docs/ReleaseNotes.rst - platform/external/llvm - Git at Google

 ======================
 LLVM 3.9 Release Notes
 ======================

 .. contents::
     :local:

 .. warning::
    These are in-progress notes for the upcoming LLVM 3.9 release.  You may
    prefer the `LLVM 3.8 Release Notes <http://llvm.org/releases/3.8.0/docs
    /ReleaseNotes.html>`_.


 Introduction
 ============

 This document contains the release notes for the LLVM Compiler Infrastructure,
 release 3.9.  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.llvm.org/mailman/listinfo/llvm-dev>`_ 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
 =================================================
 * The LLVMContext gains a new runtime check (see
   LLVMContext::discardValueNames()) that can be set to discard Value names
   (other than GlobalValue). This is intended to be used in release builds by
   clients that are interested in saving CPU/memory as much as possible.

 * There is no longer a "global context" available in LLVM, except for the C API.

 * .. note about autoconf build having been removed.

 * .. note about C API functions LLVMParseBitcode,
    LLVMParseBitcodeInContext, LLVMGetBitcodeModuleInContext and
    LLVMGetBitcodeModule having been removed. LLVMGetTargetMachineData has been
    removed (use LLVMGetDataLayout instead).

 * The C API function LLVMLinkModules has been removed.

 * The C API function LLVMAddTargetData has been removed.

 * The C API function LLVMGetDataLayout is deprecated
   in favor of LLVMGetDataLayoutStr.

 * The C API enum LLVMAttribute and associated API is deprecated in favor of
   the new LLVMAttributeRef API. The deprecated functions are
   LLVMAddFunctionAttr, LLVMAddTargetDependentFunctionAttr,
   LLVMRemoveFunctionAttr, LLVMGetFunctionAttr, LLVMAddAttribute,
   LLVMRemoveAttribute, LLVMGetAttribute, LLVMAddInstrAttribute,
   LLVMRemoveInstrAttribute and LLVMSetInstrParamAlignment.

 * ``TargetFrameLowering::eliminateCallFramePseudoInstr`` now returns an
   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
   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.

 * Introduction of ThinLTO: [FIXME: needs to be documented more extensively in
   /docs/ ; ping Mehdi/Teresa before the release if not done]

 * Raised the minimum required CMake version to 3.4.3.

 .. 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.

 Changes to the LLVM IR
 ----------------------

 * New intrinsics ``llvm.masked.load``, ``llvm.masked.store``,
   ``llvm.masked.gather`` and ``llvm.masked.scatter`` were introduced to the
   LLVM IR to allow selective memory access for vector data types.

 Changes to LLVM's IPO model
 ---------------------------

 LLVM no longer does inter-procedural analysis and optimization (except
 inlining) on functions with comdat linkage.  Doing IPO over such
 functions is unsound because the implementation the linker chooses at
 link-time may be differently optimized than the one what was visible
 during optimization, and may have arbitrarily different observable
 behavior.  See `PR26774 <http://llvm.org/PR26774>`_ for more details.

 Changes to the ARM Backend
 --------------------------

  During this release ...


 Changes to the MIPS Target
 --------------------------

  During this release ...


 Changes to the PowerPC Target
 -----------------------------

  Moved some optimizations from O3 to O2 (D18562)

 * Enable sibling call optimization on ppc64 ELFv1/ELFv2 abi

 Changes to the X86 Target
 -------------------------

 * LLVM now supports the Intel CPU codenamed Skylake Server with AVX-512
   extensions using ``-march=skylake-avx512``. The switch enables the
   ISA extensions AVX-512{F, CD, VL, BW, DQ}.

 * LLVM now supports the Intel CPU codenamed Knights Landing with AVX-512
   extensions using ``-march=knl``. The switch enables the ISA extensions
   AVX-512{F, CD, ER, PF}.

 Changes to the AMDGPU Target
 -----------------------------

  * 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
 ============================================

 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 3.9.

