[LLVMdev] LLVM Weekly - #70, May 4th 2015

[Alex Bradbury]

LLVM Weekly - #70, May 4th 2015
===============================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/70>.

Welcome to the seventieth 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

Microsoft have announced their intention to make use of the [Clang frontend on
Windows](http://blogs.msdn.com/b/vcblog/archive/2015/05/01/bringing-clang-to-windows.aspx).

Bjarne Stroustrup has recently been [talking about potential C++17
features](http://www.infoq.com/news/2015/04/stroustrup-cpp17-interview).

The Visual C++ developers are going to be open-sourcing their [GDB/LLDB debug
engine](http://blogs.msdn.com/b/vcblog/archive/2015/04/29/open-sourcing-visual-studio-s-gdb-lldb-debug-engine.aspx).

The projects accepted into Google Summer of Code for LLVM [have been
announced](https://www.google-melange.com/gsoc/org2/google/gsoc2015/llvm).
Four student projects have been accepted.

The next Bay Area LLVM social is [scheduled
for](http://article.gmane.org/gmane.comp.debugging.lldb.devel/7243) 7pm on
Thursday the 7th of May. Please sign up if you are attending.


## On the mailing lists

* Rui Ueyama has been doing quite a lot of work on LLD of late and has
proposed an [LLD improvement
plan](http://article.gmane.org/gmane.comp.compilers.llvm.devel/85190). In it,
he proposes some major changes that would hopefully ease the path to LLD
becoming a fully functional ELF, Mach-O, and PE-COFF linker. The two main
proposals are to use the 'section' rather than the 'atom' model and to stop
trying to bend the Unix model to work on other platforms, instead directly
implementing the necessary native behaviour. There are understandably some
concerns that this direction could result in LLD having to maintain
essentially three linkers, but discussion is ongoing and much feedback seems
positive.

* Alex, who will be interning at Apple this summer has posted an [RFC on a
proposed machine level IR text serialisation
format](http://article.gmane.org/gmane.comp.compilers.llvm.devel/85003). It
came out a little mangled on Gmane so you may prefer to read the [pipermail
rendering](http://lists.cs.uiuc.edu/pipermail/llvmdev/2015-April/084932.html).
A lot of the feedback revolves around the pros and cons of a YAML-based
format..

* Andrey Bokhanko suggests [replacing libgomp with
libiomp](http://article.gmane.org/gmane.comp.compilers.clang.devel/42449) as
the default OpenMP runtime library when using `-fopenmp`. Ultimately there
seems to be agreement and the only issue seems to be on the library naming.

* Nico Weber reports that although `-gline-tables-only` makes debug info much
smaller, they've [found with Chromium the resulting stackframes aren't that
usable without function parameters and
namespaces](http://article.gmane.org/gmane.comp.compilers.clang.devel/42419).
The proposal is to add a new variant that does include function parameter info
and namespace info.


## LLVM commits

* The LLVM performance tips document has gained another two entries.
[r235825](http://reviews.llvm.org/rL235825),
[r235826](http://reviews.llvm.org/rL235826).

* llvm-symbolizer now works on Windows.
[r235900](http://reviews.llvm.org/rL235900).

* SelectionDAG, DAGCombiner and codegen support for masked scatter and gather
has been added. [r235970](http://reviews.llvm.org/rL235970),
[r236211](http://reviews.llvm.org/rL236211),
[r236394](http://reviews.llvm.org/rL236394).

* Debug locations have been added to all constant SelectionDAG nodes.
[r235989](http://reviews.llvm.org/rL235989).

* Dragonegg support has been dropped from the release script.
[r236077](http://reviews.llvm.org/rL236077).

* The debug info IR constructs have been renamed from `MD*` to `DI*`. Duncan
suggests that if you're updating an out of tree target, it may be easiest to
first get things compiling with the code from before this commit, then
continue the merge. [r236120](http://reviews.llvm.org/rL236120).


## Clang commits

* Clang learned `-Wpessimizing-move` and `-Wredundant-move` warnings.
[r236075](http://reviews.llvm.org/rL236075).

* Clang can now generate dependencies in the style accepted by the NMake and
Jom build tools. [r235903](http://reviews.llvm.org/rL235903).

* New AVX-512 intrinsics have been added.
[r235986](http://reviews.llvm.org/rL235986),
[r236218](http://reviews.llvm.org/rL236218).


## Other project commits

* LLDB gained support for the SysV ABI on ARM and AArch64.
[r236097](http://reviews.llvm.org/rL236097),
[r236098](http://reviews.llvm.org/rL236098).

* The LLVM test suite gained a `frame_layout` test.
[r236085](http://reviews.llvm.org/rL236085).