============================ 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 `_. 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 `_. For more information about LLVM, including information about the latest release, please check out the `main LLVM web site `_. If you have questions or comments, the `Discourse forums `_ 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 `_. 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. * ... Update on required toolchains to build LLVM ------------------------------------------- Changes to the LLVM IR ---------------------- * The `llvm.stacksave` and `llvm.stackrestore` intrinsics now use an overloaded pointer type to support non-0 address spaces. * The constant expression variants of the following instructions have been removed: * ``and`` * ``or`` * ``lshr`` * ``ashr`` * ``zext`` * ``sext`` * ``fptrunc`` * ``fpext`` * ``fptoui`` * ``fptosi`` * ``uitofp`` * ``sitofp`` * Added `llvm.exp10` intrinsic. Changes to LLVM infrastructure ------------------------------ * Minimum Clang version to build LLVM in C++20 configuration has been updated to clang-17.0.6. Changes to building LLVM ------------------------ - 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 ------------------- * Added constructs for debugging TableGen files: * `dump` keyword to dump messages to standard error, see https://github.com/llvm/llvm-project/pull/68793. * `!repr` bang operator to inspect the content of values, see https://github.com/llvm/llvm-project/pull/68716. Changes to Interprocedural Optimizations ---------------------------------------- Changes to the AArch64 Backend ------------------------------ * Added support for Cortex-A520, Cortex-A720 and Cortex-X4 CPUs. * Neoverse-N2 was incorrectly marked as an Armv8.5a core. This has been changed to an Armv9.0a core. However, crypto options are not enabled by default for Armv9 cores, so `-mcpu=neoverse-n2+crypto` is now required to enable crypto for this core. As far as the compiler is concerned, Armv9.0a has the same features enabled as Armv8.5a, with the exception of crypto. Changes to the AMDGPU Backend ----------------------------- * `llvm.sqrt.f32` is now lowered correctly. Use `llvm.amdgcn.sqrt.f32` for raw instruction access. * Implemented `llvm.stacksave` and `llvm.stackrestore` intrinsics. * Implemented :ref:`llvm.get.rounding ` Changes to the ARM Backend -------------------------- * Added support for Cortex-M52 CPUs. * Added execute-only support for Armv6-M. Changes to the AVR Backend -------------------------- Changes to the DirectX Backend ------------------------------ Changes to the Hexagon Backend ------------------------------ Changes to the LoongArch Backend -------------------------------- Changes to the MIPS Backend --------------------------- Changes to the PowerPC Backend ------------------------------ Changes to the RISC-V Backend ----------------------------- * The Zfa extension version was upgraded to 1.0 and is no longer experimental. * Zihintntl extension version was upgraded to 1.0 and is no longer experimental. * Intrinsics were added for Zk*, Zbb, and Zbc. See https://github.com/riscv-non-isa/riscv-c-api-doc/blob/master/riscv-c-api.md#scalar-bit-manipulation-extension-intrinsics * Default ABI with F but without D was changed to ilp32f for RV32 and to lp64f for RV64. * The Zvbb, Zvbc, Zvkb, Zvkg, Zvkn, Zvknc, Zvkned, Zvkng, Zvknha, Zvknhb, Zvks, Zvksc, Zvksed, Zvksg, Zvksh, and Zvkt extension version was upgraded to 1.0 and is no longer experimental. However, the C intrinsics for these extensions are still experimental. To use the C intrinsics for these extensions, ``-menable-experimental-extensions`` needs to be passed to Clang. * XSfcie extension and SiFive CSRs and instructions that were associated with it have been removed. None of these CSRs and instructions were part of "SiFive Custom Instruction Extension" as SiFive defines it. The LLVM project needs to work with SiFive to define and document real extension names for individual CSRs and instructions. * ``-mcpu=sifive-p450`` was added. * CodeGen of RV32E/RV64E was supported experimentally. * CodeGen of ilp32e/lp64e was supported experimentally. Changes to the WebAssembly Backend ---------------------------------- Changes to the Windows Target ----------------------------- * The LLVM filesystem class ``UniqueID`` and function ``equivalent()`` no longer determine that distinct different path names for the same hard linked file actually are equal. This is an intentional tradeoff in a bug fix, where the bug used to cause distinct files to be considered equivalent on some file systems. This