LLVM Weekly - #358, November 9th 2020

Welcome to the three hundred and fifty-eighth 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 https://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

More videos from the 2020 LLVM Virtual Developers' Meeting have been uploaded.

On the mailing lists

• Vineet Kumar wrote to share a loop vectorizer prototype based on the RISC-V Vector Extension which attracted a lot of discussion, wih Sjoerd Meijer suggesting looking at the get.active.lane.mask intrinsic.

• Florian Hahn proposes combining annotation metadata and remarks. This would take the form of a new !annotation metadata kind that can be attached to arbitrary instructions to drive the generation of remarks.

• Min-Yih Hsu provided an update on upstream submission of the M68k backend.

• Jeremy Morse provided an update on debug information quality with "instruction referencing", concluding that the original objective of this work has been fulfilled (though also listing current limitations).

• David Sherwood suggests introducing the concept of invalid costs to the IR cost model. This wrapper class could safely indicate information such as whether the cost should be considered so expensive so as to disable optimisations, or if the cost us unknown.

• John Paul Adrian Glaubitz is seeking reviewers for two Clang Sparc related patches.

• Paul C. Anagnostopoulos seeks feedback on the idea of adding named template arguments to TableGen.

LLVM commits

• A community support policy was documented. 25ba6b2.

• Implementation was started on llvm.coro.async which will be used by the Swift frontend to lower async functions. ea5989b, c6543cc.

• llvm.loop.mustprogress metadata was introduced. cea0599,

• A range of fixes and improvements were made to the RISC-V backend's support for the yet-to-be-ratified bitmanip extension. d47300f, 0122a4e, cc3bf27, and more.

• parallelTransformReduce and parallelForEachError were added to LLVM's parallel utility library. c0a922b.

• A !interleave operator was added to TableGen to concatenate a list of values with delimiters. d56cd42.

• true and false literals were added to TableGen. ae2cb4f.

• A pipeline model was added for HiSilicon's TSV110 (AArch64). 93b9972.

Clang commits

• A new bugprone-signal-handler check was added to clang-tidy. d1b2a52.

• A YAML compiler for API notes was committed. 82f86ae.

• A custom config file can now be specified for clang-tidy using --config-file. d6a468d.

Other project commits

• A new 'TOSA' (Tensor Operator Set Architecture) MLIR dialect was added. b281211.

• A design document was added for runtime derived type descriptions in Flang. 8fc07fe.

• LLD now allows you to specify a custom to script to be called for missing libraries, which could be used to provide extra suggestions to the user (e.g. suggesting specific packages to install). cfc3226, 3bdeb2a.

• A C API was added for the MLIR PassManager. f61d102.