[llvm-dev] LLVM Weekly - #330, Apr 27th 2020

Alex Bradbury via llvm-dev llvm-dev at lists.llvm.org
Mon Apr 27 12:27:53 PDT 2020

LLVM Weekly - #330, Apr 27th 2020

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Welcome to the three hundred and thirtieth 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

Erich Keane wrote for the LLVM blog about [the recently added `_ExtInt`
providing support for exact bitwidth integer types in Clang.

## On the mailing lists

* Tom Stellard returned to the topic of [switching from Bugzilla to GitHub
reporting that support for subscribing to notifications for specific issue
labels will be provided through GitHub Actions. This spawned a long thread,
mostly focused on the question of how to handle existing bugs and
possibilities for keeping consistent numbering or using redirects.

* Martin Liška [announces
C-Vise](http://lists.llvm.org/pipermail/llvm-dev/2020-April/141188.html), a
Python fork of the C-Reduce tool.

* Kees Cook proposed [making -ftrivial-auto-var-init=zero a first-class
reporting a number of vendors using zero initialisation in production code
(with more responding later in the thread). There were many responses on this
thread and a consensus has yet to form, though JF Bastien indicated [interest
in seeing the work on optimising pattern initialisation
finished](http://lists.llvm.org/pipermail/cfe-dev/2020-April/065242.html) to
allow a fuller comparison.

* Sjoerd Meijer kicked off a [long thread on the clang mailing list about
mtune](http://lists.llvm.org/pipermail/cfe-dev/2020-April/065169.html). David
Greene [suggested not following GCC

* ORC JIT Weekly #13 [is
Discord user @Juicebox has written a project to enable PDB debugging on
Windows with ORC and MCJIT.

* Chris Tetreault [provides an update on refactoring the class hierarchy of

* Tom Stellard [shares the proposed 10.0.1 release
This would see rc1 tagged on May 18th, rc2 on June 18th, and 10.0.1-final on
June 25th.

## LLVM commits

* MC layer support for the Armv8.6-a matrix multiply extension was added.

* `TargetTransformInfo::getOperationCost` was removed and merged into
getUserCost. [ee959dd](https://reviews.llvm.org/rGee959ddc5ee).

* The MachineVerifier is now run after more passes.

* The integration of compiler extensions into the build system was updated.

## Clang commits

* The time profiler script will now emit a beginningOfTime parameter that can
be used for combining events from different processes while preserving their
relative timing. [2899103](https://reviews.llvm.org/rG2899103108d).

* More SVE builtins were added.

## Other project commits

* lld-macho gained basic support for linking against dylibs.

* compiler-rt started to gain support for platforms with 16-bit int.

* LLDB's reproducer infrastructure gained support for a new 'passive replay'
mode. [950a8aa](https://reviews.llvm.org/rG950a8aa165e).

* MLIR's liveness analysis now supports nested regions.

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