| ============================ |
| LLVM |release| Release Notes |
| ============================ |
| |
| .. contents:: |
| :local: |
| |
| .. only:: PreRelease |
| |
| .. warning:: |
| These are in-progress notes for the upcoming LLVM |version| release. |
| Release notes for previous releases can be found on |
| `the Download Page <https://releases.llvm.org/download.html>`_. |
| |
| |
| Introduction |
| ============ |
| |
| This document contains the release notes for the LLVM Compiler Infrastructure, |
| release |release|. 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 <https://llvm.org/releases/>`_. |
| |
| For more information about LLVM, including information about the latest |
| release, please check out the `main LLVM web site <https://llvm.org/>`_. If you |
| have questions or comments, the `Discourse forums |
| <https://discourse.llvm.org>`_ is a good place to ask |
| them. |
| |
| Note that if you are reading this file from a Git 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 <https://llvm.org/releases/>`_. |
| |
| Non-comprehensive list of changes in this release |
| ================================================= |
| .. 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. |
| |
| * Starting with LLVM 19, the Windows installers only include support for the |
| X86, ARM, and AArch64 targets in order to keep the build size within the |
| limits of the NSIS installer framework. |
| |
| * ... |
| |
| Update on required toolchains to build LLVM |
| ------------------------------------------- |
| |
| * The minimum Python version has been raised from 3.6 to 3.8 across all of LLVM. |
| This enables the use of many new Python features, aligning more closely with |
| modern Python best practices, and improves CI maintainability |
| See `#78828 <https://github.com/llvm/llvm-project/pull/78828>`_ for more info. |
| |
| Changes to the LLVM IR |
| ---------------------- |
| |
| * Added Memory Model Relaxation Annotations (MMRAs). |
| * Added ``nusw`` and ``nuw`` flags to ``getelementptr`` instruction. |
| * Renamed ``llvm.experimental.vector.reverse`` intrinsic to ``llvm.vector.reverse``. |
| * Renamed ``llvm.experimental.vector.splice`` intrinsic to ``llvm.vector.splice``. |
| * Renamed ``llvm.experimental.vector.interleave2`` intrinsic to ``llvm.vector.interleave2``. |
| * Renamed ``llvm.experimental.vector.deinterleave2`` intrinsic to ``llvm.vector.deinterleave2``. |
| * The constant expression variants of the following instructions have been |
| removed: |
| |
| * ``icmp`` |
| * ``fcmp`` |
| * ``shl`` |
| * LLVM has switched from using debug intrinsics in textual IR to using debug |
| records by default. Details of the change and instructions on how to update |
| any downstream tools and tests can be found in the `migration docs |
| <https://llvm.org/docs/RemoveDIsDebugInfo.html>`_. |
| * Semantics of MC/DC intrinsics have been changed. |
| |
| * ``llvm.instprof.mcdc.parameters``: 3rd argument has been changed |
| from bytes to bits. |
| * ``llvm.instprof.mcdc.condbitmap.update``: Removed. |
| * ``llvm.instprof.mcdc.tvbitmap.update``: 3rd argument has been |
| removed. The next argument has been changed from byte index to bit |
| index. |
| * Added ``llvm.experimental.vector.compress`` intrinsic. |
| * Added special kind of `constant expressions |
| <https://llvm.org/docs/LangRef.html#pointer-authentication-constants>`_ to |
| represent pointers with signature embedded into it. |
| * Added `pointer authentication operand bundles |
| <https://llvm.org/docs/LangRef.html#pointer-authentication-operand-bundles>`_. |
| |
| Changes to LLVM infrastructure |
| ------------------------------ |
| |
| Changes to building LLVM |
| ------------------------ |
| |
| * LLVM now has rpmalloc version 1.4.5 in-tree, as a replacement C allocator for |
