LLVM Weekly - #439, May 30th 2022

Welcome to the four 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 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.

News and articles from around the web

Krister Walfridsson blogged about branch / conditional move and compiler optimisations.

On the forums

• The minutes from the April 2022 LLVM Foundation Board Meeting have been posted.

• Tanya Lattner provided answers to frequently raised questions about the proposed LLVM project policy changes.

• Geoffrey Martin-Noble answered a question about support for running lit tests with Bazel.

• LLVM 14.0.4 was released.

• Lewis Revill announced monthly sync-ups on CHERI support in upstream LLVM and Rust.

• Min-Yih Hsu proposed always printing type aliases for certain types in the MLIR LLVM dialect.

LLVM commits

• The new -print-on-crash option will print out IR that caused the optimisation pipeline to crash. 24239e2.

• The RISC-V VSETVLI insertion pass was modified to perform a limited form of partial redundancy elimination. a95ecb2.

• The AArch64MachineScheduler will now attempt to order STP of Q registers by ascending address. 572fc7d.

• The SPIR-V version can now be set via the target triple. 72832ef.

• Heuristics for determining whether branches are more profitable than conditional moves were added. 8b42bc5, d7ebb74, 67be40d.

• Various stack frame alignment bugs with the RISC-V Vector extension were fixed. cb8681a, 08c9fb8.

• A new RISC-V pre-emit pass was added to modify instruction and register selection decisions in order to make more instruction comopressible. 29a5a7c.

• Pointer types can now be used for atomicrmw xchg. 18e6b82.

• FileCheck gained the ability to catch misspelled directives. ad1d60c.

• The G_IS_FPCLASS opcode was added to GlobalISel. bdd0093.

Clang commits

• The phrasing of diagnostics for strict function prototypes was improved. 681c50c.

• The --offload-link option was introduced to perform offload device linking. b7c8c4d.

Other project commits

• A pthread_mutex_t type and global stdout and stderr objects were added to LLVM’s libc. 2a5d507, 9b8ca3c.

• The WebAssembly linker matched the ELF linker by requiring double dashes for modern linker flags. 87628f5.

• A use-after-free checker was added for the MLIR Transform dialect. 73c3dff.