LLVM Weekly - #620, November 17th 2025

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LLVM Weekly - #620, November 17th 2025

If you prefer, you can read the canonical version of this issue at https://llvmweekly.org/issue/620.

Welcome to the six hundred and twentieth 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

Save the date for the 2026 EuroLLVM Developers’ Meeting, taking place April 13th-15th in Dublin.

The next LLVM meetup in Berlin will take place of 20th November.

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

  • Office hours with the following hosts: Johannes Doerfert, Aaron Ballman.
  • Online sync-ups on the following topics: ClangIR upstreaming, pointer authentication, vectorizer improvements, Clang C/C++ language working group, Flang, RISC-V, LLVM libc, HLSL.
  • For more details see the LLVM calendar, getting involved documentation on online sync ups and office hours.

On the forums

LLVM commits

  • The straight-line strength reduction pass was redesigned, providing infrastructure for later adding partial strength reduction support. f67409c.

  • JITLink gained initial SystemZ support. 8218055.

  • The register coalescer “terminal rule” was enabled by default for multiple targets. e95f6fa, 793ab6a, 2aa629d, and more.

  • DJAJumpThreading was disabled by default again due to detected miscompiles. 7e04336.

  • Initial codegen support was added for the RISC-V ‘P’ (packed SIMD) instruction set extension. Currently just for a small set of instructions. dfdc69b, 6b16b31.

  • The ‘modular-format’ attribute was introduced. This can be used to e.g. keep floating point support out of printf if it can be proven to be unused. c9ff2df.

  • lit’s options for controlling output were revamped with a range of new options added, and existing -q, -s, -v, -a flags defined as aliases of appropriate combinations of these new finer grained options. dbf77e4.

  • Following the addition of --save-stats to llc, opt now supports the same flag. 35ffe10.

  • A new target feature was introduced for BPF to allow misaligned memory accesses. fb2563d.

  • Assembler support was added for the AArch64 Permission Overlay Extension 2. 40a9e34.

Clang commits

  • A generic byte swap builtin, __builtin_bswapg was added, supporting all integer types. f210fc1.

  • clangDriver options-related code was factored into a new clangOptions library. 9a783b6.

  • ClangIR AddressSpace conversions support was upstreamed. 8f90716.

Other project commits

  • std::optional<T&> was implemented in libcxx. 389a23c.

  • Flang gained parser support for the prefetch directive. cf1f871.

  • The GTest version used by the runtimes build no longer has a dependency on LLVMSupport, avoiding some bootstrapping issues. 0957656.

  • An SVE implementation of strlen was added to LLVM’s libc. 8751f26.

  • The arith-to-apfloat pass was added to MLIR. It will lower floating point arithmetic operations to calls into a runtime library. 7a53d33.

  • Polly now has its own pipeline manager rather than relying on LLMV’s pass manager. 7a0f7db.

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