| hosted toolchains. This supports several host platforms such as Mac or Unix, |
| however currently only the Windows 64-bit LLVM release uses it. |
| This has a great benefit in terms of build times on Windows when using ThinLTO |
| linking, especially on machines with lots of cores, to an order of magnitude |
| or more. Clang compilation is also improved. Please see some build timings in |
| (`#91862 <https://github.com/llvm/llvm-project/pull/91862#issue-2291033962>`_) |
| For more information, refer to the **LLVM_ENABLE_RPMALLOC** option in `CMake variables <https://llvm.org/docs/CMake.html#llvm-related-variables>`_. |
| |
| * The ``LLVM_ENABLE_TERMINFO`` flag has been removed. LLVM no longer depends on |
| terminfo and now always uses the ``TERM`` environment variable for color |
| support autodetection. |
| |
| Changes to TableGen |
| ------------------- |
| |
| - We can define type aliases via new keyword ``deftype``. |
| |
| Changes to Interprocedural Optimizations |
| ---------------------------------------- |
| |
| * Hot cold region splitting analysis improvements for overlapping cold regions. |
| |
| Changes to the AArch64 Backend |
| ------------------------------ |
| |
| * Added support for Cortex-R82AE, Cortex-A78AE, Cortex-A520AE, Cortex-A720AE, |
| Cortex-A725, Cortex-X925, Neoverse-N3, Neoverse-V3 and Neoverse-V3AE CPUs. |
| |
| * ``-mbranch-protection=standard`` now enables FEAT_PAuth_LR by |
| default when the feature is enabled. The new behaviour results |
| in ``standard`` being equal to ``bti+pac-ret+pc`` when ``+pauth-lr`` |
| is passed as part of ``-mcpu=`` options. |
| |
| * SVE and SVE2 have been moved to the default extensions list for ARMv9.0, |
| making them optional per the Arm ARM. Existing v9.0+ CPUs in the backend that |
| support these extensions continue to have these features enabled by default |
| when specified via ``-march=`` or an ``-mcpu=`` that supports them. The |
| attribute ``"target-features"="+v9a"`` no longer implies ``"+sve"`` and |
| ``"+sve2"`` respectively. |
| * Added support for ELF pointer authentication relocations as specified in |
| `PAuth ABI Extension to ELF |
| <https://github.com/ARM-software/abi-aa/blob/main/pauthabielf64/pauthabielf64.rst>`_. |
| * Added codegeneration, ELF object file and linker support for authenticated |
| call lowering, signed constants and emission of signing scheme details in |
| ``GNU_PROPERTY_AARCH64_FEATURE_PAUTH`` property of ``.note.gnu.property`` |
| section. |
| * Added codegeneration support for ``llvm.ptrauth.auth`` and |
| ``llvm.ptrauth.resign`` intrinsics. |
| |
| Changes to the AMDGPU Backend |
| ----------------------------- |
| |
| * Implemented the ``llvm.get.fpenv`` and ``llvm.set.fpenv`` intrinsics. |
| * Added ``!amdgpu.no.fine.grained.memory`` and |
| ``!amdgpu.no.remote.memory`` metadata to control atomic behavior. |
| |
| * Implemented :ref:`llvm.get.rounding <int_get_rounding>` and :ref:`llvm.set.rounding <int_set_rounding>` |
| |
| * Removed ``llvm.amdgcn.ds.fadd``, ``llvm.amdgcn.ds.fmin`` and |
| ``llvm.amdgcn.ds.fmax`` intrinsics. Users should use the |
| :ref:`atomicrmw <i_atomicrmw>` instruction with `fadd`, `fmin` and |
| `fmax` with addrspace(3) instead. |
| |
| * AMDGPUAttributor is no longer run as part of the codegen pass |
| pipeline. It is expected to run as part of the middle end |
| optimizations. |
| |
| Changes to the ARM Backend |
| -------------------------- |
| |
| * Added support for Cortex-R52+ CPU. |
| * FEAT_F32MM is no longer activated by default when using `+sve` on v8.6-A or greater. The feature is still available and can be used by adding `+f32mm` to the command line options. |
