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

Alex Bradbury via llvm-dev llvm-dev at lists.llvm.org
Mon May 20 12:26:01 PDT 2019

LLVM Weekly - #281, May 20th 2019

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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
and our own [press

## News and articles from around the web

LLVM 8.0.1-rc1 [has been

An LLVM meetup will take place in Leuven, Belgium on [Wednesday June

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

## On the mailing lists

* Sander De Smalen has [updated his RFC thread on changes to
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
the responses to the RFC on better supporting targets where bytes are not 8

* 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
adding RecoveryExpr to represent invalid constructs in the Clang AST.

* Artem Dergachev has exhaustively listed the [status of 'alpha' Clang

## LLVM commits

* An initial ORC design document was committed.

* 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.

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

* Guidelines and recommendations for LLVM socials were added to the LLVM docs.

* HWASan and Kernel HWASan were ported to the new pass manager.

* 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.

* lround/llround intrinsics and SelectionDAG nodes were added.

## 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),

* The Clang AST can now be dumped to JSON.

* 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.

* lldb-server now works with ipv6.

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