[LLVMdev] LLVM Weekly - #82, Jul 27th 2015

[Alex Bradbury]

LLVM Weekly - #82, Jul 27th 2015
================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/82>

Welcome to the eighty-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](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.

I'd just like to highlight how much I really do appreciate people sending me
links for inclusion, e.g. LLVM-related blog posts or new releases of software
using LLVM (feature releases rather than simple bugfix updates). I'm not
omniescent - if an interesting blog post or software release goes unmentioned
here, I probably just didn't know about it!


## News and articles from around the web

The [call for
papers](http://article.gmane.org/gmane.comp.compilers.llvm.devel/88488) for
the 2015 LLVM Developers' meeting has now gone out. The submission deadline is
August 20th. Registration is also [now
open](https://www.eventbrite.com/e/2015-llvm-developers-meeting-tickets-17756357744).

John Regehr and his collaborators working on Souper have [shared some initial
results from the synthesizing
superoptimizer](http://blog.regehr.org/archives/1252). John is very interested
in collecting representative IR from frontends other than Clang. There is also
some discussion about these results [on the mailing
list](http://article.gmane.org/gmane.comp.compilers.llvm.devel/88588).

Microsoft have [open sourced their GDB/LLDB 'debug
engine'](http://blogs.msdn.com/b/vcblog/archive/2015/07/20/source-now-available-for-gdb-lldb-debug-engine.aspx).


## On the mailing lists

* Piotr Padlewski has [shared a plan to improve Clang's
devirtualization](http://article.gmane.org/gmane.comp.compilers.clang.devel/44022)
which he will be working on with Richard Smith at Google this Summer. The hope
is to reduce any remaining performance gap between LLVM/Clang and GCC (which
has better devirtualization support). The Google Doc [can be read
here](https://docs.google.com/document/d/1f2SGa4TIPuBGm6y6YO768GrQsA8awNfGEJSBFukLhYA/edit#).

* Rafael Espíndola has shared [some thoughts on handling ELF shared libraries
in LLD](http://article.gmane.org/gmane.comp.compilers.llvm.devel/88499).

* Marshall Clow has kicked off a discussion on [how C++ library TSes should be
packaged](http://article.gmane.org/gmane.comp.compilers.clang.devel/43985).
David Chisnall gives the [FreeBSD perspective on ABI and API compatibility in
libc++](http://article.gmane.org/gmane.comp.compilers.clang.devel/44034).

* Eric Fiselier has posted an [RFC on whether libc++ should support the atomic
header in
C++03](http://article.gmane.org/gmane.comp.compilers.clang.devel/43969).


## LLVM commits

* dsymutil gained support for one-definition-rule uniquing for C++ code. When
linking the DWARF for a debug build of clang, it generates a 150M dwarf file
instead of 700M. [r242847](http://reviews.llvm.org/rL242847).

* The last remnant of the AliasAnalysis legacy update API have been removed.
[r242881](http://reviews.llvm.org/rL242881).

* LoopUnswitch can now unswitch multiple trivial conditions in a single pass
invocation. [r243203](http://reviews.llvm.org/rL243203).


## Clang commits

* Clang gained the `isFinal()` AST matcher.
[r243107](http://reviews.llvm.org/rL243107).


## Other project commits

* A new ELF linker has been born, based on the PE/COFF linker.
[r243161](http://reviews.llvm.org/rL243161).

* libcxx gained a default searcher for `std::experimental::search`.
[r242682](http://reviews.llvm.org/rL242682).