| * armv8-r now implies only fp-armv8d16sp, rather than neon and full fp-armv8. These features are still included by default for cortex-r52. The default cpu for armv8-r is now "generic", for compatibility with variants that do not include neon, fp64, and d32. |
| |
| Changes to the AVR Backend |
| -------------------------- |
| |
| Changes to the DirectX Backend |
| ------------------------------ |
| |
| Changes to the Hexagon Backend |
| ------------------------------ |
| |
| Changes to the LoongArch Backend |
| -------------------------------- |
| |
| * i32 is now a native type in the datalayout string. This enables |
| LoopStrengthReduce for loops with i32 induction variables, among other |
| optimizations. |
| * Codegen support is added for TLS Desciptor. |
| * Interleaved vectorization and vector shuffle are supported on LoongArch and |
| the experimental feature ``auto-vec`` is removed. |
| * Allow ``f16`` codegen with expansion to libcalls. |
| * Clarify that emulated TLS is not supported. |
| * A codegen issue for ``bstrins.w`` is fixed on loongarch32. |
| * Assorted codegen improvements. |
| |
| Changes to the MIPS Backend |
| --------------------------- |
| |
| Changes to the PowerPC Backend |
| ------------------------------ |
| |
| * PPC big-endian Linux now supports ``-fpatchable-function-entry``. |
| * PPC AIX now supports local-dynamic TLS mode. |
| * PPC AIX saves the Git revision in binaries when built with LLVM_APPEND_VC_REV=ON. |
| * PPC AIX now supports toc-data attribute for large code model. |
| * PPC AIX now supports passing arguments by value having greater alignment than |
| the pointer size. Currently only compatible with the IBM XL C compiler. |
| * Add support for the per global code model attribute on AIX. |
| * Support spilling non-volatile registers for traceback table accuracy on AIX. |
| * Codegen improvements and bug fixes. |
| |
| Changes to the RISC-V Backend |
| ----------------------------- |
| |
| * Added full support for the experimental Zabha (Byte and |
| Halfword Atomic Memory Operations) extension. |
| * Added assembler/disassembler support for the experimenatl Zalasr |
| (Load-Acquire and Store-Release) extension. |
| * The names of the majority of the S-prefixed (supervisor-level) extension |
| names in the RISC-V profiles specification are now recognised. |
| * Codegen support was added for the Zimop (May-Be-Operations) extension. |
| * The experimental Ssnpm, Smnpm, Smmpm, Sspm, and Supm 1.0.0 Pointer Masking extensions are supported. |
| * The experimental Ssqosid extension is supported. |
| * Added the CSR names from the Resumable Non-Maskable Interrupts (Smrnmi) extension. |
| * llvm-objdump now prints disassembled opcode bytes in groups of 2 or 4 bytes to |
| match GNU objdump. The bytes within the groups are in big endian order. |
| * Added smstateen extension to -march. CSR names for smstateen were already supported. |
| * Zaamo and Zalrsc are no longer experimental. |
| * Processors that enable post reg-alloc scheduling (PostMachineScheduler) by default should use the `UsePostRAScheduler` subtarget feature. Setting `PostRAScheduler = 1` in the scheduler model will have no effect on the enabling of the PostMachineScheduler. |
| * Zabha is no longer experimental. |
| * B (the collection of the Zba, Zbb, Zbs extensions) is supported. |
| * Added smcdeleg, ssccfg, smcsrind, and sscsrind extensions to -march. |
| * ``-mcpu=syntacore-scr3-rv32`` and ``-mcpu=syntacore-scr3-rv64`` were added. |
| * The default atomics mapping was changed to emit an additional trailing fence |
| for sequentially consistent stores, offering compatibility with a future |
| mapping using load-acquire and store-release instructions while remaining |
| fully compatible with objects produced prior to this change. The mapping |
| (ABI) used is recorded as an ELF attribute. |
| * Ztso is no longer experimental. |
