======================
-LLVM 3.5 Release Notes
+LLVM 3.8 Release Notes
======================
.. contents::
:local:
-.. warning::
- These are in-progress notes for the upcoming LLVM 3.5 release. You may
- prefer the `LLVM 3.4 Release Notes <http://llvm.org/releases/3.4/docs
- /ReleaseNotes.html>`_.
-
Introduction
============
This document contains the release notes for the LLVM Compiler Infrastructure,
-release 3.5. Here we describe the status of LLVM, including major improvements
+release 3.8. 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
+<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
=================================================
+* With this release, the minimum Windows version required for running LLVM is
+ Windows 7. Earlier versions, including Windows Vista and XP are no longer
+ supported.
+
+* With this release, the autoconf build system is deprecated. It will be removed
+ in the 3.9 release. Please migrate to using CMake. For more information see:
+ `Building LLVM with CMake <CMake.html>`_
+
+* The C API function LLVMLinkModules is deprecated. It will be removed in the
+ 3.9 release. Please migrate to LLVMLinkModules2. Unlike the old function the
+ new one
+
+ * Doesn't take an unused parameter.
+ * Destroys the source instead of only damaging it.
+ * Does not record a message. Use the diagnostic handler instead.
+
+* The C API functions LLVMParseBitcode, LLVMParseBitcodeInContext,
+ LLVMGetBitcodeModuleInContext and LLVMGetBitcodeModule have been deprecated.
+ They will be removed in 3.9. Please migrate to the versions with a 2 suffix.
+ Unlike the old ones the new ones do not record a diagnostic message. Use
+ the diagnostic handler instead.
+
+* The deprecated C APIs LLVMGetBitcodeModuleProviderInContext and
+ LLVMGetBitcodeModuleProvider have been removed.
+
+* The deprecated C APIs LLVMCreateExecutionEngine, LLVMCreateInterpreter,
+ LLVMCreateJITCompiler, LLVMAddModuleProvider and LLVMRemoveModuleProvider
+ have been removed.
+
+* With this release, the C API headers have been reorganized to improve build
+ time. Type specific declarations have been moved to Type.h, and error
+ handling routines have been moved to ErrorHandling.h. Both are included in
+ Core.h so nothing should change for projects directly including the headers,
+ but transitive dependencies may be affected.
+
+* llvm-ar now suports thin archives.
+
+* llvm doesn't produce .data.rel.ro.local or .data.rel sections anymore.
+
+* aliases to available_externally globals are now rejected by the verifier.
+
+* the IR Linker has been split into IRMover that moves bits from one module to
+ another and Linker proper that decides what to link.
+
+* Support for dematerializing has been dropped.
+
+* RegisterScheduler::setDefault was removed. Targets that used to call into the
+ command line parser to set the DAGScheduler, and that don't have enough
+ control with setSchedulingPreference, should look into overriding the
+ SubTargetHook "getDAGScheduler()".
-* All backends have been changed to use the MC asm printer and support for the
- non MC one has been removed.
+* ``ilist_iterator<T>`` no longer has implicit conversions to and from ``T*``,
+ since ``ilist_iterator<T>`` may be pointing at the sentinel (which is usually
+ not of type ``T`` at all). To convert from an iterator ``I`` to a pointer,
+ use ``&*I``; to convert from a pointer ``P`` to an iterator, use
+ ``P->getIterator()``. Alternatively, explicit conversions via
+ ``static_cast<T>(U)`` are still available.
-* Clang can now successfully self-host itself on Linux/Sparc64 and on
- FreeBSD/Sparc64.
+* ``ilist_node<T>::getNextNode()`` and ``ilist_node<T>::getPrevNode()`` now
+ fail at compile time when the node cannot access its parent list.
+ Previously, when the sentinel was was an ``ilist_half_node<T>``, this API
+ could return the sentinal instead of ``nullptr``. Frustrated callers should
+ be updated to use ``iplist<T>::getNextNode(T*)`` instead. Alternatively, if
+ the node ``N`` is guaranteed not to be the last in the list, it is safe to
+ call ``&*++N->getIterator()`` directly.
-* LLVM now assumes the assembler supports ``.loc`` for generating debug line
- numbers. The old support for printing the debug line info directly was only
- used by ``llc`` and has been removed.
+* The `Kaleidoscope tutorials <tutorial/index.html>`_ have been updated to use
+ the ORC JIT APIs.
-* All inline assembly is parsed by the integrated assembler when it is enabled.
- Previously this was only the case for object-file output. It is now the case
- for assembly output as well. The integrated assembler can be disabled with
- the ``-no-integrated-as`` option,
+* ORC now has a basic set of C bindings.
-* llvm-ar now handles IR files like regular object files. In particular, a
- regular symbol table is created for symbols defined in IR files, including
- those in file scope inline assembly.
