Two use cases:
1. poking around in the asm for learning. Currently one can work around by
putting funcs in different files and not using -whole-module, but it is
time consuming and ugly.
2. Profiling an existing program. When a class method calls another
method in the same class, I don't have a workaround to not inline it.
Also, is there a -fno-optimize-sibling-calls equivalent for swiftc? I
don't have a pressing use but was just wondering, because it was shown in
the WWDC videos as being helpful for profiling.