llvm-project/lld/docs/ReleaseNotes.rst

========================
lld 13.0.0 Release Notes
========================

.. contents::
    :local:

.. warning::
   These are in-progress notes for the upcoming LLVM 13.0.0 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 13.0.0.
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
----------------

* ``-Bsymbolic -Bsymbolic-functions`` has been changed to behave the same as ``-Bsymbolic-functions``. This matches GNU ld.
  (`D102461 <https://reviews.llvm.org/D102461>`_)
* ``-Bno-symbolic`` has been added.
  (`D102461 <https://reviews.llvm.org/D102461>`_)
* A new linker script command ``OVERWRITE_SECTIONS`` has been added.
  (`D103303 <https://reviews.llvm.org/D103303>`_)

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

* ``--shuffle-sections=<seed>`` has been changed to ``--shuffle-sections=<section-glob>=<seed>``.
  Specify ``*`` as ``<section-glob>`` to get the previous behavior.

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

* ...

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

* ...

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

* Item 1.

WebAssembly Improvements
------------------------
Bump the trunk version to 10.0.0svn and clear the release notes. llvm-svn: 366427 2019-07-18 19:51:05 +08:00			`========================`
Bump the trunk major version to 13 and clear the release notes. 2021-01-27 11:37:08 +08:00			`lld 13.0.0 Release Notes`
Bump the trunk version to 10.0.0svn and clear the release notes. llvm-svn: 366427 2019-07-18 19:51:05 +08:00			`========================`
Start adding release notes for lld. llvm-svn: 260960 2016-02-16 21:12:55 +08:00
			`.. contents::`
			`:local:`

			`.. warning::`
Bump the trunk major version to 13 and clear the release notes. 2021-01-27 11:37:08 +08:00			`These are in-progress notes for the upcoming LLVM 13.0.0 release.`
Don't try to link to the 4.0 release notes llvm-svn: 294659 2017-02-10 07:27:17 +08:00			`Release notes for previous releases can be found on`
ReleaseNotes: update links to use https llvm-svn: 341788 2018-09-10 16:52:31 +08:00			`the Download Page <https://releases.llvm.org/download.html>`_.
Start adding release notes for lld. llvm-svn: 260960 2016-02-16 21:12:55 +08:00
			`Introduction`
			`============`

Bump the trunk major version to 13 and clear the release notes. 2021-01-27 11:37:08 +08:00			`This document contains the release notes for the lld linker, release 13.0.0.`
ReleaseNotes: user lower-case for lld in the text llvm-svn: 325869 2018-02-23 16:27:38 +08:00			`Here we describe the status of lld, including major improvements`
			`from the previous release. All lld releases may be downloaded`
ReleaseNotes: update links to use https llvm-svn: 341788 2018-09-10 16:52:31 +08:00			from the `LLVM releases web site <https://llvm.org/releases/>`_.
Start adding release notes for lld. llvm-svn: 260960 2016-02-16 21:12:55 +08:00
			`Non-comprehensive list of changes in this release`
			`=================================================`

			`ELF Improvements`
			`----------------`

[ELF] Add -Bno-symbolic This option will be available in GNU ld 2.27 (https://sourceware.org/bugzilla/show_bug.cgi?id=27834). This option can cancel previously specified -Bsymbolic and -Bsymbolic-functions. This is useful for excluding some links when the default uses -Bsymbolic-functions. Reviewed By: jhenderson, peter.smith Differential Revision: https://reviews.llvm.org/D102383 2021-05-15 00:40:32 +08:00			* ``-Bsymbolic -Bsymbolic-functions`` has been changed to behave the same as ``-Bsymbolic-functions``. This matches GNU ld.
			(`D102461 <https://reviews.llvm.org/D102461>`_)
			* ``-Bno-symbolic`` has been added.
			(`D102461 <https://reviews.llvm.org/D102461>`_)
[ELF] Add OVERWRITE_SECTIONS command This implements https://sourceware.org/bugzilla/show_bug.cgi?id=26404 An `OVERWRITE_SECTIONS` command is a `SECTIONS` variant which contains several output section descriptions. The output sections do not have specify an order. Similar to `INSERT [BEFORE\|AFTER]`, `LinkerScript::hasSectionsCommand` is not set, so the built-in rules (see `docs/ELF/linker_script.rst`) still apply. `OVERWRITE_SECTIONS` can be more convenient than `INSERT` because it does not need an anchor section. The initial syntax is intentionally narrow to facilitate backward compatible extensions in the future. Symbol assignments cannot be used. This feature is versatile. To list a few usage: * Use `section : { KEEP(...) }` to retain input sections under GC * Define encapsulation symbols (start/end) for an output section * Use `section : ALIGN(...) : { ... }` to overalign an output section (similar to ld64 `-sectalign`) When an output section is specified by both `OVERWRITE_SECTIONS` and `INSERT`, `INSERT` is processed after overwrite sections. To make this work, this patch changes `InsertCommand` to use name based matching instead of pointer based matching. (This may cause a difference when `INSERT` moves one output section more than once. Such duplicate commands should not be used in practice (seems that in GNU ld the output sections may just disappear).) A linker script can be used without -T/--script. The traditional `SECTIONS` commands are concatenated, so a wrong rule can be more noticeable from the section order. This feature if misused can be less noticeable, just like `INSERT`. Differential Revision: https://reviews.llvm.org/D103303 2021-06-14 03:41:11 +08:00			* A new linker script command ``OVERWRITE_SECTIONS`` has been added.
			(`D103303 <https://reviews.llvm.org/D103303>`_)
Update release notes. llvm-svn: 342754 2018-09-22 01:48:45 +08:00
[ELF] Add convenience TableGen classes to enforce two dashes for options not supported by GNU ld Announced on https://lists.llvm.org/pipermail/llvm-dev/2020-May/141416.html For many options, we have to support either one or two dash to be compatible with GNU ld. For newer and lld specific options, we can enforce strict double dashes. Affected options: * --thinlto-* * --lto-* * --shuffle-sections= This patch does not change `-plugin-opt=` because clang driver passes `-plugin-opt=` and I don't intend to cause churn. In 2000, GNU ld tried something similar with --omagic https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=e4897a3288f37d5f69e8acd256a6e83e607fe8d8 Reviewed By: tejohnson, psmith Differential Revision: https://reviews.llvm.org/D79371 2020-05-05 05:42:36 +08:00			`Breaking changes`
			`----------------`

