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Addresses on AArch64 can have top byte tags, memory tags and pointer authentication signatures in the upper bits. While testing memory tagging I found that memory read couldn't read a range if the two addresses had different tags. The same could apply to signed pointers given the right circumstance. (lldb) memory read mte_buf_alt_tag mte_buf+16 error: end address (0x900fffff7ff8010) must be greater than the start address (0xa00fffff7ff8000). Or it would try to read a lot more memory than expected. (lldb) memory read mte_buf mte_buf_alt_tag+16 error: Normally, 'memory read' will not read over 1024 bytes of data. error: Please use --force to override this restriction just once. error: or set target.max-memory-read-size if you will often need a larger limit. Fix this by removing non address bits before we calculate the read range. A test is added for AArch64 Linux that confirms this by using the top byte ignore feature. This means that if you do read with a tagged pointer the output does not include those tags. This is potentially confusing but I think overall it's better that we don't pretend that we're reading memory from a range that the process is unable to map. (lldb) p ptr1 (char *) $4 = 0x3400fffffffff140 "\x80\xf1\xff\xff\xff\xff" (lldb) p ptr2 (char *) $5 = 0x5600fffffffff140 "\x80\xf1\xff\xff\xff\xff" (lldb) memory read ptr1 ptr2+16 0xfffffffff140: 80 f1 ff ff ff ff 00 00 38 70 bc f7 ff ff 00 00 ........8p...... Reviewed By: omjavaid, danielkiss Differential Revision: https://reviews.llvm.org/D103626
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=========================
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LLVM 14.0.0 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 14 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 14.0.0. 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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.. 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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* ...
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Changes to the LLVM IR
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----------------------
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* Using the legacy pass manager for the optimization pipeline is deprecated and
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will be removed after LLVM 14. In the meantime, only minimal effort will be
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made to maintain the legacy pass manager for the optimization pipeline.
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* Max allowed integer type was reduced from 2^24-1 bits to 2^23 bits.
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* Max allowed alignment was increased from 2^29 to 2^32.
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Changes to building LLVM
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------------------------
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* ...
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Changes to TableGen
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-------------------
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Changes to the AArch64 Backend
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------------------------------
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* Added support for the Armv9-A, Armv9.1-A and Armv9.2-A architectures.
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* The compiler now recognises the "tune-cpu" function attribute to support
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the use of the -mtune frontend flag. This allows certain scheduling features
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and optimisations to be enabled independently of the architecture. If the
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"tune-cpu" attribute is absent it tunes according to the "target-cpu".
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Changes to the ARM Backend
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--------------------------
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* Added support for the Armv9-A, Armv9.1-A and Armv9.2-A architectures.
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* Added support for the Armv8.1-M PACBTI-M extension.
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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 Hexagon Target
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-----------------------------
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* ...
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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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* Support for ``AVX512-FP16`` instructions has been added.
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Changes to the AMDGPU Target
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-----------------------------
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During this release ...
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Changes to the AVR Target
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-----------------------------
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During this release ...
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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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* ``LLVMSetInstDebugLocation`` has been deprecated in favor of the more general
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``LLVMAddMetadataToInst``.
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Changes to the Go bindings
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--------------------------
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Changes to the FastISel infrastructure
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--------------------------------------
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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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During this release ...
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Changes to the LLVM tools
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---------------------------------
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* llvm-cov: `-name-allowlist` is now accepted in addition to `-name-whitelist`.
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`-name-whitelist` is marked as deprecated and to be removed in future
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releases.
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Changes to LLDB
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---------------------------------
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* A change in Clang's type printing has changed the way LLDB names array types
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(from ``int [N]`` to ``int[N]``) - LLDB pretty printer type name matching
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code may need to be updated to handle this.
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* The ``memory read`` command now ignores non-address bits in start and end
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addresses. In addition, non-address bits will not be shown in the addresses
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in the output.
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Changes to Sanitizers
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---------------------
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External Open Source Projects Using LLVM 14
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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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