docs/ReleaseNotes.rst - llvm - Git at Google

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

 .. contents::
     :local:

 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.

 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.

 * The autoconf build system has been removed in favor of CMake. LLVM 3.9
   requires CMake 3.4.3 or later to build. For information about using CMake
   please see the documentation on :doc:`CMake`. For information about the CMake
   language there is also a :doc:`CMakePrimer` document available.

 * 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.

 * 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
   MemorySSA.

 * The minimum density for lowering switches with jump tables has been reduced
   from 40% to 10% for functions which are not marked ``optsize`` (that is,
   compiled with ``-Os``).

 GCC ABI Tag
 -----------

 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 (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 (`D18035 <https://reviews.llvm.org/D18035>`_ and
 `D17567 <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 in the
 majority of cases, as they have been tested thoroughly. However, some bugs were
 `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
 releases (depends on how destructive it is).

 Unfortunately, these patches won't be back-ported to 3.8.x or earlier, so we
 strongly recommend people to use 3.9.x when GCC ABI cases are at stake.

 For a more in-depth view of the issue, check our `Bugzilla entry <https://llvm.org/bugs/show_bug.cgi?id=23529>`_.

 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.

 * 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 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.

 Support for ThinLTO
 -------------------

 LLVM now supports ThinLTO compilation, which can be invoked by compiling
 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
 `ThinLTO blog post <http://blog.llvm.org/2016/06/thinlto-scalable-and-incremental-lto.html>`_.

 Changes to the ARM Targets
 --------------------------

 **During this release the AArch64 backend has:**

 * Gained support for Qualcomm's Kryo and Broadcom's Vulcan CPUs, including
   scheduling models.
 * Landed a scheduling model for Samsung's Exynos M1.
 * Seen a lot of work on GlobalISel.
 * Learned a few more useful combines (fadd and fmul into fmadd, adjustments to the
   stack pointer for callee-save stack memory and local stack memory etc).
 * Gained support for the Swift calling convention.
 * Switched to using SubtargetFeatures rather than testing for specific CPUs and
   to using TableGen for handling system instruction operands.
 * Like ARM, AArch64 is now using the TargetParser, so no more StringSwitches
   matching CPU, FPU or feature names will be accepted in normal code.
 * Clang can now self-host itself using LLD on AArch64.
 * Gained a big batch of tests from Halide.

  Furthermore, LLDB now supports AArch64 compact unwind tables, as used on iOS,
  tvos and watchos.

 **During this release the ARM target has:**

 * ARMv8.2-A can now be targeted directly via Clang flags.
 * Adding preliminary support for Cortex-R8.
 * LLDB can now parse EABI attributes for an ELF input.
 * Initial ARM/Thumb support was added to LLD.
 * The ExecutionEngine now supports COFF/ARM.
 * Swift calling convention was ported to ARM.
 * A large number of codegen fixes around ARMv8, DSP, correct sub-target support,
   relocations, EABI, EHABI, Windows on ARM, atomics..
 * Improved assembler support for Linux/Android/Chromium sub-projects.
 * Initial support for MUSL (libc) on ARM.
 * Support for Thumb1 targets in libunwind.
 * Gained a big batch of tests from Halide.


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

 **During this release the MIPS target has:**

 * Enabled the Integrated Assembler by default for all ``mips-*`` and
   ``mipsel-*`` triples.
 * Significantly improved the Integrated Assembler support for the n64 ABI.
 * Added the Clang frontend ``-mcompact-branches={never,optimal,always}`` option
   that controls how LLVM generates compact branches for MIPS targets.
 * Improved performance and code size for stack pointer adjustments in functions
   with large frames.
 * Implemented many instructions from the microMIPS32R6 ISA and added CodeGen
   support for most of them.
 * Added support for the triple used by Debian Stretch for little endian
   MIPS64, ie. ``mips64el-linux-gnuabi64``.
 * Removed EABI which was neither tested nor properly supported.
 * Gained the ability to self-host on MIPS32R6.
 * Gained the ability to self-host on MIPS64R2 and MIPS64R6 when using the n64
   ABI.
 * Added support for the ``LA`` macro in PIC mode for o32.
 * Added support for safestack in compiler-rt.
 * Added support for the MIPS n64 ABI in LLD.
 * Added LLD support for TLS relocations for both o32 and n64 MIPS ABIs.

