[llvm-dev] LLVM Weekly - #323, Mar 9th 2020

[Alex Bradbury via llvm-dev]

LLVM Weekly - #323, Mar 9th 2020
================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/323>.

Welcome to the three hundred and twenty-third 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

Arnaud Allard de Grandmaison sent a [holding
note](http://lists.llvm.org/pipermail/llvm-dev/2020-March/139810.html) for
EuroLLVM'20. "If you have not yet booked your travel or accommodation, please
hold on until you receive further information from us. We expect to be able to
provide an update before the end of the week."


## On the mailing lists

* The second edition of the MLIR bi-weekly newsletter [is now
available](https://llvm.discourse.group/t/mlir-news-2nd-edition-3-6-2020/586).
As a community effort, credit is due to the range of contributors who give
their time to make it happen. Highlights include [slides from Chris Lattner's
CGO talk on MLIR](https://llvm.discourse.group/t/mlir-cgo-talk-slides/654)
which includes a suggested plan on how to incrementally migrate clang to MLIR
infrastructure, and a [canonical publication on
MLIR](https://arxiv.org/abs/2002.11054).

* ORC JIT Weekly #7 [is
out](http://lists.llvm.org/pipermail/llvm-dev/2020-March/139804.html).
JITEventListener support is in the works, and Swift's immediate mode has moved
to LLJIT.

* Louis Dionne [shared further motivations for allowing PRs on GitHub for some
subprojects](http://lists.llvm.org/pipermail/llvm-dev/2020-March/139735.html).

* Jon Chesterfield shared an RFC on [allowing cheaper indirect calls through
the generation of
trampolines](http://lists.llvm.org/pipermail/llvm-dev/2020-March/139683.html),
using a trampoline to allow a form of the function with a more optimised ABI
to co-exist with the externally visible interface.

* Fernando Magno Quintao Pereira reports they have [separated 128,411 from a
range of open source repos as part of the AnghaBench
effort](http://lists.llvm.org/pipermail/llvm-dev/2020-March/139681.html), with
the hope files in the form described may be appropriate for importing into the
LLVM test suite.

* Vangelis Tsiatsianas shared the result of their master's thesis work over
the past 7 months, [proof of concept support for live reverse debugging in
LLDB](http://lists.llvm.org/pipermail/lldb-dev/2020-March/016014.html).


## LLVM commits

* Documentation on the community code review process was rewritten and
expanded. [4d0339a](https://reviews.llvm.org/rG4d0339aecb6).

* Relaxations were implemented to reduce the number of nops needed for
alignment padding on X86 (e.g. converting near jumps to far jumps when
possible). [f708c82](https://reviews.llvm.org/rGf708c823f06).

* The GlobalISel Localizer was extended to enable intra-block localisation of
already-local uses. [e91e1df6](https://reviews.llvm.org/rGe91e1df6ab7).

* An IR MatrixBuiler was committed.
[2a70db2](https://reviews.llvm.org/rG2a70db245d6).

* LLVM learned to generate directives like `cfi_restore`.
[3c96d01](https://reviews.llvm.org/rG3c96d01d2e3).

* TimeTrace is now supported in LLVM's new pass manager.
[c5a0601](https://reviews.llvm.org/rGc5a06019d23).


## Clang commits

* Clang now defaults to C17 for C inputs, matching the behaviour of GCC 8.1.
[91cdbd5](https://reviews.llvm.org/rG91cdbd521a3).

* clang-doc's Markdown output was improved.
[7003f64](https://reviews.llvm.org/rG7003f64c1eb).

* A driver option was added to select the SYCL version.
[118b057](https://reviews.llvm.org/rG118b057f126).


## Other project commits

* New documentation was added on creating an MLIR dialect.
[d774fbc](https://reviews.llvm.org/rGd774fbc350a).

* The `__clear_cache` builtin was ported to RISC-V.
[99a8cc2](https://reviews.llvm.org/rG99a8cc2b7d8).

* libc gained implementations of `abort` and `_Exit`.
[a499d68](https://reviews.llvm.org/rGa499d680566).