dfeb3991fb
It is now translated to `<1 x i64>`, which allows the removal of a bunch of special casing. This _incompatibly_ changes the ABI of any LLVM IR function with `x86_mmx` arguments or returns: instead of passing in mmx registers, they will now be passed via integer registers. However, the real-world incompatibility caused by this is expected to be minimal, because Clang never uses the x86_mmx type -- it lowers `__m64` to either `<1 x i64>` or `double`, depending on ABI. This change does _not_ eliminate the SelectionDAG `MVT::x86mmx` type. That type simply no longer corresponds to an IR type, and is used only by MMX intrinsics and inline-asm operands. Because SelectionDAGBuilder only knows how to generate the operands/results of intrinsics based on the IR type, it thus now generates the intrinsics with the type MVT::v1i64, instead of MVT::x86mmx. We need to fix this before the DAG LegalizeTypes, and thus have the X86 backend fix them up in DAGCombine. (This may be a short-lived hack, if all the MMX intrinsics can be removed in upcoming changes.) Works towards issue #98272.
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============================
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LLVM |release| Release Notes
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============================
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.. contents::
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:local:
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.. only:: PreRelease
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.. warning::
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These are in-progress notes for the upcoming LLVM |version| release.
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Release notes for previous releases can be found on
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`the Download Page <https://releases.llvm.org/download.html>`_.
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Introduction
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============
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This document contains the release notes for the LLVM Compiler Infrastructure,
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release |release|. Here we describe the status of LLVM, including major improvements
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from the previous release, improvements in various subprojects of LLVM, and
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some of the current users of the code. All LLVM releases may be downloaded
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from the `LLVM releases web site <https://llvm.org/releases/>`_.
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For more information about LLVM, including information about the latest
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release, please check out the `main LLVM web site <https://llvm.org/>`_. If you
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have questions or comments, the `Discourse forums
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<https://discourse.llvm.org>`_ is a good place to ask
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them.
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Note that if you are reading this file from a Git checkout or the main
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LLVM web page, this document applies to the *next* release, not the current
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one. To see the release notes for a specific release, please see the `releases
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page <https://llvm.org/releases/>`_.
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Non-comprehensive list of changes in this release
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=================================================
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.. NOTE
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For small 1-3 sentence descriptions, just add an entry at the end of
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this list. If your description won't fit comfortably in one bullet
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point (e.g. maybe you would like to give an example of the
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functionality, or simply have a lot to talk about), see the `NOTE` below
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for adding a new subsection.
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* ...
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Update on required toolchains to build LLVM
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-------------------------------------------
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Changes to the LLVM IR
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----------------------
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* The ``x86_mmx`` IR type has been removed. It will be translated to
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the standard vector type ``<1 x i64>`` in bitcode upgrade.
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Changes to LLVM infrastructure
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------------------------------
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Changes to building LLVM
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------------------------
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Changes to TableGen
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-------------------
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Changes to Interprocedural Optimizations
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----------------------------------------
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Changes to the AArch64 Backend
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------------------------------
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* `.balign N, 0`, `.p2align N, 0`, `.align N, 0` in code sections will now fill
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the required alignment space with a sequence of `0x0` bytes (the requested
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fill value) rather than NOPs.
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Changes to the AMDGPU Backend
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-----------------------------
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Changes to the ARM Backend
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--------------------------
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* `.balign N, 0`, `.p2align N, 0`, `.align N, 0` in code sections will now fill
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the required alignment space with a sequence of `0x0` bytes (the requested
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fill value) rather than NOPs.
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Changes to the AVR Backend
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--------------------------
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Changes to the DirectX Backend
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------------------------------
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Changes to the Hexagon Backend
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------------------------------
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Changes to the LoongArch Backend
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--------------------------------
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Changes to the MIPS Backend
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---------------------------
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Changes to the PowerPC Backend
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------------------------------
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Changes to the RISC-V Backend
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-----------------------------
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* `.balign N, 0`, `.p2align N, 0`, `.align N, 0` in code sections will now fill
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the required alignment space with a sequence of `0x0` bytes (the requested
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fill value) rather than NOPs.
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Changes to the WebAssembly Backend
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----------------------------------
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Changes to the Windows Target
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-----------------------------
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Changes to the X86 Backend
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--------------------------
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* `.balign N, 0x90`, `.p2align N, 0x90`, and `.align N, 0x90` in code sections
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now fill the required alignment space with repeating `0x90` bytes, rather than
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using optimised NOP filling. Optimised NOP filling fills the space with NOP
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instructions of various widths, not just those that use the `0x90` byte
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encoding. To use optimised NOP filling in a code section, leave off the
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"fillval" argument, i.e. `.balign N`, `.p2align N` or `.align N` respectively.
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* Due to the removal of the ``x86_mmx`` IR type, functions with
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``x86_mmx`` arguments or return values will use a different,
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incompatible, calling convention ABI. Such functions are not
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generally seen in the wild (Clang never generates them!), so this is
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not expected to result in real-world compatibility problems.
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Changes to the OCaml bindings
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-----------------------------
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Changes to the Python bindings
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------------------------------
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Changes to the C API
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--------------------
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* The following symbols are deleted due to the removal of the ``x86_mmx`` IR type:
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* ``LLVMX86_MMXTypeKind``
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* ``LLVMX86MMXTypeInContext``
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* ``LLVMX86MMXType``
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Changes to the CodeGen infrastructure
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-------------------------------------
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Changes to the Metadata Info
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---------------------------------
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Changes to the Debug Info
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---------------------------------
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Changes to the LLVM tools
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---------------------------------
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Changes to LLDB
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---------------------------------
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Changes to BOLT
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---------------------------------
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Changes to Sanitizers
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---------------------
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Other Changes
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-------------
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External Open Source Projects Using LLVM 19
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===========================================
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* A project...
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Additional Information
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======================
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A wide variety of additional information is available on the `LLVM web page
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<https://llvm.org/>`_, in particular in the `documentation
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<https://llvm.org/docs/>`_ section. The web page also contains versions of the
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API documentation which is up-to-date with the Git version of the source
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code. You can access versions of these documents specific to this release by
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going into the ``llvm/docs/`` directory in the LLVM tree.
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If you have any questions or comments about LLVM, please feel free to contact
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us via the `Discourse forums <https://discourse.llvm.org>`_.
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