On the other hand, Apple released their 64-bit ARM backend for LLVM[1] in 2014. They announced their intention do so almost immediately after the first ARM64 phone, but the process took several months because it had to be merged with a duplicate backend developed by others.
I think it is likely that support for these instructions will be upstreamed to LLVM, and the teams involved in this monumental transition (which was announced like ~50 days ago) simply didn't put it at the highest priority on the list of things that developers need to know to get their apps working on Day 1.
A fair criticism is that some of the more technical documentation, such as on the Mach-O ABI, have disappeared from Apple's developer site, or been relegated to an unsearchable archive[2], so it's very reasonable to be skeptical of ISA extensions ever being documented there.
The developer site has always sucked though, and it seems to me they've declared bankruptcy and are rebuilding it on machine-generated docs and WWDC content for app developers. Occam's razor.
1: https://www.phoronix.com/scan.php?page=news_item&px=MTY0NzE
2: https://developer.apple.com/library/archive/navigation/
I think it is likely that support for these instructions will be upstreamed to LLVM, and the teams involved in this monumental transition (which was announced like ~50 days ago) simply didn't put it at the highest priority on the list of things that developers need to know to get their apps working on Day 1.
A fair criticism is that some of the more technical documentation, such as on the Mach-O ABI, have disappeared from Apple's developer site, or been relegated to an unsearchable archive[2], so it's very reasonable to be skeptical of ISA extensions ever being documented there.
The developer site has always sucked though, and it seems to me they've declared bankruptcy and are rebuilding it on machine-generated docs and WWDC content for app developers. Occam's razor.
1: https://www.phoronix.com/scan.php?page=news_item&px=MTY0NzE
2: https://developer.apple.com/library/archive/navigation/