New iOS architecture: arm64e

[theodelrieu]

Hello,

Apple recently added a new iOS architecture: arm64e.

From this SO thread, it seems that it uses ARM v8.3. It might be a good idea to introduce it at the same time than the one discussed in #3961.

I do not know if adding armv8.3 is the way to go, I'm far from being an expert in CPU architectures.

[lasote]

I'm investigating a bit. Thanks for telling @theodelrieu !

[lasote]

Yes, I agree. Looks like ARMv8.3 is aka arm64e. As we already have a setting armv8 instead of the corresponding arm64, we should add armv8.3.

[lasote]

So the feature will consist of:

• Introduce the new setting armv8.3 in the default settings.yml (arch, arch_build)
• Review all build helpers/flags where we do something with the arm architecture (search for it): E.g: cmake_flags.py for example, b2.py, win.py: vcvars support?, apply.py, oss.py

[theodelrieu]

Yes, seems correct, we also have to update the Apple tools to detect the new arch