LLVM Weekly - #93, Oct 12th 2015

Welcome to the ninety-third 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.

Apologies that this week's issue comes rather late in the day, my laptop gave up the ghost over the weekend while I was travelling leaving me with no way to write it. Now I'm back, I've managed to dust off an old desktop from my closet to write this issue (and to keep my unbroken streak). LLVM Weekly has been sent out every Monday since it started on the first Monday of January 2014. This weekend I was talking about lowRISC at ORConf 2015. You can find my slides here. There was a wide array of talks on open source hardware, including many on lowRISC and RISC-V. The videos should hopefully be posted in the next week or so.

News and articles from around the web

The LLVM project has hit 250,000 commits. The commit that managed to hit this milestone was this one-liner.

A new paper by Bjarne Stroustrup, Herb Sutter, and Gabriel Dos Reis gives more details on their plans for memory safety in C++.

Videos from CppCon2015 are being posted to Youtube.

On the mailing lists

• Ed Maste is taking a look at the feasibility of using the new LLD ELF linker for FreeBSD, and has shared his initial findings.

• When is addrspacecast needed? Both David Chisnall and Mats Petersson have good answers.

• Vedant Kumar has posted an RFC on cleaning up the way optional Function data is stored.

• Dehao Chen has shared an update on the AutoFDO project, which allows the use of a perf.data profile for profile-guided optimisation. Clang built with -fprofile-sample-use is about 10% faster than Clang built with -O3.

• Larisse Voufo has shared a proposal for optimizing const C++ objects in LLVM.

• Chris Matthews has announced the open-sourcing of an llvm bisect tool, for bisecting bugs using prebuilt LLVM and Clang revisions.

LLVM commits

• The Hexagon architecture gained an early if-conversion pass. r249423.

• ThinLTO has started to land, in particular support for function summary index bitcode sections and files. r249270.

• Codegen for ARM's memcpy intrinsic has been modified to make better use of LDM/STM. r249322.

• The llvm.eh.exceptioncode intrinsic was added. r249492.

• It is now possible to turn off MMX support without disabling SSE. r249731.

Clang commits

• The policy for adding new style options to clang-format has been documented. r249289.

• The libclang bindings have been extended with accessors for C++ function attributes (pure virtual, virtual, or const). r250008.

Other project commits

• GoLanguageRuntime was introduced to LLDB, which supports finding the runtime type for Go interfaces. r249456, r249459.

• The new LLD ELF linker now supports the --as-needed option. r249998.

• LLDB for MIPS is now able to emulate microMIPS instructions. r249381.

• liblldb is working towards being able to work under both Python 2.x and 3.x. r249886.