LLVM Weekly - #223, Apr 9th 2018

Welcome to the two hundred and twenty-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.

News and articles from around the web

The schedule for EuroLLVM next week has been published. I'll see you there! Also note that Arnaud de Grandmaison is looking for volunteer session moderators.

On the mailing lists

• Alex Susu reports that source code is now publicly available for an LLVM backened for the research Connex SIMD processor.

• Chad Rosier proposes adding function attributes to represent the compile-time optimisation level.

• Joel E. Denny is looking for feedback on a change to lit to have it report the line number of a failed RUN command.

• Rui Ueyama has shared an RFC on adding a new --check-library-dependency command line option to lld, which can be used to get symbol resolution semantics that are closer to the GNU linker.

LLVM commits

• The llvm-exegesis tool has been committed. As previously described on llvm-dev, this tool allows the automatic measurement of instruction scheduling properties such as latency and the number of micro-ops. r329156.

• The ShadowCallStack pass has been added. Functions marked with the shadowcallstack attribute will be instrumented to check in the prolog/epilog that the return address has not been corrupted during execution. This is supported on both X86-64 and AArch64. r329139,r329236.

• Codegen support for the RISC-V 'C' (compressed) instruction set extension has landed. When possible, a 32-bit MCInstruction is converted to the 16-bit equivalent. r329455.

• A new upate_analyze_test_checks.py script has been added. This aids the generation of checks in cost model tests. r329390.

• Support was added for llvm.coro.noop intrinsics, used to implement noop_coroutine from the C++ Coroutines TS. r328986.

• A python utility was added that uses llbm-objdump to to look for indirect calls or jumps in x86 assembly. r329050.

• Initial support for generating DWARF v5 Accelerator Tables was committed. r329179.

Clang commits

• The new bugprone-parent-virtual-call clang-tidy check will flag cases where grandparent virtual methods are called rather than an parent's overridden virtual method. r329448.

• Support for the -fsanitize=shadow-call-stack flag was added, alongside documentation of the scheme. r329122.

Other project commits

• The <experimental/filesystem> implementation in libcxx has been updated to match the C++17 spec. r329028.

• The lldb repository now contains bsd.py, a tool that can dump BSD archives. r328990.

• libcxx gained an implementation of the <compare> header. r329460.

• The documentation on preparing IR for processing by Polly has been overhauled. r329446.