 * A project


 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>`_.
	======================
	LLVM 3.9 Release Notes
	======================

	.. contents::
	:local:

	.. warning::
	These are in-progress notes for the upcoming LLVM 3.9 release. You may
	prefer the `LLVM 3.8 Release Notes <http://llvm.org/releases/3.8.0/docs
	/ReleaseNotes.html>`_.


	Introduction
	============

	This document contains the release notes for the LLVM Compiler Infrastructure,
	release 3.9. 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.llvm.org/mailman/listinfo/llvm-dev>`_ 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
	=================================================
	* The LLVMContext gains a new runtime check (see
	LLVMContext::discardValueNames()) that can be set to discard Value names
	(other than GlobalValue). This is intended to be used in release builds by
	clients that are interested in saving CPU/memory as much as possible.

	* There is no longer a "global context" available in LLVM, except for the C API.

	* .. note about autoconf build having been removed.

	* .. note about C API functions LLVMParseBitcode,
	LLVMParseBitcodeInContext, LLVMGetBitcodeModuleInContext and
	LLVMGetBitcodeModule having been removed. LLVMGetTargetMachineData has been
	removed (use LLVMGetDataLayout instead).

	* The C API function LLVMLinkModules has been removed.

	* The C API function LLVMAddTargetData has been removed.

	* The C API function LLVMGetDataLayout is deprecated
	in favor of LLVMGetDataLayoutStr.

	* The C API enum LLVMAttribute and associated API is deprecated in favor of
	the new LLVMAttributeRef API. The deprecated functions are
	LLVMAddFunctionAttr, LLVMAddTargetDependentFunctionAttr,
	LLVMRemoveFunctionAttr, LLVMGetFunctionAttr, LLVMAddAttribute,
	LLVMRemoveAttribute, LLVMGetAttribute, LLVMAddInstrAttribute,
	LLVMRemoveInstrAttribute and LLVMSetInstrParamAlignment.

	* ``TargetFrameLowering::eliminateCallFramePseudoInstr`` now returns an
	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
	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.

	* Introduction of ThinLTO: [FIXME: needs to be documented more extensively in
	/docs/ ; ping Mehdi/Teresa before the release if not done]

	* Raised the minimum required CMake version to 3.4.3.

	.. 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.

	Changes to the LLVM IR
	----------------------

	* New intrinsics ``llvm.masked.load``, ``llvm.masked.store``,
	``llvm.masked.gather`` and ``llvm.masked.scatter`` were introduced to the
	LLVM IR to allow selective memory access for vector data types.

	Changes to LLVM's IPO model
	---------------------------

	LLVM no longer does inter-procedural analysis and optimization (except
	inlining) on functions with comdat linkage. Doing IPO over such
	functions is unsound because the implementation the linker chooses at
	link-time may be differently optimized than the one what was visible
	during optimization, and may have arbitrarily different observable
	behavior. See `PR26774 <http://llvm.org/PR26774>`_ for more details.

	Changes to the ARM Backend
	--------------------------

	During this release ...


	Changes to the MIPS Target
	--------------------------

	During this release ...


	Changes to the PowerPC Target
	-----------------------------

	Moved some optimizations from O3 to O2 (D18562)

	* Enable sibling call optimization on ppc64 ELFv1/ELFv2 abi

	Changes to the X86 Target
	-------------------------

	* LLVM now supports the Intel CPU codenamed Skylake Server with AVX-512
	extensions using ``-march=skylake-avx512``. The switch enables the
	ISA extensions AVX-512{F, CD, VL, BW, DQ}.

	* LLVM now supports the Intel CPU codenamed Knights Landing with AVX-512
	extensions using ``-march=knl``. The switch enables the ISA extensions
	AVX-512{F, CD, ER, PF}.

	Changes to the AMDGPU Target
	-----------------------------

	* 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
	============================================

	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 3.9.

	* A project


	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>`_.