LLVM Weekly - #453, September 5th 2022

Welcome to the four hundred and fifty-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. 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@asbradbury.org, or @llvmweekly or @asbradbury on Twitter.

News and articles from around the web

The MLIR Bay Area Developer Summit will now take place on November 10th, the day after the LLVM Developers' meeting.

On the forums

• Tobias Hieta provided an update on the LLVM 15.0.0 release plans. At the time of writing, there are no open issues in the LLVM 15.0.0 release milestone on GitHub.

• Discussion within the thread on incubating the MLIR TCP dialect moved to more general comments about the status of the MLIR codebase and whether the incubator process is always appropriate/required for new dialects. See e.g. responses from Chris Lattner, Stephen Neuendorffer, or Renato Golin.

• Aaron Ballman created a thread about community code ownership in LLVM in general, which attracted many responses including detailed thoughts from Tanya Lattner.

• Aman LaChapelle started a thread to discuss swapping out dyn_cast_or_null and cast_or_null with dyn_cast_if_present and cast_if_present. There were a number of alternative suggestions in the responses, such as always allowing null for, or to keep _or_null variants but not allow Optionals for these.

• David Spickett shared a Juptyer kernel for TableGen, with the aim of lowering the barrier to learning how to use TableGen.

• Michele Scuttari shared a PSA on changes to code generation for tablegenned MLIR pass specifications.

• Florian Mayer gave a heads up about upcoming changes to the ASan/HWASan crash report format.

• Aart Bik provided an update on progress on the MLIR sparse compiler

• Diego Caballero and Nicolas Vasilache shared an MLIR RFC on vector masking representation in MLIR.

• Serge Guelton is seeking feedback on changes to harmonise flexible array members handling in Clang.

• Raghavan Raman initiated a discussion on the initial draft of the MLIR TCP spec.

• David Spickett proposed removing armv2/2A/3/3M codegen.

• Fangrui Song started a discussion on extending lit to support repeating a RUN line multiple time with different replacements, e.g. to make it easy to run the same test file on a range of C++ dialects in Clang.

LLVM commits

• The SPIR-V backend gained support for builtin types and ExtInsts selection. 698c800.

• -filter-passes can now be used with -print-changed. 8d95fd7.

• An llvm.vp.fabs.* intrinsics was introduced. 2f811a6.

• Base64 decoding was added to LLVM’s support library. ea9ac35.

• .size directives are no longer required for WebAssembly functions. c5c4ba3.

Clang commits

• Documentation was added on Clang’s support for standard C++ modules. b1d5af8.

• The nouwtable function attribute was introduced, which will suppress the LLVM IR uwtable function attribute. 70248bf.

• HLSL entry functions were documented. 739a747.

Other project commits

• A design doc was added for lowering parameterised derived types (PDTs) in Flang. dc549bf.

• Implementations of atanhf and atanf were added to LLVM’s libc. 6c1fc7e, 77e1d9b.

• Decode and emulation of further RISC-V instructions was added to LLDB. ff7b876.