[llvm-dev] LLVM Weekly - #93, Oct 12th 2015

[Alex Bradbury via llvm-dev]

LLVM Weekly - #93, Oct 12th 2015
================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/93>.

Welcome to the ninety-third 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.

Apologies that this week's issue comes rather late in the day, my laptop gave
up the ghost over the weekend while I was travelling leaving me with no way to
write it. Now I'm back, I've managed to dust off an old desktop from my closet
to write this issue (and to keep my unbroken streak). LLVM Weekly has been
sent out every Monday since it started on the first Monday of January 2014.
This weekend I was talking about [lowRISC](http://www.lowrisc.org) at [ORConf
2015](http://openrisc.io/orconf/). You can find my slides
[here](https://speakerdeck.com/asb/an-update-on-the-lowrisc-open-source-system-on-chip).
There was a wide array of talks on open source hardware, including many on
lowRISC and RISC-V. The videos should hopefully be posted in the next week or
so.

## News and articles from around the web

The LLVM project has hit 250,000 commits. The commit that managed to hit this
milestone was [this one-liner](http://reviews.llvm.org/rL250000).

A [new
paper](https://github.com/isocpp/CppCoreGuidelines/blob/master/docs/Introduction%20to%20type%20and%20resource%20safety.pdf)
by Bjarne Stroustrup, Herb Sutter, and Gabriel Dos Reis gives more details on
their plans for memory safety in C++.

Videos from CppCon2015 are [being posted to
Youtube](https://www.youtube.com/playlist?list=PLHTh1InhhwT75gykhs7pqcR_uSiG601oh).

## On the mailing lists

* Ed Maste is taking a look at the feasibility of using the new LLD ELF linker
for FreeBSD, and has shared [his initial
findings](http://lists.llvm.org/pipermail/llvm-dev/2015-October/091072.html).

* When is addrspacecast needed? Both [David
Chisnall](http://lists.llvm.org/pipermail/llvm-dev/2015-October/091062.html)
and [Mats
Petersson](http://lists.llvm.org/pipermail/llvm-dev/2015-October/091063.html)
have good answers.

* Vedant Kumar has posted an RFC on [cleaning up the way optional Function
data is
stored](http://lists.llvm.org/pipermail/llvm-dev/2015-October/091169.html).

* Dehao Chen has shared an [update on the AutoFDO
project](http://lists.llvm.org/pipermail/llvm-dev/2015-October/091162.html),
which allows the use of a perf.data profile for profile-guided optimisation.
Clang built with `-fprofile-use` is about 20% faster than Clang built with
`-O3`.

* Larisse Voufo has
[shared](http://lists.llvm.org/pipermail/llvm-dev/2015-October/091178.html) a
proposal for optimizing const C++ objects in LLVM.

* Chris Matthews has announced [the open-sourcing of an llvm bisect
tool](http://lists.llvm.org/pipermail/llvm-dev/2015-October/091140.html), for
bisecting bugs using prebuilt LLVM and Clang revisions.


## LLVM commits

* The Hexagon architecture gained an early if-conversion pass.
[r249423](http://reviews.llvm.org/rL249423).

* ThinLTO has started to land, in particular support for function summary
index bitcode sections and files. [r249270](http://reviews.llvm.org/rL249270).

* Codegen for ARM's memcpy intrinsic has been modified to make better use of
LDM/STM. [r249322](http://reviews.llvm.org/rL249322).

* The llvm.eh.exceptioncode intrinsic was added.
[r249492](http://reviews.llvm.org/rL249492).

* It is now possible to turn off MMX support without disabling SSE.
[r249731](http://reviews.llvm.org/rL249731).


## Clang commits

* The policy for adding new style options to clang-format has been documented.
[r249289](http://reviews.llvm.org/rL249289).

* The libclang bindings have been extended with accessors for C++ function
attributes (pure virtual, virtual, or const).
[r250008](http://reviews.llvm.org/rL250008).


## Other project commits

* GoLanguageRuntime was introduced to LLDB, which supports finding the runtime
type for Go interfaces. [r249456](http://reviews.llvm.org/rL249456),
[r249459](http://reviews.llvm.org/rL249459).

* The new LLD ELF linker now supports the `--as-needed` option.
[r249998](http://reviews.llvm.org/rL249998).

* LLDB for MIPS is now able to emulate microMIPS instructions.
[r249381](http://reviews.llvm.org/rL249381).

* liblldb is working towards being able to work under both Python 2.x and 3.x.
[r249886](http://reviews.llvm.org/rL249886).