[llvm-dev] LLVM Weekly - #94, Oct 19th 2015

Alex Bradbury via llvm-dev
Mon, 19 Oct 2015 10:49:47 -0000

LLVM Weekly - #94, Oct 19th 2015
===============================
If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/94>.

Welcome to the ninety-fourth issue of LLVM Weekly, a weekly newsletter
(published every Monday) covering developments in LLVM, Clang, and related
projects. LLVM Weekly is brought to you by [Alex
Bradbury](http://asbradbury.org). Subscribe to future issues at
<http://llvmweekly.org> and pass it on to anyone else you think may be
interested. Please send any tips or feedback to <asb at asbradbury.org>,
or
@llvmweekly or @asbradbury on Twitter.

A good time was had by all at [ORConf](http://openrisc.io/orconf/) last week
at CERN. We had over 100 open source hardware enthusiasts join us in Geneva.
You can find my [slides updating on lowRISC
here](https://speakerdeck.com/asb/an-update-on-the-lowrisc-open-source-system-on-chip).
Videos should appear on youtube in the next week or so.


## News and articles from around the web

A [six month retrospective of
LLILC](https://github.com/dotnet/llilc/blob/master/Documentation/llilc-at-six-months.md),
the project to produce an open source LLVM-based compiler for .NET, has been
posted. It describes work still to be done for garbage collection and
exception handling, code size and code quality, and JIT throughput.

The [schedule for the 2015 LLVM Developers'
Meeting](http://devmtg15.llvm.org/) is now available.

The new ELF linker in LLD is [looking pretty
fast](http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151005/304675.html).
Right now it can link Clang in about half the time of binutils gold. However,
the resulting binary is larger. It will be interesting to see how the
performance compares when both are at feature parity, but this is looking
promising.


## On the mailing lists

* Chandler Carruth, on behalf of the board of the LLVM Foundation has posted
an [RFC on introducing an LLVM Community Code of
Conduct](http://lists.llvm.org/pipermail/llvm-dev/2015-October/091218.html).
The proposal is based on the Django code of conduct and generated masses of
discussion. A couple of days later, Chandler posted a [second
draft](http://lists.llvm.org/pipermail/llvm-dev/2015-October/091408.html)
incorporated feedback and answering many of the questions raised. The response
appears to be good so far. I'll just highlight one of the questions and
answers: "Q: Is this trying to change how the community behaves?"
"A: I think
the resounding answer is no, this is very much meant to formalize the existing
extremely polite and respectful behavior that the LLVM community has had
for many years."

* There is going to be a birds of a feather section about the future of
LLVM's
C APIs at the upcoming LLVM developers' meeting, and Justin Bogner has
helpfully shared [some notes in preparation for
this](http://lists.llvm.org/pipermail/cfe-dev/2015-October/045610.html).

* Philip Reames has shared some [suggested topics for the managed languages
birds of a feather meeting at the upcoming LLVM
devmeeting](http://lists.llvm.org/pipermail/llvm-dev/2015-October/091457.html).
Joe Ranieri [suggests some additional
topics](http://lists.llvm.org/pipermail/llvm-dev/2015-October/091492.html).

* Chris Matthews has shared an RFC on [adding background workers to
LNT](http://lists.llvm.org/pipermail/llvm-dev/2015-October/091454.html).

* Diego Novillo is going to be hosting a birds of a feather on profile-guided
optimisations at the upcoming dev meeting and [has shared a preliminary list
of topics for
discussion](http://lists.llvm.org/pipermail/llvm-dev/2015-October/091478.html).

* Sanjoy Das has [updated us on his work with operand bundles and gc
transition
arguments](http://lists.llvm.org/pipermail/llvm-dev/2015-October/091434.html),
and is seeking input and opinions on his suggested ways forward.

* Zachary Turner has [written about his efforts to support Python 3 with
LLDB](http://lists.llvm.org/pipermail/lldb-dev/2015-October/008538.html).

* Evgenii Stepanov has posted an [RFC on adding an internal linkage
attribute](http://lists.llvm.org/pipermail/cfe-dev/2015-October/045580.html).
The message explains why setting `always_inline` and hidden symbol visibility
is not enough.

* Arch Robinson initiated a discussion on [extending the SLP vectorizer to
work with tuples in
Julia](http://lists.llvm.org/pipermail/llvm-dev/2015-October/091395.html).


## LLVM commits

* Hexagon gained a new pass to merge adjacent stores.
[r250542](http://reviews.llvm.org/rL250542).

* Hexagon gained skeleton support for the 'HVX' extension instructions.
[r250600](http://reviews.llvm.org/rL250600).

* The loop vectorizer will now shrink integer operations into the smallest
type possible. [r250032](http://reviews.llvm.org/rL250032).

* Documentation has been added for binary sample profile encoding.
[r250309](http://reviews.llvm.org/rL250309).

* RewriteStatpointsForGC is starting to make use of operand bundles.
[r250489](http://reviews.llvm.org/rL250489).


## Clang commits

* Clang gained support for the `-fdebug-prefix-map=` option as in GCC.
[r250094](http://reviews.llvm.org/rL250094).

* The PS4 toolchain definition has been added to Clang.
[r250262](http://reviews.llvm.org/rL250262).

* Clang now understands `-flto=thin`.
[r250398](http://reviews.llvm.org/rL250398).


## Other project commits

* The libc++ testing guide has been updated.
[r250323](http://reviews.llvm.org/rL250323).

* LLD got even faster at linking clang.
[r250315](http://reviews.llvm.org/rL250315).

* LLDB gained preliminary NetBSD support.
[r250146](http://reviews.llvm.org/rL250146).