[llvm-dev] LLVM Weekly - #320, Feb 17th 2020

[Alex Bradbury via llvm-dev]

LLVM Weekly - #320, Feb 17th 2020
=================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/320>.

Welcome to the three hundred and twentieth 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 10.0.0 RC2 [has been
tagged](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139147.html).

Don't forget to [register for
EuroLLVM'20](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139154.html).
The early brid rate will end on Feb 28th.

Trip reports are now being posted from the Prague ISO C++ meeting. See the
[/r/cpp trip report](https://old.reddit.com/r/cpp/comments/f47x4o/202002_prague_iso_c_committee_trip_report_c20_is/)
and [Herb
Sutter's](https://herbsutter.com/2020/02/15/trip-report-winter-iso-c-standards-meeting-prague/).
Technical work on C++20 was finished at this meeting, and a schedule and set
of priorities for C++23 were agreed.


## On the mailing lists

* Tanya Lattner notes that the LLVM Code of Conduct has been in draft for
several years now, and [outlines the steps and feedback needed to adopt
it](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139197.html). She
requests that feedback be given within the next two weeks.

* Raphael Isemann [proposed that the llgo Go frontend implementation be
removed from
LLVM](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139058.html).
Respondents, including its original author agreed and it has now been removed.

* Vinay Madhusudan started a discussion about [the design of the OpenMP
dialect in
MLIR](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139136.html). The
post helpfully starts by summarising the state of various efforts related to
this.

* Nico Weber suggests [it may be time to move the AVR backend out of
experimental](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139158.html).

* The 5th installment of the ORC JIT Weekly [is
out](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139200.html).
Discussion of the new JIT initializer system continues in
[D74300](https://reviews.llvm.org/D74300).

* Reid Kleckner [proposes storing basic block order in llvm::Instruction for
faster local
dominance](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139168.html).
All respondents so far are in favour.

* Simon Moll kicked off an RFC thread on [adding optional named parameter
tuples for
intrinsics](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139110.html).

* Simon Cook proposes [extending TableGen's AssemblerPredictes to support
combining feature with
ORs](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139138.html).

* The thread on representations for loop transformations generated much more
discussion. See e.g. [Chris Lattner's latest
comments](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139010.html).

* Stephan T. Lavavej shares that the list of libcxx test suite tests skipped
in MSVC's STL testing environment [is now
available](http://lists.llvm.org/pipermail/libcxx-dev/2020-February/000683.html).


## LLVM commits

* A document including a proposal and roadmap towards vector predication in
LLVM was committed. [c49b9e0](https://reviews.llvm.org/rGc49b9e0d328).

* A first version of MemorySSA-based dead store elimination (DSE) was
implemented. [d0c4d4f](https://reviews.llvm.org/rGd0c4d4fe092).

* The `update_test_check` scripts were updated to allow arguments to be
specified within the file, and to allow processing to be turned on/off for
parts of the file. [1698cc7](https://reviews.llvm.org/rG1698cc7ebab).

* An initial MASM parser was committed.
[ee2c0f7](https://reviews.llvm.org/rGee2c0f76d74).

* Documentation was added on git bisecting across the MLIR merge.
[45c6c82](https://reviews.llvm.org/rG45c6c82e904).

* LLVM's libraries were updated to use C++14-style return type deduction.
[fb45968](https://reviews.llvm.org/rGfb45968e628).

* Support for `-msave-restore` was added to the RISC-V backend. This uses
libcalls to implement common save/restore sequences in function prologues and
epilogues, reducing code size.
[07f7c00](https://reviews.llvm.org/rG07f7c00208b).

* A new DWARF transformer class was added to convert DWARF to GSYM.
[19602b7](https://reviews.llvm.org/rG19602b71949).

* The responsibility for fixing issues in experimental targets was clarified
in the developers' policy. [4e1c49c](https://reviews.llvm.org/rG4e1c49cf4d8).

* TableGen now allows register class weighting to be overridden.
[922197d](https://reviews.llvm.org/rG922197d664d).


## Clang commits

* clang-tidy gained a new misc-no-recursion check that flags when recursion is
used. [49bffa5](https://reviews.llvm.org/rG49bffa5f8b7).

* The outdated document comparing Clang with other compilers was removed.
[42ca012](https://reviews.llvm.org/rG42ca012befa).

* Clang gained an `-fignore-exceptions` flag.
[55e2678](https://reviews.llvm.org/rG55e2678fcd4).

* Papers from the Prague 2020 C++ workgroup meeting were added to the Clan
status page. [b74a381](https://reviews.llvm.org/rGb74a381296e).


## Other project commits

* llgo was deleted. [372bfc6](https://reviews.llvm.org/rG372bfc65deb).

* A new utility was added to the libcxx directory to generate and display a
header dependency graph. [99382e4](https://reviews.llvm.org/rG99382e450fb).

* The SharingPtr class used in LLDB was removed in favour of a regular
`std::shared_ptr`. [363f05b](https://reviews.llvm.org/rG363f05b83d9).

* LLVM's OpenMP library now builds in C++14 mode by default.
[3ff4e2e](https://reviews.llvm.org/rG3ff4e2eee8c).