llvm dev - Jan 2018 - LLVM Weekly - #212, Jan 22nd 2018

LLVM Weekly - #212, Jan 22nd 2018
================================
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<http://llvmweekly.org/issue/212>.

Welcome to the two hundred and twelfth 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](https://www.linkedin.com/in/alex-bradbury/). 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 6.0.0-rc1 [has been
tagged](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120506.html).

The next LLVM Social in Berlin will [take
place](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120596.html) on
Thursday 25th January. Alexander Meißner will present "Symatem -
Reinventing
Software".

The MoreVMs'18 workshop is [seeking paper
submissions](https://2018.programming-conference.org/track/MoreVMs-2018). The
deadline for abstract submission is this Friday 26th January. The workshop
will take place on April 9th in Nice, France.


## On the mailing lists

* Tobias Grosser has reignited the discussion on [including Polly and isl in
core LLVM](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120425.html).
Michael Kruse also started a
[thread](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120408.html)
focused more specifically on isl (the Integer Set Library). There's been a
lot
of discussion spread across multiple threads - check out [Chris Lattner's
initial
response](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120529.html)
and Hal Finkel's excellent
[summary](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120620.html)
of what Polly has to offer for LLVM.

* David Blaikie
[proposes](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120462.html)
expanding the LLVM Coding Standards document to discuss layering requirements.

* Sanjay Patel
[suggests](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120522.html)
allowing narrowing to i8 and i16 even when they aren't legal for the target.

* Adrian Prantl kicked off a discussion about [improving the LLDB test suite
to support out-of-tree
builds](http://lists.llvm.org/pipermail/lldb-dev/2018-January/013111.html).

* Renato Golin shares his
[perspective](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120445.html)
on remaining work to be done on vectorisation in LLVM.

* Pavel Labath is curious if [anyone else is interested in DWARF5 accelerator
table
support](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120499.html).

* Sjoerd Meijer has
[revived](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120537.html)
the RFC on half-precision floating point support in the Arm backends.

* Hongbin Zheng is [looking for
feedback](http://lists.llvm.org/pipermail/llvm-dev/2018-January/120513.html)
on a new isRegisterRich hook intended to be used for targets such as FPGAs
where register pressure is not a concern.


## LLVM commits

* Alignment arguments to memcpy/memmov/memset have been removed in favour of
alignment attributes. The commit message contains a sed script that may help
updating out-of-tree tests. [r322965](http://reviews.llvm.org/rL322965).

* MachineCSE can now be run in the middle of the GlobalISel pipeline. As the
commit description notes, being able to run optimisations like this at any
point of the ISel pipeline was one of the goals of GlobalISel.
[r322805](http://reviews.llvm.org/rL322805).

* The README for the WebAssembly backend has been updated.
[r322508](http://reviews.llvm.org/rL322508).

* Coverage of MC encoding for the base x86 ISA has been hugely expanded with
test cases covering I86, I181, I286, I386, I486, PPRO and MMX instruction
sets. [r322544](http://reviews.llvm.org/rL322544).

* GlobalISel gained support for SDNodeXForm by way of GICustomOperandRenderer
and GISDNodeXFormEquiv. [r322582](http://reviews.llvm.org/rL322582).

* The RISC-V backend gained frame pointer elimination and codegen for the
RV32M extension. [r322839](http://reviews.llvm.org/rL322839),
[r322843](http://reviews.llvm.org/rL322843).

* AArch64 will now omit callframe setup/destroy when not needed.
[r322917](http://reviews.llvm.org/rL322917).


## Clang commits

* Clang gained support for soft-float RISC-V ABI lowering.
[r322494](http://reviews.llvm.org/rL322494).

* ARMv8.2-A FP16 scalar intrinsics have been added.
[r323006](http://reviews.llvm.org/rL323006).

* clang-tidy gained a new checker to complain about the use of `goto`.
[r322626](http://reviews.llvm.org/rL322626).


## Other project commits

* libFuzzer gained support for building a private version of libc++, (as I
understand it) allowing libFuzzer to be used in cases where the code it is
being linked against uses libc++. [r322604](http://reviews.llvm.org/rL322604).

* libcxx has had constexpr modifiers sprinkled across a range of functions as
proposed in
[P0202](http://open-std.org/JTC1/SC22/WG21/docs/papers/2016/p0202r1.html).
[r322489](http://reviews.llvm.org/rL322489), and others.

## Review corner

The LLVM Weekly review corner serves to highlight patches that are stuck
waiting awaiting review, or work from first-time contributors. See
[here](http://llvmweekly.org/reviewcorner) for more information and how to
submit you work for inclusion. Of course the hope is that highlighting these
patches will enable LLVM Weekly readers will step up and help to get them
merged. I'll be reporting back each week on any activity generated on these
patches, as well as sharing a new batch. If you want your patch included you
must submit it via the linked form.

Submissions seem to have ceased, so I'm likely going to retire the review
corner section in its current form. It was an interesting experiment, huge
thanks to those who took the time to help out patches that were 'stuck'.