[llvm-dev] LLVM Weekly - #279, May 6th 2019

Mon May 6 11:17:53 PDT 2019

LLVM Weekly - #279, May 6th 2019
================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/279>.

Welcome to the two hundred and seventy-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.

## News and articles from around the web

The next Austin LLVM Social will be [on Thursday 30th
May](http://lists.llvm.org/pipermail/llvm-dev/2019-May/132098.html).

A Toronto LLVM/Clang meetup will take place [on Tuesday 14th
May](http://lists.llvm.org/pipermail/llvm-dev/2019-April/132021.html).

Jan Hubička has yet another excellent blog post on compiler optimisation, this
time on [GCC 9's link-time and inter-procedural optimisation
improvements](http://hubicka.blogspot.com/2019/05/gcc-9-link-time-and-inter-procedural.html).

GCC 9.1 [has been released](https://lwn.net/Articles/787385/).

Krister Walfridsson blogged on [how LLVM optimises geometric
sums](https://kristerw.blogspot.com/2019/04/how-llvm-optimizes-geometric-sums.html).

## On the mailing lists

* Jesper Antonsson shared an
[RFC](http://lists.llvm.org/pipermail/llvm-dev/2019-May/132080.html) on
removing the assumption that 1 byte == 8 bits. This generated plenty of
discussion.

* Graham Hunter [made an
update](http://lists.llvm.org/pipermail/llvm-dev/2019-April/132054.html) on
scalable vector types and SVE upstreaming, including a handy diagram showing
the dependencies of the different components and expected controversy level.

* Stephen Kelly [shared EuroLLVM roundtable
notes](http://lists.llvm.org/pipermail/cfe-dev/2019-May/062217.html) on future
refactoring with AST-matchers.

* Todd Snider wrote an
[RFC](http://lists.llvm.org/pipermail/llvm-dev/2019-April/132041.html) on
supporting additional symbol metadata in ELF object files as supported by some
ARM compilers. e.g. `int a __attribute__((location(0x1000))) = 4;`.

* Andrew Kaylor shares an
[RFC](http://lists.llvm.org/pipermail/llvm-dev/2019-April/132056.html) on
extending optimisation reporting. He splits this into two categories, 1) ways
to support different sorts of output, and 2) ways to create connections
between different events represented in the report.

* Serge Guelton is seeking feedback on his effort to [generalise LLVM
extensions that provide new
passes](http://lists.llvm.org/pipermail/llvm-dev/2019-May/132128.html),
allowing projects in tools/ that register themselves with an appropriate CMake
variable having their passes register in clang/opt/bugpoint.

* Johannes Doerfert is [seeking
input](http://lists.llvm.org/pipermail/llvm-dev/2019-May/132082.html) on his
proposal for the interplan of Clang and Flag and LLVM for OpenMP.

* Stephen Scalpone started a thread on [renaming
f18](http://lists.llvm.org/pipermail/llvm-dev/2019-April/132019.html),
suggesting 'fortran' as the name. Most respondents prefer using the 'flang'
name.

## LLVM commits

* The GlobalISel legalizer documentation was updated.
[r359705](https://reviews.llvm.org/rL359705).

* More gfx1010 support has been landing in the AMDGPU backend.
[r359621](https://reviews.llvm.org/rL359621),
[r359696](https://reviews.llvm.org/rL359696),
[r359698](https://reviews.llvm.org/rL359698), and more.

* In preparation for the AArch64 ILP32 support, DAG pointer size can be
different from the memory representation.
[r359676](https://reviews.llvm.org/rL359676).

* FileCheck gained @LINE numeric expressions.
[r359741](https://reviews.llvm.org/rL359741).

* The in-tree gn build system gained support for building libunwind, libcxxabi
and libc++. [r359804](https://reviews.llvm.org/rL359804),
[r359805](https://reviews.llvm.org/rL359805),
[r359806](https://reviews.llvm.org/rL359806).

* RegAllocFast gained a new heuristic to detect values not live-out of a
block. [r359906](https://reviews.llvm.org/rL359906).

## Clang commits

* Support for the C++2a explicit bool specifier was added.
[r359949](https://reviews.llvm.org/rL359949).

* Support for C++2a "familiar template syntax for generic lambdas" was
committed. [r359967](https://reviews.llvm.org/rL359967).

## Other project commits

* compiler-rt gained a simple crtbegin.o and crtend.o implementation.
[r359591](https://reviews.llvm.org/rL359591).

* The LLVM OpenMP library gained OpenMP 5.0 monotonic support.
[r359601](https://reviews.llvm.org/rL359601).