+* Optional support for linking clang and the LLVM tools with a single libLLVM
+ shared library. To enable this, pass ``-DLLVM_LINK_LLVM_DYLIB=ON`` to CMake.
+ See `Building LLVM with CMake`_ for more details.
-* LLVM now always uses cfi directives for producing most stack
- unwinding information.
+* The optimization to move the prologue and epilogue of functions in colder
+ code path (shrink-wrapping) is now enabled by default.
-* The prefix for loop vectorizer hint metadata has been changed from
- ``llvm.vectorizer`` to ``llvm.loop.vectorize``. In addition,
- ``llvm.vectorizer.unroll`` metadata has been renamed
- ``llvm.loop.interleave.count``.
+* A new target-independent gcc-compatible emulated Thread Local Storage mode
+ is added. When ``-femultated-tls`` flag is used, all accesses to TLS
+ variables are converted to calls to ``__emutls_get_address`` in the runtime
+ library.
-* Some backends previously implemented Atomic NAND(x,y) as ``x & ~y``. Now
- all backends implement it as ``~(x & y)``, matching the semantics of GCC 4.4
- and later.
+* MSVC compatible exception handling has been completely overhauled. New
+ instructions have been introduced to facilitate this:
+ `New exception handling instructions <ExceptionHandling.html#new-exception-handling-instructions>`_.
+ While we have done our best to test this feature thoroughly, it would
+ not be completely surprising if there were a few lingering issues that
+ early adopters might bump into.
.. NOTE
For small 1-3 sentence descriptions, just add an entry at the end of
Makes programs 10x faster by doing Special New Thing.
-Changes to the ARM Backend
+
+Changes to the ARM Backends
+---------------------------
+
+During this release the AArch64 target has:
+
+* Added support for more sanitizers (MSAN, TSAN) and made them compatible with
+ all VMA kernel configurations (currently tested on 39 and 42 bits).
+* Gained initial LLD support in the new ELF back-end
+* Extended the Load/Store optimiser and cleaned up some of the bad decisions
+ made earlier.
+* Expanded LLDB support, including watchpoints, native building, Renderscript,
+ LLDB-server, debugging 32-bit applications.
+* Added support for the ``Exynos M1`` chip.
+
+During this release the ARM target has:
+
+* Gained massive performance improvements on embedded benchmarks due to finally
+ running the stride vectorizer in full form, incrementing the performance gains
+ that we already had in the previous releases with limited stride vectorization.
+* Expanded LLDB support, including watchpoints, unwind tables
+* Extended the Load/Store optimiser and cleaned up some of the bad decisions
+ made earlier.
+* Simplified code generation for global variable addresses in ELF, resulting in
+ a significant (4% in Chromium) reduction in code size.
+* Gained some additional code size improvements, though there's still a long road
+ ahead, especially for older cores.
+* Added some EABI floating point comparison functions to Compiler-RT
+* Added support for Windows+GNU triple, +features in -mcpu/-march options.
+
+
+Changes to the MIPS Target
--------------------------
-Since release 3.3, a lot of new features have been included in the ARM
-back-end but weren't production ready (ie. well tested) on release 3.4.
-Just after the 3.4 release, we started heavily testing two major parts
-of the back-end: the integrated assembler (IAS) and the ARM exception
-handling (EHABI), and now they are enabled by default on LLVM/Clang.
-
-The IAS received a lot of GNU extensions and directives, as well as some
-specific pre-UAL instructions. Not all remaining directives will be
-implemented, as we made judgement calls on the need versus the complexity,
-and have chosen simplicity and future compatibility where hard decisions
-had to be made. The major difference is, as stated above, the IAS validates
-all inline ASM, not just for object emission, and that cause trouble with
-some uses of inline ASM as pre-processor magic.
-
-So, while the IAS is good enough to compile large projects (including most
-of the Linux kernel), there are a few things that we can't (and probably
-won't) do. For those cases, please use ``-fno-integrated-as`` in Clang.
-
-Exception handling is another big change. After extensive testing and
-changes to cooperate with Dwarf unwinding, EHABI is enabled by default.
-The options ``-arm-enable-ehabi`` and ``-arm-enable-ehabi-descriptors``,
-which were used to enable EHABI in the previous releases, are removed now.
-
-This means all ARM code will emit EH unwind tables, or CFI unwinding (for
-debug/profiling), or both. To avoid run-time inconsistencies, C code will
-also emit EH tables (in case they interoperate with C++ code), as is the
-case for other architectures (ex. x86_64).
-
-External Open Source Projects Using LLVM 3.5
+During this release the MIPS target has:
+
+* Significantly extended support for the Integrated Assembler. See below for
+ more information
+* Added support for the ``P5600`` processor.
+* Added support for the ``interrupt`` attribute for MIPS32R2 and later. This
+ attribute will generate a function which can be used as a interrupt handler
+ on bare metal MIPS targets using the static relocation model.
