[llvm-dev] LLVM Weekly - #321, Feb 24th 2020

[Alex Bradbury via llvm-dev]

LLVM Weekly - #321, Feb 24th 2020
=================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/321>.

Welcome to the three hundred and twenty-first 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

The Diversity and Inclusion in Compilers and Tools workshop [has been
announced](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139351.html).
It will take place on April 5th at the same venue as EuroLLVM'20.

The next Toronto LLVM meetup [will take place on February
27th](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139413.html). It
features a talk "Khronos SYCL and oneAPI: Heterogeneous Programming with
Modern C++ and Machine Learning" by Michael Wong.


## On the mailing lists

* MLIR contributors have started a biweekly newsletter covering recent
developments. The [first
issue](https://llvm.discourse.group/t/mlir-news-1st-edition-2-21-2020/544) was
shared on the LLVM Discourse group.

* ORC JIT Weekly #6 [is
out](https://lists.llvm.org/pipermail/llvm-dev/2020-February/139434.html). The
new static initializer system has landed, and JITLink has acquired a new
optimization.

* Fernando Magno Quintao Pereira wrote to [announce the release of the
AnghaBench of compilable
programs](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139422.html).
This includes one million C files mined from open source repositories, using
type inference to replace missing dependencies. Its construction is described
in the
[linked technical
report](http://lac.dcc.ufmg.br/pubs/TechReports/LaC_TechReport012020.pdf).

* Louis Dionne raised the prospect of [allowing PRs on GitHub for some
subprojects](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139381.html).
Multiple respondents felt that transitioning the LLVM community all at once
and avoiding fragmentation is important.

* Brian Gesiak reports that [LLVM's passes for C++20 coroutines now work with
the new pass
manager](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139320.html).

* Ties Stuij kicked off a discussion about [the disruption caused by
refactoring](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139207.html)
for downstream projects, and specifically raised questions about whether it
could be structured in a more downstream-friendly way (e.g.
batching). This generated lots of comments.

* Stephen Tozer posted an RFC on [allowing debug intrinsics to reference
multiple SSA
values](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139376.html).

* Hans Wennborg sent out a [reminder to help write release notes for
10.0.0](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139407.html).

* Richard Barton shared a [plan for landing flang in the
monorepo](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139378.html),
which reflects feedback from the previous discussions and emphasises the need
to better align flang to LLVM project norms.

* Fangrui Song intends to modify the integrated assembler to emit an error
when section type/flags/entsize is changed, and sent a [heads-up note about
this](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139390.html).

* Johannes Doerfert is [seeking to clarify that noalias affects only modified
objects](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139396.html).

* Vedant Kumar is seeking feedback on [enabling debug entry value production
by
default](http://lists.llvm.org/pipermail/llvm-dev/2020-February/139013.html),
initially on the ARM, AArch64, and X86 targets.


## LLVM commits

* Initial support was added for Arm's Custom Datapath Extension (CDE), which
allows custom vendor-defined CPU instructions on Arm v8-M.
[dd4d093](https://reviews.llvm.org/rGdd4d0937620).

* Support for simplifying the data dependence graph was committed.
[0a2626d](https://reviews.llvm.org/rG0a2626d0cdc).

* A proposal for AMDGPU-specific DWARF extensions was added.
[f5678d4](https://reviews.llvm.org/rGf5678d4a6a6).

* Work to port LLVM's coroutines passes to the new pass manager has started to
land. [e9849d5](https://reviews.llvm.org/rGe9849d5195e),
[7125d66](https://reviews.llvm.org/rG7125d66f996),
[00fec80](https://reviews.llvm.org/rG00fec8004ac).

* Mips GlobalISel can now legalize non-power-of-2 and unaligned load and
store. [5e32e79](https://reviews.llvm.org/rG5e32e7981b3).

* Documentation was added for the operand bundles of an llvm.assume.
[170ae68](https://reviews.llvm.org/rG170ae68fef0).


## Clang commits

* A `-std=c++20` flag was added to replace the `-std=c++2a` flag.
[24ad121](https://reviews.llvm.org/rG24ad1215824).

* Clang can now build and run the test suite of large coroutines projects when
using the new pass manager. [048239e](https://reviews.llvm.org/rG048239e46e4).


## Other project commits

* Initial signal support on Linux was added to libc.
[5d2baa9](https://reviews.llvm.org/rG5d2baa956ac).

* The MLIR integer type now has a signedness semantics bit, allowing different
dialects to make their own choice as to whether signedness is a property of
the type or if it's up to operations to decide how to interpret the bits in
that type. [35b6852](https://reviews.llvm.org/rG35b685270b4).

* The compiler-rt logb/logbl tests were fixed on platforms like RISC-V by
considering all NaNs equivalent.
[689f1e8](https://reviews.llvm.org/rG689f1e85ba6).

* libc gained an initial framework for fuzzing functions.
[a4f45ee](https://reviews.llvm.org/rGa4f45ee73a9).

* LLD gained a new `--shuffle-sections=seed` flag to shuffle sections. The
motivation is to introduce randomisation in benchmarks.
[d48d339](https://reviews.llvm.org/rGd48d3391569).

* LLDB regained some basic dwp (DWARF package) file support.
[67f63f3](https://reviews.llvm.org/rG67f63f3f7c2).

* mlir-vulkan-runner was added. This command line utility will execute an MLIR
file by translating to SPIR-V and LLVM IR.
[896ee36](https://reviews.llvm.org/rG896ee361a64).

* The MLIR tutorial gained a new section detailing the custom assembly format.
[0050e8f](https://reviews.llvm.org/rG0050e8f0cf5).