LLVM Weekly - #576, January 13th 2025

[asb]

LLVM Weekly - #576, January 13th 2025

If you prefer, you can read the canonical version of this issue at http://llvmweekly.org/issue/576.

Welcome to the five hundred and seventy-sixth 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 via email: asb@asbradbury.org, or Mastodon: @llvmweekly@fosstodon.org / @asb@fosstodon.org, or Bluesky: @llvmweekly.org / @asbradbury.org.

News and articles from around the web and events

The call for proposals for EuroLLVM 2025 is now out, submit by Feb 14th 2025. The conference will take place in Berlin, April 15-16th (with workshops on the 14th).

Fangrui Song blogged about understanding and improving Clang’s -ftime-report.

The next Portland area LLVM social will take place on January 16th.

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

• Office hours with the following hosts: Aaron Ballman, Alexey Bader, Alina Sbirlea, Phoebe Wang, Johannes Doerfert.
• Online sync-ups on the following topics: MLIR C/C++ frontend, pointer authentication, C/C++ language working group, Flang, floating point, SPIR-V, RISC-V, LLVM libc.
• For more details see the LLVM calendar, getting involved documentation on online sync ups and office hours.

On the forums

• Chris Bieneman is collecting nominations for LLVM project area teams, as part of the implementation of the new LLVM governance model.

• David Spickett is attempting to complete a survey of LLDB’s supported platforms and architectures.

• Erich Keane summarised the state of OpenACC support in Clang at the moment.

• LLVM Foundation board meeting minutes for November have now been posted.

• Alexander Richardson started a thread on clarifying the semantics of ptrtoint.

• Jonas Devlieghere started an RFC discussion on adding a status line to the command line LLDB interface, as an alternative to attempting to display progress events inline.

• Sunil Srivastava proposed changing the default C++ mode for Clang to C++20, although the consensus so far seems to be that it’s too early due to some missing features and bugs.

• Chris Bieneman posted an RFC proposal for adding an offload execution test suite, intended to test execution of programs on hardware accelerators (GPUs, FPGAs, NPUs, etc).

• Pavel Labath is looking to further speed up DWARF indexing in LLDB and started a thread to discuss this, including results from experimentation so far.

• Martin Brænne kicked off an RFC thread on adding support for a new annotate_decl attribute in Clang. This would be a general-purpose way of adding annotations for us by static analysis tools. Unlike the annotate attribute, this wouldn’t produce llvm.annotation intrinsics.

LLVM commits

• SPIR-V module analysis was made substantially faster. 83c1d00.

• The DirectX resource.load.rawbuffer intrinsic was implemented. cba9bd5.

• AArch64 and Arm were migrated to using GenericTable rather than SearchableTable for system registers. 7d53762, 5c7a696.

• MC layer support was added to the RISC-V backend for the Qualcomm Xqcicm (conditional move) extension. 737d6ca.

• LangRef documentation was added for ABI and call-site attributes. 38565da.

• The -wasm-use-legacy-eh option can be used with the WebAssembly backend to use the legacy exception handling proposal. a8e1135.

• The NVPTX backend gained intrinsics for asynchronous copy of tensor data using 'TMA. 372044e.

Clang commits

• Initial support was added for SYCL offload compilation. d00f65c.

• __builtin_sincos was added. e4e2f53.

• The mechanism for deciding the priority of functions selected in function mutli-versioning for AArch64 was updated to match changes to the ACLE. 8e65940.

• Documentation was added on the level of support for OpenMP 6.0 features. c85d516.

• Temporal profiling for IRPGO can now be enabled with -ftemporal-profile. 91892e8.

• The output of -ftime-report was reorganised to improve clarity. 0de18e7.

Other project commits

• New utility scripts were added to libcxx to help compare benchmark results between builds. 292c135.

• std::stable_sort now utilises radix sort on integers, improving performance in many cases. 69b54c1.