[llvm-dev] LLVM Weekly - #307, November 18th 2019

[Alex Bradbury via llvm-dev]

LLVM Weekly - #307, November 18th 2019
======================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/307>.

Welcome to the three hundred and seventh 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

The next Toronto LLVM/Clang social meetup [will take
place](https://www.meetup.com/LLVM-Clang-Toronto-socials/events/266410090) on
Tuesday November 26th and include a presentation on writing loop optimisations
in LLVM.

The next HelloLLVM/HelloGCC social in Shanghai [will take
place](http://lists.llvm.org/pipermail/llvm-dev/2019-November/136875.html) on
Nov 23rd.

Videos from the 2019 LLVM Dev Meeting have
[started to appear on the LLVM YouTube
channel](https://www.youtube.com/channel/UCv2_41bSAa5Y_8BacJUZfjQ/videos).


## On the mailing lists

* Tom Stellard posted an RFC on [using GitHub Actions for CI testing on the
release
branches](http://lists.llvm.org/pipermail/llvm-dev/2019-November/136703.html).

* JF Bastien and the Apple LLVM team [proposed a new security process and
associated private LLVM Security
Group](http://lists.llvm.org/pipermail/llvm-dev/2019-November/136839.html).

* Andrzej Warzynski [announced
llvm-tutor](http://lists.llvm.org/pipermail/llvm-dev/2019-November/136775.html),
a collection of out-of-tree passes, plugins, and tools for LLVM aiming to make
it easier for those looking to use LLVM for their own out-of-tree projects.

* Tom Stellard has [posted the proposed 9.0.1 release
schedule](http://lists.llvm.org/pipermail/llvm-dev/2019-November/136863.html).

* Hal Finkel is working on a patch to better document LLVM's code review
process and [seeking
input](http://lists.llvm.org/pipermail/llvm-dev/2019-November/136808.html).

* David Rector
[shared](http://lists.llvm.org/pipermail/cfe-dev/2019-November/063868.html) a
Clang 7.0 fork allowing reflection on the Clang AST. This thread triggered
discussion on the stability of the Clang AST interface and on the ongoing C++
reflection standards work.

* Johannes Doerfert [suggested two changes to the proposed restrict
support](http://lists.llvm.org/pipermail/llvm-dev/2019-November/136705.html).

* Mehdi Amini is [seeking feedback on how to integrate MLIR into the
monorepo](http://lists.llvm.org/pipermail/llvm-dev/2019-November/136813.html).
He is proposing to perform a git subtree merge, which would preserve MLIR
history.

* Johannes Doerfert [proposes creating
llvm/lib/Frontend](http://lists.llvm.org/pipermail/llvm-dev/2019-November/136743.html)
for code that can be shared between frontends (e.g. clang and flang). This
would initially be populated with the OpenMP-IR-Builder.

* Andrew Kaylor is [seeking feedback on his use of token arguments and operand
bundles for constrained FP
intrinsics](http://lists.llvm.org/pipermail/llvm-dev/2019-November/136793.html).


## LLVM commits

* An IRTransformations directory was added to the LLVM examples, to contains
example transformation/analysis code used by tutorials.
[7d0b1d7](https://reviews.llvm.org/rG7d0b1d77b3d).

* LLVM's SHA1 implementation was optimised, resulting in a 10% improvement of
linking time for LLD. [43ff634](https://reviews.llvm.org/rG43ff6347725).

* The AArch64 backend can now spill/fill callee-saved SVE registers.
[84a0c8e](https://reviews.llvm.org/rG84a0c8e3ae9).

* InitializePasses.h includes were sunk in order to reduce the number of
recompiles needed when it's modified.
[05da2fe](https://reviews.llvm.org/rG05da2fe5216).

* More work has been done on MIPS GlobalISel, with support for selecting
addiu, andri, ori, xori. [dda8e95](https://reviews.llvm.org/rGdda8e955407),
[1f55935](https://reviews.llvm.org/rG1f559353a78).

* The RISC-V backend can now handle variable sized objects on the stack in the
case that the stack must be realigned.
[cf6cf0c](https://reviews.llvm.org/rGcf6cf0cd147).


## Clang commits

* `-Wtautological-compare` was added to `-Wall`.
[9740f9f](https://reviews.llvm.org/rG9740f9f0b6e).

* The `-march` and `-mabi` selection logic for RISC-V in the Clang driver was
updated to more closely mirror GCC defaults.
[e3d5ff5](https://reviews.llvm.org/rGe3d5ff5a0b1).

* Clang gained intrinsics for Arm MVE contiguous load/stores, vector get/set
lane, and more. [a12f588](https://reviews.llvm.org/rGa12f588ebb1),
[9e37892](https://reviews.llvm.org/rG9e37892773c).


## Other project commits

* The imported GCC C Torture Suite was enabled for Mips.
[45c8b76](https://reviews.llvm.org/rG45c8b766).

* The libcxx status page was updated with new papers from the Belfast C++
standards meting. [2f4fb20](https://reviews.llvm.org/rG2f4fb200b6b).