Alex Bradbury via llvm-dev
2020-May-04 19:18 UTC
[llvm-dev] LLVM Weekly - #331, May 4th 2020
LLVM Weekly - #331, May 4th 2020 =============================== If you prefer, you can read a HTML version of this email at <http://llvmweekly.org/issue/331>. Welcome to the three hundred and thirty-first 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 Emmanuel Roche has authored a [fifth instalment](http://wiki.nervtech.org/doku.php?id=blog:2020:0425_jit_compiler_part5_improvements) in the blog series on building a JIT C++ compiler with LLVM on Windows 10. ## On the mailing lists * Tom Stellard [provided an updated RFC on migrating to GitHub issues](http://lists.llvm.org/pipermail/llvm-dev/2020-April/141290.html). This proposal would maintain issue numbers my overwriting existing ones with migrated issue contents. A variant on this is currently being investigated, which would involve creating a new repository (i.e. with no issues or PRs already present), migrating the issues, and replacing the current llvm-project repo on GitHub with it. * Amara Emerson asked for input on [propagating int/float type information in GlobalISel IR translation](http://lists.llvm.org/pipermail/llvm-dev/2020-May/141350.html). * JF Bastien follows up on the thread regarding `-ftrivial-auto-var-init=zero` to [provide collated feedback from people's spoken to](http://lists.llvm.org/pipermail/cfe-dev/2020-April/065361.html), while Richard shares [more thoughts on trapping](http://lists.llvm.org/pipermail/cfe-dev/2020-May/065372.html). * The 6th edition of the MLIR (bi)weekly newsletter [is now available](https://llvm.discourse.group/t/mlir-news-6th-edition-5-1-2020/949). * ORC JIT Weekly #14 [is out](http://lists.llvm.org/pipermail/llvm-dev/2020-May/141379.html). A preliminary patch to support removable code in OrcV2 has been posted for review. * Matthew Malcomson started a [discussion on the exception unwinding ABI for MTE](http://lists.llvm.org/pipermail/llvm-dev/2020-May/141345.html). * Hal Finkel is intending to remove support for the IBM BG/Q supercomputer from the PowerPC backend and is [asking if anyone still makes use of that support](http://lists.llvm.org/pipermail/llvm-dev/2020-April/141295.html). * Sam Parker kicked off an RFC thread on ["being explicit in the cost model"](http://lists.llvm.org/pipermail/llvm-dev/2020-April/141263.html). His latest patch aims to added a `TargetCostKind` as an argument to almost all `get*Cost` methods. * Sjoerd Meijer [proposes a new llvm.set.loop.elements.i32](http://lists.llvm.org/pipermail/llvm-dev/2020-May/141341.html) intrinsic to allow "tail predication" in the loop vectoriser. ## LLVM commits * New IR constructs were added for 'preallocated', which provides a replacement for inalloca. [3b0450a](https://reviews.llvm.org/rG3b0450acecb). * SmallVector size and capacity will now use word-size integers when element are small, in order to increase the maximum size of `SamllVector<char>`. [dda3c19](https://reviews.llvm.org/rGdda3c19a361). * The atomic expansion pass was updated to handle part-word LL/SC. [25a4b19](https://reviews.llvm.org/rG25a4b1904c1). * Lit now prints the number of tests that were discovered but not executed due to test selection options. [8cb8fe9](https://reviews.llvm.org/rG8cb8fe909bc). * WebAssembly SIMD opcodes have been renumbered to match the latest specification (intended to the final reorganisation of the SIDM opcode space before standardisation). [e0f5284](https://reviews.llvm.org/rGe0f52842c8b). ## Clang commits * A draft specification for matrix support in Clang was committed. [7363ffe](https://reviews.llvm.org/rG7363ffe95f0). * The x86/x86-64 calling convention for `_ExtInt` was updated, so they are passed indirectly if larger than the largest integer register and otherwise passed like ints. `_ExtInt` must now be explicitly enabled per-target. [5a1d9c0](https://reviews.llvm.org/rG5a1d9c0f5ac), [911add1](https://reviews.llvm.org/rG911add149af). * clang-format got better at parsing C# properties. [44ad58b](https://reviews.llvm.org/rG44ad58b9915). ## Other project commits * lld-macho development continues with support for basic symbol table output and support for emitting trivial dylibs. [4f0cccd](https://reviews.llvm.org/rG4f0cccdd7a0), [62b8f32](https://reviews.llvm.org/rG62b8f32f769). * MLIR gained a generic buffer assignment transformation, ported from TensorFlow. [5c352e6](https://reviews.llvm.org/rG5c352e69e76). * The scudo secure memory allocator now supports pattern-initialisation of memory. [45b7d44](https://reviews.llvm.org/rG45b7d44ecb0). * Flang now has a proposal document describing how uniquing of internal names is done. [7875362](https://reviews.llvm.org/rG7875362986f). * libcxx gained a small DSL for defining lit features and parameters. [e82f0a5](https://reviews.llvm.org/rGe82f0a598f8).