[llvm-dev] LLVM Weekly - #354, October 12th 2020

[Alex Bradbury via llvm-dev]

LLVM Weekly - #354, October 12th 2020
=====================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/354>.

Welcome to the three hundred and fifty-fourth 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.

I try to keep LLVM Weekly focused and to the point, but I do have to share
that my incredibly talented wife Carrie Anne has been [awarded an MBE for
services to
education](https://www.raspberrypi.org/blog/carrie-anne-philbin-mbe/). I
couldn't be more proud of everything she's done for inclusive computing
education.


## News and articles from around the web

LLVM 11.0.0 [has now been
released](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145750.html).
Thank you to everyone involved in preparing this release.

Luís Marques has written a blog post about [using differential testing to
rapidly find and fix missed optimisation opportunities in the RISC-V LLVM
backend](https://www.lowrisc.org/blog/2020/10/how-we-used-differential-testing-to-rapidly-find-and-fix-missed-optimisation-opportunities-in-llvms-risc-v-backend/).


## On the mailing lists

* Paul C. Anagnostopoulos posted some [proposals to enhance TableGen's ability
to analyze and manipulate
DAGs](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145740.html).

* Serge Guelton has [produced a prototype replacing llvm-build with pure
CMake](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145718.html) and
is seeking feedback for this "llvmbuildectomy".

* Sean M Bartell shared [minutes from the code size birds of a feather session
at the LLVM Dev
Meeting](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145639.html).

* Reid Kleckner posted [notes from a chat about dbg.value at the LLVM Dev
Meeting](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145697.html).

* Juneyoung Lee distributed a [follow-up and plan to a round-table discussion
on undef and poison at the LLVM Dev
Meeting](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145692.html).

* Kristóf Umann shared a [survey of dataflow analyses in
Clang](http://lists.llvm.org/pipermail/cfe-dev/2020-October/066937.html).

* Andrzej Warzynski [proposed an RFC on improving clang
-help](http://lists.llvm.org/pipermail/cfe-dev/2020-October/066953.html).

* The GlobalISel roundtable at the LLVM Dev Meeting generated follow-up posts
from Dominik Montada on [register bank
select](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145656.html) and
[multi-stage
legalisation](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145654.html).

* Siva Chandra distributed a [summary of discussions at an llvm-libc round
table](http://lists.llvm.org/pipermail/libc-dev/2020-October/000210.html),
including a Q&A with questions such as "What is the timeline you believe until
at least one operating system is fully supported?" (answer: ~2 years until
Clang can build fully against LLVM libc).

* Adrien Guinet [proposed an `apple_abi` function
attribute](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145680.html)
to compiler functions for the Apple ARM64 ABI when targeting other ARM64 OSes.

* Jeroen Dobbelaere shared [minutes from an Alias Analysis round table at the
LLVM dev
meeting](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145640.html).


## LLVM commits

* The vector reduction intrinsics are no longer "experimental".
[322d0af](https://reviews.llvm.org/rG322d0afd875).

* Loop terminology in LLVM documentation has been revised with the addition of
new diagrams. [c3f12dd](https://reviews.llvm.org/rGc3f12dd6069).

* The AMDGPU MC layer now has improved detection of and error messages for
unsupported instructions. [e2452f5](https://reviews.llvm.org/rGe2452f57faa).

* The ImplicitNullChecks pass was updated to support complex addressing mode.
[35cb45c](https://reviews.llvm.org/rG35cb45c533f).

* The LoopInterchange and FixIrreducible passes have been ported to the new
pass manager. [9c21c6c](https://reviews.llvm.org/rG9c21c6c9663),
[0689dab](https://reviews.llvm.org/rG0689dab8443).

* Initial infrastructure was committed for the C-SKY backend.
[e1c38dd](https://reviews.llvm.org/rGe1c38dd55d9).


## Clang commits

* Documentation was added on APINotes.
[85d5064](https://reviews.llvm.org/rG85d50640008).

* A DirectoryWatcher implementation was added for Windows.
[5d74c43](https://reviews.llvm.org/rG5d74c435117).


## Other project commits

* A FreeBSD remote process plugin was added to LLDB, capable of debugging
simple single-threaded programs.
[1a60026](https://reviews.llvm.org/rG1a600266c3a).

* Flang gained new DiagnosticConsumer classes.
[8d51d37](https://reviews.llvm.org/rG8d51d37e062).