0c3704fdbd
The deduplication requires a DenseMap of the same size of the local part of .strtab . I optimized it in e20544543478b259eb09fa0a253d4fb1a5525d9e but it is still quite slow. For Release build of clang, deduplication makes .strtab 1.1% smaller and makes the link 3% slower. For chrome, deduplication makes .strtab 0.1% smaller and makes the link 6% slower. I suggest that we only perform the optimization with -O2 (default is -O1). Not deduplicating local symbol names will simplify parallel symbol table write. Reviewed By: peter.smith Differential Revision: https://reviews.llvm.org/D118577
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========================
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lld 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 14.0.0 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 14.0.0.
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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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* ``--export-dynamic-symbol-list`` has been added.
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(`D107317 <https://reviews.llvm.org/D107317>`_)
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* ``--why-extract`` has been added to query why archive members/lazy object files are extracted.
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(`D109572 <https://reviews.llvm.org/D109572>`_)
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* ``e_entry`` no longer falls back to the address of ``.text`` if the entry symbol does not exist.
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Instead, a value of 0 will be written.
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(`D110014 <https://reviews.llvm.org/D110014>`_)
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* If ``-Map`` is specified, ``--cref`` will be printed to the specified file.
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(`D114663 <https://reviews.llvm.org/D114663>`_)
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* No longer deduplicate local symbol names at the default optimization level of ``-O1``.
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This results in a larger ``.strtab`` (usually less than 1%) but a faster link
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time. Use optimization level ``-O2`` to restore the deduplication.
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Architecture specific changes:
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* The x86-32 port now supports TLSDESC (``-mtls-dialect=gnu2``).
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(`D112582 <https://reviews.llvm.org/D112582>`_)
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* The x86-64 port now handles non-RAX/non-adjacent ``R_X86_64_GOTPC32_TLSDESC``
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and ``R_X86_64_TLSDESC_CALL`` (``-mtls-dialect=gnu2``).
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(`D114416 <https://reviews.llvm.org/D114416>`_)
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* For x86-64, ``--no-relax`` now suppresses ``R_X86_64_GOTPCRELX`` and
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``R_X86_64_REX_GOTPCRELX`` GOT optimization
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(`D113615 <https://reviews.llvm.org/D113615>`_)
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Breaking changes
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----------------
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* ...
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COFF Improvements
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-----------------
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* ...
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MinGW Improvements
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------------------
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* ...
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MachO Improvements
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------------------
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* Item 1.
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WebAssembly Improvements
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------------------------
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