[llvm-dev] LLVM Weekly - #345, August 10th 2020

Alex Bradbury via llvm-dev llvm-dev at lists.llvm.org
Mon Aug 10 10:44:05 PDT 2020

LLVM Weekly - #345, August 10th 2020

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Welcome to the three hundred and forty-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

LLVM 10.0.1 has [been

Dan Curran has written a blog post about [implementing Unified Function
Calling Syntax (UFCS) in

## On the mailing lists

* Snehasish Kumar presented a [machine function
optimisation pass, which splits functions into hot and cold parts, reporting
2% performance improvement on clang bootstrap, ~1% improvement on Google
workloads and 1.6% mean performance improvement on SPEC IntRate 2017.

* Wenlei He is seeking feedback on upstreaming [context-sensitive sample PGO
built at Facebook as an alternative to AutoFDO.

* Kazu Hirata proposed [introducing the "dump
a mechanism to dump arbitrary messages into object files during compilation
and retrieve them from the final executable. Some of the respondents [ask
about whether optimisations remarks could be used for

* Nicolai Hähnle posted a detailed RFC on [introducing convergence control
bundles and

* Bill Wendling posted an RFC on [adding support for zeroing caller saved
for use by the KSSP project to improve Linux kernel security.

* Nathan Lanza [suggested deprecating Python 2 in the LLDB scripting
API](http://lists.llvm.org/pipermail/lldb-dev/2020-August/016387.html) and
adding type annotations.

* Paul C. Anagnostopoulos [suggested changing TableGen's range syntax to use
`..` to avoid ambiguity in the current use of

* Bevin Hansson proposed [moving fixed-point classes from Clang to LLVM and
adding a
providing a canonical LLVM IR interface for constructing fixed-point

* Nicolai Hähnle suggested [creating a Discourse category for the AMDGPU

* ORC JIT Weekly #19 [is
llvm-jitlink now supports object-level mocking/testing.

## LLVM commits

* A new llvm-profdata 'overlap' feature was implemented, reporting weighted
similarity and unweighted overlap metrics at program and function level.

* As part of the ongoing new pass manager work, a machine pass manager was
introduced. [911565d](https://reviews.llvm.org/rG911565d1085).

* A new utility `split-file` was added to help produce test cases involving
multiple documents in the same input file.

* The llvm-readobj test cases were cleaned up.

* LoopVersioning was ported to the new pass manager.

* lit gained a `--time-trace-output` command line options to emit a
chrome://tracking compatible trace file.

* Documentation was added on using CHECK-SAME in FileCheck tests.

## Clang commits

* Diagnostics were improved for misaligned and large atomics.

* A new webkit.UncountedLambdaCapturesChecker was added to flag when raw
pointers and references to uncounted types are captured in lambdas.

* A new `-Wtautological-value-range-compare` warning was added.

## Other project commits

* Initial C APIs were introduced for MLIR.

* Classes were added to MLIR to model LLVM IR types without wrapping them, and
MLIR was migrated to make use of these.

* LLD `.debug_*` tombstone values were changed back to match GNU ld more
closely. [004be40](https://reviews.llvm.org/rG004be4037e1).

* flang's I/O runtime gained support for OutputDescriptor() and
InputDescriptor(). [cc01194](https://reviews.llvm.org/rGcc01194c2fa).

* LLVM's libc gained implementations of isblank, iscntrl, isgraph, ispunct,
isspace, isprint, isxdigit, strspn, tolower, toupper, strcpsn, and strpbrk.

* A `--dependency-file` option was added to LLD to create a dependency file in
a Make-compatible format. [81eeabb](https://reviews.llvm.org/rG81eeabbd97f).

* lldb-vscode now supports syntax highlighting in the disassembly view.

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