LLVM Project News and Details from the Trenches

Monday, February 15, 2016

LLVM Weekly - #111, Feb 15th 2016

Welcome to the one hundred and eleventh 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 http://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.

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News and articles from around the web

There has been a new release of the CilkPlus compiler. This includes an update to the latest LLVM and Clang trunk. CilkPlus implements the Cilk Plus language extensions for data and task parallelism in Clang.

There's been some more papers appearing from the C++ standards committee. P0225R0, or as you may prefer to call it "Why I want Concepts, and why I want them sooner rather than later" is worth a read. There's also been a few other recently published papers on iterator facades, the filesystem technical specification, and unified function call syntax.

On the mailing lists

LLVM commits

  • The WholeProgramDevirt pass has been added. This implements whole program optimization of virtual calls where the list of callees is known to be fixed. r260312.

  • The AVR backend upstreaming continues with the addition of the AVR tablegen instruction definitions. r260363.

  • There's been a bunch of other work on the new global instruction selection mechanism this week, but the commits I'd pick out are the addition of support for translating Add instructions and for lowering returns. It is currently being tests with the AArch64 backend. r260549, r260562, r260600.

  • The AArch64 backend gained support (including a scheduling model) for the Qualcomm Kryo CPU. r260686.

  • LoopUnrollAnalyzer has been abstracted out from LoopUnrollPass, and gained unit tests for its functionality. r260169.

  • llvm-config gained preliminary Windows support. r260263.

  • The details of the convergent attribute have been clarified in the language reference. The convergent attribute will now be removed on functions which provably don't converge or invoke any convergent functions. r260316, r260319.

Clang commits

  • It is now possible to perform a 3-stage Clang build using CMake. It is suggested in the commit message this may be useful for detecting non-determinism in the compiler by verifying stage2 and stage3 are identical. r260261.

  • ARMv8.2-A can be targeted using appropriate Clang options. r260533.

  • Clang's CMake build system learned the CLANG_DEFAULT_CXX_STDLIB to set the default C++ standard library. r260662.

Other project commits

  • The new LLD ELF linker gained initial link-time optimisation support. r260726.

  • LLDB has seen some more updates for Python 3 support, though not yet enough for a clean testsuite run. r260721.