 **The MIPS target has also fixed various bugs including the following notable
 fixes:**

 * Delay slots are no longer filled multiple times when either ``-save-temps``
   or ``-via-file-asm`` are used.
 * Updated n32 and n64 to follow the standard ELF conventions for label prefixes
   (``.L``), whereas o32 still uses its own (``$``).
 * Properly sign-extend values to GPR width for instructions that expect 32-bit
   values on 64-bit ISAs.
 * Several fixes for the delay-slot filler pass, including correct
   forbidden-slot hazard handling.
 * Fixed several errors caught by the machine verifier when turned on for MIPS.
 * Fixed broken predicate for ``SELECT`` patterns in MIPS64.
 * Fixed wrong truncation of memory address for ``LL``/``SC`` seqeuences in
   MIPS64.
 * Fixed the o32, n32 and n64 handling of ``.cprestore`` directives when inside
   a ``.set noat`` region by the Integrated Assembler.
 * Fixed the ordering of ``HI``/``LO`` pairs in the relocation table.
 * Fixed the generated ELF ``EFlags`` when Octeon is the target.


 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}.

 * LLVM will now prefer ``PUSH`` instructions rather than ``%esp``-relative
   ``MOV`` instructions for function calls at all optimization levels greater
   than ``-O0``. Previously this transformation only occurred at ``-Os``.

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

  * Added backend support for OpenGL shader image, buffer storage, atomic
    counter, and compute shader extensions (supported since Mesa 12)

  * Mesa 11.0.x is no longer supported


 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.

 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, FreeBSD and Windows and also Linux on ARM
 and PowerPC (32/64 bit). Ports to other architectures like AArch64 and MIPS64
 are underway.


 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:

	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.

	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.

	* The autoconf build system has been removed in favor of CMake. LLVM 3.9
	requires CMake 3.4.3 or later to build. For information about using CMake
	please see the documentation on :doc:`CMake`. For information about the CMake
	language there is also a :doc:`CMakePrimer` document available.

	* 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.

	* 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
	MemorySSA.

	* The minimum density for lowering switches with jump tables has been reduced
	from 40% to 10% for functions which are not marked ``optsize`` (that is,
	compiled with ``-Os``).

	GCC ABI Tag
	-----------

	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 (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 (`D18035 <https://reviews.llvm.org/D18035>`_ and
	`D17567 <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 in the
	majority of cases, as they have been tested thoroughly. However, some bugs were
	`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
	releases (depends on how destructive it is).

	Unfortunately, these patches won't be back-ported to 3.8.x or earlier, so we
	strongly recommend people to use 3.9.x when GCC ABI cases are at stake.

	For a more in-depth view of the issue, check our `Bugzilla entry <https://llvm.org/bugs/show_bug.cgi?id=23529>`_.

	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.

	* 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 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.

	Support for ThinLTO
	-------------------

	LLVM now supports ThinLTO compilation, which can be invoked by compiling
	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
	`ThinLTO blog post <http://blog.llvm.org/2016/06/thinlto-scalable-and-incremental-lto.html>`_.

	Changes to the ARM Targets
	--------------------------

	During this release the AArch64 backend has:

	* Gained support for Qualcomm's Kryo and Broadcom's Vulcan CPUs, including
	scheduling models.
	* Landed a scheduling model for Samsung's Exynos M1.
	* Seen a lot of work on GlobalISel.
	* Learned a few more useful combines (fadd and fmul into fmadd, adjustments to the
	stack pointer for callee-save stack memory and local stack memory etc).
	* Gained support for the Swift calling convention.
	* Switched to using SubtargetFeatures rather than testing for specific CPUs and
	to using TableGen for handling system instruction operands.
	* Like ARM, AArch64 is now using the TargetParser, so no more StringSwitches
	matching CPU, FPU or feature names will be accepted in normal code.
	* Clang can now self-host itself using LLD on AArch64.
	* Gained a big batch of tests from Halide.

