[mono] Tracking: iOS - Size reduction

[imhameed]

This tracks runtime-specific issues and work items in support of reducing the size of the iOS apps we generate.

Achieved in 7.0.0

• [mono] iOS - Size reduction: optimize corelib runtime type checks in generic functions #54849
• [mono] iOS - Size reduction: don't emit impossible generic function instantiations #54850
• [mono] iOS - Size reduction: _mono_aot_corelib_eh_frame is twice is large on .NET 6 compared to legacy mono #70679

Future work (8.0.0)

• [mono] iOS - Size reduction: many more corelib symbols are materialized/AOT compiled in netcore compared to legacy Mono #56385

Size breakdown:

• Sizes by file included in the app bundle: .NET: SingleView app size macios#10249 (comment)
• Sizes by symbols included in the app binary: .NET: SingleView app size macios#10249 (comment)

How to build MySingleView:

1. Clone https://github.com/xamarin/xamarin-macios
2. Build xamarin-macios. Instructions: https://github.com/xamarin/xamarin-macios/wiki/Build-&-Run
3. cd tests/dotnet/size-comparison/MySingleView; make compare: https://github.com/xamarin/xamarin-macios/blob/61e43f8486451c6f1844c77df73f914e140b9f4d/tests/dotnet/Makefile#L41

Bloaty can be used to view Mach-O arm64 symbol and section sizes.

End Goals

• Same or smaller size .NET: SingleView app size macios#10249 app for release arm64 output (less than 4.35 MB)
• Same or smaller size default MAUI app template for iOS than Xamarin.Forms (TBD)