[llvm-dev] LLVM Weekly - #293, August 12th 2019

Alex Bradbury via llvm-dev llvm-dev at lists.llvm.org
Mon Aug 12 13:52:29 PDT 2019

LLVM Weekly - #293, August 12th 2019

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Welcome to the two hundred and ninety-third 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 deadline for submissions to the 2019 LLVM Dev Meeting [is
Monday 12th August. Applications for [student travel
grants](http://llvm.org/devmtg/2019-10/index.html#grant) close on August 16th.

Serge Guelton has authored a blog post on [Clang optimisation

## On the mailing lists

* Michael Paszkowski [describes the
developed after seeing Puyan Lotfi's talk on mir-canon. Michal is looking for
feedback from the community on the design and implementation of the tool, and
has [posted it to Phabricator](https://reviews.llvm.org/D66029).

* Richard Trieu has been working on [new clang warnings and improvements to
warnings](http://lists.llvm.org/pipermail/cfe-dev/2019-August/063065.html) and
would like further comments and review.

* Medhi Amini
some key elements of the EuroLLVM round table discussion on the use of the
Bazel build system for LLVM.

* Sjoerd Meijer is [looking for
thoughts](http://lists.llvm.org/pipermail/cfe-dev/2019-August/063054.html) on
whether setting a transformation option should also imply the transformation
(and proposes that it should, and this should be done consistently).

* Happy Mahto and a group of other IIT Hyderabad students started an RFC
thread on [adding new vectorization pragms to
LLVM](http://lists.llvm.org/pipermail/llvm-dev/2019-August/134432.html). Hal
with some feedback.

## LLVM commits

* llvm-readelf learned a new `--stack-sizes` option.

* Initial SVE calling convention support was committed.

* `update_test_checks.py` can now be run in an `--update-only` mode where it
will skip any tests that weren't automatically generated. This functionality
has also been made available to other `update_*_checks.py` scripts.

* The new Loop Cache Analysis pass can be used to estimate the number of cache
lines required by a loop nest.[r368439](https://reviews.llvm.org/rL368439).

* As part of the effort to redesign bugpoint, a new delta IR reduction tool was
committed (llvm-reduce). [r368358](https://reviews.llvm.org/rL368358).

* x86-experimental-vector-widening-legalization is now enabled by default,
which changes the default legalization behaviour for 16/32/64-bit vectors with
i8/i16/i32/i64 scalar types from promotion to widening.

* A new KnownBits analysis pass was added for GlobalISel.

* A new llvm.licm.disable metadata was reduced to indicate loop-invariant code
motion shouldn't be performed on the indicated loop.

* ABI register names can now be used in assembly constraints for the RISC-V
target, meaning frontends no longer need to convert to architectural register
names. [r368303](https://reviews.llvm.org/rL368303).

## Clang commits

* SVE built-in types have been introduced, which are intended to become
sizeless types. [r368413](https://reviews.llvm.org/rL368413).

* A new `-stdlib++-isystem` command line option was introduced, allowing
explicit control over the C++ standard library search paths.

* ASTImporter now has documentation.

* clang-scan-deps gained a new fast scanning mode, where preprocessing is done
on file that are minimised using the dependency directives source minimiser.

## Other project commits

* HWASan learned to instrument globals.

* LLDB was updated to support loading binaries that were linked
deterministically on macOS. [r368199](https://reviews.llvm.org/rL368199).

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