[llvm-dev] LLVM Weekly - #269, February 25th 2019

[Alex Bradbury via llvm-dev]

LLVM Weekly - #269, February 25th 2019
======================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/269>.

Welcome to the two hundred and sixty-ninth 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.

If you're interested in working on RISC-V LLVM, open source hardware design,
and more then consider [applying to work with me at lowRISC
CIC](https://www.lowrisc.org/jobs/). We are hiring for multiple positions to
deliver on an exciting, high impact, open source hardware roadmap in
collaboration with Google and other industry partners.

## News and articles from around the web

Slides from the C4ML "Compilers for Machine Learning" workshop at CGO 2019 are
[now available](https://www.c4ml.org/). Slides from the talk on
[MLIR](https://drive.google.com/file/d/1hUeAJXcAXwz82RXA5VtO5ZoH8cVQhrOK/view)
presented by Chris Lattner and Jacques Pienaar will be of particular interest
to the LLVM community.

At the C++ Committee meeting in Kona, C++20 was declared feature complete. See
this
[reddit /r/cpp trip
report](https://old.reddit.com/r/cpp/comments/au0c4x/201902_kona_iso_c_committee_trip_report_c20/)
for full details.
Most notably, modules and coroutines were added to C++20 at the Kona meeting.


## On the mailing lists

* Hans Wennborg is
[requesting](http://lists.llvm.org/pipermail/llvm-dev/2019-February/130325.html)
release note additions for 8.0.0.

* Zachary Turner started a thread on [expectations of buildbot email
notifications](http://lists.llvm.org/pipermail/llvm-dev/2019-February/130331.html).
Specifically, should quick "revert-to-green" be used if an issue was found
only in a silent or unofficial buildbot? There seems to be substantial
agreement that the answer to this is
[yes](http://lists.llvm.org/pipermail/llvm-dev/2019-February/130340.html).

* James Y Knight
[proposes](http://lists.llvm.org/pipermail/llvm-dev/2019-February/130414.html)
an improvement to the textual IR format for nameless blocks, aiming to make
the syntax clearer.

* Hans Wennborg is [seeking
assistance](http://lists.llvm.org/pipermail/llvm-dev/2019-February/130386.html)
with a [blocker on the 8.0.0 release](https://llvm.org/PR40761), "Sanitizers
broken on FreeBSD".

* Alex L shared an
[RFC](http://lists.llvm.org/pipermail/cfe-dev/2019-February/061387.html) on
adding "(+asserts)" to the Clang version output when it's built with
assertions enabled.



## LLVM commits

* `Optional<T>` is now trivially copyable when `T` is trivially copyable.
[r352464](https://reviews.llvm.org/rL352464).

* The DAGCombiner learned to fold overlapping constant stores.
[r354676](https://reviews.llvm.org/rL354676).

* On macOS/iOS etc, LLVM can now use the `os_signpost()` API to expose timing
information for Instruments. [r354365](https://reviews.llvm.org/rL354365).

* The RISC-V assembler can now handle pseudo-instructions for load/store of a
symbol address. [r354430](https://reviews.llvm.org/rL354430).


## Clang commits

* Coroutine support is now enabled under `-std=c++2a`.
[r354736](https://reviews.llvm.org/rL354736).

* The Clang driver gained support for the `-static-pie` argument as understood
by GCC. [r354502](https://reviews.llvm.org/rL354502).


## Other project commits

* LLD can now handle cross-mode (regular to/from microMIPS) jumps.
[r354311](https://reviews.llvm.org/rL354311).

* LLVM's OpenMP impementation now has GOMP compatible cancellation support.
[r354637](https://reviews.llvm.org/rL35467).