LLVM/Clang Adds Support For ARMv9.3-A

It was nearly one year ago that Arm announced the Armv9 architecture as the successor to ARMv8 that was introduced a decade ago. Since then Arm has been working on adding Armv9 support to the open-source compilers such as GCC and LLVM/Clang. That initial Armv9 support has been in place for months now while on the LLVM/Clang today it received support for Armv9.3-A as the latest iteration.

Last September Arm outlined their 2021 Architecture Developments with optimized memcpy functions, non-maskable interrupts, Pointer Authentication updates, PMU updates, and other changes. Those 2021 updates are rolled into the form of Armv8.8-A and then in the Armv9 world as Armv9.3-A.

The open-source compilers already worked out their Armv8.8-A support while hitting mainline LLVM's mono repository today is the Armv9.3-A support.

The LLVM patch and Clang patch reaffirm that it's the Armv8.8-A extensions already supported by the compiler but applied for the Armv9 architecture. Given the v8.8-A support already in place, the Armv9.3-A addition is quite small.

This Armv9.3-A targeting code is in Git now and will be found in LLVM/Clang 14.0 that should be out as stable in March.