ReleaseNotes: tidy up

  please see the documentation on :doc:`CMake`. For information about the CMake

  language there is also a :doc:`CMakePrimer` document available.

* .. note about C API functions LLVMParseBitcode,

* C API functions LLVMParseBitcode,

  LLVMParseBitcodeInContext, LLVMGetBitcodeModuleInContext and

  LLVMGetBitcodeModule having been removed. LLVMGetTargetMachineData has been

  removed (use LLVMGetDataLayout instead).

  iterator to the next instruction instead of ``void``. Targets that previously

  did ``MBB.erase(I); return;`` now probably want ``return MBB.erase(I);``.

* ``SelectionDAGISel::Select`` now returns ``void``. Out of tree targets will

* ``SelectionDAGISel::Select`` now returns ``void``. Out-of-tree targets will

  need to be updated to replace the argument node and remove any dead nodes in

  cases where they currently return an ``SDNode *`` from this interface.

* Raised the minimum required CMake version to 3.4.3.

* Added the MemorySSA analysis, which hopes to replace MemoryDependenceAnalysis.

  It should provide higher-quality results than MemDep, and be algorithmically

  faster than MemDep. Currently, GVNHoist (which is off by default) makes use of

  from 40% to 10% for functions which are not marked ``optsize`` (that is,

  compiled with ``-Os``).

.. 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.

* ... 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.

GCC ABI Tag

-----------

Recently, many of the Linux distributions (ex. `Fedora <http://developerblog.redhat.com/2015/02/10/gcc-5-in-fedora/>`_,

Recently, many of the Linux distributions (e.g. `Fedora <http://developerblog.redhat.com/2015/02/10/gcc-5-in-fedora/>`_,

`Debian <https://wiki.debian.org/GCC5>`_, `Ubuntu <https://wiki.ubuntu.com/GCC5>`_)

have moved on to use the new `GCC ABI <https://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Attributes.html>`_

to work around `C++11 incompatibilities in libstdc++ <https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html>`_.

This caused `incompatibility problems <https://gcc.gnu.org/ml/gcc-patches/2015-04/msg00153.html>`_

with other compilers (ex. Clang), which needed to be fixed, but due to the

with other compilers (e.g. Clang), which needed to be fixed, but due to the

experimental nature of GCC's own implementation, it took a long time for it to

land in LLVM (`here <https://reviews.llvm.org/D18035>`_ and

`here <https://reviews.llvm.org/D17567>`_), not in time for the 3.8 release.

Those patches are now present in the 3.9.0 release and should be working on the

Those patches are now present in the 3.9.0 release and should be working in the

majority of cases, as they have been tested thoroughly. However, some bugs were

`filled in GCC <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71712>`_ and have not

`filed in GCC <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71712>`_ and have not

yet been fixed, so there may be corner cases not covered by either GCC or Clang.

Bug fixes to those problems should be reported in Bugzilla (either LLVM or GCC),

and patches to LLVM's trunk are very likely to be back-ported to future 3.9.x

  ``llvm.masked.gather`` and ``llvm.masked.scatter`` were introduced to the

  LLVM IR to allow selective memory access for vector data types.

* The new ``notail`` attribute prevents optimization passes from adding ``tail``

  or ``musttail`` markers to a call. It is used to prevent tail call

  optimization from being performed on the call.

Changes to LLVM's IPO model

---------------------------

-------------------

LLVM now supports ThinLTO compilation, which can be invoked by compiling

and linking with -flto=thin. The gold linker plugin, as well as linkers

and linking with ``-flto=thin``. The gold linker plugin, as well as linkers

that use the new ThinLTO API in libLTO (like ld64), will transparently

execute the ThinLTO backends in parallel threads.

For more information on ThinLTO and the LLVM implementation, see the

Changes to the PowerPC Target

-----------------------------

 Moved some optimizations from O3 to O2 (D18562)

* Moved some optimizations from O3 to O2 (D18562)

* Enable sibling call optimization on ppc64 ELFv1/ELFv2 abi

 * Mesa 11.0.x is no longer supported

Changes to the OCaml bindings

-----------------------------

 During this release ...

Support for attribute 'notail' has been added

---------------------------------------------

This marker prevents optimization passes from adding 'tail' or

'musttail' markers to a call. It is used to prevent tail call

optimization from being performed on the call.

External Open Source Projects Using LLVM 3.9

============================================

a lot of other language and tools projects. This section lists some of the

projects that have already been updated to work with LLVM 3.9.

* A project

LDC - the LLVM-based D compiler

-------------------------------