[llvm-dev] LLVM Weekly - #355, October 19th 2020

[Alex Bradbury via llvm-dev]

LLVM Weekly - #355, October 19th 2020
=====================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/355>.

Welcome to the three hundred and fifty-fifth 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

A new paper describes an extension to Clang to support syntax plugins, and
applies it to embed a DSL directly within a C++ codebase. See [Really
Embedding Domain-Specific Languages into C++ for more
details](https://arxiv.org/abs/2010.08439).


## On the mailing lists

* Roger Ferrer Ibáñez shared an RFC on [code generation for the RISC-V vector
extension](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145850.html)
and is seeking input on the described strategy.

* Serge Guelton provided an [update on the Python 3
migration](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145793.html),
where the plan is to require Python 3.6 for LLVM 12.0.0.

* Kristof Beyls shared [minutes from a round table on AArch64 pointer
authentication ABI at the LLVM Dev
Meeting](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145839.html).
He also shared [minutes from the LLVM security group round
table](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145792.html).

* ORC JIT Weekly #24 [is
out](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145866.html). Big
update: OrcV1 has been removed, removable code has landed, and the C API and
lookup system have received significant updates.

* Arten Dergachev shared [provides further thoughts on static analyzer and
clang-tidy
interoperation](http://lists.llvm.org/pipermail/cfe-dev/2020-October/067002.html).

* Paul C. Anagnostopoulos shared a [revised proposal for enhancing TableGen's
ability to analyze and manipulate
DAGs](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145855.html).

* Tanya Lattner [offers the use of the Remo collaboration platform for LLVM
meetups](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145856.html),
noting that the Foundation has a subscription.

* Atmn Patel posted an [RFC on introducing the maxobjsize
attribute](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145803.html)
tracking the size of the object that a pointer points to.

* Manman Ren produced a proposal on [providing global analysis and runtime
checks for
`objc_direct/objc_non_runtime_protocol`](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145753.html),
which is currently per-transluation-unit.

* Mircea Trofin distributed [notes from the round table on machine learning
guided compiler
optimisations](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145802.html)
that took place at the LLVM Dev Meeting.

* Alina Sbirlea shared [meeting notes and a poll for future meetings on
MemorySSA](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145766.html).

* Simon Moll is [proposing a vector predication round-table this
Thursday](http://lists.llvm.org/pipermail/llvm-dev/2020-October/145784.html).


## LLVM commits

* Support was added for recording substitutions between pairs of (instruction,
operand) numbers using `DBG_INSTR_REF`.
[c521e44](https://reviews.llvm.org/rGc521e44defb).

* The AArch64 backend implemented stack frame reordering.
[2e794a4](https://reviews.llvm.org/rG2e794a46b58).

* The LLVM security documentation now has information about expected response
time for reports. [05ef552](https://reviews.llvm.org/rG05ef552e566).

* The LoopExtract pass was ported to the new pass manager.
[518ec05](https://reviews.llvm.org/rG518ec05a104).

* The default cutoff threshold for the machine function splitter was updated
based on internal benchmarking at Google.
[24bf6ff](https://reviews.llvm.org/rG24bf6ff4e08).

* The TableGen language gained `!not` and `!xor` operators.
[4767bb2](https://reviews.llvm.org/rG4767bb2c0c7).



## Clang commits

* X86-64 micro-architecture levels (as defined in the psABI) can now be
specified using `-march`. [012dd42](https://reviews.llvm.org/rG012dd42e027).

* The `-f[no-]split-code-code` options were introduced to toggle splitting.
[273c299](https://reviews.llvm.org/rG273c299d5d6).

* Support was added for `-mtune` when targeting RISC-V.
[cfa7094](https://reviews.llvm.org/rGcfa7094e49c).


## Other project commits

* The runtime component of the recently added memory profiling support was
added to compiler-rt. [3d4bba3](https://reviews.llvm.org/rG3d4bba302d2).

* Flang's OpenACC lowering now handles the parallel and data constructs.
[e944455](https://reviews.llvm.org/rGe944455eaf1),
[388d373](https://reviews.llvm.org/rG388d373294e).

* Scaffolding for `thread trace dump instructions` was added to LLDB.
[26d861c](https://reviews.llvm.org/rG26d861cbbd5).

* A linear algebra codegen strategy was added to MLIR.
[af5be38](https://reviews.llvm.org/rGaf5be38a010).