libobjc2 is out of date

[davidchisnall]

After a period where I thought we were done, we've had a flurry of development in libobjc2. Features since your last import include:

• Support for direct methods (needs a newer clang, I think you have a new-enough one).
• RISC-V support
• PowerPC support for block trampolines.
• Fast-path alloc-family methods (mostly a code-size reduction, can be a speedup too)
• The legacy GC stuff is gone.
• Several bug fixes including a couple of data corruption and one deadlock

[mszoek]

Awesome! I'll pull the changes! We have clang 18 now... should be ok?

[davidchisnall]

Yup, 18 is fine. With older clang, noting breaks, but if you do -fobjc-runtime=gnustep-2.1 you’ll get the 2.0 behaviour. The runtime is backwards compatible, so that just means the generated code will be (slightly) slower and larger, but it will still work.

[davidchisnall]

I’m not sure if you’re doing anything with Swift, but there’s also an open PR to (optionally) use the Swift blocks runtime instead of our own, which would probably help a bit if you are.

[mszoek]

Swift is definitely planned so that should be really helpful.