[llvm-dev] LLVM Weekly - #127, June 6th 2016

Alex Bradbury via llvm-dev llvm-dev at lists.llvm.org
Mon Jun 6 07:52:10 PDT 2016

LLVM Weekly - #127, June 6th 2016

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Welcome to the one hundred and twenty-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](http://asbradbury.org). 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

Graham Markall at Embecosm has been comparing the code size of [RISC-V
binaries produced by the GCC and LLVM
as well as compared to ARM. GCC is currently ahead, though it is worth noting
the LLVM port has seen much less attention.

Matthias Reisinger is a Google Summer of Code student working on enabling
polyhedral optimisations for the Julia programming language. He's written a
blog post detailing his [initial steps and immediate future
plans](http://www.mreisinger.com/?p=43). Hopefully we'll see more posts over
the summer.

Loïc Hamot has been working on a [C++ to D
implemented using Clang.

The MSVC team have blogged about the [latest release of Clang with Microsoft
based on Clang 3.8.

There is going to be a [clang-tidy code
dojo](http://lists.llvm.org/pipermail/llvm-dev/2016-June/100647.html) in
Warsaw on Tuesday the 7th of June.

## On the mailing lists

* Renato Golin has kicked off a discussion on [moving LLVM's repository
hosting to
GitHub](http://lists.llvm.org/pipermail/llvm-dev/2016-May/100310.html). Chris
Lattner [came out in
specifically motivated by GitHub's community aspects. Renato has very
helpfully [summarised the

* Peter Smith has shared his [initial port of LLD to
ARM](http://lists.llvm.org/pipermail/llvm-dev/2016-June/100598.html) along
with his planned roadmap. The currently submitted patch is just enough to link
a hello world executable on ARM Linux.

* The apt repo hosted at llvm.org has been [temporarily turned
off](http://lists.llvm.org/pipermail/llvm-foundation/2016-May/000020.html) as
it is resulting in excessive I/O and network activity. Some commenters ask
about setting up an Ubuntu PPA or using the OpenSUSE build service.

* David Blaikie has written a GDB pretty printer script for some common LLVM
types and [described how to use

* Michael LeMay has posted an [RFC on using segmentation to harden

* Rui Ueyama has been investigating [using sendfile to copy file contents in
LLD](http://lists.llvm.org/pipermail/llvm-dev/2016-June/100700.html) and
shares his results. He concludes the performance improvement is too modest to
be worth the change.

* If you're interested in register allocation, then [delve in to this thread
on LLVM's PBQP allocator and copy

* Daniel Dunbar is [suggesting some changes to the lit default

* Steven Wu shares a follow-up RFC on [embedded

* There's a useful discussion in [this thread on lowering loops to use a
hardware loop

* Peter Collingbourne [proposes renaming and slightly redesigning the bitset

## LLVM commits

* LLVM gained support for 'SJLJ' (setjmp/longjmp) exception handling on x86
targets. [r271244](http://reviews.llvm.org/rL271244).

* LLVM now requires CMake 3.4.3 to build

* Support was added for attaching metadata to global variables.

* The AArch64 backend switched to use SubtargetFeatures rather than testing
for specific CPUs. [r271555](http://reviews.llvm.org/rL271555).

## Clang commits

* The release notes have been updated to explain the current level of OpenMP
support (full support of non-offloading features of OpenMP 4.5).

* Clang's source-based code coverage has been documented.

## Other project commits

* An `-fno-exceptions` libc++abi library variant was defined, to match the
`-fno-exceptions` libc++ build. [r271267](http://reviews.llvm.org/rL271267).

* LLDB's compact unwind printing tool gained support for ARMv7's compact
unwind format. [r271744](http://reviews.llvm.org/rL271744).

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