LLVM Weekly - #535, April 1st 2024

Welcome to the five hundred and thirty-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. 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 [email protected], @llvmweekly or @asbradbury on Twitter, or @[email protected] or @[email protected].

News and articles from around the web and events

A fork of Clang that implements the P2996 C++ reflection specification is available, by Dan Katz and others at Bloomberg, amongst other contributors. See the previous link for information on the implementation choices and the /r/cpp discussion.

Bartosz Taudul blogged about pretty printing Arm Neon registers in LLDB.

According to the LLVM calendar in the coming week there will be the following:

• Office hours with the following hosts: Anastasia Stulova, Quentin Colombet, Johannes Doerfert.
• Online sync-ups on the following topics: Flang, MLIR C/C++ frontend, MemorySSA, new contributors, LLVM/offload, classic flang, loop optimisations, OpenMP in Flang, MLIR open meeting, PowerPC, HLSL.
• For more details see the LLVM calendar, getting involved documentation on online sync ups and office hours.

On the forums

• Tom Stellard indicated that he’s now hoping to collate release notes for LLVM point releases, starting from 18.1.3.

• If April fools jokes are your thing, you’ll enjoy this MLIR syntax proposal.

• There were more discussions about criteria for LLVM commit access in light of the recent xz backdoor.

• Noah Goldstein proposed supporting the nneg flag for uitofp.

• Fangrui Song shared details of work on supporting --compress-sections in llvm-objcopy.

• Matt Arsenault is seeking feedback on supporting atomicrmw with floating-point vector operations.

• People are trying to get feedback on EuroLLVM round tables, e.g. for MLIR or on debuginfo (and perhaps others I missed).

LLVM commits

• An alternative translation of -wasm-enable-sjlj was implemented. 6420f37.

• TableGen’s implementation was restructured into a “Basic” and “Common” library. fa3d789.

• The SPIRVUsage documentation was expanded. f5e1cd5.

• The RISCVMakeCompressible pass learned to handle byte/half load/store for the Zcb extension. 22bfc58.

• The va_list related intrinsics were made generic, meaning arguments don’t have to be address space 0 pointers. ab7dba2.

• The language reference was expanded to better clarify some metadata semantics. eee8c61.

• The nuw and nsw nowrap flags can now be used for trunc. 7d3924c.

Clang commits

• The optin.performance.Padding checker from the Clang static analyzer was documented. b8cc838.

• Flexible arrays in unions or alone in structs are now allowed. 14ba782.

• The -Wformat-signedness warning is now supported. ea92b1f.

Other project commits

• Support for REDUCE() was implemented in Flang’s runtime. 3ada883.

• The C23 fmaximum and fminimum functions were implemented in LLVM’s libc. 3e3f0c3.

• Guidelines for adding [[nodiscard]] to the libcxx implementation was documented. 2684a09.

• BufferOriginAnalysis was added to MLIR. dbfc38e.