[llvm-dev] LLVM Weekly - #242, August 20th 2018

[Alex Bradbury via llvm-dev]

LLVM Weekly - #242, August 20th 2018
====================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/242>.

Welcome to the two hundred and forty-second 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

Bekket McClane has authored [part 2 of his tutorial on writing an LLVM pass in
2018](https://medium.com/@mshockwave/writing-llvm-pass-in-2018-part-ii-640f680978ec).


## On the mailing lists

* Further GSoC reports were published this week. Piotr Padlewski [summarized
work on devirtualization
v2](http://lists.llvm.org/pipermail/llvm-dev/2018-August/125277.html).
Alexander Polyakov worked on [re-implementing lldb-mi on top of the LLDB
public API](https://apolyakov.github.io/GSoC-2018/). Paul Semel [worked on
making LLVM binutils equivalents command-line
compatible](http://paulsemel.org/posts/command-line-replacements-in-llvm-binutils/).
Réka Nikolett Kovács worked on [a Clang Static Analyzer checker for dangling
string pointers in C++](https://rnkovacs.github.io/gsoc2018/). Mikhail Ramalho
worked on [bug validation in the Clang Static Analyzer using the Z3 SMT
solver](http://lists.llvm.org/pipermail/cfe-dev/2018-August/058912.html).

* Artyom is [proposing to merge an m68k codegen target
upstream](http://lists.llvm.org/pipermail/llvm-dev/2018-August/125317.html).
Respondents to the thread suggest it would be worth splitting up to smaller
patches for easier review.

* James Henderson has
[proposed](http://lists.llvm.org/pipermail/llvm-dev/2018-August/125395.html)
syntax for FileCheck numeric variables and expressions.

* John Brawn has shared an RFC on [delaying phi-to-select transformation until
later in the pass
pipeline](http://lists.llvm.org/pipermail/llvm-dev/2018-August/125313.html).

* Louis Dionne suggests [setting up a dedicated mailing list for
libc++](http://lists.llvm.org/pipermail/cfe-dev/2018-August/058946.html)
rather than using cfe-dev. Responses are positive so far.

* Fabien Giesen has a [very detailed
response](http://lists.llvm.org/pipermail/llvm-dev/2018-August/125324.html) to
a question about static branch prediction.


## LLVM commits

* Support was added for generating DWARF debug information for labels.
[r340039](https://reviews.llvm.org/rL340039).

* A new API was added exposing a 'CFG update struct', allowing passes or
analysis to access a CFG snapshot.
[r339689](https://reviews.llvm.org/rL339689).

* The memory management strategy for MachineMemOperand pointers attached to
MachineSDNodes was modified. [r339740](https://reviews.llvm.org/rL339740).

* A C API was added for llvm::Error.
[r339802](https://reviews.llvm.org/rL339802).

* The MS Demangler learned to demangle string literals.
[r339892](https://reviews.llvm.org/rL339892).

* The lowering of UMULO (unsigned multiply with overflow) has been improved.
[r339922](https://reviews.llvm.org/rL339922).

* The AArch64 backend gained the ability to generate pointer authentication
instructions. [r340018](https://reviews.llvm.org/rL340018).


## Clang commits

* The new AArch64 clang option `-msign-return-address` enables return address
signing. [r340019](https://reviews.llvm.org/rL340019).

* New rotate builtins were introduced.
[r340141](https://reviews.llvm.org/rL340141).


## Other project commits

* FastDemangle was removed from LLDB.
[r339671](https://reviews.llvm.org/rL339671).

* Image dilate and bilateral filtering kernels were added to the benchmarks in
the LLVM test suite. [r339564](https://reviews.llvm.org/rL339564),
[r340002](https://reviews.llvm.org/rL340002).