| * The WCH / Nanjing Qinheng Microelectronics QingKe "XW" compressed opcodes are |
| supported under the name "Xwchc". |
| * ``-mcpu=native`` now detects available features with hwprobe (RISC-V Hardware Probing Interface) on Linux 6.4 or later. |
| * The version of Zicfilp/Zicfiss is updated to 1.0. |
| |
| Changes to the WebAssembly Backend |
| ---------------------------------- |
| |
| Changes to the Windows Target |
| ----------------------------- |
| |
| Changes to the X86 Backend |
| -------------------------- |
| |
| - Removed knl/knm specific ISA intrinsics: AVX512PF, AVX512ER, PREFETCHWT1, |
| while assembly encoding/decoding supports are kept. |
| |
| - Removed ``3DNow!``-specific ISA intrinsics and codegen support. The ``3dnow`` and ``3dnowa`` target features are no longer supported. The intrinsics ``llvm.x86.3dnow.*``, ``llvm.x86.3dnowa.*``, and ``llvm.x86.mmx.femms`` have been removed. Assembly encoding/decoding for the corresponding instructions remains supported. |
| |
| |
| Changes to the OCaml bindings |
| ----------------------------- |
| |
| Changes to the Python bindings |
| ------------------------------ |
| |
| Changes to the C API |
| -------------------- |
| |
| * Added ``LLVMGetBlockAddressFunction`` and ``LLVMGetBlockAddressBasicBlock`` |
| functions for accessing the values in a blockaddress constant. |
| |
| * Added ``LLVMConstStringInContext2`` function, which better matches the C++ |
| API by using ``size_t`` for string length. Deprecated ``LLVMConstStringInContext``. |
| |
| * Added the following functions for accessing a function's prefix data: |
| |
| * ``LLVMHasPrefixData`` |
| * ``LLVMGetPrefixData`` |
| * ``LLVMSetPrefixData`` |
| |
| * Added the following functions for accessing a function's prologue data: |
| |
| * ``LLVMHasPrologueData`` |
| * ``LLVMGetPrologueData`` |
| * ``LLVMSetPrologueData`` |
| |
| * Deprecated ``LLVMConstNUWNeg`` and ``LLVMBuildNUWNeg``. |
| |
| * Added ``LLVMAtomicRMWBinOpUIncWrap`` and ``LLVMAtomicRMWBinOpUDecWrap`` to |
| ``LLVMAtomicRMWBinOp`` enum for AtomicRMW instructions. |
| |
| * Added ``LLVMCreateConstantRangeAttribute`` function for creating ConstantRange Attributes. |
| |
| * Added the following functions for creating and accessing data for CallBr instructions: |
| |
| * ``LLVMBuildCallBr`` |
| * ``LLVMGetCallBrDefaultDest`` |
| * ``LLVMGetCallBrNumIndirectDests`` |
| * ``LLVMGetCallBrIndirectDest`` |
| |
| * The following functions for creating constant expressions have been removed, |
| because the underlying constant expressions are no longer supported. Instead, |
| an instruction should be created using the ``LLVMBuildXYZ`` APIs, which will |
| constant fold the operands if possible and create an instruction otherwise: |
| |
| * ``LLVMConstICmp`` |
| * ``LLVMConstFCmp`` |
| * ``LLVMConstShl`` |
| |
| **Note:** The following changes are due to the removal of the debug info |
| intrinsics from LLVM and to the introduction of debug records into LLVM. |
| They are described in detail in the `debug info migration guide <https://llvm.org/docs/RemoveDIsDebugInfo.html>`_. |
| |
| * Added the following functions to insert before the indicated instruction but |
| after any attached debug records. |
| |
| * ``LLVMPositionBuilderBeforeDbgRecords`` |
| * ``LLVMPositionBuilderBeforeInstrAndDbgRecords`` |
| |
| Same as ``LLVMPositionBuilder`` and ``LLVMPositionBuilderBefore`` except the |
| insertion position is set to before the debug records that precede the target |
| instruction. ``LLVMPositionBuilder`` and ``LLVMPositionBuilderBefore`` are |
| unchanged. |
| |
| * Added the following functions to get/set the new non-instruction debug info format. |
| They will be deprecated in the future and they are just a transition aid. |
| |
| * ``LLVMIsNewDbgInfoFormat`` |
| * ``LLVMSetIsNewDbgInfoFormat`` |
| |
