LLVM Weekly - #622, December 1st 2025

Welcome to the six hundred and twenty-second 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

Amr Hesham wrote on the LLVM blog about their ClangIR upstreaming GSoC project.

Matt Godbolt is doing a series of blog posts “Advent of Compiler Optimisations". The first one has now been posted.

The deadline for submissions to the FOSDEM 2026 LLVM dev room has been extended to December 7th.

According to the LLVM Calendar in the coming week there will be the following.

• Office hours with the following hosts: Quentin Colombet, Johannes Doerfert, Renato Golin.
• Online sync-ups on the following topics: MLIR C/C++ frontend, ClangIR upstreaming, pointer authentication, MemorySSA, overflow behavior types, qualification group, libc++, OpenMP, Clang C/C++ language working group, Flang, RISC-V, embedded toolchains, MLGO, reflection.
• For more details see the LLVM calendar, getting involved documentation on online sync ups and office hours.

On the forums

• Last call for volunteers for the EuroLLVM developers' meeting program committee (apply by end of today, December 1st).

• “gbMattN” started RFCs on the behaviour of TypeSanitizer when Clang’s TBAA is incorrect and adding TBAA metadata to returned aggregates

• “valadaptive” posted an RFC aiming to resolve issues around the semantics for various floating point minimum and maximum operations.

• Nikita Popov is re-checking if anyone has views on deprecating C API functions using the global context.

• Charles Zablit would like to add a check-python subcommand to lldb and lldb-dap to allow tools like the VSCode lldb-dap extension to check Python is correctly configured.

• Luke Lau proposes allowing non-constant offsets in the llvm.vector.splice intrinsic.

• Endre Fülöp started an RFC discussion on offering finer grained control on when the security.insecureAPI.DeprecatedOrUnsafeBufferHandling checker reports warnings for deprecated buffer handling functions.

• More round table notes were posted: “safe mode”, C++ safety adoption tooling, and C/C++ bounds safety.

• Fangrui Song shared some results from porting the Mach-O compact unwind format to ELF.

LLVM commits

• Rematerialization for scalar loads was enabled in the RISC-V backend. 4b35ff5.

• BPF now has a new allow-builtin-calls target feature (you’ll never guess what it does!). 23907a2.

• Guidance for reviewing commit access requests was documented. d7dcc10.

• A vector scheduling model was added for the Tenstorrent Ascalon D8 RISC-V processor. ad3d9fb.

• Dwarf fission (-gsplit-dwarf) can now be used for RISC-V. 5f777b2, cc1c417.

• Support was added for “deactivation symbols”. Used by pointer field protection, these allow object files to disable specific instructions in other object files at link time. 6227eb9.

Clang commits

• Documentation on how Clang-generated HIP fat binaries are registered and unregistered with the HIP runtime was improved. 1b8626b.

• Amongst many other ClangIR patches this week, support was added for __builtin_operator_{new,delete}. e6f60a6.

Other project commits

• The BOLT inliner was extended to work on functions with pointer authentication. bab1c29.

• Lowering was implemented for the Flang PAUSE statement. 70970d0.

• LLVM’s libc gained clock_gettime for Darwin. 80e4a3f.

• picolibc and newlib suport was added to the RUNTIMES_USE_LIBC build option in libcxx. a6643f2.

• A ControllerAccess interface was added to orc-rt, providing bidirectional RPC between the executor (containing JITted code) and the controller (containing the llvm::orc::ExecutionSession). bfc732e.