[llvm-dev] LLVM Weekly - #413, November 29th 2021

[Alex Bradbury via llvm-dev]

LLVM Weekly - #413, November 29th 2021
======================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/413>.

Welcome to the four hundred and thirteenth 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

I didn't spot anything this week. As always, tips via email are greatly
appreciated!


## On the mailing lists

* James King posted an RFC on [improving support for debugging Clang's AST
  matchers](https://lists.llvm.org/pipermail/cfe-dev/2021-November/069383.html).

* Dmitry Makogon [proposed introducing new intrinsics for memory comparison
  operations such as
  memcmp](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153846.html).

* Simon Pilgrim shared an RFC to [raise the minimum Visual Studio version to
  VS2019](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153881.html)..
  All respondents so far have been in favour.

* The LLVM bugzilla migration is underway. After much discussion about details
  of the conversion, Anton Korobeynikov [shared a repository set up to act as
  a
  preview](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153886.html).
  Status of the migration can be tracked [in this Google
  Doc](https://docs.google.com/document/d/11_3rgYuv-QO0g1oO6T0MmkFhacqJg6o24eWFFVNSX_o/edit).
  Anton has also [sent a
  note](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153995.html)
  to flag that people who filled out the Bugzilla transition survey (i.e.
  indicated they'd like to associate their Bugzilla email with a GitHub
  account) but aren't LLVM committers can expect an invitation to join the
  LLVM GitHub organisation.

* Bardia Mahjour [shared notes and
  outcomes](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153861.html)
  from the Future of the Loop Optimization Working Group roundtable.

* Krishna (Chaitanya) Sankisa posted an RFC on [allowing bitcasts between
  address spaces with the same point
  size](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153968.html).

* The TLX 'Tensor LLVM eXtensions' proposal generated more discussion. Florian
  Hahn [posted a series of
  questions](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153914.html)
  which were
  [answered](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153926.html)
  by Akash Kothari, and [Christ Lattner shared some additional
  feedback](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153991.html).


## LLVM commits

* Parallel chunk processing was added to llvm-reduce, significantly speeding
  up reductions for very large inputs.
  [8ef460f](https://reviews.llvm.org/rG8ef460fc5137).

* Best practices for configuring a fast builder were documented.
  [73d52ee](https://reviews.llvm.org/rG73d52ee7859f).

* The order of restoring callee-saved registers was reversed for the RISC-V
  backend, maximising the distance between the load of the return address and
  its use. [137d347](https://reviews.llvm.org/rG137d3474ca39).


## Clang commits

* Support was added for -fplugin-arg- to pass arguments to plugins.
  [3e67cf2](https://reviews.llvm.org/rG3e67cf21a19a).

* The file documenting the clang-format status of each file in the repo was
  updated. [3c8666e](https://reviews.llvm.org/rG3c8666ef9a21).


## Other project commits

* ThreadSanitizer switched to a new runtime offering 2x smaller shadow memory
  and faster fully vectorized race detection amongst other features.
  [66d4ce7](https://reviews.llvm.org/rG66d4ce7e26a5).

* `std::{strong,weak,partial}_order` were implemented in libcxx.
  [d8380ad](https://reviews.llvm.org/rGd8380ad977e9).

* LLDB formatters were added for libstdc++ unordered_map, unordered_set,
  unordered_multimap, unordered_multiset, and optional.
  [fcd288b](https://reviews.llvm.org/rGfcd288b52aa7),
  [e3dea5c](https://reviews.llvm.org/rGe3dea5cf0e32).

* Patches to support mutli-root PDL patterns for kernel matching in MLIR were
  committed. [842b686](https://reviews.llvm.org/rG842b6861c01c),
  [3eb1647](https://reviews.llvm.org/rG3eb1647af036),
  [6df7cc7](https://reviews.llvm.org/rG6df7cc7f47d2),
  [a76ee58](https://reviews.llvm.org/rGa76ee58f3cbc).