[llvm-dev] LLVM Weekly - #335, June 1st 2020

[Alex Bradbury via llvm-dev]

LLVM Weekly - #335, June 1st 2020
=================================

If you prefer, you can read a HTML version of this email at
<http://llvmweekly.org/issue/335>.

Welcome to the three hundred and thirty-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

PLDI 2020 (now of course an online conference) will feature a [series of "Ask
Me Anything" live Q+A
sessions](https://pldi20.sigplan.org/track/pldi-2020-ask-me-anything#program),
including with Chris Lattner.


## On the mailing lists

* Chris Lattner provided a [batch of responses to comments on his thread about
LLVM decision
making](http://lists.llvm.org/pipermail/llvm-dev/2020-May/141798.html) and
[created a new draft of the decision making
proposal](http://lists.llvm.org/pipermail/llvm-dev/2020-May/141810.html), this
time hosted on Google Docs for ease of commenting.

* Tanya Lattner is [seeking volunteers for the LLVM Developers' Meeting
Program
Committee](http://lists.llvm.org/pipermail/llvm-dev/2020-May/141946.html).

* The 8th MLIR newsletter [is now
available](https://llvm.discourse.group/t/mlir-news-8th-edition-5-29-2020/1087),
containing the usual mix of updates on MLIR commits, discussions, and
ecosystem projects.

* David Blaikie started a thread to discuss [issues arond DWARF-awareness in
the linker](http://lists.llvm.org/pipermail/llvm-dev/2020-May/141885.html),
specifically focusing on zer length GCed/duplicated functions.

* Christudasan Devadasan is seeking feedback on [allowing CostperUse for
registers to be set more
dynamically](http://lists.llvm.org/pipermail/llvm-dev/2020-May/141925.html).

* Bill Wendling posted an RFC on [loading bitfields with the smallest needed
types](http://lists.llvm.org/pipermail/llvm-dev/2020-May/141837.html).

* Chris Tetreault followed up to the thread on refactoring the class hierarchy
of VectorType with a [summary of a discussion on the SVE call about
this](http://lists.llvm.org/pipermail/llvm-dev/2020-May/141910.html).

* Jeremy Morse provided an [update on an alternate approach to specifying
variable locations
post-isel](http://lists.llvm.org/pipermail/llvm-dev/2020-May/141867.html),
providing a report on his initial prototype.

* Dean Sutherland provided a [summary of how debug locations were handled in a
previous commercial
compiler](http://lists.llvm.org/pipermail/cfe-dev/2020-May/065553.html). Chris
Lattner
[commented](http://lists.llvm.org/pipermail/cfe-dev/2020-May/065564.html) that
this is similar to the model MLIR ended up at, and suggested it may be
interesting to port this design to LLVM IR.


## LLVM commits

* A BFloat MachineValueType was added, and basic support for bfloat was added
to AArch64.
[0508fb4](https://reviews.llvm.org/rG0508fb45dfb),
[42eba9b](https://reviews.llvm.org/rG42eba9b40b2),
[78bd0c0](https://reviews.llvm.org/rG78bd0c0e5e8).

* The hardware loop intrinsics are now documented in LLVM's language
reference. [880c35a](https://reviews.llvm.org/rG880c35a5549).

* The llvm.roundeven intrinsic was introduced, implementing the
roundToIntegralTiesToEven IEEE-754 operation.
[4d20e31](https://reviews.llvm.org/rG4d20e31f736).

* FileCheck now allows parenthesized expressions.
[3be5e53](https://reviews.llvm.org/rG3be5e53f208).

* The VE backend gained a minimal machine code layer, including AsmParser
support. [0e0907f](https://reviews.llvm.org/rG0e0907fa0e2).


## Clang commits

* An explicit `-fno-semantic-interposition` will now infer `dso_local`.
[9d55e4e](https://reviews.llvm.org/rG9d55e4ee136).

* The release notes were updated with a porting guide for AST matchers.
[63f927b](https://reviews.llvm.org/rG63f927b17a1).

* A new webkit.WebKitNoUncountedMemberChecker was added to the static
analyzer. [660cda57](https://reviews.llvm.org/rG660cda572d6).

* A new `generate_formatted_state.py` tool was added to generate a summary of
the clang-format status for the whole LLVM project.
[6f56a58](https://reviews.llvm.org/rG6f56a586c50).


## Other project commits

* Support for constexpr in std::array was overhauled.
[77b9abf](https://reviews.llvm.org/rG77b9abfc8e8).

* Basic OpenMP parallel operations were added to the OpenMP MLIR dialect.
[5ba874e](https://reviews.llvm.org/rG5ba874e4724).