| * Added the following functions to insert a debug record (new debug info format). |
| |
| * ``LLVMDIBuilderInsertDeclareRecordBefore`` |
| * ``LLVMDIBuilderInsertDeclareRecordAtEnd`` |
| * ``LLVMDIBuilderInsertDbgValueRecordBefore`` |
| * ``LLVMDIBuilderInsertDbgValueRecordAtEnd`` |
| |
| * Deleted the following functions that inserted a debug intrinsic (old debug info format). |
| |
| * ``LLVMDIBuilderInsertDeclareBefore`` |
| * ``LLVMDIBuilderInsertDeclareAtEnd`` |
| * ``LLVMDIBuilderInsertDbgValueBefore`` |
| * ``LLVMDIBuilderInsertDbgValueAtEnd`` |
| |
| * Added the following functions for accessing a Target Extension Type's data: |
| |
| * ``LLVMGetTargetExtTypeName`` |
| * ``LLVMGetTargetExtTypeNumTypeParams``/``LLVMGetTargetExtTypeTypeParam`` |
| * ``LLVMGetTargetExtTypeNumIntParams``/``LLVMGetTargetExtTypeIntParam`` |
| |
| * Added the following functions for accessing/setting the no-wrap flags for a |
| GetElementPtr instruction: |
| |
| * ``LLVMBuildGEPWithNoWrapFlags`` |
| * ``LLVMConstGEPWithNoWrapFlags`` |
| * ``LLVMGEPGetNoWrapFlags`` |
| * ``LLVMGEPSetNoWrapFlags`` |
| |
| * Added the following functions for creating and accessing data for ConstantPtrAuth constants: |
| |
| * ``LLVMConstantPtrAuth`` |
| * ``LLVMGetConstantPtrAuthPointer`` |
| * ``LLVMGetConstantPtrAuthKey`` |
| * ``LLVMGetConstantPtrAuthDiscriminator`` |
| * ``LLVMGetConstantPtrAuthAddrDiscriminator`` |
| |
| Changes to the CodeGen infrastructure |
| ------------------------------------- |
| |
| Changes to the Metadata Info |
| --------------------------------- |
| |
| Changes to the Debug Info |
| --------------------------------- |
| |
| * LLVM has switched from using debug intrinsics internally to using debug |
| records by default. This should happen transparently when using the DIBuilder |
| to construct debug variable information, but will require changes for any code |
| that interacts with debug intrinsics directly. Debug intrinsics will only be |
| supported on a best-effort basis from here onwards; for more information, see |
| the `migration docs <https://llvm.org/docs/RemoveDIsDebugInfo.html>`_. |
| |
| * When emitting DWARF v2 and not in strict DWARF mode, LLVM will now add |
| a ``DW_AT_type`` to instances of ``DW_TAG_enumeration_type``. This is actually |
| a DWARF v3 feature which tells tools what the enum's underlying type is. |
| Emitting this for v2 as well will help users who have to build binaries with |
| DWARF v2 but are using tools that understand newer DWARF standards. Older |
| tools will ignore it. (`#98335 <https://github.com/llvm/llvm-project/pull/98335>`_) |
| |
| Changes to the LLVM tools |
| --------------------------------- |
| * llvm-nm and llvm-objdump can now print symbol information from linked |
| WebAssembly binaries, using information from exports or the "name" |
| section for functions, globals and data segments. Symbol addresses and sizes |
| are printed as offsets in the file, allowing for binary size analysis. Wasm |
| files using reference types and GC are also supported (but also only for |
| functions, globals, and data, and only for listing symbols and names). |
| |
| * llvm-ar now utilizes LLVM_DEFAULT_TARGET_TRIPLE to determine the archive format |
| if it's not specified with the ``--format`` argument and cannot be inferred from |
| input files. |
| |
| * llvm-ar now allows specifying COFF archive format with ``--format`` argument |
| and uses it by default for COFF targets. |
| |
| * llvm-ranlib now supports ``-V`` as an alias for ``--version``. |
| ``-v`` (``--verbose`` in llvm-ar) has been removed. |
| (`#87661 <https://github.com/llvm/llvm-project/pull/87661>`_) |
| |
| * llvm-objcopy now supports ``--set-symbol-visibility`` and |
| ``--set-symbols-visibility`` options for ELF input to change the |
