[llvm-dev] LLVM Weekly - #358, November 9th 2020

[Alex Bradbury via llvm-dev]

LLVM Weekly - #358, November 9th 2020
=====================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/358>.

Welcome to the three hundred and fifty-eighth 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

More videos from the 2020 LLVM Virtual Developers' Meeting
[have been uploaded](https://www.youtube.com/playlist?list=PL_R5A0lGi1ABzH_FIZSx0sHQkOqI7p4Cg).


## On the mailing lists

* Vineet Kumar wrote to share a [loop vectorizer prototype based on the RISC-V
Vector
Extension](http://lists.llvm.org/pipermail/llvm-dev/2020-November/146319.html)
which attracted a lot of discussion, wih Sjoerd Meijer suggesting [looking at
the get.active.lane.mask
intrinsic](http://lists.llvm.org/pipermail/llvm-dev/2020-November/146399.html).

* Florian Hahn proposes [combining annotation metadata and
remarks](http://lists.llvm.org/pipermail/llvm-dev/2020-November/146393.html).
This would take the form of a new `!annotation` metadata kind that can be
attached to arbitrary instructions to drive the generation of remarks.

* Min-Yih Hsu provided an update on [upstream submission of the M68k
backend](http://lists.llvm.org/pipermail/llvm-dev/2020-November/146361.html).

* Jeremy Morse provided an update on [debug information quality with
"instruction
referencing"](http://lists.llvm.org/pipermail/llvm-dev/2020-November/146444.html),
concluding that the original objective of this work has been fulfilled (though
also listing current limitations).

* David Sherwood suggests [introducing the concept of invalid costs to the IR
cost
model](http://lists.llvm.org/pipermail/llvm-dev/2020-November/146408.html).
This wrapper class could safely indicate information such as whether the cost
should be considered so expensive so as to disable optimisations, or if the
cost us unknown.

* John Paul Adrian Glaubitz is [seeking reviewers for two Clang Sparc related
patches](http://lists.llvm.org/pipermail/llvm-dev/2020-November/146396.html).

* Paul C. Anagnostopoulos seeks feedback on the idea of [adding named template
arguments to
TableGen](http://lists.llvm.org/pipermail/llvm-dev/2020-November/146331.html).


## LLVM commits

* A community support policy was documented.
[25ba6b2](https://reviews.llvm.org/rG25ba6b2bcd1).

* Implementation was started on `llvm.coro.async` which will be used by the
Swift frontend to lower async functions.
[ea5989b](https://reviews.llvm.org/rGea5989b43ad),
[c6543cc](https://reviews.llvm.org/rGc6543cc6b8f).

* llvm.loop.mustprogress metadata was introduced.
[cea0599](https://reviews.llvm.org/rGcea0599aa75),

* A range of fixes and improvements were made to the RISC-V backend's support
for the yet-to-be-ratified bitmanip extension.
[d47300f](https://reviews.llvm.org/rGd47300f503c),
[0122a4e](https://reviews.llvm.org/rG0122a4ea661),
[cc3bf27](https://reviews.llvm.org/rGcc3bf270776), and more.

* parallelTransformReduce and parallelForEachError were added to LLVM's
parallel utility library. [c0a922b](https://reviews.llvm.org/rGc0a922b3db2).

* A `!interleave` operator was added to TableGen to concatenate a list of
values with delimiters. [d56cd42](https://reviews.llvm.org/rGd56cd4291e4).

* true and false literals were added to TableGen.
[ae2cb4f](https://reviews.llvm.org/rGae2cb4f4273).

* A pipeline model was added for HiSilicon's TSV110 (AArch64).
[93b9972](https://reviews.llvm.org/rG93b99728b16).


## Clang commits

* A new bugprone-signal-handler check was added to clang-tidy.
[d1b2a52](https://reviews.llvm.org/rGd1b2a523191).

* A YAML compiler for API notes was committed.
[82f86ae](https://reviews.llvm.org/rG82f86ae01a5).

* A custom config file can now be specified for clang-tidy using
`--config-file`. [d6a468d](https://reviews.llvm.org/rGd6a468d622b).


## Other project commits

* A new 'TOSA' (Tensor Operator Set Architecture) MLIR dialect was added.
[b281211](https://reviews.llvm.org/rGb28121133d8).

* A design document was added for runtime derived type descriptions in Clang.
[8fc07fe](https://reviews.llvm.org/rG8fc07fed32b).

* LLD now allows you to specify a custom to script to be called for missing
libraries, which could be used to provide extra suggestions to the user (e.g.
suggesting specific packages to install).
[cfc3226](https://reviews.llvm.org/rGcfc32267e27),
[3bdeb2a](https://reviews.llvm.org/rG3bdeb2ac2ef).

* A C API was added for the MLIR PassManager.
[f61d102](https://reviews.llvm.org/rGf61d1028fa5).