[llvm-dev] LLVM Weekly - #215, Feb 12th 2018

[Alex Bradbury via llvm-dev]

LLVM Weekly - #215, Feb 12th 2018
=================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/215>.

Welcome to the two hundred and fifteenth 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](https://www.linkedin.com/in/alex-bradbury/). 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.

I [became a father last
week](https://twitter.com/asbradbury/status/961607772520484865), and Archie
has been keeping my wife and I busy ever since. More so than usual, please do
drop me an email if there's something you think should definitely be featured
in LLVM Weekly.


## News and articles from around the web

LLVM 6.0.0-rc2 [has been
tagged](http://lists.llvm.org/pipermail/llvm-dev/2018-February/121058.html).

Slides and recordings from the
[LLVM Devroom at FOSDEM
2018](https://fosdem.org/2018/schedule/track/llvm_toolchain/)
are now available.


## On the mailing lists

* Tanya Lattner is
[looking](http://lists.llvm.org/pipermail/llvm-dev/2018-February/121161.html)
for project proposals for Outreachy internships. "LLVM is participating in the
Outreachy May 2018 to August 2018 internships. We are seeking mentors to
propose projects that Outreachy interns can work on during their internship.
For our first time with this program, the LLVM Foundation will be sponsoring 1
intern. Ideally we would like a few project proposals for applicants to pick
from. These can range from entry level documentation projects to more
technical."

* Davide Italiano started an RFC discussion on [improvements to the LLDB test
suite and future
directions](http://lists.llvm.org/pipermail/lldb-dev/2018-February/013240.html).
He proposes making aspects of testing more like LLVM, sticking to LLVM
policies regarding reverting commits that break the buildbots, and removing
support for unmaintained languages (Java/Go/Swift).

* Quentin Colombet started an RFC thread on [bumping the bitcode version in
LLVM 6.0](http://lists.llvm.org/pipermail/llvm-dev/2018-February/121114.html),
due to the changes in fast math flags in bitcode.

* Florian Hahn
[proposes](http://lists.llvm.org/pipermail/llvm-dev/2018-February/121000.html)
making LoopVectorize aware of superword-level parallelism (SLP) operations.

* David Li has written a short
[summary](http://lists.llvm.org/pipermail/llvm-dev/2018-February/120964.html)
of developments in profile-guided optimisation with LLVM over the past 18
months.

* Michael Haidl started a discussion on [upstreaming
PACXX](http://lists.llvm.org/pipermail/llvm-dev/2018-February/120965.html).
"he main goal for my research was to develop a single-source programming model
equal to CUDA or SYCL for accelerators supported by LLVM (e.g., Nvidia GPUs).
PACXX uses Clang as front-end for code generation and comes with a runtime
library (PACXX-RT) to execute kernels on the available hardware."


## LLVM commits

* LLVM now supports representing discriminated unions in DWARF, as required by
Rust. [r324426](http://reviews.llvm.org/rL324426).

* Code generation for Armv8.2-A FP16 has been added.
[r324321](http://reviews.llvm.org/rL324321).

* The MergeICmps pass is now enabled by default.
[r324465](http://reviews.llvm.org/rL324465).

* `utils/update_llc_test_checks.py` and `utils/update_test_checks.py` have
been updated to share more code. [r324803](http://reviews.llvm.org/rL324803).

## Clang commits

* The `trivial_abi` attribute has been added. This indicates the annotated C++
class/struct/union to be passed or returned using the C ABI for the underlying
type. [r324269](http://reviews.llvm.org/rL324269).

* The flags `-fdiscard-value-names` and `-fno-discard-value-names` were added
to allow user control over whether names should be discarded in IR output.
[r324498](http://reviews.llvm.org/rL324498).

* A TemplateInstantiationObserver class was added. This is used in order to
implement the [TempLight](http://plc.inf.elte.hu/templight/) C++ template
debugging tool. [r324808](https://reviews.llvm.org/rL324808).


## Other project commits

* LLD now has a man page. [r324512](https://reviews.llvm.org/rL324512).

* The sanitizer allocator has seen a variety of local cache improvements.
[r324257](https://reviews.llvm.org/rL324257).