[llvm-dev] LLVM Weekly - #281, May 20th 2019

[Alex Bradbury via llvm-dev]

LLVM Weekly - #281, May 20th 2019
=================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/281>.

Welcome to the two hundred and eighty-first 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.

Readers may be interested in recent news about lowRISC, the not-for-profit
open source engineering organisation I co-founded. This is an exciting step
forwards on our open source hardware mission. See the coverage on the [Google
Open Source
blog](https://opensource.googleblog.com/2019/05/google-fosters-open-source-hardware.html)
and our own [press
release](https://www.lowrisc.org/blog/2019/05/lowrisc-expands-press-release/).


## News and articles from around the web

LLVM 8.0.1-rc1 [has been
tagged](http://lists.llvm.org/pipermail/llvm-dev/2019-May/132465.html).

An LLVM meetup will take place in Leuven, Belgium on [Wednesday June
19th](http://lists.llvm.org/pipermail/llvm-dev/2019-May/132509.html).

The 6th HelloLLVM/HelloGCC social in Beijing, China will [take
place](http://lists.llvm.org/pipermail/llvm-dev/2019-May/132375.html) on May
25th.


## On the mailing lists

* Sander De Smalen has [updated his RFC thread on changes to
llvm.experimental.vector.reduce
intrinsics](http://lists.llvm.org/pipermail/llvm-dev/2019-May/132455.html)
with a summary of feedback so far.

* Will Bundy [gave detailed
feedback](http://lists.llvm.org/pipermail/llvm-dev/2019-May/132432.html) to
the RFC on extending optimisation reporting, based on work done in this area
at Sony Playstation.

* Jesper Antonsson
[summarises](http://lists.llvm.org/pipermail/llvm-dev/2019-May/132395.html)
the responses to the RFC on better supporting targets where bytes are not 8
bits.

* Louis Dionne has [shared a
proposal](http://lists.llvm.org/pipermail/libcxx-dev/2019-May/000358.html) on
how to better handle experimental features in libc++, and is seeking feedback.

* Sam McCall
[proposes](http://lists.llvm.org/pipermail/cfe-dev/2019-May/062262.html)
adding RecoveryExpr to represent invalid constructs in the Clang AST.

* Artem Dergachev has exhaustively listed the [status of 'alpha' Clang
checkers](http://lists.llvm.org/pipermail/cfe-dev/2019-May/062298.html).


## LLVM commits

* An initial ORC design document was committed.
[r361089](https://reviews.llvm.org/rL361089).

* Support in ELF for "dependent libraries" was committed, intended to support
simple "autolinking" use cases. [r360984](https://reviews.llvm.org/rL360984).

* The SystemZ backend was updated to start to model the floating-point control
register. [r360570](https://reviews.llvm.org/rL360570).

* Basic target feature definitions were added for Arm SVE2 as well as initial
MC layer support. [r360573](https://reviews.llvm.org/rL360573),
[r360682](https://reviews.llvm.org/rL360682), and more.

* Constrained fptrunc and fpext intrinsics were added.
[r360581](https://reviews.llvm.org/rL360581).

* The in-tree gn build system can now build the Lanai, Sparc, and Hexagon
backends. [r360644](https://reviews.llvm.org/rL360644),
[r360645](https://reviews.llvm.org/rL360645),
[r360647](https://reviews.llvm.org/rL360647).

* Guidelines and recommendations for LLVM socials were added to the LLVM docs.
[r360651](https://reviews.llvm.org/rL360651).

* HWASan and Kernel HWASan were ported to the new pass manager.
[r360707](https://reviews.llvm.org/rL360707).

* In order to fix a layering problem, backends were modified to have a new
TargetInfo header. [r360709](https://reviews.llvm.org/rL360709), and more.

* A scheduling model for the Cortex-M4 was added.
[r360768](https://reviews.llvm.org/rL360768).

* lround/llround intrinsics and SelectionDAG nodes were added.
[r360889](https://reviews.llvm.org/rL360889).


## Clang commits

* Virtual function calls and `dynamic_cast` can now be used in constant
expression evaluation in C++20.[r360635](https://reviews.llvm.org/rL360635),
[r360806](https://reviews.llvm.org/rL360806).

* The Clang AST can now be dumped to JSON.
[r360622](https://reviews.llvm.org/rL360622).

* A new language mode was added for C2x, with `[[attribute]]` support enabled
by default. [r360667](https://reviews.llvm.org/rL360667).

* A new bugprone-branch-clone check was added to clang-tiy, which detects
if/else chains or swtich statements where consecutive branches contain
identical code. [r360779](https://reviews.llvm.org/rL360779).


## Other project commits

* LLD gained support for `-n` and to disable page alignment and `-N` to both
disable page alignment and mark the executable segment as writable.
[r360593](https://reviews.llvm.org/rL360593).

* lldb-server now works with ipv6.
[r361079](https://reviews.llvm.org/rL361079).