Alex Bradbury via llvm-dev
2018-Dec-24 18:00 UTC
[llvm-dev] LLVM Weekly - #260, December 24th 2018
LLVM Weekly - #260, December 24th 2018 ===================================== If you prefer, you can read a HTML version of this email at <http://llvmweekly.org/issue/260>. Welcome to the two hundred and sixtieth 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](https://www.linkedin.com/in/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 at asbradbury.org>, or @llvmweekly or @asbradbury on Twitter. ## News and articles from around the web Registration is [now open](http://llvm.org/devmtg/2019-04/#registration) for EuroLLVM'19 and the call for papers [remains open](http://llvm.org/devmtg/2019-04/#cfp). LLVM 7.0.1 has been [released](http://lists.llvm.org/pipermail/llvm-announce/2018-December/000081.html). ## On the mailing lists * Nicolai Hähnle started an RFC discussion on [adding thread group semantics to the LangRef](http://lists.llvm.org/pipermail/llvm-dev/2018-December/128662.html), motivated by GPU requirements. * Chandler Carruth has shared a [holiday update on the LLVM relicensing effort](http://lists.llvm.org/pipermail/llvm-dev/2018-December/128695.html). Over 500 individual agreements have been completed, covering 73% of committers and 80% of commits in the last 6 months and 63% of committers and 74% of commits in the last 2 years. As explained in the email, please fill out the individual agreement and forward the relicensing page to your employer if they're [not already listed](http://llvm.org/foundation/relicensing/#corporate_agreement) as having signed or been contacted. * JF Bastien shares that Intel's Parallel STL implementation has [now been contributed to LLVM](http://lists.llvm.org/pipermail/cfe-dev/2018-December/060606.html). * Todd Snider is [seeking comments](http://lists.llvm.org/pipermail/llvm-dev/2018-December/128632.html) on the 'used' attribute semantics, which he observes seems to be used inconsistently. * Carey Williams wrote an RFC on [allocatable global register variable for ARM](http://lists.llvm.org/pipermail/llvm-dev/2018-December/128706.html). There is currently limited support for this for the stack pointer, but this RFC proposes extended this for other registers. ## LLVM commits * AArch64 now has a control flow speculation tracking pass aimed at mitigating Spectre V1 style vulnerabilities.This tracks control flow miss speculation into a taint regiter, which can be used to mask off registers with sensitive data. See the detailed commit message for much more information. [r349456](https://reviews.llvm.org/rL349456). * FileCheck gained support for dumping its input annotated with diagnostics to aid debugging. This helps to visualise FileCheck's matching behaviour. [r349418](https://reviews.llvm.org/rL349418). * The llvm-mca library was moved from tools/llvm-mca to lib/MCA. [r349332](https://reviews.llvm.org/rL349332). * AggressiveInstCombine learned to to convert a rorate with guard branch into a funnel shift. [r349396](https://reviews.llvm.org/rL349396). * TableGen will now only write output if it changed, instead of relying on CMake to compare the previous output to the new output. [r349624](https://reviews.llvm.org/rL349624). * The BPF backend can now generated BTF (BPF Type Format) debug info. [r349640](https://reviews.llvm.org/rL349640). * `llvm.loop.parallel_accesses` and `llvm.access.group` metadata was introduced. [r349725](https://reviews.llvm.org/rL349725). ## Clang commits * Clang gained an option to initialise automatic variables with either a pattern or with zeroes. The commit message does a fantastic job of summarising the implementation choices and options considered, so is well worth a read. [r349442](https://reviews.llvm.org/rL349442). * Clang will now generate `llvm.loop.parallel_accesses` instead of `llvm.mem.parallel_loop_access` metadata. [r349823](https://reviews.llvm.org/rL349823). ## Other project commits * The LLVM test suite now contains the 'CoMD' molecular dynamics DoE proxy app. [r349922](https://reviews.llvm.org/rL349922). * The sanitizer support code was updated to support running without only open file descriptors (as may happen in the Linux 'init' process). [r349817](https://reviews.llvm.org/rL349817). * lld gained support for ARM v6m thunks. [r349337](https://reviews.llvm.org/rL349337).