LLVM Weekly - #214, Feb 5th 2018

Welcome to the two hundred and fourteenth 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

Reminder: the deadline for paper submissions for EuroLLVM 2018 is this Friday, February 9th.

Adrien Guinet has released DragonFFI, a C Foreign Function Interface (FFI) library based on Clang/LLVM. It aims to provide broader ABI support than libffi and to work around the limitations of Python's cffi C parser through the use of Clang.

On the mailing lists

• Fāng-ruì Sòng started a discussion on moving the LLVM developer-facing utility scripts to Python 3.

• Tanya Lattner is looking for help in fleshing out the LLVM GSoC'18 proposed projects list.

• Paul Robinson gave a helpful summary of recent work on improving 'debuggability' of optimized code.

• George Karpenkov wrote up short investigation of exploration strategies and paths for Clang analyzer.

• Sean Perry has been looking at implementing support for -fexec-charset and -finput-charset, and is seeking feedback.

LLVM commits

• LLVM's policies on library layering and header isolation have been documented in the coding standards doc. r324004.

• The sigil for machine IR physical registers is now $ rather than %. r323922.

• Support has been added to dsymutil for generating Apple accelerator tables. r323655.

• update_test_checks.py and update_llc_test_checks.py have been refactored to share common code. r323718.

• A scheduling model has been added for the Exynos M3. r323773.

• A new extension is now supported, linker options can be passed from the frontend to the linker through the linker_options section. r323783.

• The X86 retpoline think insertion pass is now a machine function pass rather than a module pass. r323915.

• InstCombine will now canonicalise to i8/i16/i32 operations even if the resulting type isn't legal according to the datalayout. See the llvm-dev thread for more justification. r324174.

Clang commits

• Debug information is now generated for C99 VLA (variable-length array) types. r323952.

• Partial support for CUDA-9.1 has been added to Clang. r323713.

• clangd has been refactored to pass its Context object implicitly using thread local storage. r323872.

Other project commits

• As previously announced, a number of experimental APIs that have been superseded by versions adopted by the C++ standard have been removed. experimental/optional, experimental/any, experimental/numeric and experimental::sample. r323971, r323972, r323975, r323979.

• The libcxxabi demangler gained improved support for variadic templates and seen a large refactoring. r323906, r324111.

• New python utilities were added to make it easier to write LLDB tests for when LLDB is acting as a client of a gdb-remote connection. r323636.

• LLDB tests are now compiled out-of-tree. r323803.