[ELF] Change --shuffle-sections=<seed> to --shuffle-sections=<section-glob>=<seed> `--shuffle-sections=<seed>` applies to all sections. The new `--shuffle-sections=<section-glob>=<seed>` makes shuffling selective. To the best of my knowledge, the option is only used as debugging, so just drop the original form. `--shuffle-sections '.init_array=-1'` `--shuffle-sections '.fini_array=-1'`. reverses static constructors/destructors of the same priority. Useful to detect some static initialization order fiasco. `--shuffle-sections '.data=-1'` reverses `.data` sections. Useful to detect unfunded pointer comparison results of two unrelated objects. If certain sections have an intrinsic order, the old form cannot be used. Differential Revision: https://reviews.llvm.org/D98679 2021-03-19 01:18:19 +08:00			* ``--shuffle-sections=<seed>`` has been changed to ``--shuffle-sections=<section-glob>=<seed>``.
			Specify ``*`` as ``<section-glob>`` to get the previous behavior.
[ELF] Add convenience TableGen classes to enforce two dashes for options not supported by GNU ld Announced on https://lists.llvm.org/pipermail/llvm-dev/2020-May/141416.html For many options, we have to support either one or two dash to be compatible with GNU ld. For newer and lld specific options, we can enforce strict double dashes. Affected options: * --thinlto-* * --lto-* * --shuffle-sections= This patch does not change `-plugin-opt=` because clang driver passes `-plugin-opt=` and I don't intend to cause churn. In 2000, GNU ld tried something similar with --omagic https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=e4897a3288f37d5f69e8acd256a6e83e607fe8d8 Reviewed By: tejohnson, psmith Differential Revision: https://reviews.llvm.org/D79371 2020-05-05 05:42:36 +08:00
Start adding release notes for lld. llvm-svn: 260960 2016-02-16 21:12:55 +08:00			`COFF Improvements`
			`-----------------`

Bump the trunk version to 9.0.0svn llvm-svn: 351320 2019-01-16 18:57:02 +08:00			`* ...`
[docs] Mention some notable feature in the release notes Differential Revision: https://reviews.llvm.org/D52908 llvm-svn: 343878 2018-10-06 03:43:20 +08:00
			`MinGW Improvements`
			`------------------`

Bump the trunk version to 10.0.0svn and clear the release notes. llvm-svn: 366427 2019-07-18 19:51:05 +08:00			`* ...`
[docs] Mention some notable feature in the release notes Differential Revision: https://reviews.llvm.org/D52908 llvm-svn: 343878 2018-10-06 03:43:20 +08:00
Start adding release notes for lld. llvm-svn: 260960 2016-02-16 21:12:55 +08:00			`MachO Improvements`
			`------------------`

			`* Item 1.`
[WebAssembly] Initial support for shared objects (-shared) Based on the initial spec proposal: https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md The llvm/codegen side of this is still missing but I believe this change is still worth landing as an incremental step Differential Revision: https://reviews.llvm.org/D54249 llvm-svn: 346918 2018-11-15 08:37:21 +08:00
			`WebAssembly Improvements`
			`------------------------`