LLVM Weekly - #596, June 2nd 2025

Welcome to the five hundred and ninety-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 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

Alex Denisov has authored the missing guide to dataflow analysis in MLIR.

If you’re interested in how RISC-V vector code generation has been developing in LLVM over the past couple of releases, I’ve written the talk I gave recently at RISC-V Summit Europe as a blog post.

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

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

On the forums

• There was quite a bit more discussion on the RFC on potentially changing LLVM’s release process.

• Aaron Ballman proposed removing support for delayed typo correction in Clang as the feature has no maintainer and a number of bugs with no path to being fixed.

• Slava Zakharin proposed adding llvm.loop.vectorize.reassociation.enable metadata which would allow unsafe reassociations during loop vectorisation.

• Elvis Wang would like to introduce a new VPlan transform that conditionally executes vector basic blocks based on mask activity.

• LLVM 20.1.6 was released.

• Abhikrant Sharma posted an MLIR RFC on supporting requantisation in the quant dialect.

• John Harrison discussed adding typing annotations to LLDB’s python code.

• If you have a workshop proposal for just before the next US LLVM Developers Meeting you have until June 6th to submit it.

• Alexis Engelke shared results from ‘TPDE’ which aims to provide baseline compilation much faster than FastISel. See the paper and GitHub repo for more information.

LLVM commits

• The PTRADD SelectionDAG node was introduced. 8adcc8a.

• llvm.vector.[de]interleave{4,6,8} intrinsics were added. 3033f20.

• The automated message for good-first-issue labeled issue was updated not to suggest requesting assignment. 50937eb.

• Support for the MemProf summary section was added. cc6f446.

• llvm-remarkutil now has a tool to print a histogram of instruction frequencies, optionally filtered by function name via a regex. cb647ec.

• A flag was added to control call folding in the ConstantFolding pass. 1f7885c.

• --max-retries-per-test was added to lit, which will retry running failed tests up to the given number of times. 84fd907.

Clang commits

• Clang’s ThreadSafetyAnalysis now supports reentrant capabilities. c7ccfc6.

• SpirvType and SpirvOpaqueType were added to HLSL. 5a45711.

• Clang’s debuginfo was updated to emit a symbol for the debugger that points for the vtable address for the given class. This allows a debugger to associate classes with the physical location of their vtables using only the DWARF information. d1b0cbf.

• The clang-doc tool was updated with a command line option to enable the Mustache template backend. 79023db.

Other project commits

• A device-side malloc implementation was implemented in LLVM’s libc for GPU. b4bc8c6.

• Flang started added noalias to function arguments but was backed out for now as it leads to a performance regression due to function specialisation no longer kicking in. d16ecad.

• The new --pointer-match-depth option for LLDB’s type summary add command can be used to specify how many layers of pointers can be dereferenced at most when matching a summary formatter of type T. 02916a4.