[llvm-dev] LLVM Weekly - #287, July 1st 2019

[Alex Bradbury via llvm-dev]

LLVM Weekly - #287, July 1st 2019
=================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/287>.

Welcome to the two hundred and eighty-seventh 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

Registration is [now
open](https://www.eventbrite.com/e/2019-llvm-developers-meeting-bay-area-tickets-63481303287)
for the 2019 LLVM Developers' Meeting, to be held October 22-23rd in San Jose.

The Linux Plumbers Toolchain micro-conference has [put out a call for
papers](http://lists.llvm.org/pipermail/llvm-dev/2019-June/133433.html). The
conference will take place in Lisbon, September 9th-11th.

This month's LLVM bay area social [will be held on July
11th](http://lists.llvm.org/pipermail/llvm-dev/2019-June/133359.html) rather
than the usial first Thursday of the month.

LLVM 8.0.1-rc3 [has been
tagged](http://lists.llvm.org/pipermail/llvm-dev/2019-June/133439.html).


## On the mailing lists

* By far the biggest discussion topic this week was started by Siva Chandra's
message about [contributing a libc to
LLVM](http://lists.llvm.org/pipermail/llvm-dev/2019-June/133269.html). This
triggered many questions about the scope of the proposed project, and about
where libc implementations such as Musl, glibc, or the BSDs fail to meet the
Google team's requirements. To pick out a few responses: Chris Lattner
[responded
positively](http://lists.llvm.org/pipermail/llvm-dev/2019-June/133274.html),
Rich Felker (author of musl libc) [felt it was a bad
idea](http://lists.llvm.org/pipermail/llvm-dev/2019-June/133308.html), Siva
[gave more info on the
motivations](http://lists.llvm.org/pipermail/llvm-dev/2019-June/133360.html),
Saleem Abulrasool gives a [strawman requirements
list](http://lists.llvm.org/pipermail/llvm-dev/2019-June/133444.html) for a
libc that might serve the "full community" (rather then narrowly targeting a
few use cases), and Stephen Canon
[queries](http://lists.llvm.org/pipermail/llvm-dev/2019-June/133477.html) the
practicality of avoiding assembly while keeping high performance (noting wins
available for core string and memory functions).

* Tanya Lattner is [seeking
volunteers](http://lists.llvm.org/pipermail/llvm-dev/2019-June/133498.html)
for those wishing to present tutorials aimed at newcomers.

* Bill Wendling and Nick Desulniers shared an RFC on [asm goto with output
constraints](http://lists.llvm.org/pipermail/llvm-dev/2019-June/133427.html).

* Bardia Mahjour
[queries](http://lists.llvm.org/pipermail/llvm-dev/2019-June/133397.html) the
status of the new pass manager. Leonard Chan reports that [Fuchsia hopes to
switch to the new PM by
default](http://lists.llvm.org/pipermail/llvm-dev/2019-June/133400.html),
while Philip Reames shares that his downstream project [has already
switched](http://lists.llvm.org/pipermail/llvm-dev/2019-June/133404.html).


## LLVM commits

* GlobalISel was modified to allow multiple vregs for lowerFormalArgs and
lowerCall. This allows the target to decide for itself whether to handle them
as separate pieces or to use a single register.
[r364510](https://reviews.llvm.org/rL364510).

* MC layer support has now been merged for all Arm MVE instructions.
[r364291](https://reviews.llvm.org/rL364291),
[r364292](https://reviews.llvm.org/rL364292).

* A class has been introduced for registers in CodeGen, rather than just an
`unsigned`. [r364191](https://reviews.llvm.org/rL364191).

* llvm-symbolizer learned a FRAME command which prints a description of the
referenced function's stack frame.
[r364225](https://reviews.llvm.org/rL364225).

* Pseudo-instructions to model Arm v8.1-m low overhead loops
were introduced. r364288](https://reviews.llvm.org/rL364288).

* LoopUnroll can now handle loops with exiting headers and unconditional
latches. [r364398](https://reviews.llvm.org/rL364398).

* WebAssembly gained support for tail calls.
[r364445](https://reviews.llvm.org/rL364445).


## Clang commits

* When dumping the AST to JSON, source locations and ranges are now emitted
directly rather than in separate JSON objects.
[r364226](https://reviews.llvm.org/rL364226).

* The clang-doc tool gained basic support for templates and typedef.
[r364222](https://reviews.llvm.org/rL364222).


## Other project commits

* C and C++ wrappers for the standalone scudo allocator were committed. The
commit message explains this is the final piece needed for a functional C and
C++ allocator based on Scudo. [r364332](https://reviews.llvm.org/rL364332).

* LLDB now implements the Windows ABI for `x86_64`.
[r364216](https://reviews.llvm.org/rL364216).