LLVM Weekly - #573, December 23rd 2024

Welcome to the five hundred and seventy-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 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

Peter Chou blogged about their GSoC project to improve the clang-doc documentation generator.

The dates for EuroLLVM and AsiaLLVM 2025 have been announced. EuroLLVM will take place April 14th-16th in Berlin and AsiaLLVM on June 10th in Tokyo.

As usual you can check the LLVM calendar for planned events. I won’t list them for the coming week as it seems likely many will be canceled due to holidays/christmas.

On the forums

• Mingming Liu, Snehasish Kumar, and David Xinliang Li started an RFC thread on profile guided static data partitioning, for segrating data in binay ELF sections based on access frequency.

• LLVM 19.1.6 was released.

• Jonathan Thackray proposes splitting Clang’s CGbuiltin.cpp noting it is over 23000 lines long and takes over a minute to compile.

• There was further discussion on shrink wrap save/restore points splitting with notes from a recent RISC-V contributor sync-up on this shared by Alex Bradbury.

• gbMattN suggests TypeSanitizer should use an ‘outlined’ instrumentation mode by default.

• Hongren Zheng proposes adding OpAsm{Type,Attr}Interface to MLIR to aid pretty-printing.

• Suraj Sudhir posted an MLIR RFC on incrementing the TOSA dialect version to v1.0.

• Fraser Cormack started an RFC thread on changing the behaviour of elementwise builtins in scalar integer types.

LLVM commits

• The type sanitizer was committed. a487b79.

• SDNode::uses() was renamed to SDNode::users() and SDNode::use_iterator was split into user_iterator and use_iterator meaning you can now write range-based for loops using SDUse& and SDNode::uses. 104ad92, e6b2495.

• llvm-mc now accepts a --hex argument to disassemble unprefixed hex bytes. c6ff809.

• The RISCVVLOptimizer pass is now enabled by default for RISC-V. 169c32e.

• The LLVM Security Group was renamed to the LLVM Security Response Group. ccb66bf.

• The DXILResourceAccess pass was added, transforming resource access via llvm.dx.resource.getpointer to buffer loads and stores. 0fca76d.

• llvm-exegesis gained support for RISC-V. 8e8692a.

• A scheduling model was added for the MIPS P8700 RISC-V CPU and the scalar part of the scheduling model for the Tenstorrent Ascalon D8. 3222060, e934a39.

• The unused PoisonChecking utility pass was deleted. 0517772.

• The Hexagon backend now supports the Hexagon V75 architecture. 8b37c1c.

Clang commits

• Floating point, pointer, and function types were added to ClangIR. 8ae8a90.

• Initial type sanitizer support was added to Clang. c135f6f.

• Matrix types can now be used in pseudo-destructor expressions, which allows them to be stored in STL containers. eb5c211.

• A -Wtautological-compare diagnostic was introduced which warns when a check for pointer addition overflow is always true or false. 6d34cfa.

• The -ubsan-unique-traps flag was removed as the functionality has been superseded by -fno-sanitize-merge. cb8a90b, 5bb6503.

• ThreadSafetyAnalysis was improved to support passing scoped capabilities into functions. c1e7e45.

Other project commits

• MLIR’s python binding was ported to nanobind, motivated by improved performance. b56d1ec, 5cd4274.

• BOLT gained a conservatively safe variant of its identical code folding implementation. 3c357a49.

• The Type Sanitizer runtime was committed. 641fbf1.

• Flang now supports the UNSIGNED datatype with -funsigned. fc97d2e.

• LLDB’s progress report mechanism can now be rate limited. 0dbdc23.