lld/docs/ReleaseNotes.rst

===========================
lld |release| Release Notes
===========================

.. contents::
    :local:

.. only:: PreRelease

  .. warning::
     These are in-progress notes for the upcoming LLVM |release| release.
     Release notes for previous releases can be found on
     `the Download Page <https://releases.llvm.org/download.html>`_.

Introduction
============

This document contains the release notes for the lld linker, release |release|.
Here we describe the status of lld, including major improvements
from the previous release. All lld releases may be downloaded
from the `LLVM releases web site <https://llvm.org/releases/>`_.

Non-comprehensive list of changes in this release
=================================================

ELF Improvements
----------------

* Link speed improved greatly compared with lld 15.0. Notably input section
  initialization and relocation scanning are now parallel.
  (`D130810 <https://reviews.llvm.org/D130810>`_)
  (`D133003 <https://reviews.llvm.org/D133003>`_)
* ``ELFCOMPRESS_ZSTD`` compressed input sections are now supported.
  (`D129406 <https://reviews.llvm.org/D129406>`_)
* ``--compress-debug-sections=zstd`` is now available to compress debug
  sections with zstd (``ELFCOMPRESS_ZSTD``).
  (`D133548 <https://reviews.llvm.org/D133548>`_)
* ``--no-warnings``/``-w`` is now available to suppress warnings.
  (`D136569 <https://reviews.llvm.org/D136569>`_)
* ``DT_RISCV_VARIANT_CC`` is now produced if at least one ``R_RISCV_JUMP_SLOT``
  relocation references a symbol with the ``STO_RISCV_VARIANT_CC`` bit.
  (`D107951 <https://reviews.llvm.org/D107951>`_)
* ``DT_STATIC_TLS`` is now set for AArch64/PPC32/PPC64 initial-exec TLS models
  when producing a shared object.
* ``--no-undefined-version`` is now the default; symbols named in version
  scripts that have no matching symbol in the output will be reported. Use
  ``--undefined-version`` to revert to the old behavior.
  (`D135402 <https://reviews.llvm.org/D135402>`_)
* ``-V`` is now an alias for ``-v`` to support ``gcc -fuse-ld=lld -v`` on many targets.
* ``-r`` no longer defines ``__global_pointer$`` or ``_TLS_MODULE_BASE_``.
* A corner case of mixed GCC and Clang object files (``STB_WEAK`` and
  ``STB_GNU_UNIQUE`` in different COMDATs) is now supported.
  (`D136381 <https://reviews.llvm.org/D136381>`_)
* The output ``SHT_RISCV_ATTRIBUTES`` section now merges all input components
  instead of picking the first input component.
  (`D138550 <https://reviews.llvm.org/D138550>`_)
* For x86-32, ``-fno-plt`` GD/LD TLS models ``call *___tls_get_addr@GOT(%reg)``
  are now supported. Previous output might have runtime crash.
* Armv4(T) thunks are now supported.
  (`D139888 <https://reviews.llvm.org/D139888>`_)
  (`D141272 <https://reviews.llvm.org/D141272>`_)

Breaking changes
----------------

COFF Improvements
-----------------

* The linker command line entry in ``S_ENVBLOCK`` of the PDB is now stripped
  from input files, to align with MSVC behavior.
  (`D137723 <https://reviews.llvm.org/D137723>`_)
* Switched from SHA1 to BLAKE3 for PDB type hashing / ``-gcodeview-ghash``
  (`D137101 <https://reviews.llvm.org/D137101>`_)
* Improvements to the PCH.OBJ files handling. Now LLD behaves the same as MSVC
  link.exe when merging PCH.OBJ files that don't have the same signature.
  (`D136762 <https://reviews.llvm.org/D136762>`_)
* Changed the OrdinalBase for DLLs from 0 to 1, matching the output from
  both MS link.exe and GNU ld. (`D134140 <https://reviews.llvm.org/D134140>`_)

MinGW Improvements
------------------

* The lld-specific options ``--guard-cf``, ``--no-guard-cf``,
  ``--guard-longjmp`` and ``--no-guard-longjmp`` has been added to allow
  enabling Control Flow Guard and long jump hardening. These options are
  disabled by default, but enabling ``--guard-cf`` will also enable
  ``--guard-longjmp`` unless ``--no-guard-longjmp`` is also specified.
  ``--guard-longjmp`` depends on ``--guard-cf`` and cannot be used by itself.
  Note that these features require the ``_load_config_used`` symbol to contain
  the load config directory and be filled with the required symbols.
  (`D132808 <https://reviews.llvm.org/D132808>`_)

* Pick up libraries named ``<name>.lib`` when linked with ``-l<name>``, even
  if ``-static`` has been specified. This fixes conformance to what
  GNU ld does. (`D135651 <https://reviews.llvm.org/D135651>`_)

* Unwinding in Rust code on i386 in MinGW builds has been fixed, by avoiding
  to leave out the ``rust_eh_personality`` symbol.
  (`D136879 <https://reviews.llvm.org/D136879>`_)

MachO Improvements
------------------

WebAssembly Improvements
------------------------