LLVM Weekly - #342, July 20th 2020

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

News and articles from around the web

Danila Kutenin wrote up his experience optimising 128-bit division, resulting in a patch to compiler-rt.

LLVM Foundation President Tanya Lattner recently took part in a video interview.

Vince Bridges will be hosting an online LLVM meetup on Wed July 22 at 6.30pm Central US time and will be presenting on how to write a new static analysis checker.

LLVM 11 has now branched.

Clang developer Bruno Cardoso Lopes was a guest on this week's CppCast, discussing clang modules and pattern matching amongst other topics.

On the mailing lists

• Rahman Lavaee proposed a section metadata based approach for mapping binary address to machine basic blocks, contrasting the approach to the one used by -fbasicblock-sections=labels.

• Nathan James posted an RFC on adding support for line anchors to FileCheck (numeric variables holding the value of the line number on which they were defined).

• David Blaikie proposed switching lld to match ld.bfd "tombstoning" behaviour by default. This relates to resolving relocations from debug sections to dead code.

• Fangrui Song started a discussion about specifying multiple independent tests in one file.

• ORC JIT Weekly #17 is out. Initial JITLink support for ELF/x86-64 has landed, along with new APIs for target process control.

LLVM commits

• A new "expensive check" was added to ensure passes correctly set their Modified status. 3667d87.

• The definitions of matrix operations in the language reference has been tightened. 2b3c505.

• A machine learning-based native size estimator has been added for training the -Oz inliner. 83080a2.

• A new check_ninja_deps.py script was added to help spot missing dependencies in the build scripts. 86d362f.

• Call Frame Information handling for basic block sections was committed. c3e6555.

• Guidance on omitting braces was updated. 140c296.

• ORC gained new TargetProcessControl and TPCIndirectionUtils APIs. 0e940d5.

• Work on llvm-libtool-darwin (an LLVM replacement of cctool's libtool) has started. 6c43ed60.

Clang commits

• A new -Wsuggest-override warning was added. 1111678.

• The Clang static analyzer benchmarking framework as added. 5b4f143.

• Support was added for -mcpu for RISC-V. 294d1ea.

Other project commits

• MLIR started to gain support for lowering OpenMP parallel operations to LLVM IR. d9067dc.

• MLIR gained a RegionKindInterface, which can be used to declare the kind of an operation's contained region (e.g. SSACFG or Graph). 6282886.

• The scudo secure memory allocator was tweaked to release smaller blocks less often. 79de8f8.

• flang gained a parser for OpenACC 3.0. 0a90ffa.

• The "xunit" result formatter was removed from LLDB's testing infrastructure. a580376.