LLVM Weekly - #355, October 19th 2020

Welcome to the three hundred and fifty-fifth 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 to asb@asbradbury.org, or @llvmweekly or @asbradbury on Twitter.

News and articles from around the web

A new paper describes an extension to Clang to support syntax plugins, and applies it to embed a DSL directly within a C++ codebase. See Really Embedding Domain-Specific Languages into C++ for more details.

On the mailing lists

• Roger Ferrer Ibáñez shared an RFC on code generation for the RISC-V vector extension and is seeking input on the described strategy.

• Serge Guelton provided an update on the Python 3 migration, where the plan is to require Python 3.6 for LLVM 12.0.0.

• Kristof Beyls shared minutes from a round table on AArch64 pointer authentication ABI at the LLVM Dev Meeting. He also shared minutes from the LLVM security group round table.

• ORC JIT Weekly #24 is out. Big update: OrcV1 has been removed, removable code has landed, and the C API and lookup system have received significant updates.

• Arten Dergachev shared provides further thoughts on static analyzer and clang-tidy interoperation.

• Paul C. Anagnostopoulos shared a revised proposal for enhancing TableGen's ability to analyze and manipulate DAGs.

• Tanya Lattner offers the use of the Remo collaboration platform for LLVM meetups, noting that the Foundation has a subscription.

• Atmn Patel posted an RFC on introducing the maxobjsize attribute tracking the size of the object that a pointer points to.

• Manman Ren produced a proposal on providing global analysis and runtime checks for objc_direct/objc_non_runtime_protocol, which is currently per-transluation-unit.

• Mircea Trofin distributed notes from the round table on machine learning guided compiler optimisations that took place at the LLVM Dev Meeting.

• Alina Sbirlea shared meeting notes and a poll for future meetings on MemorySSA.

• Simon Moll is proposing a vector predication round-table this Thursday.

LLVM commits

• Support was added for recording substitutions between pairs of (instruction, operand) numbers using DBG_INSTR_REF. c521e44.

• The AArch64 backend implemented stack frame reordering. 2e794a4.

• The LLVM security documentation now has information about expected response time for reports. 05ef552.

• The LoopExtract pass was ported to the new pass manager. 518ec05.

• The default cutoff threshold for the machine function splitter was updated based on internal benchmarking at Google. 24bf6ff.

• The TableGen language gained !not and !xor operators. 4767bb2.

Clang commits

• X86-64 micro-architecture levels (as defined in the psABI) can now be specified using -march. 012dd42.

• The -f[no-]split-code-code options were introduced to toggle splitting. 273c299.

• Support was added for -mtune when targeting RISC-V. cfa7094.

Other project commits

• The runtime component of the recently added memory profiling support was added to compiler-rt. 3d4bba3.

• Flang's OpenACC lowering now handles the parallel and data constructs. e944455, 388d373.

• Scaffolding for thread trace dump instructions was added to LLDB. 26d861c.

• A linear algebra codegen strategy was added to MLIR. af5be38.