change fixed the issues https://github.com/llvm/llvm-project/issues/61401 and https://github.com/llvm/llvm-project/issues/22079. Changes to the X86 Backend -------------------------- * Add support for the ``RDMSRLIST and WRMSRLIST`` instructions. * Add support for the ``WRMSRNS`` instruction. * Support ISA of ``AMX-FP16`` which contains ``tdpfp16ps`` instruction. * Support ISA of ``CMPCCXADD``. * Support ISA of ``AVX-IFMA``. * Support ISA of ``AVX-VNNI-INT8``. * Support ISA of ``AVX-NE-CONVERT``. * ``-mcpu=raptorlake``, ``-mcpu=meteorlake`` and ``-mcpu=emeraldrapids`` are now supported. * ``-mcpu=sierraforest``, ``-mcpu=graniterapids`` and ``-mcpu=grandridge`` are now supported. * ``__builtin_unpredictable`` (unpredictable metadata in LLVM IR), is handled by X86 Backend. ``X86CmovConversion`` pass now respects this builtin and does not convert CMOVs to branches. * Add support for the ``PBNDKB`` instruction. * Support ISA of ``SHA512``. * Support ISA of ``SM3``. * Support ISA of ``SM4``. * Support ISA of ``AVX-VNNI-INT16``. * ``-mcpu=graniterapids-d`` is now supported. * The ``i128`` type now matches GCC and clang's ``__int128`` type. This mainly benefits external projects such as Rust which aim to be binary compatible with C, but also fixes code generation where LLVM already assumed that the type matched and called into libgcc helper functions. * Support ISA of ``USER_MSR``. * Support ISA of ``AVX10.1-256`` and ``AVX10.1-512``. * ``-mcpu=pantherlake`` and ``-mcpu=clearwaterforest`` are now supported. * ``-mapxf`` is supported. * Marking global variables with ``code_model = "small"/"large"`` in the IR now overrides the global code model to allow 32-bit relocations or require 64-bit relocations to the global variable. * The medium code model's code generation was audited to be more similar to the small code model where possible. Changes to the OCaml bindings ----------------------------- Changes to the Python bindings ------------------------------ * The python bindings have been removed. Changes to the C API -------------------- * Added ``LLVMGetTailCallKind`` and ``LLVMSetTailCallKind`` to allow getting and setting ``tail``, ``musttail``, and ``notail`` attributes on call instructions. * 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: * ``LLVMConstAnd`` * ``LLVMConstOr`` * ``LLVMConstLShr`` * ``LLVMConstAShr`` * ``LLVMConstZExt`` * ``LLVMConstSExt`` * ``LLVMConstZExtOrBitCast`` * ``LLVMConstSExtOrBitCast`` * ``LLVMConstIntCast`` * ``LLVMConstFPTrunc`` * ``LLVMConstFPExt`` * ``LLVMConstFPToUI`` * ``LLVMConstFPToSI`` * ``LLVMConstUIToFP`` * ``LLVMConstSIToFP`` * ``LLVMConstFPCast`` * Added ``LLVMCreateTargetMachineWithOptions``, along with helper functions for an opaque option structure, as an alternative to ``LLVMCreateTargetMachine``. The option structure exposes an additional setting (i.e., the target ABI) and provides default values for unspecified settings. * Added ``LLVMGetNNeg`` and ``LLVMSetNNeg`` for getting/setting the new nneg flag on zext instructions, and ``LLVMGetIsDisjoint`` and ``LLVMSetIsDisjoint`` for getting/setting the new disjoint flag on or instructions. * Added the following functions for manipulating operand bundles, as well as building ``call`` and ``invoke`` instructions that use operand bundles: * ``LLVMBuildCallWithOperandBundles`` * ``LLVMBuildInvokeWithOperandBundles`` * ``LLVMCreateOperandBundle`` * ``LLVMDisposeOperandBundle`` * ``LLVMGetNumOperandBundles`` * ``LLVMGetOperandBundleAtIndex`` * ``LLVMGetNumOperandBundleArgs`` * ``LLVMGetOperandBundleArgAtIndex`` * ``LLVMGetOperandBundleTag`` * Added ``LLVMGetFastMathFlags`` and ``LLVMSetFastMathFlags`` for getting/setting the fast-math flags of an instruction, as well as ``LLVMCanValueUseFastMathFlags`` for checking if an instruction can use such flags Changes to the CodeGen infrastructure ------------------------------------- * A new debug type ``isel-dump`` is added to show only the SelectionDAG dumps after each ISel phase (i.e. ``-debug-only=isel-dump``). This new debug type can be filtered by function names using ``-filter-print-funcs=``, the same flag used to filter IR dumps after each Pass. Note that the existing ``-debug-only=isel`` will take precedence over the new behavior and print SelectionDAG dumps of every single function regardless of ``-filter-print-funcs``'s values. * ``PrologEpilogInserter`` no longer supports register scavenging during forwards frame index elimination. Targets should use backwards frame index elimination instead. * ``RegScavenger`` no longer supports forwards register scavenging. Clients should use backwards register scavenging instead, which is preferred because it does not depend on accurate kill flags. Changes to the Metadata Info --------------------------------- * Added a new loop metadata `!