LLVM Weekly - #42, Oct 20th 2014

Welcome to the forty-second 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.

If you're local to London, you may be interested to know that I'll be talking about lowRISC at the Open Source Hardware User Group on Thursday.

News and articles from around the web

ELLCC, the LLVM-based cross-compilation toolchain now has pre-built binaries for all LLVM tools.

Eli Bendersky's repository of examples for using LLVM and Clang as libraries and for building new passes aren't new, but they are incredibly useful for newcomers to LLVM/Clang and I haven't featured them before. If you want to build something using LLVM or Clang, the llvm-clang-samples repos is one of the best places to start.

On the mailing lists

• If you enjoy bikeshedding, I have the perfect thread for you. Should LLVM change its naming convention for variables? There actually seems to be a lot of consensus that the current approach of using capitalized variable names is weird.

• Richard Smith has proposed switching the default C language mode from gnu99 to gnu11. GNU trunk has just switched from gnu89 by default to gnu11. There seems to be almost universal support for gnu11 by default.

• Junio Cezar writes to the mailing list to share his experiments on time taken in various LLVM passes. His webpage has plots of time taken in each stage for csmith-generated programs. Hal Finkel had some suggestions on improving the analysis.

• Bill Wendling is stepping down as LLVM release manager. He nominated Tom Stellard and Hans Wennborg as his replacements, who have been accepted by unanimous agreement.

• Chandler Carruth suggests making DataLayout non-optional.

LLVM commits

• Go LLVM bindings have been committed. r219976.

• Invoking patchpoint intrinsics is now supported. r220055.

• LLVM gained a workaround for a Cortex-A53 erratum. r219603.

• Basic support for ARM Cortex-A17 was added. r219606.

• The C API has been extended with the LLVMWriteBitcodeToMemoryBuffer function. r219643.

• NumOperands has been moved from User to Value. On 64-bit host architectures this reduces sizeof(User) and subclasses by 8. r219845.

• The LLVMParseCommandLineOptions was added to the C API. r219975.

Clang commits

• Constant expressions can now be used in pragma loop hints. r219589.

• The libclang API gained a function to retrieve the storage class of a declaration. r219809.

• With the -fsanitize-address-field-padding flag, Clang can insert poisoned paddings between fields in C++ classes to allow AddressSanitizer to find intra-object overflow bugs. r219961.

Other project commits

• lldb now supports a gdb-style batch mode. r219654.