LLVM Weekly - #339, June 29th 2020

Welcome to the three hundred and thirty-ninth 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.

News and articles from around the web

The call for papers for the LLVM-HPC2020 workshop is now open. The submission deadline is September 1st, and the workshop will take place on November 16th.

LLVM 10.0.1-rc2 has been tagged.

The development version of GCC has now changed the default C++ dealect to C++17.

On the mailing lists

• Teresa Johnson posted an RFC for a sanitizer-based heap profiler, noting particularly the proposed refactoring sanitizer shadow setup code.

• Nathan James shared an RFC on adding support for plugin modules to clang-tidy.

• Last week's note about the need for someone to take over Phabricator maintenance or to move to GitHub PRs has seen much more follow-up discussion.

• Alexey Bader proposed re-using OpenCL address space attributes for SYCL.

• Michael Kruse proposes introducing compiled regression tests for IR passes, aiming to combine the advantages of the current regression tests in llvm/test an the unittests in llvm/unittests. Much of the ensuing discussion is about clarifying the perceived limitations of FileCheck-based tests.

• Gábor Márton posted an RFC on the future of StdLibraryFunctionsChecker, seeking feedback on how to handle cases where it overlaps with other checkers (e.g. MallocChecker, CStringModeling which could also handle argument constraints).

• Louis Dionne is seeking a mechanism for importing a declaration only when it exists. This is motivated by porting libc++ to other platforms, which often results in new ifdefs to conditionally exclude some declarations.

• Ammar Ben Khadra introduced bcov, and open-source binary-level coverage analysis tool.

• Johannes Doerfert provided on update on the revisiting llvm.assume thread, noting that the most commonly generated assume has now been moved to the bundle representation.

• Guillame Chatelet returned to the RFC on small bitfield utilities to collect feedback on three possibly syntaxes.

• Stella Laurenzo requested that mlir-npcomp be accepted into LLVM as an incubator project. mlir-npcomp is an MLIR based numpy compiler. There are many positive responses, with most discussion about pinning down the details of the incubator process.

• The 10th MLIR Newsletter is now available, highlighting work such as an RFC on async/await, a proposed MLIR test case reduction tool, and much more.

• Hal Finkel shared notes from the last alias analysis technical call as well as a pool for finding a new regular time.

• Sameed A. Pervaiz queried the extent to which llvm-libc math.h targets speed vs accuracy. The respondents so far suggest accuracy as a starting goal.

LLVM commits

• An optional pre-push hook is now available, which for now will warn about noisy arcanist tags. a61c73d.

• Initial MC layer support for the experimental RISC-V V (vector) instruction set extension has landed. 66da87d.

• The MSP430 backend gained some basic support for debug information. a5bd75a.

• Work has started to define OpenMP common declarations in tablegen to share common parts between different frontends. d90443b.

• The AVR backend now supports decoding more instructions. 01c2209, ec9efb8, 9f09c29, eac4a60.

• A new AssertAlign ISD node was introduced. b1360ca.

• The implementation of the AVR calling convention was rewritten. b9c26a9.

• Alignment assumptions are now encoded using operand bundles. c95ffad.

Clang commits

• -ast-dump-decl-types was added to include type of value and type declarations in AST dumps. e135cf8.

• Clang toolchain support for the VE target was added, allowing the compilation of C code for this target. 96d4ccf.

• A dockerized testing environment was added for the Static Analyzer. e010d14, 3770f5c.

Other project commits

• LLDB patches have started to landed to prepare for the recently announced Apple Silicon, e.g. initial support for spawning a different debugserver for translated processes. fd19ddb.

• New check-debuginfo-* CMake targets were added. ac567ee.

• The libcxx build system was updated to remove support for building through llvm-config. 8bc62db.