Alex Bradbury via llvm-dev
2021-Nov-15 18:16 UTC
[llvm-dev] LLVM Weekly - #411, November 15th 2021
LLVM Weekly - #411, November 15th 2021 ===================================== If you prefer, you can read a HTML version of this email at <http://llvmweekly.org/issue/411>. Welcome to the four 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](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 The 2021 LLVM Developers' Meeting is [taking place virtually this week](https://llvm.org/devmtg/2021-11/), Nov 16th-19th. Simon Byrne blogged about [dangers posed by 'fast-math' compiler flags](https://simonbyrne.github.io/notes/fastmath/). ## On the mailing lists * Akash Kothari (on behalf of a consortium of authors) shared a [proposal for TLX: Tensor LLVM eXtensions](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153725.html). * Jeremy Morse posted an RFC on [enabling 'instruction referencing' variable locations for x86_64](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153653.html). Respondents so far are in favour. * Johannes Doerfert [asked if it would make sense to have a 'GPU working group'](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153654.html) with regular meetings. * Mircea Trofin shared an RFC on [applying machine learning to live range eviction for the 'greedy' register allocator](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153639.html), noting a 0.3%-1.5% improvement in queries per second on selected datacenter-type applications. * Zarko Todorovski is [proposing to rename llvm-cov option -name-whitelist to -name-allow-list](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153639.html). * Florian Hahn provided an [and updated on adding new vector math builtins to Clang](https://lists.llvm.org/pipermail/cfe-dev/2021-November/069311.html). * Itay Bookstein is [seeking feedback](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153690.html) on the IR-level semantics of a GlobalIFunc whose resolver is a declaration. * After some systematic testing with a simple Python script, Jay Foad [highlighted some missed optimisations of bitwise expressions](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153659.html). 'Beginner' tagged bugs have [now been filed](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153677.html). * Johannes Doerfert posted an updated RFC on [introducing non-capturing stores](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153677.html). * Alan Phipps kicked off an RFC thread on [source-based modified condition/decision coverage](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153634.html). * ORC JIT Weekly #44 [is out](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153732.html), providing an update on support for MachO debugging. * LLVM GPU News #23 [is out](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153731.html). * Arthur Eubanks initiated a thread on [removing optimisation size level from the LLVM IR pipeline and relying on minsize/optsize attributes](https://lists.llvm.org/pipermail/llvm-dev/2021-November/153705.html). This generated a fair amount of discussion, both about this specific proposal and about when function attributes should be used to represent optimisation information. ## LLVM commits * The llvm-tli-checker tool was committed. This tool compares TargetLibraryInfo's opinion of the availability of library function calls against the functions actually exported by a specified set of libraries. [38be8f4](https://reviews.llvm.org/rG38be8f4057c1). * MC layer support for CSKY's 16-bit instructions was added. [4fb282f](https://reviews.llvm.org/rG4fb282fec5ef). * The initial implementation of a module level inliner was committed. [6cad45d](https://reviews.llvm.org/rG6cad45d5c6f5). * Minimal support for the D programming language was added to LLVM's demangler. A fuzzer for it was also contributed. [22a1aa5](https://reviews.llvm.org/rG22a1aa5a43cb), [9af467e](https://reviews.llvm.org/rG9af467ed8b53). * The operands-skip pass was added to llvm-reduce. This will try to remove instructions in the middle of dependency chains. [c15f930](https://reviews.llvm.org/rGc15f930e9656). ## Clang commits * LambdaCapture-related matchers were added. [c0b298f](https://reviews.llvm.org/rGc0b298fc213c). * A new clang-tidy check was added to detect misleading unicode identifiers. [a35efc4](https://reviews.llvm.org/rGa35efc4dcb70). * Clang support was added for the SPIR-V target. [a10a69f](https://reviews.llvm.org/rGa10a69fe9c74). * The `# NNN`-based line control extension was documented. [bf6986d](https://reviews.llvm.org/rGbf6986d99eaa). * Some of the generated resource headers were conditionalised upon the relevant target being registered. This was motivated by the size the RISC-V headers add to the resource directory. [c17d9b4](https://reviews.llvm.org/rGc17d9b4b125e). * A new clang-tidy check was added for the initialisation of `absl::Cleanup`. [16b07c8](https://reviews.llvm.org/rG16b07c866ae7). ## Other project commits * A libMLIR-C.so shared library can now be built. [c265170](https://reviews.llvm.org/rGc265170110b2). * compiler-rt's memprof gained support for a raw binary profile serialisation format. [545866c](https://reviews.llvm.org/rG545866cb05b9). * The performance of string to float conversion in LLVM's libc was improved. [8298424](https://reviews.llvm.org/rG8298424cae9b), [499ca80](https://reviews.llvm.org/rG499ca806dcfb). * Outdated LLD design documentation was removed. [43bb5f0](https://reviews.llvm.org/rG43bb5f01854b). * Identical code folding (ICF) for the LLD MachO linker can now deduplicate functions with identical unwind info. [d9b6f7e](https://reviews.llvm.org/rGd9b6f7e312c1).