{!"llvm.loop.align", i32 64}` Changes to the Debug Info --------------------------------- Changes to the LLVM tools --------------------------------- * llvm-symbolizer now treats invalid input as an address for which source information is not found. * llvm-readelf now supports ``--extra-sym-info`` (``-X``) to display extra information (section name) when showing symbols. * ``llvm-readobj --elf-output-style=JSON`` no longer prefixes each JSON object with the file name. Previously, each object file's output looked like ``"main.o":{"FileSummary":{"File":"main.o"},...}`` but is now ``{"FileSummary":{"File":"main.o"},...}``. This allows each JSON object to be parsed in the same way, since each object no longer has a unique key. Tools that consume ``llvm-readobj``'s JSON output should update their parsers accordingly. * ``llvm-objdump`` now uses ``--print-imm-hex`` by default, which brings its default behavior closer in line with ``objdump``. * ``llvm-nm`` now supports the ``--line-numbers`` (``-l``) option to use debugging information to print symbols' filenames and line numbers. * llvm-symbolizer and llvm-addr2line now support addresses specified as symbol names. * llvm-objcopy now supports ``--gap-fill`` and ``--pad-to`` options, for ELF input and binary output files only. Changes to LLDB --------------------------------- * ``SBWatchpoint::GetHardwareIndex`` is deprecated and now returns -1 to indicate the index is unavailable. * Methods in SBHostOS related to threads have had their implementations removed. These methods will return a value indicating failure. * ``SBType::FindDirectNestedType`` function is added. It's useful for formatters to quickly find directly nested type when it's known where to search for it, avoiding more expensive global search via ``SBTarget::FindFirstType``. * ``lldb-vscode`` was renamed to ``lldb-dap`` and and its installation instructions have been updated to reflect this. The underlying functionality remains unchanged. * The ``mte_ctrl`` register can now be read from AArch64 Linux core files. * LLDB on AArch64 Linux now supports debugging the Scalable Matrix Extension (SME) and Scalable Matrix Extension 2 (SME2) for both live processes and core files. For details refer to the `AArch64 Linux documentation `_. * LLDB now supports symbol and binary acquisition automatically using the DEBUFINFOD protocol. The standard mechanism of specifying DEBUFINOD servers in the ``DEBUGINFOD_URLS`` environment variable is used by default. In addition, users can specify servers to request symbols from using the LLDB setting ``plugin.symbol-locator.debuginfod.server_urls``, override or adding to the environment variable. * When running on AArch64 Linux, ``lldb-server`` now provides register field information for the following registers: ``cpsr``, ``fpcr``, ``fpsr``, ``svcr`` and ``mte_ctrl``. :: (lldb) register read cpsr cpsr = 0x80001000 = (N = 1, Z = 0, C = 0, V = 0, SS = 0, IL = 0, <...> This is only available when ``lldb`` is built with XML support. Where possible the CPU's capabilities are used to decide which fields are present, however this is not always possible or entirely accurate. If in doubt, refer to the numerical value. Changes to Sanitizers --------------------- * HWASan now defaults to detecting use-after-scope bugs. Other Changes ------------- * The ``Flags`` field of ``llvm::opt::Option`` has been split into ``Flags`` and ``Visibility`` to simplify option sharing between various drivers (such as ``clang``, ``clang-cl``, or ``flang``) that rely on Clang's Options.td. Overloads of ``llvm::opt::OptTable`` that use ``FlagsToInclude`` have been deprecated. There is a script and instructions on how to resolve conflicts - see https://reviews.llvm.org/D157150 and https://reviews.llvm.org/D157151 for details. * On Linux, FreeBSD, and NetBSD, setting the environment variable ``LLVM_ENABLE_SYMBOLIZER_MARKUP`` causes tools to print stacktraces using :doc:`Symbolizer Markup `. This works even if the tools have no embedded symbol information (i.e. are fully stripped); :doc:`llvm-symbolizer ` can symbolize the markup afterwards using ``debuginfod``. External Open Source Projects Using LLVM 15 =========================================== * A project... Additional Information ====================== A wide variety of additional information is available on the `LLVM web page `_, in particular in the `documentation `_ 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 `_.