Attachment: Download

Issue Description:

When parallel compilation is enabled. The compiler always generates symbols for `main` in the first .o file. Symbols for the rest of the source files are shuffled into the remaining .o files.

$ swiftc -incremental -whole-module-optimization -num-threads 3 a.swift main.swift b.swift

$ swift -frontend -c a.swift main.swift b.swift -num-threads 3 -o a.o -o main.o -o b.o

nm -nm a.o

(_TEXT,_text) external _main

nm -nm main.o

(_TEXT,_text) private external _$S1a4fooASiyF