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Diffstat (limited to 'docs/ReleaseNotes.rst')
| -rw-r--r-- | docs/ReleaseNotes.rst | 149 |
1 files changed, 142 insertions, 7 deletions
diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst index 54f2d530b1e7..dc76617a87b2 100644 --- a/docs/ReleaseNotes.rst +++ b/docs/ReleaseNotes.rst @@ -40,7 +40,10 @@ Non-comprehensive list of changes in this release * There is no longer a "global context" available in LLVM, except for the C API. -* .. note about autoconf build having been removed. +* 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. * .. note about C API functions LLVMParseBitcode, LLVMParseBitcodeInContext, LLVMGetBitcodeModuleInContext and @@ -69,11 +72,13 @@ Non-comprehensive list of changes in this release 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. +* 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. + .. 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 @@ -93,6 +98,32 @@ Non-comprehensive list of changes in this release 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/>`_, +`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 +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 +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 +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 ---------------------- @@ -110,16 +141,98 @@ 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 +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 ... +**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 ... +**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 @@ -140,9 +253,16 @@ Changes to the X86 Target 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 @@ -167,6 +287,21 @@ projects that have already been updated to work with LLVM 3.9. * A project +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 ====================== |