I don't think the use of the system linker is why Swift has SIL, nor Rust has MIR. It's true that one of the possible benefits of Rust's MIR is faster compilati

I don't think the use of the system linker is why Swift has SIL, nor Rust has MIR. It's true that one of the possible benefits of Rust's MIR is faster compilations, but it is fundamentally motivated by representing (and checking) semantic information that is unavailable at the LLVM level. Whatever linker LLVM happens to use is orthogonal to this.