The LLVM 64-bit ARM64/AArch64 Back-Ends Have Merged

Back in March Apple open-sourced their ARM 64-bit LLVM back-end (dubbed ARM64) many months after other ARM vendors had already developed a competing 64-bit ARM back-end (dubbed "AArch64" as ARM's official name for architecture). Since Apple opened up their back-end, Apple and outside LLVM developers have been working to converge the competing 64-bit ARM back-ends into a single 64-bit ARM target. That work is now complete.

The LLVM 64-bit back-end merging that they have been doing over the past several weeks is merging all of the features/improvements found within the existing AArch64 compiler back-end into Apple's "ARM64" back-end that was overall in better shape and easier to be on the receiving end of this work. All of those improvements have now landed into the ARM64 back-end where there's no regressions compared to either back-end previously and everything is in good shape. With that aligned, within the LLVM code-base the Apple ARM64 back-end was then renamed to AArch64 to reflect the official 64-bit ARM architecture title.

The change-over happened this morning with nuking the old back-end and then the renaming. There were also changed to Clang that happened this Saturday morning for the back-end shake-up.

This new and improved 64-bit ARM back-end will be part of LLVM 3.5 that should be officially released in August.