llvm dev - Jan 2018 - LLVM Weekly - #213, Jan 29th 2018

LLVM Weekly - #213, Jan 29th 2018
================================
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<http://llvmweekly.org/issue/213>.

Welcome to the two 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

You now have [two
weeks](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120737.html) to
submit your proposals for EuroLLVM. Also, [registration is now
open](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120640.html).

The [LLVM Toolchain
devroom](https://fosdem.org/2018/schedule/track/llvm_toolchain/)
at FOSDEM will take place next Sunday 4th February. Unfortunately I can't
make
it to FOSDEM this year, but the devroom has a great line-up thanks to the high
quality submissions from the LLVM community.

The next Cambridge LLVM social [will take
place](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120764.html) on
Feb 7th 6pm-8pm at the Microsoft Research building.

The next LLVM Social in Paris [will be
held](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120684.html)
tomorrow, January 30th. It will feature talks about 'vlang : a C++ RTL
simulator and VHDL convertor' and building an LLVM bitcode obfuscator.

The JuliaCon CfP is [now open](http://juliacon.org/2018/cfp) and closes on
April 30th. JuliaCon will be held August 7th-11th in London, UK. LLVM-related
talks are very welcome.


## On the mailing lists

* Peter Collingbourne has written up an RFC on [using link-time optimization
to eliminate
retpolines](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120672.html).

* Greg Clayton started a discussion about how to deal with [demangling huge
symbols slowing down
LLDB](http://lists.llvm.org/pipermail/lldb-dev/2018-January/013180.html). His
example symbol de-mangles to something that is 72MB in size and takes 280
seconds.

* Marshall Clow [reminds
us](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120808.html) that a
number of components will be removed from `std::experimental` in libcxx in
just a few days.

* Peter Smith has provided a [mini
guide](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120723.html) on
adding a new target to LLD.

* John Reagan has posted a detailed RFC on [improving x86-64 compact unwind
descriptors](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120741.html).

* Tom Tromey is looking for feedback on [plans for adding Rust language
support to
LLDB](http://lists.llvm.org/pipermail/lldb-dev/2018-January/013198.html).

* Don Hinton has written an RFC on [re-organising the handling of CMake
policies](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120707.html).


## LLVM commits

* Support for the 'retpoline' mitigation against Spectre on x86 has been
merged. [r323155](http://reviews.llvm.org/rL323155).

* New documentation has been added on adding exception handling support for a
target. [r323311](http://reviews.llvm.org/rL323311).

* A new utility has been written which uses bugpoint to reduce failures in
GlobalISel tests. [r323248](http://reviews.llvm.org/rL323248).

* The AggressiveInstCombine pass has been introduced. This differs from
InstCombine in that it can contain optimisations with greater than O(1)
complexity. [r323321](http://reviews.llvm.org/rL323321).

* A series of refactoring patches have enabled false dependencies for X86
POPCNT, LZCN and TZCNT to be broken.
[r323096](http://reviews.llvm.org/rL323096).

* llvm-extract gained support for extracting a basic block from a function.
[r323266](http://reviews.llvm.org/rL323266).

* SelectionDAGISel now prints the current node before calling select, meaning
targets don't have to add this logic themselves.
[r323551](http://reviews.llvm.org/rL323551).


## Clang commits

* The `-fexperimental-isel` driver option can be used to enable/disable
GlobalISel. [r323485](http://reviews.llvm.org/rL323485).

* clangd gained a helper to report estimated memory usage per-file.
[r323425](http://reviews.llvm.org/rL323425).


## Other project commits

* The LLD portion of the 'retpoline' mitigation against Spectre on x86
has
landed. [r323155](http://reviews.llvm.org/rL323155).

* LLDB gained an ABI plugin for PPC64le.
[r323100](http://reviews.llvm.org/rL323100).