LLVM Weekly - #508, September 25th 2023

Welcome to the five hundred and eighth 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 to [email protected], @llvmweekly or @asbradbury on Twitter, or @[email protected] or @[email protected].

News and articles from around the web and events

LLVM 17.0.1 has been released (this is in fact the first release in the 17.0.x series, as there was an issue with the tagging of 17.0.0). Congratulations and thank you to everyone involved!

As a reminder, the restarted LLVM Social Stockholm will take place this Wed September 27th.

Takuya Shimizu authored a post on the LLVM blog about diagnostic improvements in Clang 17.

According to the LLVM calendar in the coming week there will be:

• Office hours with the following hosts: Kristof Beyls, Johannes Doerfert.
• Online sync-ups on the following topics: MLIR C/C++ frontend, pointer authentication, OpenMP in LLVM, Flang, RISC-V, MLIR open meeting, SPIR-V.
• For more details see the LLVM calendar, getting involved documentation on online sync ups and office hours.

On the forums

• Tanya Lattner has invited anyone hoping to attend the Community.o workshop at the 2023 LLVM Developers' Meeting but unable to do so due to cost, to reach out for a discount code.

• Mircea Trofin kicked off an RFC discussion on improving profile information propagation unittesting.

• Stephen Tozer posted an RFC on adding a new optdebug attribute for prioritising debuggability in LLVM passes. This is related to the RFC on redefining Og and adding a new level of Og.

• Chengji Yao shared a lengthy MLIR RFC on “sharding framework for device mesh”.

• Alex Bradbury started an RFC thread on report_fatal_error and its default behaviour of printing a backtrace and a suggestion to file a bug report, as it had come up in review that several people felt the default was wrong.

• Vlad Serebrennikov proposes deprecating obsolete Objective C features.

• Phoebe Wang posted an RFC on the design for AVX10 options support.

LLVM commits

• Modified versions of patches to alter lit’s test output were relanded. 1495d51, f223022, fba457d.

• An InferAlignmentPass was added that will infer alignment for memory operations such as loads and stores based on trailing zero known bits information. 0f152a5, 3e992d8.

• llvm-nm gained a --line-numbers flag. c649f29.

• A new code-format-helper.py script for CI was added which will format Python files with black/darker and C/C++ files with clang-format. a1177b0.

• Support for the deprecated AMDGPU Code Object V2 was removed. fe2f67e.

• The instcombine-infinite-loop-threshold option was removed as it’s been superseded by the fixpoint verification functionality. c00f49c.

Clang commits

• The Clang driver logic for finding compatible Android runtime directories was improved. 58288c6.

• Clang can now print descriptions for extensions listed by --print-supported-extensions. 73779bb.

• Mangling rules were implemented for C++20 concepts and requires-expressions. 4b163e3.

Other project commits

• ranges::ends_with was implemented in libcxx. 0218ea4.

• Support for wasm exception handling was added to libunwind. 058222b.

• A new ‘modify’ watchpoint type was added to LLDB and is now the default. Like GDB’s default watchpoint type, it only triggers when the watched memory region changes. 933ad5c.

• LLDB’s differences to the LLVM style were documented. ca723f2.

• Support for AArch64 SME registers was added to LLDB. d99d9d8, a0768b8, 46b961f, and others.