[llvm-dev] LLVM Weekly - #325, Mar 23rd 2020

Alex Bradbury via llvm-dev llvm-dev at lists.llvm.org
Mon Mar 23 13:30:55 PDT 2020

LLVM Weekly - #325, Mar 23rd 2020

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Welcome to the three hundred and twenty-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 10.0.0-rc6 [has been

## On the mailing lists

* The 3rd MLIR newsletter is [now

* ORC JIT Weekly #9 [is
out](http://lists.llvm.org/pipermail/llvm-dev/2020-March/140162.html). OrcV2
JITEventListener support (with fixes) has landed.

* Anton Korobeynikov has sent a note out [for students thinking of submitting
proposals for LLVM in

* Rahman Lavaee shared a plan for [handling Intel JCC mitigation using

* Farzad Sadeghi posted an RFC on [adding his cgrep utility to

* Kristóf Umann has [shared a patch implementing reaching definitions
calculation for
C++](http://lists.llvm.org/pipermail/cfe-dev/2020-March/064913.html) and is
seeking feedback.

* Ties Stuij proposes [adding a new bfloat IR type for the C bfloat16 format
in Armv8.6-a](http://lists.llvm.org/pipermail/cfe-dev/2020-March/064948.html).
Respondents discussed whether an IR type was necessary.

* Evandro Menezes shared a [draft proposal for a compact code model for

## LLVM commits

* The register data flow (RDF) framework was moved from the Hexagon backend to
the shared CodeGen library, to enable it to be used by other targets.

* Known bits constant folding was removed on the basis that it is incredibly
expensive but almost never has an impact on generated code. As a further
follow-up, the ExpensiveCombines option was removed altogether.

* Lit gained support for flaky tests through the `ALLOW_RETRIES` keyword.

* Documentation was added to explain loop rotation.

* The second in a series of patches to enable basic block sections (one BB per
ELF section) was committed. [df082ac](https://reviews.llvm.org/rGdf082ac45aa).

* Arm learned to spill extra registers when compiling for `-Oz` in cases where
inter-procedural register allocation may benefit from this.

* The RISC-V backend gained improved codegen for materialising +0.0 floating
point immediates. [3c24aee](https://reviews.llvm.org/rG3c24aee7ee8).

## Clang commits

* A tablegen backend was added to generated builtins and a header for SVE.

* Support was added for the `-mdouble=x` flag to set the width of double types
for AVR. [4add249](https://reviews.llvm.org/rG4add2492055).

* clang-format can now handle C# generic type constraints.

* The Clang driver now accepts and `-mstall-data-limit` argument for RISC-V,
which will put global and static data smaller than the limit into a special
section. [fc37526](https://reviews.llvm.org/rGfc3752665f4).

## Other project commits

* libc gained implementations of `memcpy`, `sigaction`, and `signal`.

* libc now has a range of Arm optimised routines.

* MLIR gained support for out of tree projects embedding it using CMake.

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