SIL in hindsight (Score 1)

If I have it right, swiftc translates code to Swift Intermediate Language, in which several optimizations occur, which is then translated to LLVM's Intermediate Language, which gets its own optimizations before being translated to an .o file.

In retrospect, are these 2 similar but separate levels an unfortunate hack/necessary compromise, or still an nice design decision? I'd think it would have been better if swift's optimizations could be done in a single intermediate representation and streamline two compilation phases into one, but perhaps wrong. Do you foresee a future giant refactoring of swift compiler & LLVM that introduces a redesigned IL that obviates the need for a separate SIL??

Also, what are your opinions on the Mill CPU?