[llvm-dev] LLVM Weekly - #390, June 21st 2021
Alex Bradbury via llvm-dev
llvm-dev at lists.llvm.org
Mon Jun 21 10:57:35 PDT 2021
LLVM Weekly - #390, June 21st 2021
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Welcome to the three hundred and ninetieth 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
Uma Srinivasan will be presenting "From Packing Decimals With Cobol to
Optimizing Tweets With Scala: A Journey Through Space, Time, & Culture with
Compilers" at the [Women in Compilers and Tools June
24th, 6pm PDT.
A new book on LLVM has been published - [Learn LLVM 12 by Kai
## On the mailing lists
* The [thread suggesting a migration to
has seen continued discussions. To pick a few messages:
* Christian Kühnel
a [draft migration
* James Y Knight
that the [Open Source Community
Infrastructure](https://www.osci.io/tenants/) would be willing to provide
* John McCall provided a [summary of issues with mailing
"Now, forums have their own usability annoyances, without question. [...]
My point is that those problems should not be treated as blockers when we
have equal or worse problems with mailing lists that we've just come to
* Reid Kleckner [summarised responses to the RFC on
* Tom Stellard announced that [12.0.1-rc2 has been
an extended deadline for requesting backports.
* Matt Morehouse responded to an old thread on first-class metadata with a
[list of potential use
* Gulfem Savrun Yeniceri
adding a binary id to profiles, in order to aid matching executables to
* John McCall responded to the RFC thread on byte types in LLVM, [summarising
how this may relate to work to add a provenance model to
arguing that it would be better to start by considering inttoptr and
* Luke Drummond started a conversation about [when it is appropriate to use the
* LLVM GPU News Issue #14 [is
* Kito Cheng posted an [RFC on providing a #pragma to implement the
avoiding the parsing of ~60k lines. David Rector [pointed
work to solve a similar problem in OpenCL.
## LLVM commits
* A CustomBehaviour class was added llvm-mca, intended to allow developers to
implement modelling for instructions that require special handling.
* The SpeculateAroundPHIs pass was removed, with the commit message noting
some of the regressions observed with the NewPM transition may have been
caused by it. [e523645](https://reviews.llvm.org/rGe52364532afb).
* `DW_CFA_LLVM_` was added, as part of the work to add extensions for
heterogeneous debugging on AMDGPU.
* DebugInfo handling was added for IR outlined functions.
* Initial GlobalISel infrastructure was added for M68k.
* Relocation emission for RISC-V was refactored and improved, bringing it more
closely in line with GNU as.
* The MIRPrinter gained machine metadata support.
## Clang commits
* Improvements were made for named return value optimisation.
* The performance-unnecessary-copy-initialization checker was updated to fix
some false positive cases.
## Other project commits
* EmitC, an MLIR dialect for emitting C++, was upstreamed to MLIR.
* Identical code folding was implemented in lld-macho.
* An implementation of a two-level distributed barrier was added to LLVM's
OpenMP library. [25073a4](https://reviews.llvm.org/rG25073a4ecfc9).
* LLVM's libc gained implementation of a set of abstract elementary operations
acting on fixed chunks of memory, intended to be used as building blocks for
higher level abstractions.
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