Swift -Osize leads to runtime crash under Xcode 11.4

While attempting to update to Xcode 11.4, we ran into a runtime crash that is triggered when SWIFT_OPTIMIZATION_LEVEL is set to -Osize.

I was able to narrow the unexpected behavior down to a demo project: demo project. As attached, the project has zombies enables so it'll break every time. However, if you disable zombies run the tests a few times and you'll experience the runtime crash.


If you haven't yet, please file a report at bugs.swift.org. Thank you!