LLVM Weekly - #65, Mar 30th 2015

Welcome to the sixty-fifth 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

The Z3 theorem prover from Microsoft Research is now on Github, and more importantly now released under the MIT license. This is a true open source license allowing commercial use, unlike the previous non-commercial use only license. It's been used with LLVM in the ALIVe project.

The schedule for EuroLLVM has been published. There are still a number of early registration tickets left. If you can be in London on 13th and 14th of April then I'd highly recommend registering.

On the mailing lists

• Tom Stellard, maintainer of the R600 backend has a question about manipulating the machine scheduler to intermix ALU instruction with loads.

• Sanjoy Das is seeking feedback on an optimisation issue he's seeing due to llvm.$op.with.overflow intrinsics. There is some followup discussion on how this should be dealt with.

• Martin O'Riordan from Movidius asks for guidance on submitting contributing changes back upstream. Tom Stellard has a useful response.

• Dylan McKay is working on an AVR backend port and is seeking advice on lowering division calls. The current version of his backend is here.

• Benoit Belley writes in with an optimisation puzzle, looking for an explanation for why an icmp isn't removed. Daniel Berlin responds just a couple of hours later with an explanation of the missed optimisation as well as a path to fix it.

• Gordon Kaiser is looking for anyone interested in a backend for the Fujitsu FR-series processors, now manufactured by Spansion.

LLVM commits

• The GlobalMerge pass will no longer run at O1 on AArch64+ARM, and instead will only be enabled at O3. r233024.

• A float2int pass was added which, as the name suggests, attempts to demote from float to int where possible. r233062.

• A simple Orc-based lazy JIT has been added to lli. r233182.

• LLVM gained support for PowerPC hardware transactional memory. r233204.

• The ARMv8.1a architecture has been added along with some of its new instructions. r233290, r233301

Clang commits

• The on-disk hash table for modules should now have a stable representation. r233156, r233249.

• Intrinsics have been added for PowerPC hardware transaction memory support. r233205.

• An initial version of a clang-fuzzer has been added, making use of the LLVMFuzzer library. r233455.

Other project commits

• libclc gained more builtin implementations. r232977, r232965, r232964.

• lld learnt how to understand the MIPS N64 relocation record format (which is described in the commit message). r233057.

• lld's ARM support has improved with with the addition of indirect function handling and GOT relocations. r233383, r233277.