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Differential D23695

Add a note that 3.9 is a major milestone for us.
ClosedPublic

Authored by ruiu on Aug 18 2016, 2:28 PM.

Details

Reviewers
emaste
davide
Commits
rG945a843fca8e: Add a note that 3.9 is a major milestone for us.
rL279260: Add a note that 3.9 is a major milestone for us.
Summary

Can you confirm that we are now able to link most FreeBSD userland
programs with LLD?

Diff Detail

Repository
rL LLVM

Event Timeline

ruiu updated this revision to Diff 68606.Aug 18 2016, 2:28 PM
ruiu retitled this revision from to Add a note that 3.9 is a major milestone for us..
ruiu updated this object.
ruiu added reviewers: emaste, davide.
ruiu added a subscriber: llvm-commits.
Herald added a subscriber: emaste. · View Herald TranscriptAug 18 2016, 2:28 PM
Eugene.Zelenko added a subscriber: Eugene.Zelenko.Aug 18 2016, 4:05 PM

It's worth to mention that LLVM/Clang/Extra-tools/Compiler-RT/Polly/LLD (but not LLDB) could be linked with LLD on RHEL (I tried on 6) on second stage.

I really would like to see build bot with this functionality.

ruiu updated this revision to Diff 68631.Aug 18 2016, 4:09 PM
  • add ", including LLVM/Clang/LLD themselves."
Eugene.Zelenko added a comment.Aug 18 2016, 4:13 PM

It may be worth to mention LLVM CMake LLVM_ENABLE_LLD option with will add -fuse-ld=lld to CMAKE_EXE_LINKER_FLAGS CMAKE_MODULE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS.

ruiu updated this revision to Diff 68633.Aug 18 2016, 4:29 PM
  • Add a note about LLVM_ENABLE_LLD CMake variable.
emaste edited edge metadata.Aug 19 2016, 3:03 AM

The statement about most userland components on FreeBSD is correct.

I've been testing against FreeBSD-HEAD, which contains a few general FreeBSD cleanups for improved lld compatibility. I couldn't link the rescue tools (a sort of busybox-like multi-binary) and I also had to tweak the version script for libcxxrt (due to issues with demangled symbol matching / wildcards).

The kernel and boot loader components don't link with 3.9.

docs/ReleaseNotes.rst
29–30 ↗(On Diff #68633)

This statement seems a little confusing. I think the point is that the new functionality doesn't come at the cost of performance, compared to earlier versions of LLD which were not usable for real-world linking. But that context is not apparent here for readers of the release note, who may be learning about LLD for the first time from the note.

davide edited edge metadata.Aug 19 2016, 7:51 AM

What Ed said makes sense to me. I have no strong opinion about the 2x faster than gold fact. If you want to back it up with real numbers, you can use the measurements I and Rafael got for our talk @BSDCan.

ruiu updated this revision to Diff 68689.Aug 19 2016, 8:07 AM
ruiu edited edge metadata.
  • removed a mention about speed
davide added a comment.Aug 19 2016, 8:28 AM

lgtm

Closed by commit rL279260: Add a note that 3.9 is a major milestone for us. (authored by ruiu). · Explain WhyAug 19 2016, 8:39 AM
This revision was automatically updated to reflect the committed changes.

Revision Contents

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lld/
branches/
release_39/
docs/
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Diff 68695

lld/branches/release_39/docs/ReleaseNotes.rst

Show All 10 Lines
This document contains the release notes for the LLD linker, release 3.9. This document contains the release notes for the LLD linker, release 3.9.
Here we describe the status of LLD, including major improvements Here we describe the status of LLD, including major improvements
from the previous release. All LLD releases may be downloaded from the previous release. All LLD releases may be downloaded
from the `LLVM releases web site <http://llvm.org/releases/>`_. from the `LLVM releases web site <http://llvm.org/releases/>`_.
What's new in ELF Support? What's new in ELF Support?
========================== ==========================
LLD 3.9 is a major milestone for us. It is the first release that can
link real-world large userland programs, including LLVM/Clang/LLD
themselves. In fact, for example, it can now be used to produce most
userland programs distributed as part of FreeBSD.
Many contributors have joined to the project to develop new features,
port it to new architectures and fix issues since the last release.
Link-Time Optimization Link-Time Optimization
---------------------- ----------------------
Initial support for LTO has been added. It is compatible with Initial support for LTO has been added. It is compatible with
`the LLVM gold plugin <http://llvm.org/docs/GoldPlugin.html>`_ in terms of `the LLVM gold plugin <http://llvm.org/docs/GoldPlugin.html>`_ in terms of
command line flags and input file format so that LLD is usable as a command line flags and input file format so that LLD is usable as a
drop-in replacement for GNU gold. LTO is implemented as a native drop-in replacement for GNU gold. LTO is implemented as a native
feature unlike the GNU gold's plugin mechanism. feature unlike the GNU gold's plugin mechanism.
▲ Show 20 Lines • Show All 51 Lines • ▼ Show 20 Lines
- Identical Code Folding option: ``-icf``. - Identical Code Folding option: ``-icf``.
Changes to the MIPS Target Changes to the MIPS Target
-------------------------- --------------------------
* Added support for MIPS N64 ABI. * Added support for MIPS N64 ABI.
* Added support for TLS relocations for both O32 and N64 MIPS ABIs. * Added support for TLS relocations for both O32 and N64 MIPS ABIs.
Building LLVM Toolchain with LLD
--------------------------------
A new CMake variable, ``LLVM_ENABLE_LLD``, has been added to use LLD
to build the LLVM toolchain. If the varaible is true, ``-fuse-ld=lld``
option will be added to linker flags so that ``ld.lld`` is used
instead of default ``ld``. Because ``-fuse-ld=lld`` is a new compiler
driver option, you need Clang 3.8 or newer to use the feature.