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=========================
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LLVM 11.0.0 Release Notes
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=========================
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.. contents::
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:local:
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.. warning::
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These are in-progress notes for the upcoming LLVM 11 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 11.0.0. 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 `LLVM Developer's Mailing List
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<https://lists.llvm.org/mailman/listinfo/llvm-dev>`_ is a good place to send
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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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.. NOTE
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If you would like to document a larger change, then you can add a
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subsection about it right here. You can copy the following boilerplate
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and un-indent it (the indentation causes it to be inside this comment).
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Special New Feature
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-------------------
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Makes programs 10x faster by doing Special New Thing.
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Changes to the LLVM IR
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----------------------
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* The callsite attribute `vector-function-abi-variant
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<https://llvm.org/docs/LangRef.html#call-site-attributes>`_ has been
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added to describe the mapping between scalar functions and vector
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functions, to enable vectorization of call sites. The information
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provided by the attribute is interfaced via the API provided by the
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``VFDatabase`` class.
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* `dereferenceable` attributes and metadata on pointers no longer imply
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anything about the alignment of the pointer in question. Previously, some
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optimizations would make assumptions based on the type of the pointer. This
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behavior was undocumented. To preserve optimizations, frontends may need to
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be updated to generate appropriate `align` attributes and metadata.
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* The DIModule metadata is extended to contain file and line number
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information. This information is used to represent Fortran modules debug
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info at IR level.
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Changes to building LLVM
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------------------------
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Changes to the ARM Backend
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--------------------------
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During this release ...
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* Implemented C-language intrinsics for the full Arm v8.1-M MVE instruction
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set. ``<arm_mve.h>`` now supports the complete API defined in the Arm C
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Language Extensions.
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* Added support for assembly for the optional Custom Datapath Extension (CDE)
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for Arm M-profile targets.
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* Implemented C-language intrinsics ``<arm_cde.h>`` for the CDE instruction set.
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* Clang now defaults to ``-fomit-frame-pointer`` when targeting non-Android
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Linux for arm and thumb when optimizations are enabled. Users that were
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previously not specifying a value and relying on the implicit compiler
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default may wish to specify ``-fno-omit-frame-pointer`` to get the old
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behavior. This improves compatibility with GCC.
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Changes to the MIPS Target
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--------------------------
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During this release ...
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Changes to the PowerPC Target
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-----------------------------
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During this release ...
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Changes to the X86 Target
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-------------------------
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During this release ...
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* Functions with the probe-stack attribute set to "inline-asm" are now protected
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against stack clash without the need of a third-party probing function and
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with limited impact on performance.
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* -x86-enable-old-knl-abi command line switch has been removed. v32i16/v64i8
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vectors are always passed in ZMM register when avx512f is enabled and avx512bw
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is disabled.
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* Vectors larger than 512 bits with i16 or i8 elements will be passed in
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multiple ZMM registers when avx512f is enabled. Previously this required
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avx512bw otherwise they would split into multiple YMM registers. This means
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vXi16/vXi8 vectors are consistently treated the same as
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vXi32/vXi64/vXf64/vXf32 vectors of the same total width.
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Changes to the AMDGPU Target
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-----------------------------
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* The backend default denormal handling mode has been switched to on
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for all targets for all compute function types. Frontends wishing to
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retain the old behavior should explicitly request f32 denormal
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flushing.
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Changes to the AVR Target
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-----------------------------
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* Moved from an experimental backend to an official backend. AVR support is now
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included by default in all LLVM builds and releases and is available under
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the "avr-unknown-unknown" target triple.
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Changes to the WebAssembly Target
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---------------------------------
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During this release ...
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Changes to the OCaml bindings
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-----------------------------
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Changes to the C API
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--------------------
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Changes to the Go bindings
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--------------------------
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Changes to the DAG infrastructure
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---------------------------------
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Changes to the Debug Info
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---------------------------------
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* LLVM now supports the debug entry values (DW_OP_entry_value) production for
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the x86, ARM, and AArch64 targets by default. Other targets can use
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the utility by using the experimental option ("-debug-entry-values").
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This is a debug info feature that allows debuggers to recover the value of
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optimized-out parameters by going up a stack frame and interpreting the values
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passed to the callee. The feature improves the debugging user experience when
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debugging optimized code.
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Changes to the LLVM tools
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---------------------------------
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* Added an option (--show-section-sizes) to llvm-dwarfdump to show the sizes
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of all debug sections within a file.
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Changes to LLDB
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===============
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External Open Source Projects Using LLVM 11
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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 `mailing lists <https://llvm.org/docs/#mailing-lists>`_.
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