LLVM Weekly - #669, October 26th 2026

Welcome to the six hundred and sixty-ninth 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 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 calls for presentations for the LLVM FOSDEM 2027 devroom and the MLIR FOSDEM 2027 devroom are now up. In both cases, the deadline for submissions is the 22nd November. FOSDEM will take place on 30th and 31st January.

The LLVM Bay Area Monthly Meetup is taking place today, Monday 26th October.

According to the LLVM Calendar in the coming week there will be the following. It’s the LLVM Dev Meeting this week (sorry I can’t make it this time!) so it’s possible some of the scheduled meetings wont take place.

• Office hours with the following hosts: Amara Emerson.
• Online sync-ups on the following topics: Flang, modules, libc++, LLVM/Offload, HLSL, LLVM memory safety working group, reflection.
• For more details see the LLVM calendar, getting involved documentation on online sync ups and office hours.

On the forums

• Grigory Pastukhov made an LLD proposal on mixing small and large code models “When small code references a large section through a 32-bit relocation, we propose to demote that section to a small one. Demotion clears SHF_X86_64_LARGE and drops the l prefix from the section name, so the linker places it together with the small sections. This makes it practical to link translation units (TUs) compiled with the small and large code models into the same binary.”

• Stephen Tozer posted a public service announcement on planned LLVM debug info API changes.

• Paul Osmialowski would like to introduce LLVM’s mathvec (libc/src/mathvec) library as another veclib functions provider.

• Alexander Yermolovich suggests declaring LLVM’s optimisation remark kinds in TableGen and adding a !remark metadata kind that attaches a remark to the instruction it describes.

• A new update on Flang development is now available.

• Wontae Choi and Rohan Jacob-Rao started an RFC discussion on a spatial safety mode for C++ (-fspatial-safety). It would build on top of existing technologies such as the -Wunsafe-buffer-usage checker, UBSan, and libc++ hardening.

• Henry Cheang (of Nintendo) posted an RFC about introducing Nintendo target triples to Clang and LLVM.

• LLVM Foundation board meeting minutes for September were shared.

• LLVM 23.1.4 was released.

• Matthew Nagy wrote an RFC on compressing TypeSanitizer shadow memory using descriptor indices. i.e. storing 32-bit indices into lookup tables of type descriptors rather than 64-bit pointers directly to those descriptors.

• Aaron Ballman and the Clang area team initiated a discussion on library layering of Parser and Sema noting that for a range of reasons (including language standards committees increasingly specifying semantics in the form of language rewriting rules) it may be worth considering if it still makes sense for Parser and Sema to remain separate. A design discussion will be hosted on this topic and interested people are requested to indicate availability to help find the best slot.

• Xiaoyang Gong is seeking input on a flexible multi-pass algorithm for branch-range extension. This would be used for resolving out-of-range Arm64 branches in LLD’s Mach-O port.

• Raphael Isemann started threads on the situation with flaky LLDB tests and removing LLDB’s GUI mode.

• Yingwei Zheng shares that the llvm-ub-aware-interpreter now has an online ‘llubi playground’ using a Wasm build.

LLVM commits

• LLVM docs “landing your changes” was updated to reflect the current workflow. 3b4061c.

• The llvm-readobj --call-graph-info output format was documented. 4aecd4c.

• The transition to TableGen-based command line option definitions continues. 6ec4fff.

• LiveDebugVariables was fixed to avoid quadratic rescans of inserted DBG_VALUEs. 3cfa4fc.

• MachineCombiner support was added for LoongArch. 59cdc9a.

• Function filtering support was added to opt-bisect. 849bf7e.

• The exception model is now read from the module flag. 64c7493, e7ffa95.

Clang commits

• Loop hint lowering was implemented in ClangIR. d48c176.

• The aarch64-unknown-uefi target was added. 91a6410.

• Initial Xtensa ABI handling was implemented. ebeb26d.

• The C defect report status page was updated. 87cefb0.

Other project commits

• As part of supporting address sanitizer on AIX, shadow memory is now supported. 52f8774.

• The LoopTripCountVersioning pass was added to Flang, which will version an innermost fir.do_loop whose trip count is a runtime value likely to equal a compile-time constant N. 7bb03d8.

• popen and pclose were implemented in LLVM’s libc. c759b57.

• LLDB data formatters were added for some libcxx data types. 62141d5.

• LLD’s identical code folding (ICF) was sped up. 6ceff48, 86c2b09.