llvm-project/lld/docs/ReleaseNotes.rst

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===========================
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
----------------
* ``-z pack-relative-relocs`` is now available to support ``DT_RELR`` for glibc 2.36+.
(`D120701 <https://reviews.llvm.org/D120701>`_)
* ``--no-fortran-common`` (pre 12.0.0 behavior) is now the default.
* ``FORCE_LLD_DIAGNOSTICS_CRASH`` environment variable is now available to force LLD to crash.
(`D128195 <https://reviews.llvm.org/D128195>`_)
Breaking changes
----------------
* The GNU ld incompatible ``--no-define-common`` has been removed.
* The obscure ``-dc``/``-dp`` options have been removed.
* ``-d`` is now ignored.
* If a prevailing COMDAT group defines STB_WEAK symbol, having a STB_GLOBAL symbol in a non-prevailing group is now rejected with a diagnostic.
(`D120626 <https://reviews.llvm.org/D120626>`_)
* Support for the legacy ``.zdebug`` format has been removed. Run
``objcopy --decompress-debug-sections`` in case old object files use ``.zdebug``.
(`D126793 <https://reviews.llvm.org/D126793>`_)
* ``--time-trace-file=<file>`` has been removed.
Use ``--time-trace=<file>`` instead.
(`D128451 <https://reviews.llvm.org/D128451>`_)
COFF Improvements
-----------------
* Added autodetection of MSVC toolchain, a la clang-cl. Also added
``/winsysroot:`` support for explicit specification of MSVC toolchain
location, similar to clang-cl's ``/winsysroot``. For now,
``/winsysroot:`` requires also passing in an explicit ``/machine:`` flag.
(`D118070 <https://reviews.llvm.org/D118070>`_)
* ...
MinGW Improvements
------------------
* ...
MachO Improvements
------------------
* We now support proper relocation and pruning of EH frames. **Note:** this
comes at some performance overhead on x86_64 builds, and we recommend adding
the ``-femit-compact-unwind=no-compact-unwind`` compile flag to avoid it.
(`D129540 <https://reviews.llvm.org/D129540>`_,
`D122258 <https://reviews.llvm.org/D122258>`_)
WebAssembly Improvements
------------------------