ReleaseNotes: add lld/ELF notes

[MaskRay]

Summary

For the release/14.x branch.

[MaskRay]

lld/docs/ReleaseNotes.rst

44

Note this archive thing to improve performance and simplify symbol resolution.

(Note: mold already did this)

48

Note this .symtab thing to facilitate parallelism.

102

The warning change has not been made yet.

[MaskRay]

lld/docs/ReleaseNotes.rst

82

Perhaps: .o files compiled with and without `-mtls-dialect=gnu2` can now be linked together.

[jhenderson]

Some wording comments. I haven't been following LLD closely enough to be able to identify whether anything should/should not be documented in the release notes that isn't/is here though.

lld/docs/ReleaseNotes.rst

39

44

Given that this is only a "may", I might recommend changing "in the next release" to "in a future release".

61

I would suggest "is now run in parallel" instead of "is now parallel".

67–68

82

I'd use "object" or "objects" instead of ".o", as I feel the ".o" shortening doesn't feel right given the rest of the sentence is full prose. Concrete suggestion:

"i.e. mixing objects compiled with and without -mtls-dialect=gnu2 is now supported."

102–103

Again, not locking into a specific release in case things change/get delayed.

[MaskRay]

thanks for the suggestions! applied

[jhenderson]

Looks good from a grammar point of view. I'll leave it to someone else for the technical side of things.

lld/docs/ReleaseNotes.rst

102–103

Any particular reason this hasn't been addressed (if you are 100% confident this is going in the next release, then it's fine, although I guess there's no guarantee that 15.0.0 will be the next release, if there's a sudden change in how LLVM versions things :-)

[MaskRay]

lld/docs/ReleaseNotes.rst

102–103

Thanks. https://reviews.llvm.org/D119108 has been pushed, so --[no-]define-common and -dp are definitely gone for 15.0.0 I'll keep the wording.

102–103

Forgot to push a comment I made several hours ago...

[MaskRay]

Pushed to release/14.x as https://github.com/llvm/llvm-project/commit/2f23d4b0ac0aba4629fa484264b4e5b52bf774ca
We can make incremental changes if needed.

lld/docs/ReleaseNotes.rst

 
 ELF Improvements
 ----------------
 
 * ``--export-dynamic-symbol-list`` has been added.
   (`D107317 <https://reviews.llvm.org/D107317>`_)
 * ``--why-extract`` has been added to query why archive members/lazy object files are extracted.
   (`D109572 <https://reviews.llvm.org/D109572>`_)
-* ``e_entry`` no longer falls back to the address of ``.text`` if the entry symbol does not exist.
-  Instead, a value of 0 will be written.
-  (`D110014 <https://reviews.llvm.org/D110014>`_)
 * If ``-Map`` is specified, ``--cref`` will be printed to the specified file.
   (`D114663 <https://reviews.llvm.org/D114663>`_)
+* ``-z bti-report`` and ``-z cet-report`` are now supported.
+  (`D113901 <https://reviews.llvm.org/D113901>`_)
+* ``--lto-pgo-warn-mismatch`` has been added.
+  (`D104431 <https://reviews.llvm.org/D104431>`_)
+* Archives without an index (symbol table) are now supported and work with
+  ``--warn-backrefs``. One may build such an archive with ``llvm-ar rcS
+  [--thin]`` to save space.
+  (`D117284 <https://reviews.llvm.org/D117284>`_)
+  The archive index may be `entirely ignored
+  <https://reviews.llvm.org/D119074>` in a future release.
 * No longer deduplicate local symbol names at the default optimization level of ``-O1``.
   This results in a larger ``.strtab`` (usually less than 1%) but a faster link
-  time. Use optimization level ``-O2`` to restore the deduplication.
+  time. Use optimization level ``-O2`` to restore the deduplication. The ``-O2``
+  deduplication may be dropped in the future to help parallel ``.symtab`` write.
+* In relocatable output, relocations to discarded symbols now use tombstone
+  values.
+  (`D116946 <https://reviews.llvm.org/D116946>`_)
+* Orphan section placement now picks a more suitable segment. Previously the
+  algorithm might pick a readonly segment for a writable orphan section and make
+  the segment writable.
+  (`D111717 <https://reviews.llvm.org/D111717>`_)
+* An empty output section moved by an ``INSERT`` comment now gets appropriate
+  flags.
+  (`D118529 <https://reviews.llvm.org/D118529>`_)
+* Negation in a memory region attribute is now correctly handled.
+  (`D113771 <https://reviews.llvm.org/D113771>`_)
+* ``--compress-debug-sections=zlib`` is now run in parallel. ``{clang,gcc} -gz`` link
+  actions are significantly faster.
+  (`D117853 <https://reviews.llvm.org/D117853>`_)
+* "relocation out of range" diagnostics and a few uncommon diagnostics
+  now report an object file location beside a source file location.
+  (`D112518 <https://reviews.llvm.org/D117853>`_)
+* The write of ``.rela.dyn`` and ``SHF_MERGE|SHF_STRINGS`` sections (e.g.
+  ``.debug_str``) is now run in parallel.
 
 Architecture specific changes:
 
+* The AArch64 port now supports adrp+ldr and adrp+add optimizations.
+  ``--no-relax`` can suppress the optimization.
+  (`D112063 <https://reviews.llvm.org/D112063>`_)
+  (`D117614 <https://reviews.llvm.org/D117614>`_)
 * The x86-32 port now supports TLSDESC (``-mtls-dialect=gnu2``).
   (`D112582 <https://reviews.llvm.org/D112582>`_)
 * The x86-64 port now handles non-RAX/non-adjacent ``R_X86_64_GOTPC32_TLSDESC``
   and ``R_X86_64_TLSDESC_CALL`` (``-mtls-dialect=gnu2``).
   (`D114416 <https://reviews.llvm.org/D114416>`_)
+* The x86-32 and x86-64 ports now support mixed TLSDESC and TLS GD, i.e. mixing
+  objects compiled with and without ``-mtls-dialect=gnu2`` referencing the same
+  TLS variable is now supported.
+  (`D114416 <https://reviews.llvm.org/D114416>`_)
 * For x86-64, ``--no-relax`` now suppresses ``R_X86_64_GOTPCRELX`` and
   ``R_X86_64_REX_GOTPCRELX`` GOT optimization
   (`D113615 <https://reviews.llvm.org/D113615>`_)
+* ``R_X86_64_PLTOFF64`` is now supported.
+  (`D112386 <https://reviews.llvm.org/D112386>`_)
+* ``R_AARCH64_NONE``, ``R_PPC_NONE``, and ``R_PPC64_NONE`` in input REL
+  relocation sections are now supported.
 
 Breaking changes
 ----------------
 
-* ...
+* ``e_entry`` no longer falls back to the address of ``.text`` if the entry symbol does not exist.
+  Instead, a value of 0 will be written.
+  (`D110014 <https://reviews.llvm.org/D110014>`_)
+* ``--lto-pseudo-probe-for-profiling`` has been removed. In LTO, the compiler
+  enables this feature automatically.
+  (`D110209 <https://reviews.llvm.org/D110209>`_)
+* Use of ``--[no-]define-common``, ``-d``, ``-dc``, and ``-dp`` will now get a
+  warning. They will be removed or ignored in 15.0.0.
+  (`llvm-project#53660 <https://github.com/llvm/llvm-project/issues/53660>`_)
 
 COFF Improvements
 -----------------
 
 * Correctly handle a signed immediate offset in ARM64 adr/adrp relocations.
   (`D114347 <https://reviews.llvm.org/D114347>`_)
 
 * Omit section and label symbols from the symbol table.