[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
* 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
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
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
* 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
* flang's I/O runtime gained support for OutputDescriptor() and
* 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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