[llvm-dev] LLVM Weekly - #289, July 15th 2019

[Alex Bradbury via llvm-dev]

LLVM Weekly - #289, July 15th 2019
==================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/289>.

Welcome to the two hundred and eighty-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

LLVM 8.0.1-rc4 [has been
tagged](http://lists.llvm.org/pipermail/llvm-dev/2019-July/133807.html).

Visual Studio 2019 16.2 Preview 3 [includes built-in Clang/LLVM support for
MSBuild
projects](https://devblogs.microsoft.com/cppblog/clang-llvm-support-for-msbuild-projects/).

See the lowRISC blog for [further background on plans for RISC-V LLVM in
LLVM/Clang
9.0](https://www.lowrisc.org/blog/2019/07/risc-v-llvm-backend-in-clang-llvm-9.0/)
and on our [large-scale testing using
buildroot](https://www.lowrisc.org/blog/2019/07/large-scale-risc-v-llvm-testing-with-buildroot/)
(90% of buildroot's 2000+ packages can be built).


## On the mailing lists

* Siva Chendra followed up on his LLVM libc thread with a [draft
charter](http://lists.llvm.org/pipermail/llvm-dev/2019-July/133861.html) to
better explain the motivation and aims for the project. Rich Felker, author of
Musl libc [provided further
feedback](http://lists.llvm.org/pipermail/llvm-dev/2019-July/133892.html).

* Guillaume Chatelet has worked to [introduce an Alignment object in
LLM](http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html), so
alignment is consistently represented in the codebase. He is seeking feedback
on the next steps for this work (i.e. upstreaming).

* Tom Stellard [reminds
us](http://lists.llvm.org/pipermail/llvm-dev/2019-July/133840.html) that
LLVM's subversion is scheudled to be retired by Oct 21 2019, and enourages
everyone to move their workflow to GitHub as soon as possible. See the [GitHub
migration status](http://llvm.org/GitHubMigrationStatus.html) for more info.

* Jonas Devlieghere is proposing an LLDB BoF for the upcoming LLVM Dev Meeting
and is [seeking
input](http://lists.llvm.org/pipermail/llvm-dev/2019-July/133765.html) on
topics.

* Seiya Nuta is [seeking
feedback](http://lists.llvm.org/pipermail/llvm-dev/2019-July/133701.html) on
syntax highlighting llvm-objdump output.

* LLVM 9.0.0 [will
branch](http://lists.llvm.org/pipermail/llvm-dev/2019-July/133808.html) on
18th July 2019.

* See [this
thread](http://lists.llvm.org/pipermail/llvm-dev/2019-July/133788.html) for an
interesting discussion on the challenges of writing a backend for the WDC
65816 (as used in the SNES).

* Scott Manley [shared an
rFC](http://lists.llvm.org/pipermail/llvm-dev/2019-July/133787.html) on making
`-fp-contract=off` disable FMAs.


## LLVM commits

* New `preserve_{array,union,struct}_access_index` intrinsics were added to
preerve debug information, used for new BPF "compile once and run everywhere"
functionality.
[r365352](https://reviews.llvm.org/rL365352),
[r365503](https://reviews.llvm.org/rL365503).

* Support was added for the next-generation arch13 SystemZ CPU architecture.
[r365932](https://reviews.llvm.org/rL365932).

* A 'nofree' function attribute was introduced, and can now be inferred.
[r365336](https://reviews.llvm.org/rL365336).

* The "returned" argument can now be deduced.
[r365407](https://reviews.llvm.org/rL365407).

* Documentation for the LLVM remarks infrastructure was added.
[r365578](https://reviews.llvm.org/rL365578).

* The SanitizerCoverage pass was ported to the new pass manager.
[r365838](https://reviews.llvm.org/rL365838).


## Clang commits

* Syntax trees, "a tooling-focused alternative to the AST" where introduced.
As described in the commit message, there is more work to come in this area.
[r365355](https://reviews.llvm.org/rL365355).

* A CastValueChecker was added to the Clang static analyzer, supporting the
LLVM casts. [r365582](https://reviews.llvm.org/rL365582).

* The minimum supported Visual Studio version to compile LLVM and Clang is now
VS2017. [r365454](https://reviews.llvm.org/rL365454).

* A new DirectoryWatcher library was added, to be used by
index-while-building. [r365574](https://reviews.llvm.org/rL365574).

* The `__VERSION__` macro was removed.
[r365962](https://reviews.llvm.org/rL365962).

## Other project commits

* LLD has had its codebase renamed to use camelBack for local variables.
[r365595](https://reviews.llvm.org/rL365595).

* Support for running the LLVM test suite with qemu user mode emulation using
CMake/lit was fixed. [r365783](https://reviews.llvm.org/rL365783).

* hwasan gained improved precision for its checks using "short granule tags".
[r365551](https://reviews.llvm.org/rL365551).

* The version of the Google benchmark library in the LLVM test suite gained a
backported patch adding RISC-V support.
[r365610](https://reviews.llvm.org/rL365610).