| ====================== |
| 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>`_. |
| |