	Furthermore, LLDB now supports AArch64 compact unwind tables, as used on iOS,
	tvos and watchos.

	During this release the ARM target has:

	* ARMv8.2-A can now be targeted directly via Clang flags.
	* Adding preliminary support for Cortex-R8.
	* LLDB can now parse EABI attributes for an ELF input.
	* Initial ARM/Thumb support was added to LLD.
	* The ExecutionEngine now supports COFF/ARM.
	* Swift calling convention was ported to ARM.
	* A large number of codegen fixes around ARMv8, DSP, correct sub-target support,
	relocations, EABI, EHABI, Windows on ARM, atomics..
	* Improved assembler support for Linux/Android/Chromium sub-projects.
	* Initial support for MUSL (libc) on ARM.
	* Support for Thumb1 targets in libunwind.
	* Gained a big batch of tests from Halide.


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

	During this release the MIPS target has:

	* Enabled the Integrated Assembler by default for all ``mips-*`` and
	``mipsel-*`` triples.
	* Significantly improved the Integrated Assembler support for the n64 ABI.
	* Added the Clang frontend ``-mcompact-branches={never,optimal,always}`` option
	that controls how LLVM generates compact branches for MIPS targets.
	* Improved performance and code size for stack pointer adjustments in functions
	with large frames.
	* Implemented many instructions from the microMIPS32R6 ISA and added CodeGen
	support for most of them.
	* Added support for the triple used by Debian Stretch for little endian
	MIPS64, ie. ``mips64el-linux-gnuabi64``.
	* Removed EABI which was neither tested nor properly supported.
	* Gained the ability to self-host on MIPS32R6.
	* Gained the ability to self-host on MIPS64R2 and MIPS64R6 when using the n64
	ABI.
	* Added support for the ``LA`` macro in PIC mode for o32.
	* Added support for safestack in compiler-rt.
	* Added support for the MIPS n64 ABI in LLD.
	* Added LLD support for TLS relocations for both o32 and n64 MIPS ABIs.

	**The MIPS target has also fixed various bugs including the following notable
	fixes:**

	* Delay slots are no longer filled multiple times when either ``-save-temps``
	or ``-via-file-asm`` are used.
	* Updated n32 and n64 to follow the standard ELF conventions for label prefixes
	(``.L``), whereas o32 still uses its own (``$``).
	* Properly sign-extend values to GPR width for instructions that expect 32-bit
	values on 64-bit ISAs.
	* Several fixes for the delay-slot filler pass, including correct
	forbidden-slot hazard handling.
	* Fixed several errors caught by the machine verifier when turned on for MIPS.
	* Fixed broken predicate for ``SELECT`` patterns in MIPS64.
	* Fixed wrong truncation of memory address for ``LL``/``SC`` seqeuences in
	MIPS64.
	* Fixed the o32, n32 and n64 handling of ``.cprestore`` directives when inside
	a ``.set noat`` region by the Integrated Assembler.
	* Fixed the ordering of ``HI``/``LO`` pairs in the relocation table.
	* Fixed the generated ELF ``EFlags`` when Octeon is the target.


	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}.

	* LLVM will now prefer ``PUSH`` instructions rather than ``%esp``-relative
	``MOV`` instructions for function calls at all optimization levels greater
	than ``-O0``. Previously this transformation only occurred at ``-Os``.

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

	* Added backend support for OpenGL shader image, buffer storage, atomic
	counter, and compute shader extensions (supported since Mesa 12)

	* Mesa 11.0.x is no longer supported


	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.

	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, FreeBSD and Windows and also Linux on ARM
	and PowerPC (32/64 bit). Ports to other architectures like AArch64 and MIPS64
	are underway.


	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>`_.