code
-  generation.
- - Multiply and multiply-accumulate instructions can now use all four
-   accumulators.
- - Instruction selection patterns have been added so that DSP instructions
-   are emitted without having to use builtins.
-
-- Delay slot filler pass can now search successor blocks for instructions to
-  fill delay slots (use option -disable-mips-df-succbb-search=false).
-
-PowerPC Target
---------------
-
-New features and improvements:
-
-- PowerPC now supports an assembly parser.
-- Support added for thread-local storage.  64-bit ELF subtarget only.
-- Support added for medium and large code model (-mcmodel=medium,large).
-  Medium code model is now the default.  64-bit ELF subtarget only.
-- Improved register allocation (fewer reserved registers).
-- 64-bit atomic load and store are now supported.
-- Improved code generation for unaligned memory accesses of scalar types.
-- Improved performance of floating-point divide and square root
-  with -ffast-math.
-- Support for predicated returns.
-- Improved code generation for comparisons.
-- Support added for inline setjmp and longjmp.
-- Support added for many instructions introduced in PowerISA 2.04, 2.05,
-  and 2.06.
-- Improved spill code for vector registers.
-- Support added for -mno-altivec.
-- ABI compatibility fixes for complex parameters, 128-bit integer parameters,
-  and varargs functions.  64-bit ELF subtarget only.
+- 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``.
+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.
-
-SystemZ/s390x Backend
----------------------
-
-LLVM and clang now support IBM's z/Architecture.  At present this support
-is restricted to GNU/Linux (GNU triplet s390x-linux-gnu) and requires
-z10 or greater.
-
-
-Sub-project Status Update
-=========================
-
-In addition to the core LLVM 3.3 distribution of production-quality compiler
-infrastructure, the LLVM project includes sub-projects that use the LLVM core
-and share the same distribution license.  This section provides updates on these
-sub-projects.
-
-
-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, 4.6, 4.7 and 4.8, 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++.  Note that gcc-4.6 is the best supported version, and that Ada in
-particular doesn't work well with gcc-4.7 and newer.
-
-The `3.3 release <http://llvm.org/apt/>`_ has the following notable changes.
-
-- supports gcc-4.8 (requires gcc-4.8.1 or newer)
-- object files can be written directly using LLVM's integrated assembler
-- produces saner debug info
-- bitfields can now contain arbitrary scalar types (useful for Ada)
-
-
-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 scripts and other
-applications. LLDB uses the following components of the LLVM core distribution
-to support the latest language features and target support:
-
-- the Clang parser for high-quality parsing of C, C++ and Objective C
-- the LLVM disassembler
-- the LLVM JIT compiler (MCJIT) for expression evaluation
-
-The `3.3 release <http://lldb.llvm.org/download.html>`_ has the following notable changes.
-
-Features now supported on Linux:
-
-- Debugging multi-threaded programs
-- Support for watchpoints
-- Process list, attach and fork
-- `vim integration <http://llvm.org/svn/llvm-project/lldb/branches/release_33/utils/vim-lldb/README>`_ for LLDB
-
-Portability:
-
-- Builds with cmake, ninja, auto-tools, clang 3.3 and gcc 4.6
-
-Linux Improvements:
-
-- Improved register support including vector registers
-- Basic debugging of i386 programs
-- Bug fixes for expression evaluation
+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
+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.
+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 <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.
-
-Just-in-time Adaptive Decoder Engine (Jade)
--------------------------------------------
-
-`Jade <https://github.com/orcc/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
-<http://orcc.sf.net>`_) and requires it to translate the RVC-CAL standard
-library of video coding tools into an LLVM assembly code.
-
-LDC - the LLVM-based D compiler
--------------------------------
-
-`D <http://dlang.org>`_ is a language with C-like syntax and static typing. It
-pragmatically combines efficiency, control, and modeling power, with safety and
-programmer productivity. D supports powerful concepts like Compile-Time Function
-Execution (CTFE) and Template Meta-Programming, provides an innovative approach
-to concurrency and offers many classical paradigms.
-
-`LDC <http://wiki.dlang.org/LDC>`_ uses the frontend from the reference compiler
-combined with LLVM as backend to produce efficient native code. LDC targets
-x86/x86_64 systems like Linux, OS X and Windows and also Linux/PPC64. Ports to
-other architectures like ARM are underway.
+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>`_.