[llvm-dev] LLVM Weekly - #134, Jul 25th 2016

[Alex Bradbury via llvm-dev]

LLVM Weekly - #134, Jul 25th 2016
=================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/134>.

Welcome to the one hundred and thirty-fourth 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

LLVM/Clang 3.9 has [now
branched](http://lists.llvm.org/pipermail/llvm-dev/2016-July/102468.html). A
first release candidate should be available shortly. As you may recall there
was a very long mailing list discussion about what the successor to 3.9 would
be. In the end, it was decided it should be 4.0.

As a reminder, I am organising a one-day LLVM conference the [LLVM
 Cauldron](http://llvm.org/devmtg/2016-09/)
to be held in Hebden Bridge, UK on September 8th. This is immediately followed
by the [GNU Tools Cauldron](http://gcc.gnu.org/wiki/cauldron2016). The
submission deadline is August 8th, so get your talk proposals in now.


## On the mailing lists

* By far the most active thread this week was on [whether a proposed move from
SVN to Git should result in a single monolithic repository or
not](http://lists.llvm.org/pipermail/llvm-dev/2016-July/102602.html). Richard
Smith's
[suggestion](http://lists.llvm.org/pipermail/llvm-dev/2016-July/102754.html)
was well received by several others. As he points out, the move to Git and a
potential repository re-organisation don't need to happen at the same time.
Renato Golin has also shared the [final cut of the proposal to move to
Github](http://lists.llvm.org/pipermail/llvm-dev/2016-July/102456.html).

* Dean Michael Berris has shared [instructions and early results of using XRay
function
tracing](http://lists.llvm.org/pipermail/llvm-dev/2016-July/102552.html).

* Jaques Pienaar has proposed [making the Lanai backend
non-experimental](http://lists.llvm.org/pipermail/llvm-dev/2016-July/102480.html).
This triggered some discussion on when a backend would be accepted upstream
and when it would be considered official. Renato Golin posted a
[summary](http://lists.llvm.org/pipermail/llvm-dev/2016-July/102505.html) of
the criteria from his perspective.

* Tom Stellard has posted a notice for out-of-tree code owners, that
[assumptions about intrinsics will be
changing](http://lists.llvm.org/pipermail/llvm-dev/2016-July/102458.html).
Specifically, it will no longer be assumed that intrinsics can't read or write
global variables. They should be marked with `IntrNoMem` or `IntrArgMemOnly`
as appropriate.


## LLVM commits

* LLVM trunk is now 4.0.0svn. [r275827](http://reviews.llvm.org/rL275827).

* The first piece of coroutines support in LLVM has landed, the documentation.
[r276513](http://reviews.llvm.org/rL276513).

* The MemorySSA pass has been updated to use a new walking algorithm
(iteratively expanded depth-first search).
[r275940](http://reviews.llvm.org/rL275940).

* There's been some more progress on global instruction selection. A
legalization pass has been started, though it currently only supports
splitting a vector `G_ADD` in to one acting on smaller vectors.
[r276461](http://reviews.llvm.org/rL276461).

* The recently added CFLAnders analysis gained the ability to distinguish
reads from writes and to support interprocedural analysis.
[r276023](http://reviews.llvm.org/rL276023),
[r276026](http://reviews.llvm.org/rL276026).

* A script was added to check for code coverage regressions.
[r276199](http://reviews.llvm.org/rL276199).


## Clang commits

* The `-masm` flag was added for x86 assembly targets to specify on the
command line whether Intel or AT&T syntax should be used.
[r275877](http://reviews.llvm.org/rL275877).

* clang-rename has been improved with better symbol finding.
[r276414](http://reviews.llvm.org/rL276414).


## Other project commits

* libcxx has imported the Google Benchmark library in order to use it for
benchmark tests. [r276049](http://reviews.llvm.org/rL276049).

* libcxx now has an implementation of `std::string_view`.
[r276328](http://reviews.llvm.org/rL276328).

* Test cases from the Halide suite have started to be imported.
[r275897](http://reviews.llvm.org/rL275897).

* libclc gained implementations of the cosh and cbrt builtins.
[r276496](http://reviews.llvm.org/rL276496),
[r276497](http://reviews.llvm.org/rL276497).