1d96e4bc2d
The current default, build-id=fast, is only 8 bytes due to the usage of
64-bit XXH3. This is incompatible with RPM packaging tools which
requires >=16 bytes [1].
In Clang the ENABLE_LINKER_BUILD_ID define makes it pass --build-id
without a specific hash type. When also defaulting to LLD, this provides
a pretty broken default out-of-box.
Using XXH3 was a considerable performance advantage when build-id was
first implemented, because sha1 was really sha1 and rather slow.
Nowadays sha1 is just 160-bit BLAKE3 which is decently fast and not
cryptographically broken, so it should be a good default.
Note that the default remains "fast" for wasm because sha1 for wasm is
still real sha1.
Close https://github.com/llvm/llvm-project/issues/43483.
[1]:
b7d427728b/build/files.c (L1883)
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===========================
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lld |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 |release| 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 lld linker, release |release|.
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Here we describe the status of lld, including major improvements
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from the previous release. All lld releases may be downloaded
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from the `LLVM releases web site <https://llvm.org/releases/>`_.
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Non-comprehensive list of changes in this release
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=================================================
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ELF Improvements
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----------------
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* ``--compress-sections <section-glib>={none,zlib,zstd}[:level]`` is added to compress
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matched output sections without the ``SHF_ALLOC`` flag.
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(`#84855 <https://github.com/llvm/llvm-project/pull/84855>`_)
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(`#90567 <https://github.com/llvm/llvm-project/pull/90567>`_)
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* The default compression level for zlib is now independent of linker
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optimization level (``Z_BEST_SPEED``).
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* ``GNU_PROPERTY_AARCH64_FEATURE_PAUTH`` notes, ``R_AARCH64_AUTH_ABS64`` and
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``R_AARCH64_AUTH_RELATIVE`` relocations are now supported.
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(`#72714 <https://github.com/llvm/llvm-project/pull/72714>`_)
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* ``--debug-names`` is added to create a merged ``.debug_names`` index
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from input ``.debug_names`` sections. Type units are not handled yet.
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(`#86508 <https://github.com/llvm/llvm-project/pull/86508>`_)
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* ``--enable-non-contiguous-regions`` option allows automatically packing input
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sections into memory regions by automatically spilling to later matches if a
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region would overflow. This reduces the toil of manually packing regions
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(typical for embedded). It also makes full LTO feasible in such cases, since
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IR merging currently prevents the linker script from referring to input
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files. (`#90007 <https://github.com/llvm/llvm-project/pull/90007>`_)
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* ``--force-group-allocation`` is implemented to discard ``SHT_GROUP`` sections
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and combine relocation sections if their relocated section group members are
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placed to the same output section.
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(`#94704 <https://github.com/llvm/llvm-project/pull/94704>`_)
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* ``--build-id`` now defaults to generating a 20-byte digest ("sha1") instead
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of 8-byte ("fast"). This improves compatibility with RPM packaging tools.
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(`#93943 <https://github.com/llvm/llvm-project/pull/93943>`_)
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Breaking changes
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----------------
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COFF Improvements
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-----------------
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MinGW Improvements
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------------------
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MachO Improvements
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------------------
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WebAssembly Improvements
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------------------------
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Fixes
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#####
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