| visibility of symbols. |
| |
| * llvm-objcopy now supports ``--skip-symbol`` and ``--skip-symbols`` options |
| for ELF input to skip the specified symbols when executing other options |
| that can change a symbol's name, binding or visibility. |
| |
| * llvm-objcopy now supports ``--compress-sections`` to compress or decompress |
| arbitrary sections not within a segment. |
| (`#85036 <https://github.com/llvm/llvm-project/pull/85036>`_.) |
| |
| * llvm-profgen now supports COFF+DWARF binaries. This enables Sample-based PGO |
| on Windows using Intel VTune's SEP. For details on usage, see the `end-user |
| documentation for SPGO |
| <https://clang.llvm.org/docs/UsersManual.html#using-sampling-profilers>`_. |
| |
| * llvm-readelf's ``-r`` output for RELR has been improved. |
| (`#89162 <https://github.com/llvm/llvm-project/pull/89162>`_) |
| ``--raw-relr`` has been removed. |
| |
| * llvm-mca now aborts by default if it is given bad input where previously it |
| would continue. Additionally, it can now continue when it encounters |
| instructions which lack scheduling information. The behaviour can be |
| controlled by the newly introduced |
| ``--skip-unsupported-instructions=<none|lack-sched|parse-failure|any>``, as |
| documented in ``--help`` output and the command guide. (`#90474 |
| <https://github.com/llvm/llvm-project/pull/90474>`_) |
| |
| * llvm-readobj's LLVM output format for ELF core files has been changed. |
| Similarly, the JSON format has been fixed for this case. The NT_FILE note |
| now has a map for the mapped files. (`#92835 |
| <https://github.com/llvm/llvm-project/pull/92835>`_). |
| |
| * llvm-cov now generates HTML report with JavaScript code to allow simple |
| jumping between uncovered parts (lines/regions/branches) of code |
| using buttons on top-right corner of the page or using keys (L/R/B or |
| jumping in reverse direction with shift+L/R/B). (`#95662 |
| <https://github.com/llvm/llvm-project/pull/95662>`_). |
| |
| * llvm-objcopy now verifies format of ``.note`` sections for ELF input. This can |
| be disabled by ``--no-verify-note-sections``. (`#90458 |
| <https://github.com/llvm/llvm-project/pull/90458>`). |
| |
| * llvm-objdump now supports the ``--file-headers`` option for XCOFF object files. |
| |
| Changes to LLDB |
| --------------------------------- |
| |
| * Register field information is now provided on AArch64 FreeBSD for live |
| processes and core files (previously only provided on AArch64 Linux). |
| |
| * Register field information can now include enums to represent field |
| values. Enums have been added for ``fpcr.RMode`` and ``mte_ctrl.TCF`` |
| for AArch64 targets:: |
| |
| (lldb) register read fpcr |
| fpcr = 0x00000000 |
| = (AHP = 0, DN = 0, FZ = 0, RMode = RN, <...>) |
| |
| If you need to know the values of the enum, these can be found in |
| the output of ``register info`` for the same register. |
| |
| Changes to BOLT |
| --------------------------------- |
| * Now supports ``--match-profile-with-function-hash`` to match profiled and |
| binary functions with exact hash, allowing for the matching of renamed but |
| identical functions. |
| |
| Changes to Sanitizers |
| --------------------- |
| |
| Other Changes |
| ------------- |
| |
| External Open Source Projects Using LLVM 19 |
| =========================================== |
| |
| * A project... |
| |
| Additional Information |
| ====================== |
| |
| A wide variety of additional information is available on the `LLVM web page |
| <https://llvm.org/>`_, in particular in the `documentation |
| <https://llvm.org/docs/>`_ section. The web page also contains versions of the |
| API documentation which is up-to-date with the Git 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 `Discourse forums <https://discourse.llvm.org>`_. |
