[llvm-dev] LLVM Weekly - #92, Oct 5th 2015

[Alex Bradbury via llvm-dev]

LLVM Weekly - #92, Oct 5th 2015
===============================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/92>.

Welcome to the ninety-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.

## News and articles from around the web

Most of the presentation materials from CppCon2015 are [now
online](https://github.com/CppCon/CppCon2015). Talks that may be of particular
interest include [Kostya Serebryany on fuzzing with
libFuzzer](https://github.com/CppCon/CppCon2015/blob/master/Presentations/Beyond%20Sanitizers/Beyond%20Sanitizers%20-%20Kostya%20Serebryany%20-%20CppCon%202015.pdf),
[Piotr Padlewski on C++ devirtualization in
Clang](https://github.com/CppCon/CppCon2015/blob/master/Lightning%20Talks%20and%20Lunch%20Sessions/C++%20devirtualization%20in%20clang/C++%20devirtualization%20in%20clang%20-%20Piotr%20Padlewski%20-%20CppCon%202015.pdf),
and [JF Bastien talking about C++ on the
web](https://github.com/CppCon/CppCon2015/blob/master/Presentations/C++%20on%20the%20Web/C++%20on%20the%20Web%20-%20JF%20Bastien%20-%20CppCon%202015.pdf).

Rafael Espíndola wrote in to share an impressive milestone for the new LLD ELF
linker. It can now link itself and all of LLVM and Clang (though not all tests
pass, and you must use `LLVM_ENABLE_THREADS=OFF`). Things will of course get
really interesting once LLD matures if it can compete with Gold in terms of
speed.

The next Paris LLVM social will [take place on October
15th](http://lists.llvm.org/pipermail/llvm-dev/2015-September/090813.html).
Calixte Denizet will be talking about Scilab's usage of LLVM.


## On the mailing lists

* David Li has posted an [update on efforts to reduce the overhead of
profile-guided optimisation size
overhead](http://lists.llvm.org/pipermail/llvm-dev/2015-September/090860.html).
He's produced an initial implementation of one of the proposals, which reduces
the size of a release clang binary with coverage mapping from 986MB to 569MB.

* It's a new month, so time for a [new update on CMake's ability to replace
autoconf in
LLVM](http://lists.llvm.org/pipermail/llvm-dev/2015-October/090958.html). As
Chris says, we're getting very close now.

* Tom Stellard has posted a [proposed release schedule for LLVM/Clang
3.7.x](http://lists.llvm.org/pipermail/llvm-dev/2015-October/090992.html)
point releases. The deadline to propose patches for 3.7.1 is November 2nd and
November 30th for 3.7.2. Tom is also asking that people nominate patches using
Phabricator rather than email.

* Renato has kicked off a discussion on [buildbot
noise](http://lists.llvm.org/pipermail/llvm-dev/2015-October/090945.html) with
a good summary of the issues and potential ways forward.

* Chris Matthews is [looking for feedback on how people are using orders in
LNT](http://lists.llvm.org/pipermail/llvm-dev/2015-September/090840.html), so
as to better understand how to improve things. As he explains, the 'Order' is
the SVN revision of the compiler.

* Jeroen Ketema is asking if anyone has any [objections to a change to ARM's
NEON vld and vst
intrinsics](http://lists.llvm.org/pipermail/llvm-dev/2015-September/090826.html).
The change would allow an address space to be associated with the pointer
these intrinsics take.

* Jonas Paulsson is curious about [how to control selection of two-address vs
three-address instruction
forms](http://lists.llvm.org/pipermail/llvm-dev/2015-September/090845.html).
Several responses suggest just allowing three-address forms to be selected and
have a late pass that converts to the two-address form where possible. Jonas
has an interesting followup questions as to whether the register allocator
will produce the maximum number of opportunities for this conversion.


## LLVM commits

* A scheduler for the MIPS P5600 processor landed.
[r248725](http://reviews.llvm.org/rL248725).

* Align metadata for the load instruction was introduced.
[r248721](http://reviews.llvm.org/rL248721).

* Support for windows exception handling continues with support in AsmPrinter
for 'funclets'. [r248824](http://reviews.llvm.org/rL248824).

* Support landed for the HHVM JIT calling convention.
[r248832](http://reviews.llvm.org/rL248832).


## Clang commits

* clang-format's `#include` sorting functionality has been extended.
[r248782](http://reviews.llvm.org/rL248782).


## Other project commits

* The new ELF linker gained initial support for MIPS.
[r248779](http://reviews.llvm.org/rL248779).

* Some basic linker script support was added to the new ELF linker, enough to
parse Linux's libc.so. [r248918](http://reviews.llvm.org/rL248918).

* .ARM.exidx and .ARM.extab unwind information is now supported by lldb.
[r248903](http://reviews.llvm.org/rL248903).