[Bug target/96168] GCC support for Apple Silicon (Arm64) on macOS requested

[gcczilla at cpellegrino dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96168

--- Comment #7 from Claudia Pellegrino <gcczilla at cpellegrino dot de> ---
Thanks Eric, and thank you Iain for the ballpark estimate.

Just to add a piece of data to get a better idea of the work involved, here’s a
link to a document published by Apple. It specifies how their ABI differs from
the standard ARM64 one:
https://developer.apple.com/library/archive/documentation/Xcode/Conceptual/iPhoneOSABIReference/Articles/ARM64FunctionCallingConventions.html

Note that the document says iPhone OS but after a few cursory checks, the ABI
of macOS 11 on Apple Silicon seems entirely identical to the iOS one – which
makes sense, given the SoCs are the same and their kernels and large parts of
either OS are known to be built from the same source.

To give proper credit: I didn’t do those quick checks myself but macOS/iOS
security researcher Saagar Jha did, who is cc’ed on this bug and knows a ton
more about Apple’s OSes than I do.