LLVM Weekly - #181, Jun 19th 2017

Welcome to the one hundred and eighty-first 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

Registration is now open for the 2017 LLVM Developers' Meeting. It will be held on October 18-19th in San Jose. Registration fees are $300, with a student rate of $50. Additionally, there will be a Women in Compilers and Tools pre-conference event on October 17th.

hobbes is a newly released project built on LLVM. As described by its main developer, it is a Haskell-family programming language, which can be used for analysis of large data sets. It has been used in production within Morgan Stanley for several years.

Scala Native 0.3.0 has been released. The main highlight is the new garbage collector, based on Immix.

On the mailing lists

• Quentin Colombet has sent an update on the proposal to make GlobalISel the default at O0 on AArch64. This change has now been postponed, and you can read reasoning behind this in the linked mailing list thread. One major concern was that enabling it by default now may send the message that the design is set in stone and is ready for broader adoption.

• Paul Robinson notes that the total open bug count is now over 10000. He observes that the increase in open bugs has been remarkably consistent.

• Alex Lorenz has shared an RFC on adding refactoring support to Clang. This is part of the effort to upstream features shipping in Xcode.

• Jakub Kuderski is interning at Google this summer and has shared an RFC on improving dominators in LLVM.

• Tanya Lattner is seeking volunteers to help staff the LLVM stand at the 2017 Grace Hopper Conference. It will be held October 4th-6th in Orlando.

• Hans Wennborg has shared the proposed schedule for 5.0.0. With this release in particular, he is hoping for more community assistance with the release management process.

• Michael Spencer has written an RFC on profile guided section layout, sharing initial results from his prototype implementation.

LLVM commits

• scavengeRegisterBackwards() was added to the register scavenger. This has the advantage over the previous scavengeRegister() functions of not being dependent on the quality of the kill flags in the basic block. r305625.

• The git-r utility has been added. This utility (written in Go) allows svn revisions to be mapped to git revisions in the proposed LLVM mono-repository. r305598.

• The stack coloring pass has been modified to be much less conservative. r305193.

• llvm-pdbutil has seen a redesign of its "raw" output style. r305495.

• Control flow integrity for indirect function calls in ThinLTO has been implemented. r305533.

Clang commits

• UBSan learned to detect invalid unsigned pointer index expressions. r305216.

• Recent UBSan improvements are summarised in the draft release notes. r305269.

Other project commits

• LLDB's new thread backtrace unique command will de-duplicate the output from threads that share the same call stacks. As noted in the commit message, this is particularly useful for applications with large but mostly inactive thread pools. r305197.

• LLD's monolithic Target.cpp has been split in to smaller files. r305565.

• Polly can now compile all of Android, and uses this as part of its automated testing. r305334.