[llvm-dev] LLVM Weekly - #311, December 16th 2019

[Alex Bradbury via llvm-dev]

LLVM Weekly - #311, December 16th 2019
======================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/311>.

Welcome to the three hundred and eleventh 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

All videos from the 2019 LLVM Developers' Meeting are now posted and available
in a [handy YouTube
playlist](https://www.youtube.com/playlist?list=PL_R5A0lGi1AAxLTNN21BA0w8CA_xDR0F8).

LLVM 9.0.1-rc3 [has been
tagged](http://lists.llvm.org/pipermail/llvm-dev/2019-December/137597.html).


## On the mailing lists

* Teresa Johnson shared an RFC on [supporting agressive whole program
devirtualization without
-fvsibility=hidden](http://lists.llvm.org/pipermail/llvm-dev/2019-December/137543.html).

* Jonas Devlieghere wrote up an RFC on [supporting Lua scripting in
LLDB](http://lists.llvm.org/pipermail/lldb-dev/2019-December/015812.html).

* Sam McCall starts a [discussion on providing network RPC in LLVM
projects](http://lists.llvm.org/pipermail/llvm-dev/2019-December/137576.html),
and is seeking feedback on depending on external libraries like Thrift, grpc
etc.

* Sander De Smalen [shares notes from last week's SVE sync-up
call](http://lists.llvm.org/pipermail/llvm-dev/2019-December/137615.html) and
the agenda for the next one.

* Raphael Isemann shared a summary detailing [the future of modern-type-lookup
in LLDB](http://lists.llvm.org/pipermail/lldb-dev/2019-December/015831.html).
"modern-type-lookup is a flag that makes LLDB use `clang::ExternalASTMerger`
instead of directly using the `clang::ASTImporter` via our ClangASTImporter
wrapper."


## LLVM commits

* Initial matrix intrinsics and a lowering pass were added.
[526244b](https://reviews.llvm.org/rG526244b187d).

* Initial work related to profile guided size opimization was committed. This
adds instrumentation, but doesn't yet enable size optimisation.
[d9ae493](https://reviews.llvm.org/rGd9ae493937c).

* Support for a Vector Function Database was merged.
[0be8196](https://reviews.llvm.org/rG0be81968a28).

* The Arm cost model now understands cases where a shift can be folded into
other instructions. [be7a107](https://reviews.llvm.org/rGbe7a1070700).

* New tests were added for resolving of RISC-V relocations.
[707e970](https://reviews.llvm.org/rG707e9707814).

* Dead loop update instructions are now removed from Arm low overhead loops.
[d97cf1f](https://reviews.llvm.org/rGd97cf1f8890).

* getIntImmCost was renamed to getIntImmCostInst and getIntImmCostIntrin.
[85ba5f6](https://reviews.llvm.org/rG85ba5f637af).

* Target-specific intrinsic enums were split into separate headers. This saves
222MB of object file size in a Windows optimised+debug build.
[5d98695](https://reviews.llvm.org/rG5d986953c8b).


## Clang commits

* A new TableGen backend was added for generating serialisation classes.
[6404bd2](https://reviews.llvm.org/rG6404bd23624),
[d505e57](https://reviews.llvm.org/rGd505e57cc27)..

* Clang support was added for constrained FP builtins.
[6515c52](https://reviews.llvm.org/rG6515c524b0a).

* Clang now defaults to `-fuse-init-array`, using `-fno-use-init-array` only
for platforms known not to support `.init_array`.
[b2b5cac](https://reviews.llvm.org/rGb2b5cac3ec0).

* Clang learned to synthesise defaulted comparison functions for C++20.
[cafc741](https://reviews.llvm.org/rGcafc7416baf).


## Other project commits

* A new script was added for symbolising hwasan reports after the fact.
[9ef451d](https://reviews.llvm.org/rG9ef451d1fda).

* Fuzzing was added for parts of `<random>` in libcxx.
[daacf57](https://reviews.llvm.org/rGdaacf570324).