+* Added support for the ``ERETNC`` instruction found in MIPS32R5 and later.
+* Added support for OpenCL. See http://portablecl.org/.
+
+ * Address spaces 1 to 255 are now reserved for software use and conversions
+ between them are no-op casts.
+
+* Removed the ``mips16`` value for the -mcpu option since it is an :abbr:`ASE
+ (Application Specific Extension)` and not a processor. If you were using this,
+ please specify another CPU and use ``-mips16`` to enable MIPS16.
+* Removed ``copy_u.w`` from 32-bit MSA and ``copy_u.d`` from 64-bit MSA since
+ they have been removed from the MSA specification due to forward compatibility
+ issues. For example, 32-bit MSA code containing ``copy_u.w`` would behave
+ differently on a 64-bit processor supporting MSA. The corresponding intrinsics
+ are still available and may expand to ``copy_s.[wd]`` where this is
+ appropriate for forward compatibility purposes.
+* Relaxed the ``-mnan`` option to allow ``-mnan=2008`` on MIPS32R2/MIPS64R2 for
+ compatibility with GCC.
+* Made MIPS64R6 the default CPU for 64-bit Android triples.
+
+The MIPS target has also fixed various bugs including the following notable
+fixes:
+
+* Fixed reversed operands on ``mthi``/``mtlo`` in the DSP :abbr:`ASE
+ (Application Specific Extension)`.
+* The code generator no longer uses ``jal`` for calls to absolute immediate
+ addresses.
+* Disabled fast instruction selection on MIPS32R6 and MIPS64R6 since this is not
+ yet supported.
+* Corrected addend for ``R_MIPS_HI16`` and ``R_MIPS_PCHI16`` in MCJIT
+* The code generator no longer crashes when handling subregisters of an 64-bit
+ FPU register with undefined value.
+* The code generator no longer attempts to use ``$zero`` for operands that do
+ not permit ``$zero``.
+* Corrected the opcode used for ``ll``/``sc`` when using MIPS32R6/MIPS64R6 and
+ the Integrated Assembler.
+* Added support for atomic load and atomic store.
+* Corrected debug info when dynamically re-aligning the stack.
+
+Integrated Assembler
+^^^^^^^^^^^^^^^^^^^^
+We have made a large number of improvements to the integrated assembler for
+MIPS. In this release, the integrated assembler isn't quite production-ready
+since there are a few known issues related to bare-metal support, checking
+immediates on instructions, and the N32/N64 ABI's. However, the current support
+should be sufficient for many users of the O32 ABI, particularly those targeting
+MIPS32 on Linux or bare-metal MIPS32.
+
+If you would like to try the integrated assembler, please use
+``-fintegrated-as``.
+
+Changes to the PowerPC Target
+-----------------------------
+
+There are numerous improvements to the PowerPC target in this release:
+
+* Shrink wrapping optimization has been enabled for PowerPC Little Endian
+
+* Direct move instructions are used when converting scalars to vectors
+
+* Thread Sanitizer (TSAN) is now supported for PowerPC
+
+* New MI peephole pass to clean up redundand XXPERMDI instructions
+
+* Add branch hints to highly biased branch instructions (code reaching
+ unreachable terminators and exceptional control flow consructs)
+
+* Promote boolean return values to integer to prevent excessive usage of
+ condition registers
+
+* Additional vector APIs for vector comparisons and vector merges have been
+ added to altivec.h
+
+* Many bugs have been identified and fixed
+
+
+Changes to the X86 Target
+-----------------------------
+
+ During this release ...
+
+* TLS is enabled for Cygwin as emutls.
+
+* Smaller code for materializing 32-bit 1 and -1 constants at ``-Os``.
+
+* More efficient code for wide integer compares. (E.g. 64-bit compares
+ on 32-bit targets.)
+
+* Tail call support for ``thiscall``, ``stdcall``, ``vectorcall``, and
+ ``fastcall`` functions.
+
+Changes to the Hexagon Target
+-----------------------------
+
+In addition to general code size and performance improvements, Hexagon target
+now has basic support for Hexagon V60 architecture and Hexagon Vector
+Extensions (HVX).
+
+Changes to the AVR Target
+-------------------------
+
+Slightly less than half of the AVR backend has been merged in at this point. It is still
+missing a number large parts which cause it to be unusable, but is well on the
+road to being completely merged and workable.
+
+Changes to the OCaml bindings
+-----------------------------
+
+ During this release ...
+
+* The ocaml function link_modules has been replaced with link_modules' which
+ uses LLVMLinkModules2.
+
+
+External Open Source Projects Using LLVM 3.8
============================================
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 3.5.
+projects that have already been updated to work with LLVM 3.8.
+
+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 PowerPC (32/64 bit)
+and ARM. Ports to other architectures like AArch64 and MIPS64 are underway.
Additional Information
projects / oota-llvm.git / blobdiff