[llvm-dev] LLVM Weekly - #115, Mar 14th 2016

[Alex Bradbury via llvm-dev]

LLVM Weekly - #115, Mar 14th 2016
=================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/115>.

Welcome to the one hundred and fifteenth 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.

We have an LLVM-related research position currently being [advertised here at
the University of Cambridge Computer
Lab](http://lists.llvm.org/pipermail/llvm-dev/2016-March/096751.html). If
you'd like an informal chat about what it's like working in this group or on
this project please don't hesitate to get in touch with me.


## News and articles from around the web

LLVM and Clang 3.8 have now been released. Check out the
[LLVM](http://llvm.org/releases/3.8.0/docs/ReleaseNotes.html) and
[Clang](http://llvm.org/releases/3.8.0/tools/clang/docs/ReleaseNotes.html)
release notes for a run-down of the new features.

It's GDC this week and if you're attending you may be interested that there's
an [LLVM meetup scheduled for
Thursday](http://lists.llvm.org/pipermail/llvm-dev/2016-March/096446.html).

Felix Angell has a detailed blog post introducing [generating LLVM IR from
Go](https://blog.felixangell.com/an-introduction-to-llvm-in-go/).


## On the mailing lists

* Jason Henline has posted a very detailed RFC on [creating a new parallel
runtime
library](http://lists.llvm.org/pipermail/llvm-dev/2016-March/096576.html).
StreamExecutor wraps both the CUDA and OpenCL runtimes and is used internally
at Google.

* Ed Maste has shared an update on [linking the FreeBSD base system using
LLD](http://lists.llvm.org/pipermail/llvm-dev/2016-March/096449.html). With a
few workarounds, the full amd64 FreeBSD system is now buildable.

* Vedant Kumar has shared an [RFC on removing redundant profile counter
updates](http://lists.llvm.org/pipermail/llvm-dev/2016-March/096643.html).

* Sean Silva is seeking to [formalize the 'revert for more design review
policy'](http://lists.llvm.org/pipermail/llvm-dev/2016-March/096529.html).
Overall, the comments seem to be positive.

* With EuroLLVM coming up this week, people have been advertising their birds
of a feather sessions. e.g. the [LLVM on PowerPC and
SystemZ](http://lists.llvm.org/pipermail/llvm-dev/2016-March/096667.html)
session and the session on [surviving
downstream](http://lists.llvm.org/pipermail/llvm-dev/2016-March/096638.html).

* Rafael Espíndola reports that compilation with LLVM and Clang has been
[getting slower over
time](http://lists.llvm.org/pipermail/llvm-dev/2016-March/096488.html). Hal
Finkel has some good input on [potential areas for
improvement](http://lists.llvm.org/pipermail/llvm-dev/2016-March/096491.html).


## LLVM commits

* Loop invariant code motion learnt the ability the exploit the fact a memory
location is known to be thread-local.
[r263072](http://reviews.llvm.org/rL263072).

* A new `llvm.experimental.deoptimize` intrinsic has been added.
[r26328](http://reviews.llvm.org/rL263281).

* A ThinLTOCodeGenerator was added in order to provide a proof-of-concept
implementation. [r262977](http://reviews.llvm.org/rL262977).

* The Sparc backend gained support for co-processor condition branching and
conditional traps. [r263044](http://reviews.llvm.org/rL263044).


## Clang commits

* Clang gained support for the `[[nodiscard]]` attribute.
[r262872](http://reviews.llvm.org/rL262872).

* New AST matchers were added for addrLabelExpr, atomicExpr,
binaryCondtionalOperator, designatedINitExpr, designatedInitExpr,
designatorCountIs, hasSyntacticForm, implicitValueINitExpr, labelDecl,
opaqueValueExpr, parenListExpr, predefinedExpr, requiresZeroInitialization,
and stmtExpr. [r263027](http://reviews.llvm.org/rL263027).


## Other project commits

* Error and warning messages in LLD are now more consistent.
[r263125](http://reviews.llvm.org/rL263125).

* Documentation on the new ELF and COFF LLD linkers has been updated.
[r263336](http://reviews.llvm.org/rL263336).